Merge branch releases/1.8 revisions r6168 through r6170 into trunk.

- Updates libpng to 1.6.37 (from 1.6.23) Note: Seems svn can't merge it automatic when a folder was removed and readded with same name. Easier to update libs by deleting all files - copying new ones over and then check svn stat for differences and resolve them manually. git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6171 dfc29bdd-3216-0410-991c-e03cc46cb475
2024-12-25 07:32:25 +01:00 · 2020-12-19 14:35:50 +00:00 · 2020-12-19 14:35:50 +00:00 · 7f76377bad
commit 7f76377bad
parent 4d13cab50e
43 changed files with 5806 additions and 4846 deletions
--- a/changes.txt
+++ b/changes.txt
@ -304,6 +304,7 @@ Changes in 1.9 (not yet released)
 --------------------------
 Changes in 1.8.5
 - Update libpng to 1.6.37 (from 1.6.23)
 - Fix CIrrDeviceSDL::getVideoModeList which didn't return video modes before. Thx @kas1e for report and patch.
 - CIrrDeviceMacOSX now sets the SEvent.MouseInput Shift and Control values on mouse events like the other devices. Thanks @ Zero King  for patch (#321)
 - isWindowFocused in IrrDeviceSDL device now returns the input focus like the other devices. Before it was returning a mouse-over-window state.
--- a/source/Irrlicht/libpng/ANNOUNCE
+++ b/source/Irrlicht/libpng/ANNOUNCE
@ -1,48 +1,47 @@
-Libpng 1.6.23 - June 9, 2016
+libpng 1.6.37 - April 14, 2019
 ==============================
-This is a public release of libpng, intended for use in production codes.
+This is a public release of libpng, intended for use in production code.
 Files available for download:
-Source files with LF line endings (for Unix/Linux) and with a
+Files available for download
-"configure" script
+----------------------------
-   libpng-1.6.23.tar.xz (LZMA-compressed, recommended)
+Source files with LF line endings (for Unix/Linux):
   libpng-1.6.23.tar.gz
-Source files with CRLF line endings (for Windows), without the
+ * libpng-1.6.37.tar.xz (LZMA-compressed, recommended)
-"configure" script
+ * libpng-1.6.37.tar.gz
-   lpng1623.7z  (LZMA-compressed, recommended)
+Source files with CRLF line endings (for Windows):
-   lpng1623.zip
+
 * lp1637.7z (LZMA-compressed, recommended)
 * lp1637.zip
 Other information:
-   libpng-1.6.23-README.txt
+ * README.md
-   libpng-1.6.23-LICENSE.txt
+ * LICENSE.md
-   libpng-1.6.23-*.asc (armored detached GPG signatures)
+ * AUTHORS.md
 * TRADEMARK.md
 Changes since the last public release (1.6.22):
-  Stop a potential memory leak in png_set_tRNS() (Bug report by Ted Ying).
+Changes since the previous public release (version 1.6.36)
-  Fixed the progressive reader to handle empty first IDAT chunk properly
+----------------------------------------------------------
    (patch by Timothy Nikkel).  This bug was introduced in libpng-1.6.0 and
    only affected the libpng16 branch.
  Added tests in pngvalid.c to check zero-length IDAT chunks in various
    positions.  Fixed the sequential reader to handle these more robustly
    (John Bowler).
  Corrected progressive read input buffer in pngvalid.c. The previous version
    the code invariably passed just one byte at a time to libpng.  The intent
    was to pass a random number of bytes in the range 0..511.
  Moved sse2 prototype from pngpriv.h to contrib/intel/intel_sse.patch.
  Added missing ")" in pngerror.c (Matt Sarrett).
  Fixed undefined behavior in png_push_save_buffer(). Do not call
    memcpy() with a null source, even if count is zero (Leon Scroggins III).
  Fixed bad link to RFC2083 in png.5 (Nikola Forro).
-(subscription required; visit
+ * Fixed a use-after-free vulnerability (CVE-2019-7317) in png_image_free.
 * Fixed a memory leak in the ARM NEON implementation of png_do_expand_palette.
 * Fixed a memory leak in pngtest.c.
 * Fixed two vulnerabilities (CVE-2018-14048, CVE-2018-14550) in
   contrib/pngminus; refactor.
 * Changed the license of contrib/pngminus to MIT; refresh makefile and docs.
   (Contributed by Willem van Schaik)
 * Fixed a typo in the libpng license v2.
   (Contributed by Miguel Ojeda)
 * Added makefiles for AddressSanitizer-enabled builds.
 * Cleaned up various makefiles.
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net.
 Subscription is required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
-to subscribe)
+to subscribe.
 or to glennrp at users.sourceforge.net
 Glenn R-P
--- a/source/Irrlicht/libpng/AUTHORS
+++ b/source/Irrlicht/libpng/AUTHORS
@ -0,0 +1,45 @@
 PNG REFERENCE LIBRARY AUTHORS
 =============================
 This is the list of PNG Reference Library ("libpng") Contributing
 Authors, for copyright and licensing purposes.
 * Andreas Dilger
 * Cosmin Truta
 * Dave Martindale
 * Eric S. Raymond
 * Gilles Vollant
 * Glenn Randers-Pehrson
 * Greg Roelofs
 * Guy Eric Schalnat
 * James Yu
 * John Bowler
 * Kevin Bracey
 * Magnus Holmgren
 * Mandar Sahastrabuddhe
 * Mans Rullgard
 * Matt Sarett
 * Mike Klein
 * Paul Schmidt
 * Sam Bushell
 * Samuel Williams
 * Simon-Pierre Cadieux
 * Tim Wegner
 * Tom Lane
 * Tom Tanner
 * Vadim Barkov
 * Willem van Schaik
 * Zhijie Liang
 * Arm Holdings
   - Richard Townsend
 * Google Inc.
   - Matt Sarett
   - Mike Klein
 The build projects, the build scripts, the test scripts, and other
 files in the "projects", "scripts" and "tests" directories, have other
 copyright owners, but are released under the libpng license.
 Some files in the "contrib" directory, and some tools-generated files
 that are distributed with libpng, have other copyright owners, and are
 released under other open source licenses.
--- a/source/Irrlicht/libpng/CHANGES
+++ b/source/Irrlicht/libpng/CHANGES
@ -1,4 +1,3 @@
 #if 0
 CHANGES - changes for libpng
 version 0.1 [March 29, 1995]
@ -833,7 +832,7 @@ Version 1.0.7beta11 [May 7, 2000]
  Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes
    which are no longer used.
  Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is
-    defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED
+    defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXt_SUPPORTED
    is defined.
  Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory
    overrun when old applications fill the info_ptr->text structure directly.
@ -1454,7 +1453,7 @@ Version 1.2.6beta4 [July 28, 2004]
    sequential read support.
  Added some "#if PNG_WRITE_SUPPORTED" blocks.
  Added #ifdef to remove some redundancy in png_malloc_default().
-  Use png_malloc instead of png_zalloc to allocate the pallete.
+  Use png_malloc instead of png_zalloc to allocate the palette.
 Version 1.0.16rc1 and 1.2.6rc1 [August 4, 2004]
  Fixed buffer overflow vulnerability (CVE-2004-0597) in png_handle_tRNS().
@ -3259,7 +3258,7 @@ Version 1.5.2beta01 [February 13, 2011]
  Revised PNG_EXPORTA macro to not use an empty parameter, to accommodate the
    old VisualC++ preprocessor.
  Turned on interlace handling in png_read_png().
-  Fixed gcc pendantic warnings.
+  Fixed gcc pedantic warnings.
  Handle longjmp in Cygwin.
  Fixed png_get_current_row_number() in the interlaced case.
  Cleaned up ALPHA flags and transformations.
@ -3359,7 +3358,7 @@ Version 1.5.3beta05 [May 6, 2011]
  Pass "" instead of '\0' to png_default_error() in png_err().  This mistake
    was introduced in libpng-1.2.20beta01.  This fixes CVE-2011-2691.
  Added PNG_WRITE_OPTIMIZE_CMF_SUPPORTED macro to make the zlib "CMF" byte
-    optimization configureable.
+    optimization configurable.
  IDAT compression failed if preceded by a compressed text chunk (bug
    introduced in libpng-1.5.3beta01-02).  This was because the attempt to
    reset the zlib stream in png_write_IDAT happened after the first IDAT
@ -3643,7 +3642,7 @@ Version 1.5.6beta05 [October 12, 2011]
  Fixed bug in png_write_chunk_header() debug print, introduced in 1.5.6beta01.
 Version 1.5.6beta06 [October 17, 2011]
-  Removed two redundant tests for unitialized row.
+  Removed two redundant tests for uninitialized row.
  Fixed a relatively harmless memory overwrite in compressed text writing
    with a 1 byte zlib buffer.
  Add ability to call png_read_update_info multiple times to pngvalid.c.
@ -3689,7 +3688,7 @@ Version 1.5.7beta01 [November 4, 2011]
    crash.  The pngmem.c implementation of png_malloc() included a cast
    to png_size_t which would fail on large allocations on 16-bit systems.
  Fix for the preprocessor of the Intel C compiler. The preprocessor
-    splits adjacent @ signs with a space; this changes the concatentation
+    splits adjacent @ signs with a space; this changes the concatenation
    token from @-@-@ to PNG_JOIN; that should work with all compiler
    preprocessors.
  Paeth filter speed improvements from work by Siarhei Siamashka. This
@ -3735,7 +3734,7 @@ Version 1.5.7beta03 [November 17, 2011]
    gray (on palette) itself.
  Fixes for C++ compilation using g++ When libpng source is compiled
    using g++. The compiler imposes C++ rules on the C source; thus it
-    is desireable to make the source work with either C or C++ rules
+    is desirable to make the source work with either C or C++ rules
    without throwing away useful error information.  This change adds
    png_voidcast to allow C semantic (void*) cases or the corresponding
    C++ static_cast operation, as appropriate.
@ -4061,7 +4060,7 @@ Version 1.6.0beta17 [March 10, 2012]
    possible to call png_inflate() incrementally.  A warning is no longer
    issued if the language tag or translated keyword in the iTXt chunk
    has zero length.
-  If benign errors are disabled use maximum window on ancilliary inflate.
+  If benign errors are disabled use maximum window on ancillary inflate.
    This works round a bug introduced in 1.5.4 where compressed ancillary
    chunks could end up with a too-small windowBits value in the deflate
    header.
@ -4176,7 +4175,7 @@ Version 1.6.0beta27 [August 11, 2012]
    declared even though the functions are never actually defined.  This
    change provides a dummy definition so that the declarations work, yet any
    implementation will fail to compile because of an incomplete type.
-  Re-eliminated the use of strcpy() in pngtest.c.  An unncessary use of
+  Re-eliminated the use of strcpy() in pngtest.c.  An unnecessary use of
    strcpy() was accidentally re-introduced in libpng16; this change replaces
    it with strncpy().
  Eliminated use of png_sizeof(); use sizeof() instead.
@ -4309,7 +4308,7 @@ Version 1.6.0beta31 [November 1, 2012]
    resulting in VS2010 having to update the files.
  Removed non-working ICC profile support code that was mostly added to
    libpng-1.6.0beta29 and beta30. There was too much code for too little
-    gain; implementing full ICC color correction may be desireable but is left
+    gain; implementing full ICC color correction may be desirable but is left
    up to applications.
 Version 1.6.0beta32 [November 25, 2012]
@ -4592,7 +4591,7 @@ Version 1.6.3beta07 [June 8, 2013]
    the optimizations ('check' vs 'api') are exposed in the public header files
    except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
    decision about whether or not to use the optimizations.
-  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS usage.
    Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
    on __ARM_NEON__ from configure time to compile time.  This breaks symbol
    prefixing because the definition of the special png_init_filter_functions
@ -5596,11 +5595,515 @@ Version 1.6.23rc02 [June 4, 2016]
 Version 1.6.23 [June 9, 2016]
  Fixed bad link to RFC2083 in png.5 (Nikola Forro).
-Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+Version 1.6.24beta01 [June 11, 2016]
-(subscription required; visit
+  Avoid potential overflow of the PNG_IMAGE_SIZE macro.  This macro
-https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+    is not used within libpng, but is used in some of the examples.
 to subscribe)
 or to glennrp at users.sourceforge.net
-Glenn R-P
+Version 1.6.24beta02 [June 23, 2016]
-#endif
+  Correct filter heuristic overflow handling. This was broken when the
    write filter code was moved out-of-line; if there is a single filter and
    the heuristic sum overflows the calculation of the filtered line is not
    completed.  In versions prior to 1.6 the code was duplicated in-line
    and the check not performed, so the filter operation completed; however,
    in the multi-filter case where the sum is performed the 'none' filter would
    be selected if all the sums overflowed, even if it wasn't in the filter
    list.  The fix to the first problem is simply to provide PNG_SIZE_MAX as
    the current lmins sum value; this means the sum can never exceed it and
    overflows silently.  A reasonable compiler that does choose to inline
    the code will simply eliminate the sum check.
  The fix to the second problem is to use high precision arithmetic (this is
    implemented in 1.7), however a simple safe fix here is to chose the lowest
    numbered filter in the list from png_set_filter (this only works if the
    first problem is also fixed) (John Bowler).
  Use a more efficient absolute value calculation on SSE2 (Matthieu Darbois).
  Fixed the case where PNG_IMAGE_BUFFER_SIZE can overflow in the application
    as a result of the application using an increased 'row_stride'; previously
    png_image_finish_read only checked for overflow on the base calculation of
    components.  (I.e. it checked for overflow of a 32-bit number on the total
    number of pixel components in the output format, not the possibly padded row
    length and not the number of bytes, which for linear formats is twice the
    number of components.)
  MSVC does not like '-(unsigned)', so replaced it with 0U-(unsigned)
  MSVC does not like (uInt) = -(unsigned) (i.e. as an initializer), unless
    the conversion is explicitly invoked by a cast.
  Put the SKIP definition in the correct place. It needs to come after the
    png.h include (see all the other .c files in contrib/libtests) because it
    depends on PNG_LIBPNG_VER.
  Removed the three compile warning options from the individual project
    files into the zlib.props globals.  It increases the warning level from 4
    to All and adds a list of the warnings that need to be turned off.  This is
    semi-documentary; the intent is to tell libpng users which warnings have
    been examined and judged non-fixable at present.  The warning about
    structure padding is fixable, but it would be a significant change (moving
    structure members around).
 Version 1.6.24beta03 [July 4, 2016]
  Optimized absolute value calculation in filter selection, similar to
    code in the PAETH decoder in pngrutil.c. Build with PNG_USE_ABS to
    use this.
  Added pngcp to the build together with a pngcp.dfa configuration test.
  Added high resolution timing to pngcp.
  Added "Common linking failures" section to INSTALL.
  Relocated misplaced #endif in png.c sRGB profile checking.
  Fixed two Coverity issues in pngcp.c.
 Version 1.6.24beta04 [July 8, 2016]
  Avoid filter-selection heuristic sum calculations in cases where only one
    filter is a candidate for selection. This trades off code size (added
    private png_setup_*_row_only() functions) for speed.
 Version 1.6.24beta05 [July 13, 2016]
  Fixed some indentation to comply with our coding style.
  Added contrib/tools/reindent.
 Version 1.6.24beta06 [July 18, 2016]
  Fixed more indentation to comply with our coding style.
  Eliminated unnecessary tests of boolean png_isaligned() vs 0.
 Version 1.6.24rc01 [July 25, 2016]
  No changes.
 Version 1.6.24rc02 [August 1, 2016]
  Conditionally compile SSE2 headers in contrib/intel/intel_sse.patch
  Conditionally compile png_decompress_chunk().
 Version 1.6.24rc03 [August 2, 2016]
  Conditionally compile ARM_NEON headers in pngpriv.h
  Updated contrib/intel/intel_sse.patch
 Version 1.6.24[August 4, 2016]
  No changes.
 Version 1.6.25beta01 [August 12, 2016]
  Reject oversized iCCP profile immediately.
  Cleaned up PNG_DEBUG compile of pngtest.c.
  Conditionally compile png_inflate().
 Version 1.6.25beta02 [August 18, 2016]
  Don't install pngcp; it conflicts with pngcp in the pngtools package.
  Minor editing of INSTALL, (whitespace, added copyright line)
 Version 1.6.25rc01 [August 24, 2016]
  No changes.
 Version 1.6.25rc02 [August 29, 2016]
  Added MIPS support (Mandar Sahastrabuddhe <Mandar.Sahastrabuddhe@imgtec.com>).
  Only the UP filter is currently implemented.
 Version 1.6.25rc03 [August 29, 2016]
  Rebased contrib/intel/intel_sse.patch after the MIPS implementation.
 Version 1.6.25rc04 [August 30, 2016]
  Added MIPS support for SUB, AVG, and PAETH filters (Mandar Sahastrabuddhe).
 Version 1.6.25rc05 [August 30, 2016]
  Rebased contrib/intel/intel_sse.patch after the MIPS implementation update..
 Version 1.6.25 [September 1, 2016]
  No changes.
 Version 1.6.26beta01 [September 26, 2016]
  Fixed handling zero length IDAT in pngfix (bug report by Agostino Sarubbo,
    bugfix by John Bowler).
  Do not issue a png_error() on read in png_set_pCAL() because png_handle_pCAL
    has allocated memory that libpng needs to free.
  Conditionally compile png_set_benign_errors() in pngread.c and pngtest.c
  Issue a png_benign_error instead of a png_error on ADLER32 mismatch
    while decoding compressed data chunks.
  Changed PNG_ZLIB_VERNUM to ZLIB_VERNUM in pngpriv.h, pngstruct.h, and
    pngrutil.c.
  If CRC handling of critical chunks has been set to PNG_CRC_QUIET_USE,
    ignore the ADLER32 checksum in the IDAT chunk as well as the chunk CRCs.
  Issue png_benign_error() on ADLER32 checksum mismatch instead of png_error().
  Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
  Merged pngtest.c with libpng-1.7.0beta84/pngtest.c
 Version 1.6.26beta02 [October 1, 2016]
  Updated the documentation about CRC and ADLER32 handling.
  Quieted 117 warnings from clang-3.8 in pngtrans.c, pngread.c,
     pngwrite.c, pngunknown.c, and pngvalid.c.
  Quieted 58 (out of 144) -Wconversion compiler warnings by changing
    flag definitions in pngpriv.h from 0xnnnn to 0xnnnnU and trivial changes
    in png.c, pngread.c, and pngwutil.c.
 Version 1.6.26beta03 [October 2, 2016]
  Removed contrib/libtests/*.orig and *.rej that slipped into the tarballs.
  Quieted the 86 remaining -Wconversion compiler warnings by
    revising the png_isaligned() macro and trivial changes in png.c,
    pngerror.c, pngget.c, pngmem.c, pngset.c, pngrtran.c, pngrutil.c,
    pngwtran.c, pngwrite.c, and pngwutil.c.
 Version 1.6.26beta04 [October 3, 2016]
  Quieted (bogus?) clang warnings about "absolute value has no effect"
    when PNG_USE_ABS is defined.
  Fixed offsets in contrib/intel/intel_sse.patch
 Version 1.6.26beta05 [October 6, 2016]
  Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
    to avoid a signed/unsigned compare in the preprocessor.
 Version 1.6.26beta06 [October 7, 2016]
  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
    optionally avoid ADLER32 evaluation.
 Version 1.6.26rc01 [October 12, 2016]
  No changes.
 Version 1.6.26 [October 20, 2016]
  Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
  Despammed email addresses (replaced "@" with " at ").
 Version 1.6.27beta01 [November 2, 2016]
  Restrict the new ADLER32-skipping to IDAT chunks.  It broke iCCP chunk
    handling: an erroneous iCCP chunk would throw a png_error and reject the
    entire PNG image instead of rejecting just the iCCP chunk with a warning,
    if built with zlib-1.2.8.1.
 Version 1.6.27rc01 [December 27, 2016]
  Control ADLER32 checking with new PNG_IGNORE_ADLER32 option. Fixes
    an endless loop when handling erroneous ADLER32 checksums; bug
    introduced in libpng-1.6.26.
  Removed the use of a macro containing the pre-processor 'defined'
    operator.  It is unclear whether this is valid; a macro that
    "generates" 'defined' is not permitted, but the use of the word
    "generates" within the C90 standard seems to imply more than simple
    substitution of an expression itself containing a well-formed defined
    operation.
  Added ARM support to CMakeLists.txt (Andreas Franek).
 Version 1.6.27 [December 29, 2016]
  Fixed a potential null pointer dereference in png_set_text_2() (bug report
    and patch by Patrick Keshishian, CVE-2016-10087).
 Version 1.6.28rc01 [January 3, 2017]
  Fixed arm/aarch64 detection in CMakeLists.txt (Gianfranco Costamagna).
  Added option to Cmake build allowing a custom location of zlib to be
    specified in a scenario where libpng is being built as a subproject
    alongside zlib by another project (Sam Serrels).
  Changed png_ptr->options from a png_byte to png_uint_32, to accommodate
    up to 16 options.
 Version 1.6.28rc02 [January 4, 2017]
  Added "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
  Moved SSE2 optimization code into the main libpng source directory.
    Configure libpng with "configure --enable-intel-sse" or compile
    libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
 Version 1.6.28rc03 [January 4, 2017]
  Backed out the SSE optimization and last CMakeLists.txt to allow time for QA.
 Version 1.6.28 [January 5, 2017]
  No changes.
 Version 1.6.29beta01 [January 12, 2017]
  Readded "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
  Moved SSE2 optimization code into the main libpng source directory.
    Configure libpng with "configure --enable-intel-sse" or compile
    libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
  Simplified conditional compilation in pngvalid.c, for AIX (Michael Felt).
 Version 1.6.29beta02 [February 22, 2017]
  Avoid conditional directives that break statements in pngrutil.c (Romero
    Malaquias)
  The contrib/examples/pngtopng.c recovery code was in the wrong "if"
    branches; the comments were correct.
  Added code for PowerPC VSX optimisation (Vadim Barkov).
 Version 1.6.29beta03 [March 1, 2017]
  Avoid potential overflow of shift operations in png_do_expand() (Aaron Boxer).
  Change test ZLIB_VERNUM >= 0x1281 to ZLIB_VERNUM >= 0x1290 in pngrutil.c
    because Solaris 11 distributes zlib-1.2.8.f that is older than 1.2.8.1,
    as suggested in zlib FAQ, item 24.
  Suppress clang warnings about implicit sign changes in png.c
 Version 1.6.29 [March 16, 2017]
  No changes.
 Version 1.6.30beta01 [April 1, 2017]
  Added missing "$(CPPFLAGS)" to the compile line for c.pic.o in
    makefile.linux and makefile.solaris-x86 (Cosmin).
  Revised documentation of png_get_error_ptr() in the libpng manual.
  Silence clang -Wcomma and const drop warnings (Viktor Szakats).
  Update Sourceforge URLs in documentation (https instead of http).
 Version 1.6.30beta02 [April 22, 2017]
  Document need to check for integer overflow when allocating a pixel
    buffer for multiple rows in contrib/gregbook, contrib/pngminus,
    example.c, and in the manual (suggested by Jaeseung Choi). This
    is similar to the bug reported against pngquant in CVE-2016-5735.
  Removed reference to the obsolete PNG_SAFE_LIMITS macro in the documentation.
 Version 1.6.30beta03 [May 22, 2017]
  Check for integer overflow in contrib/visupng and contrib/tools/genpng.
  Do not double evaluate CMAKE_SYSTEM_PROCESSOR in CMakeLists.txt.
  Test CMAKE_HOST_WIN32 instead of WIN32 in CMakeLists.txt.
  Fix some URL in documentation.
 Version 1.6.30beta04 [June 7, 2017]
  Avoid writing an empty IDAT when the last IDAT exactly fills the
    compression buffer (bug report by Brian Baird). This bug was
    introduced in libpng-1.6.0.
 Version 1.6.30rc01 [June 14, 2017]
  No changes.
 Version 1.6.30rc02 [June 25, 2017]
  Update copyright year in pnglibconf.h, make ltmain.sh executable.
  Add a reference to the libpng.download site in README.
 Version 1.6.30 [June 28, 2017]
  No changes.
 Version 1.6.31beta01 [July 5, 2017]
  Guard the definition of _POSIX_SOURCE in pngpriv.h (AIX already defines it;
    bug report by Michael Felt).
  Revised pngpriv.h to work around failure to compile arm/filter_neon.S
    ("typedef" directive is unrecognized by the assembler). The problem
    was introduced in libpng-1.6.30beta01.
  Added "Requires: zlib" to libpng.pc.in (Pieter Neerincx).
  Added special case for FreeBSD in arm/filter_neon.S (Maya Rashish).
 Version 1.6.31beta02 [July 8, 2017]
  Added instructions for disabling hardware optimizations in INSTALL.
  Added "--enable-hardware-optimizations" configuration flag to enable
    or disable all hardware optimizations with one flag.
 Version 1.6.31beta03 [July 9, 2017]
  Updated CMakeLists.txt to add INTEL_SSE and MIPS_MSA platforms.
  Changed "int" to "png_size_t" in intel/filter_sse2.c to prevent
    possible integer overflow (Bug report by John Bowler).
  Quieted "declaration after statement" warnings in intel/filter_sse2.c.
  Added scripts/makefile-linux-opt, which has hardware optimizations enabled.
 Version 1.6.31beta04 [July 11, 2017]
  Removed one of the GCC-7.1.0 'strict-overflow' warnings that result when
    integers appear on both sides of a compare.  Worked around the others by
    forcing the strict-overflow setting in the relevant functions to a level
    where they are not reported (John Bowler).
  Changed "FALL THROUGH" comments to "FALLTHROUGH" because GCC doesn't like
    the space.
  Worked around some C-style casts from (void*) because g++ 5.4.0 objects
    to them.
  Increased the buffer size for 'sprint' to pass the gcc 7.1.0 'sprint
    overflow' check that is on by default with -Wall -Wextra.
 Version 1.6.31beta05 [July 13, 2017]
  Added eXIf chunk support.
 Version 1.6.31beta06 [July 17, 2017]
  Added a minimal eXIf chunk (with Orientation and FocalLengthIn35mmFilm
    tags) to pngtest.png.
 Version 1.6.31beta07 [July 18, 2017]
  Revised the eXIf chunk in pngtest.png to fix "Bad IFD1 Directory" warning.
 Version 1.6.31rc01 [July 19, 2017]
  No changes.
 Version 1.6.31rc02 [July 25, 2017]
  Fixed typo in example.c (png_free_image should be png_image_free) (Bug
    report by John Smith)
 Version 1.6.31 [July 27, 2017]
  No changes.
 Version 1.6.32beta01 [July 31, 2017]
  Avoid possible NULL dereference in png_handle_eXIf when benign_errors
    are allowed. Avoid leaking the input buffer "eXIf_buf".
  Eliminated png_ptr->num_exif member from pngstruct.h and added num_exif
    to arguments for png_get_eXIf() and png_set_eXIf().
  Added calls to png_handle_eXIf(() in pngread.c and png_write_eXIf() in
    pngwrite.c, and made various other fixes to png_write_eXIf().
  Changed name of png_get_eXIF and png_set_eXIf() to png_get_eXIf_1() and
    png_set_eXIf_1(), respectively, to avoid breaking API compatibility
    with libpng-1.6.31.
 Version 1.6.32beta02 [August 1, 2017]
  Updated contrib/libtests/pngunknown.c with eXIf chunk.
 Version 1.6.32beta03 [August 2, 2017]
  Initialized btoa[] in pngstest.c
  Stop memory leak when returning from png_handle_eXIf() with an error
    (Bug report from the OSS-fuzz project).
 Version 1.6.32beta04 [August 2, 2017]
  Replaced local eXIf_buf with info_ptr-eXIf_buf in png_handle_eXIf().
  Update libpng.3 and libpng-manual.txt about eXIf functions.
 Version 1.6.32beta05 [August 2, 2017]
  Restored png_get_eXIf() and png_set_eXIf() to maintain API compatibility.
 Version 1.6.32beta06 [August 2, 2017]
  Removed png_get_eXIf_1() and png_set_eXIf_1().
 Version 1.6.32beta07 [August 3, 2017]
  Check length of all chunks except IDAT against user limit to fix an
    OSS-fuzz issue (Fixes CVE-2017-12652).
 Version 1.6.32beta08 [August 3, 2017]
  Check length of IDAT against maximum possible IDAT size, accounting
    for height, rowbytes, interlacing and zlib/deflate overhead.
  Restored png_get_eXIf_1() and png_set_eXIf_1(), because strlen(eXIf_buf)
    does not work (the eXIf chunk data can contain zeroes).
 Version 1.6.32beta09 [August 3, 2017]
  Require cmake-2.8.8 in CMakeLists.txt. Revised symlink creation,
    no longer using deprecated cmake LOCATION feature (Clifford Yapp).
  Fixed five-byte error in the calculation of IDAT maximum possible size.
 Version 1.6.32beta10 [August 5, 2017]
  Moved chunk-length check into a png_check_chunk_length() private
    function (Suggested by Max Stepin).
  Moved bad pngs from tests to contrib/libtests/crashers
  Moved testing of bad pngs into a separate tests/pngtest-badpngs script
  Added the --xfail (expected FAIL) option to pngtest.c. It writes XFAIL
    in the output but PASS for the libpng test.
  Require cmake-3.0.2 in CMakeLists.txt (Clifford Yapp).
  Fix "const" declaration info_ptr argument to png_get_eXIf_1() and the
    num_exif argument to png_get_eXIf_1() (Github Issue 171).
 Version 1.6.32beta11 [August 7, 2017]
  Added "eXIf" to "chunks_to_ignore[]" in png_set_keep_unknown_chunks().
  Added huge_IDAT.png and empty_ancillary_chunks.png to testpngs/crashers.
  Make pngtest --strict, --relax, --xfail options imply -m (multiple).
  Removed unused chunk_name parameter from png_check_chunk_length().
  Relocated setting free_me for eXIf data, to stop an OSS-fuzz leak.
  Initialize profile_header[] in png_handle_iCCP() to fix OSS-fuzz issue.
  Initialize png_ptr->row_buf[0] to 255 in png_read_row() to fix OSS-fuzz UMR.
  Attempt to fix a UMR in png_set_text_2() to fix OSS-fuzz issue.
  Increase minimum zlib stream from 9 to 14 in png_handle_iCCP(), to account
    for the minimum 'deflate' stream, and relocate the test to a point
    after the keyword has been read.
  Check that the eXIf chunk has at least 2 bytes and begins with "II" or "MM".
 Version 1.6.32rc01 [August 18, 2017]
  Added a set of "huge_xxxx_chunk.png" files to contrib/testpngs/crashers,
    one for each known chunk type, with length = 2GB-1.
  Check for 0 return from png_get_rowbytes() and added some (size_t) typecasts
    in contrib/pngminus/*.c to stop some Coverity issues (162705, 162706,
    and 162707).
  Renamed chunks in contrib/testpngs/crashers to avoid having files whose
    names differ only in case; this causes problems with some platforms
    (github issue #172).
 Version 1.6.32rc02 [August 22, 2017]
  Added contrib/oss-fuzz directory which contains files used by the oss-fuzz
    project (https://github.com/google/oss-fuzz/tree/master/projects/libpng).
 Version 1.6.32 [August 24, 2017]
  No changes.
 Version 1.6.33beta01 [August 28, 2017]
  Added PNGMINUS_UNUSED macro to contrib/pngminus/p*.c and added missing
    parenthesis in contrib/pngminus/pnm2png.c (bug report by Christian Hesse).
  Fixed off-by-one error in png_do_check_palette_indexes() (Bug report
    by Mick P., Source Forge Issue #269).
 Version 1.6.33beta02 [September 3, 2017]
  Initialize png_handler.row_ptr in contrib/oss-fuzz/libpng_read_fuzzer.cc
    to fix shortlived oss-fuzz issue 3234.
  Compute a larger limit on IDAT because some applications write a deflate
    buffer for each row (Bug report by Andrew Church).
  Use current date (DATE) instead of release-date (RDATE) in last
    changed date of contrib/oss-fuzz files.
  Enabled ARM support in CMakeLists.txt (Bernd Kuhls).
 Version 1.6.33beta03 [September 14, 2017]
  Fixed incorrect typecast of some arguments to png_malloc() and
    png_calloc() that were png_uint_32 instead of png_alloc_size_t
    (Bug report by "irwir" in Github libpng issue #175).
  Use pnglibconf.h.prebuilt when building for ANDROID with cmake (Github
    issue 162, by rcdailey).
 Version 1.6.33rc01 [September 20, 2017]
  Initialize memory allocated by png_inflate to zero, using memset, to
    stop an oss-fuzz "use of uninitialized value" detection in png_set_text_2()
    due to truncated iTXt or zTXt chunk.
  Initialize memory allocated by png_read_buffer to zero, using memset, to
    stop an oss-fuzz "use of uninitialized value" detection in
    png_icc_check_tag_table() due to truncated iCCP chunk.
  Removed a redundant test (suggested by "irwir" in Github issue #180).
 Version 1.6.33rc02 [September 23, 2017]
  Added an interlaced version of each file in contrib/pngsuite.
  Relocate new memset() call in pngrutil.c.
  Removed more redundant tests (suggested by "irwir" in Github issue #180).
  Add support for loading images with associated alpha in the Simplified
    API (Samuel Williams).
 Version 1.6.33 [September 28, 2017]
  Revert contrib/oss-fuzz/libpng_read_fuzzer.cc to libpng-1.6.32 state.
  Initialize png_handler.row_ptr in contrib/oss-fuzz/libpng_read_fuzzer.cc
  Add end_info structure and png_read_end() to the libpng fuzzer.
 Version 1.6.34 [September 29, 2017]
  Removed contrib/pngsuite/i*.png; some of them caused test failures.
 Version 1.6.35beta01 [March 6, 2018]
  Restored 21 of the contrib/pngsuite/i*.png, which do not cause test
    failures. Placed the remainder in contrib/pngsuite/interlaced/i*.png.
  Added calls to png_set_*() transforms commonly used by browsers to
    the fuzzer.
  Removed some unnecessary brackets in pngrtran.c
  Fixed miscellaneous typos (Patch by github user "luzpaz").
  Change "ASM C" to "C ASM" in CMakeLists.txt
  Fixed incorrect handling of bKGD chunk in sub-8-bit files (Cosmin)
  Added hardware optimization directories to zip and 7z distributions.
  Fixed incorrect bitmask for options.
  Fixed many spelling typos.
 Version 1.6.35beta02 [March 28, 2018]
  Make png_get_iCCP consistent with man page (allow compression-type argument
  to be NULL, bug report by Lenard Szolnoki).
 Version 1.6.35 [July 15, 2018]
  Replaced the remaining uses of png_size_t with size_t (Cosmin)
  Fixed the calculation of row_factor in png_check_chunk_length
    (reported by Thuan Pham in SourceForge issue #278)
  Added missing parentheses to a macro definition
    (suggested by "irwir" in GitHub issue #216)
 Version 1.6.36 [December 1, 2018]
  Optimized png_do_expand_palette for ARM processors.
  Improved performance by around 10-22% on a recent ARM Chromebook.
    (Contributed by Richard Townsend, ARM Holdings)
  Fixed manipulation of machine-specific optimization options.
    (Contributed by Vicki Pfau)
  Used memcpy instead of manual pointer arithmetic on Intel SSE2.
    (Contributed by Samuel Williams)
  Fixed build errors with MSVC on ARM64.
    (Contributed by Zhijie Liang)
  Fixed detection of libm in CMakeLists.
    (Contributed by Cameron Cawley)
  Fixed incorrect creation of pkg-config file in CMakeLists.
    (Contributed by Kyle Bentley)
  Fixed the CMake build on Windows MSYS by avoiding symlinks.
  Fixed a build warning on OpenBSD.
    (Contributed by Theo Buehler)
  Fixed various typos in comments.
    (Contributed by "luz.paz")
  Raised the minimum required CMake version from 3.0.2 to 3.1.
  Removed yet more of the vestigial support for pre-ANSI C compilers.
  Removed ancient makefiles for ancient systems that have been broken
    across all previous libpng-1.6.x versions.
  Removed the Y2K compliance statement and the export control
    information.
  Applied various code style and documentation fixes.
 Version 1.6.37 [April 14, 2019]
  Fixed a use-after-free vulnerability (CVE-2019-7317) in png_image_free.
  Fixed a memory leak in the ARM NEON implementation of png_do_expand_palette.
  Fixed a memory leak in pngtest.c.
  Fixed two vulnerabilities (CVE-2018-14048, CVE-2018-14550) in
    contrib/pngminus; refactor.
  Changed the license of contrib/pngminus to MIT; refresh makefile and docs.
    (Contributed by Willem van Schaik)
  Fixed a typo in the libpng license v2.
    (Contributed by Miguel Ojeda)
  Added makefiles for AddressSanitizer-enabled builds.
  Cleaned up various makefiles.
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net.
 Subscription is required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe.
--- a/source/Irrlicht/libpng/CMakeLists.txt
+++ b/source/Irrlicht/libpng/CMakeLists.txt
@ -1,58 +1,52 @@
 # CMakeLists.txt
-# Copyright (C) 2007,2009-2016 Glenn Randers-Pehrson
+# Copyright (C) 2018 Cosmin Truta
 # Copyright (C) 2007,2009-2018 Glenn Randers-Pehrson
 # Written by Christian Ehrlicher, 2007
 # Revised by Roger Lowman, 2009-2010
-# Revised by Clifford Yapp, 2011-2012
+# Revised by Clifford Yapp, 2011-2012,2017
 # Revised by Roger Leigh, 2016
 # Revised by Andreas Franek, 2016
 # Revised by Sam Serrels, 2017
 # Revised by Vadim Barkov, 2017
 # Revised by Vicky Pfau, 2018
 # Revised by Cameron Cawley, 2018
 # Revised by Cosmin Truta, 2018
 # Revised by Kyle Bentley, 2018
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
 # and license in png.h
-cmake_minimum_required(VERSION 2.8.3)
+cmake_minimum_required(VERSION 3.1)
-cmake_policy(VERSION 2.8.3)
+cmake_policy(VERSION 3.1)
-# Set MacOSX @rpath usage globally.
+project(libpng C ASM)
 if (POLICY CMP0020)
  cmake_policy(SET CMP0020 NEW)
 endif(POLICY CMP0020)
 if (POLICY CMP0042)
  cmake_policy(SET CMP0042 NEW)
 endif(POLICY CMP0042)
 # Use new variable expansion policy.
 if (POLICY CMP0053)
  cmake_policy(SET CMP0053 NEW)
 endif(POLICY CMP0053)
 if (POLICY CMP0054)
  cmake_policy(SET CMP0054 NEW)
 endif(POLICY CMP0054)
 set(CMAKE_CONFIGURATION_TYPES "Release;Debug;MinSizeRel;RelWithDebInfo")
 project(libpng C)
 enable_testing()
 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 23)
+set(PNGLIB_RELEASE 37)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
-# needed packages
+include(GNUInstallDirs)
 find_package(ZLIB REQUIRED)
 include_directories(${ZLIB_INCLUDE_DIR})
-if(NOT WIN32)
+# needed packages
-  find_library(M_LIBRARY
+
-    NAMES m
+# Allow users to specify location of Zlib.
-    PATHS /usr/lib /usr/local/lib
+# Useful if zlib is being built alongside this as a sub-project.
-  )
+option(PNG_BUILD_ZLIB "Custom zlib Location, else find_package is used" OFF)
-  if(NOT M_LIBRARY)
+
-    message(STATUS "math lib 'libm' not found; floating point support disabled")
+if(NOT PNG_BUILD_ZLIB)
-  endif()
+  find_package(ZLIB REQUIRED)
  include_directories(${ZLIB_INCLUDE_DIR})
 endif()
 if(UNIX AND NOT APPLE AND NOT BEOS AND NOT HAIKU)
  find_library(M_LIBRARY m)
 else()
-  # not needed on windows
+  # libm is not needed and/or not available
  set(M_LIBRARY "")
 endif()
@ -64,11 +58,144 @@ option(PNG_TESTS  "Build libpng tests" ON)
 # Many more configuration options could be added here
 option(PNG_FRAMEWORK "Build OS X framework" OFF)
 option(PNG_DEBUG "Build with debug output" OFF)
-option(PNGARG        "Disable ANSI-C prototypes" OFF)
+option(PNG_HARDWARE_OPTIMIZATIONS "Enable hardware optimizations" ON)
 set(PNG_PREFIX "" CACHE STRING "Prefix to add to the API function names")
 set(DFA_XTRA "" CACHE FILEPATH "File containing extra configuration settings")
 if(PNG_HARDWARE_OPTIMIZATIONS)
 # set definitions and sources for arm
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
  CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64")
  set(PNG_ARM_NEON_POSSIBLE_VALUES check on off)
  set(PNG_ARM_NEON "check" CACHE STRING "Enable ARM NEON optimizations:
     check: (default) use internal checking code;
     off: disable the optimizations;
     on: turn on unconditionally.")
  set_property(CACHE PNG_ARM_NEON PROPERTY STRINGS
     ${PNG_ARM_NEON_POSSIBLE_VALUES})
  list(FIND PNG_ARM_NEON_POSSIBLE_VALUES ${PNG_ARM_NEON} index)
  if(index EQUAL -1)
    message(FATAL_ERROR
            "PNG_ARM_NEON must be one of [${PNG_ARM_NEON_POSSIBLE_VALUES}]")
  elseif(NOT ${PNG_ARM_NEON} STREQUAL "off")
    set(libpng_arm_sources
      arm/arm_init.c
      arm/filter_neon.S
      arm/filter_neon_intrinsics.c
      arm/palette_neon_intrinsics.c)
    if(${PNG_ARM_NEON} STREQUAL "on")
      add_definitions(-DPNG_ARM_NEON_OPT=2)
    elseif(${PNG_ARM_NEON} STREQUAL "check")
      add_definitions(-DPNG_ARM_NEON_CHECK_SUPPORTED)
    endif()
  else()
    add_definitions(-DPNG_ARM_NEON_OPT=0)
  endif()
 endif()
 # set definitions and sources for powerpc
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "^powerpc*" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "^ppc64*")
  set(PNG_POWERPC_VSX_POSSIBLE_VALUES on off)
  set(PNG_POWERPC_VSX "on" CACHE STRING "Enable POWERPC VSX optimizations:
     off: disable the optimizations.")
  set_property(CACHE PNG_POWERPC_VSX PROPERTY STRINGS
     ${PNG_POWERPC_VSX_POSSIBLE_VALUES})
  list(FIND PNG_POWERPC_VSX_POSSIBLE_VALUES ${PNG_POWERPC_VSX} index)
  if(index EQUAL -1)
    message(FATAL_ERROR
            "PNG_POWERPC_VSX must be one of [${PNG_POWERPC_VSX_POSSIBLE_VALUES}]")
  elseif(NOT ${PNG_POWERPC_VSX} STREQUAL "off")
    set(libpng_powerpc_sources
      powerpc/powerpc_init.c
      powerpc/filter_vsx_intrinsics.c)
    if(${PNG_POWERPC_VSX} STREQUAL "on")
      add_definitions(-DPNG_POWERPC_VSX_OPT=2)
    endif()
  else()
    add_definitions(-DPNG_POWERPC_VSX_OPT=0)
  endif()
 endif()
 # set definitions and sources for intel
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "^i?86" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "^x86_64*")
  set(PNG_INTEL_SSE_POSSIBLE_VALUES on off)
  set(PNG_INTEL_SSE "on" CACHE STRING "Enable INTEL_SSE optimizations:
     off: disable the optimizations")
  set_property(CACHE PNG_INTEL_SSE PROPERTY STRINGS
     ${PNG_INTEL_SSE_POSSIBLE_VALUES})
  list(FIND PNG_INTEL_SSE_POSSIBLE_VALUES ${PNG_INTEL_SSE} index)
  if(index EQUAL -1)
    message(FATAL_ERROR
            "PNG_INTEL_SSE must be one of [${PNG_INTEL_SSE_POSSIBLE_VALUES}]")
  elseif(NOT ${PNG_INTEL_SSE} STREQUAL "off")
    set(libpng_intel_sources
      intel/intel_init.c
      intel/filter_sse2_intrinsics.c)
    if(${PNG_INTEL_SSE} STREQUAL "on")
      add_definitions(-DPNG_INTEL_SSE_OPT=1)
    endif()
  else()
    add_definitions(-DPNG_INTEL_SSE_OPT=0)
  endif()
 endif()
 # set definitions and sources for MIPS
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "mipsel*" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "mips64el*")
  set(PNG_MIPS_MSA_POSSIBLE_VALUES on off)
  set(PNG_MIPS_MSA "on" CACHE STRING "Enable MIPS_MSA optimizations:
     off: disable the optimizations")
  set_property(CACHE PNG_MIPS_MSA PROPERTY STRINGS
     ${PNG_MIPS_MSA_POSSIBLE_VALUES})
  list(FIND PNG_MIPS_MSA_POSSIBLE_VALUES ${PNG_MIPS_MSA} index)
  if(index EQUAL -1)
    message(FATAL_ERROR
            "PNG_MIPS_MSA must be one of [${PNG_MIPS_MSA_POSSIBLE_VALUES}]")
  elseif(NOT ${PNG_MIPS_MSA} STREQUAL "off")
    set(libpng_mips_sources
      mips/mips_init.c
      mips/filter_msa_intrinsics.c)
    if(${PNG_MIPS_MSA} STREQUAL "on")
      add_definitions(-DPNG_MIPS_MSA_OPT=2)
    endif()
  else()
    add_definitions(-DPNG_MIPS_MSA_OPT=0)
  endif()
 endif()
 else(PNG_HARDWARE_OPTIMIZATIONS)
 # set definitions and sources for arm
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64")
  add_definitions(-DPNG_ARM_NEON_OPT=0)
 endif()
 # set definitions and sources for powerpc
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "^powerpc*" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "^ppc64*")
  add_definitions(-DPNG_POWERPC_VSX_OPT=0)
 endif()
 # set definitions and sources for intel
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "^i?86" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "^x86_64*")
  add_definitions(-DPNG_INTEL_SSE_OPT=0)
 endif()
 # set definitions and sources for MIPS
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "mipsel*" OR
   CMAKE_SYSTEM_PROCESSOR MATCHES "mips64el*")
  add_definitions(-DPNG_MIPS_MSA_OPT=0)
 endif()
 endif(PNG_HARDWARE_OPTIMIZATIONS)
 # SET LIBNAME
 set(PNG_LIB_NAME png${PNGLIB_MAJOR}${PNGLIB_MINOR})
@ -124,10 +251,10 @@ function(symbol_prefix)
  foreach(line ${OUT})
    string(REGEX MATCH "^PREFIX=" found_match "${line}")
    if(found_match)
-      STRING(REGEX REPLACE "^PREFIX=(.*\)" "\\1" prefix "${line}")
+      string(REGEX REPLACE "^PREFIX=(.*\)" "\\1" prefix "${line}")
      string(REGEX MATCH "__USER_LABEL_PREFIX__" found_match "${prefix}")
      if(found_match)
-        STRING(REGEX REPLACE "(.*)__USER_LABEL_PREFIX__(.*)" "\\1\\2" prefix "${prefix}")
+        string(REGEX REPLACE "(.*)__USER_LABEL_PREFIX__(.*)" "\\1\\2" prefix "${prefix}")
      endif()
      set(SYMBOL_PREFIX "${prefix}")
    endif()
@ -145,7 +272,7 @@ find_program(AWK NAMES gawk awk)
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
-if(NOT AWK)
+if(NOT AWK OR ANDROID)
  # No awk available to generate sources; use pre-built pnglibconf.h
  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
                 ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
@ -159,11 +286,11 @@ else()
    set(oneValueArgs INPUT OUTPUT)
    set(multiValueArgs DEPENDS)
    cmake_parse_arguments(_GC "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GC_INPUT)
+    if(NOT _GC_INPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires input.")
+      message(FATAL_ERROR "generate_chk: Missing INPUT argument")
    endif()
-    if (NOT _GC_OUTPUT)
+    if(NOT _GC_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires output.")
+      message(FATAL_ERROR "generate_chk: Missing OUTPUT argument")
    endif()
    add_custom_command(OUTPUT "${_GC_OUTPUT}"
@ -182,11 +309,11 @@ else()
    set(oneValueArgs INPUT OUTPUT)
    set(multiValueArgs DEPENDS)
    cmake_parse_arguments(_GO "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GO_INPUT)
+    if(NOT _GO_INPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires input.")
+      message(FATAL_ERROR "generate_out: Missing INPUT argument")
    endif()
-    if (NOT _GO_OUTPUT)
+    if(NOT _GO_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_out requires output.")
+      message(FATAL_ERROR "generate_out: Missing OUTPUT argument")
    endif()
    add_custom_command(OUTPUT "${_GO_OUTPUT}"
@ -205,8 +332,8 @@ else()
    set(oneValueArgs OUTPUT)
    set(multiValueArgs DEPENDS)
    cmake_parse_arguments(_GSO "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-    if (NOT _GSO_OUTPUT)
+    if(NOT _GSO_OUTPUT)
-      message(FATAL_ERROR "Invalid arguments.  generate_source requires output.")
+      message(FATAL_ERROR "generate_source: Missing OUTPUT argument")
    endif()
    add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${_GSO_OUTPUT}"
@ -307,7 +434,7 @@ else()
                    WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
  # A single target handles generation of all generated files.  If
-  # they are dependend upon separately by multiple targets, this
+  # they are depended upon separately by multiple targets, this
  # confuses parallel make (it would require a separate top-level
  # target for each file to track the dependencies properly).
  add_custom_target(genfiles DEPENDS
@ -324,7 +451,7 @@ else()
    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.chk"
    "${CMAKE_CURRENT_BINARY_DIR}/scripts/symbols.out"
    "${CMAKE_CURRENT_BINARY_DIR}/scripts/vers.out")
-endif(NOT AWK)
+endif(NOT AWK OR ANDROID)
 # OUR SOURCES
 set(libpng_public_hdrs
@ -338,7 +465,7 @@ set(libpng_private_hdrs
  pnginfo.h
  pngstruct.h
 )
-if(AWK)
+if(AWK AND NOT ANDROID)
  list(APPEND libpng_private_hdrs "${CMAKE_CURRENT_BINARY_DIR}/pngprefix.h")
 endif()
 set(libpng_sources
@ -359,6 +486,10 @@ set(libpng_sources
  pngwrite.c
  pngwtran.c
  pngwutil.c
  ${libpng_arm_sources}
  ${libpng_intel_sources}
  ${libpng_mips_sources}
  ${libpng_powerpc_sources}
 )
 set(pngtest_sources
  pngtest.c
@ -384,7 +515,7 @@ set(png_fix_itxt_sources
 if(MSVC)
  add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
-endif(MSVC)
+endif()
 if(PNG_DEBUG)
  add_definitions(-DPNG_DEBUG)
@ -464,7 +595,7 @@ if(NOT PNG_LIB_TARGETS)
  message(SEND_ERROR
    "No library variant selected to build. "
    "Please enable at least one of the following options: "
-    " PNG_STATIC, PNG_SHARED, PNG_FRAMEWORK")
+    "PNG_STATIC, PNG_SHARED, PNG_FRAMEWORK")
 endif()
 if(PNG_SHARED AND WIN32)
@ -477,11 +608,11 @@ function(png_add_test)
  set(multiValueArgs OPTIONS FILES)
  cmake_parse_arguments(_PAT "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
-  if (NOT _PAT_NAME)
+  if(NOT _PAT_NAME)
-    message(FATAL_ERROR "Invalid arguments.  png_add_test requires name.")
+    message(FATAL_ERROR "png_add_test: Missing NAME argument")
  endif()
-  if (NOT _PAT_COMMAND)
+  if(NOT _PAT_COMMAND)
-    message(FATAL_ERROR "Invalid arguments.  png_add_test requires command.")
+    message(FATAL_ERROR "png_add_test: Missing COMMAND argument")
  endif()
  set(TEST_OPTIONS "${_PAT_OPTIONS}")
@ -489,19 +620,11 @@ function(png_add_test)
  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/scripts/test.cmake.in"
                 "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake" @ONLY)
  if(CMAKE_MAJOR_VERSION GREATER 2) # have generator expressions
  add_test(NAME "${_PAT_NAME}"
           COMMAND "${CMAKE_COMMAND}"
           "-DLIBPNG=$<TARGET_FILE:png>"
           "-DTEST_COMMAND=$<TARGET_FILE:${_PAT_COMMAND}>"
           -P "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake")
  else() # old 2.x add_test; limited and won't work well on Windows
    # Note LIBPNG is a dummy value as there are no generator expressions
    add_test("${_PAT_NAME}" "${CMAKE_COMMAND}"
             "-DLIBPNG=${CMAKE_CURRENT_BINARY_DIR}/libpng.so"
             "-DTEST_COMMAND=./${_PAT_COMMAND}"
             -P "${CMAKE_CURRENT_BINARY_DIR}/tests/${_PAT_NAME}.cmake")
  endif()
 endfunction()
 if(PNG_TESTS AND PNG_SHARED)
@ -566,11 +689,11 @@ if(PNG_TESTS AND PNG_SHARED)
        set(TEST_PNG_VALID TRUE)
        if(TEST_PNG_ALPHA)
-          if (NOT "${alpha_type}" STREQUAL "alpha")
+          if(NOT "${alpha_type}" STREQUAL "alpha")
            set(TEST_PNG_VALID FALSE)
          endif()
        else()
-          if ("${alpha_type}" STREQUAL "alpha")
+          if("${alpha_type}" STREQUAL "alpha")
            set(TEST_PNG_VALID FALSE)
          endif()
        endif()
@ -634,31 +757,51 @@ if(PNG_SHARED)
  list(APPEND PNG_BIN_TARGETS png-fix-itxt)
 endif()
 # Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set
 IF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
  SET(CMAKE_LIBRARY_OUTPUT_DIRECTORY "lib")
 ENDIF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
 # Set a variable with CMake code which:
 # Creates a symlink from src to dest (if possible) or alternatively
 # copies if different.
-macro(CREATE_SYMLINK SRC_FILE DEST_FILE)
+include(CMakeParseArguments)
-  FILE(REMOVE ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
+
-  if(WIN32 AND NOT CYGWIN AND NOT MSYS)
+function(create_symlink DEST_FILE)
-    ADD_CUSTOM_COMMAND(
+
-        OUTPUT ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE}   ${CMAKE_CURRENT_BINARY_DIR}/${DEST_FILE}
+  cmake_parse_arguments(S "" "FILE;TARGET" "" ${ARGN})
-        COMMAND ${CMAKE_COMMAND} -E copy_if_different  "${SRC_FILE}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE}
+
-        COMMAND ${CMAKE_COMMAND} -E copy_if_different  "${SRC_FILE}" ${CMAKE_CURRENT_BINARY_DIR}/${DEST_FILE}
+  if(NOT S_TARGET AND NOT S_FILE)
-        DEPENDS ${PNG_LIB_TARGETS}
+    message(FATAL_ERROR "create_symlink: Missing TARGET or FILE argument")
-        )
+  endif()
-    ADD_CUSTOM_TARGET(${DEST_FILE}_COPY ALL DEPENDS ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
+
-  else(WIN32 AND NOT CYGWIN AND NOT MSYS)
+  if(S_TARGET AND S_FILE)
-    get_filename_component(LINK_TARGET "${SRC_FILE}" NAME)
+    message(FATAL_ERROR "create_symlink: Both source file ${S_FILE} and build target ${S_TARGET} arguments are present; can only have one.")
-    execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
+  endif()
-    execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
-    execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+  if(S_FILE)
-  endif(WIN32 AND NOT CYGWIN AND NOT MSYS)
+    # If we don't need to symlink something that's coming from a build target,
-endmacro()
+    # we can go ahead and symlink/copy at configure time.
    if(CMAKE_HOST_WIN32 AND NOT CYGWIN)
      execute_process(
        COMMAND "${CMAKE_COMMAND}" -E copy_if_different ${S_FILE} ${DEST_FILE}
        WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
    else()
      execute_process(
        COMMAND ${CMAKE_COMMAND} -E create_symlink ${S_FILE} ${DEST_FILE}
        WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
    endif()
  endif()
  if(S_TARGET)
    # We need to use generator expressions, which can be a bit tricky, so for
    # simplicity make the symlink a POST_BUILD step and use the TARGET
    # signature of add_custom_command.
    if(CMAKE_HOST_WIN32 AND NOT CYGWIN)
      add_custom_command(TARGET ${S_TARGET} POST_BUILD
        COMMAND "${CMAKE_COMMAND}" -E copy_if_different $<TARGET_LINKER_FILE_NAME:${S_TARGET}> $<TARGET_LINKER_FILE_DIR:${S_TARGET}>/${DEST_FILE})
    else()
      add_custom_command(TARGET ${S_TARGET} POST_BUILD
        COMMAND "${CMAKE_COMMAND}" -E create_symlink $<TARGET_LINKER_FILE_NAME:${S_TARGET}> $<TARGET_LINKER_FILE_DIR:${S_TARGET}>/${DEST_FILE})
    endif()
  endif()
 endfunction()
 # Create source generation scripts.
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genchk.cmake.in
@ -668,53 +811,43 @@ configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/genout.cmake.in
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/gensrc.cmake.in
               ${CMAKE_CURRENT_BINARY_DIR}/scripts/gensrc.cmake @ONLY)
 # libpng is a library so default to 'lib'
 if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
  set(CMAKE_INSTALL_LIBDIR lib)
-endif(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+endif()
 # CREATE PKGCONFIG FILES
-# we use the same files like ./configure, so we have to set its vars
+# We use the same files like ./configure, so we have to set its vars.
 # Only do this on Windows for Cygwin - the files don't make much sense outside
-# a UNIX look alike
+# of a UNIX look-alike.
 if(NOT WIN32 OR CYGWIN OR MINGW)
  set(prefix      ${CMAKE_INSTALL_PREFIX})
  set(exec_prefix ${CMAKE_INSTALL_PREFIX})
-  set(libdir      ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR})
+  set(libdir      ${CMAKE_INSTALL_FULL_LIBDIR})
-  set(includedir  ${CMAKE_INSTALL_PREFIX}/include)
+  set(includedir  ${CMAKE_INSTALL_FULL_INCLUDEDIR})
  set(LIBS        "-lz -lm")
  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng.pc.in
    ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}.pc @ONLY)
-  CREATE_SYMLINK(${PNGLIB_NAME}.pc libpng.pc)
+  create_symlink(libpng.pc FILE ${PNGLIB_NAME}.pc)
  configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng-config.in
    ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config @ONLY)
-  CREATE_SYMLINK(${PNGLIB_NAME}-config libpng-config)
+  create_symlink(libpng-config FILE ${PNGLIB_NAME}-config)
-endif(NOT WIN32 OR CYGWIN OR MINGW)
+endif()
 # SET UP LINKS
 if(PNG_SHARED)
  set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.23
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.37
    VERSION 16.${PNGLIB_RELEASE}.0
    SOVERSION 16
    CLEAN_DIRECT_OUTPUT 1)
 endif()
 # If CMake > 2.4.x, we set a variable used below to export
 # targets to an export file.
 # TODO: Use VERSION_GREATER after our cmake_minimum_required >= 2.6.2
 if(CMAKE_MAJOR_VERSION GREATER 1 AND CMAKE_MINOR_VERSION GREATER 4)
  set(PNG_EXPORT_RULE EXPORT libpng)
 elseif(CMAKE_MAJOR_VERSION GREATER 2) # future proof
  set(PNG_EXPORT_RULE EXPORT libpng)
 endif()
 # INSTALL
-if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
+if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL)
  install(TARGETS ${PNG_LIB_TARGETS}
-      ${PNG_EXPORT_RULE}
+          EXPORT libpng
          RUNTIME DESTINATION bin
          LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
          ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
@ -723,48 +856,44 @@ if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
  if(PNG_SHARED)
    # Create a symlink for libpng.dll.a => libpng16.dll.a on Cygwin
    if(CYGWIN OR MINGW)
-       get_target_property(BUILD_TARGET_LOCATION png LOCATION_${CMAKE_BUILD_TYPE})
+      create_symlink(libpng${CMAKE_IMPORT_LIBRARY_SUFFIX} TARGET png)
-       CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_IMPORT_LIBRARY_SUFFIX})
+      install(FILES $<TARGET_LINKER_FILE_DIR:png>/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX}
       install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX}
              DESTINATION ${CMAKE_INSTALL_LIBDIR})
-    endif(CYGWIN OR MINGW)
+    endif()
    if(NOT WIN32)
-      get_target_property(BUILD_TARGET_LOCATION png LOCATION_${CMAKE_BUILD_TYPE})
+      create_symlink(libpng${CMAKE_SHARED_LIBRARY_SUFFIX} TARGET png)
-      CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_SHARED_LIBRARY_SUFFIX})
+      install(FILES $<TARGET_LINKER_FILE_DIR:png>/libpng${CMAKE_SHARED_LIBRARY_SUFFIX}
      install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_SHARED_LIBRARY_SUFFIX}
              DESTINATION ${CMAKE_INSTALL_LIBDIR})
-    endif(NOT WIN32)
+    endif()
-  endif(PNG_SHARED)
+  endif()
  if(PNG_STATIC)
    if(NOT WIN32 OR CYGWIN OR MINGW)
-      get_target_property(BUILD_TARGET_LOCATION png_static LOCATION_${CMAKE_BUILD_TYPE})
+      create_symlink(libpng${CMAKE_STATIC_LIBRARY_SUFFIX} TARGET png_static)
-      CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_STATIC_LIBRARY_SUFFIX})
+      install(FILES $<TARGET_LINKER_FILE_DIR:png_static>/libpng${CMAKE_STATIC_LIBRARY_SUFFIX}
      install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_STATIC_LIBRARY_SUFFIX}
              DESTINATION ${CMAKE_INSTALL_LIBDIR})
-    endif(NOT WIN32 OR CYGWIN OR MINGW)
+    endif()
  endif()
 endif()
-if(NOT SKIP_INSTALL_HEADERS AND NOT SKIP_INSTALL_ALL )
+if(NOT SKIP_INSTALL_HEADERS AND NOT SKIP_INSTALL_ALL)
  install(FILES ${libpng_public_hdrs} DESTINATION include)
  install(FILES ${libpng_public_hdrs} DESTINATION include/${PNGLIB_NAME})
 endif()
-if(NOT SKIP_INSTALL_EXECUTABLES AND NOT SKIP_INSTALL_ALL )
+if(NOT SKIP_INSTALL_EXECUTABLES AND NOT SKIP_INSTALL_ALL)
  if(NOT WIN32 OR CYGWIN OR MINGW)
    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config DESTINATION bin)
-    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
+    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config DESTINATION bin)
-            DESTINATION bin)
+  endif()
  endif(NOT WIN32 OR CYGWIN OR MINGW)
 endif()
-if(NOT SKIP_INSTALL_PROGRAMS AND NOT SKIP_INSTALL_ALL )
+if(NOT SKIP_INSTALL_PROGRAMS AND NOT SKIP_INSTALL_ALL)
  install(TARGETS ${PNG_BIN_TARGETS}
          RUNTIME DESTINATION bin)
 endif()
-if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
+if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL)
  # Install man pages
  if(NOT PNG_MAN_DIR)
    set(PNG_MAN_DIR "share/man")
@ -772,7 +901,7 @@ if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
  install(FILES libpng.3 libpngpf.3 DESTINATION ${PNG_MAN_DIR}/man3)
  install(FILES png.5 DESTINATION ${PNG_MAN_DIR}/man5)
  # Install pkg-config files
-  if(NOT WIN32 OR CYGWIN OR MINGW)
+  if(NOT CMAKE_HOST_WIN32 OR CYGWIN OR MINGW)
    install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng.pc
            DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config
@ -781,12 +910,11 @@ if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
            DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
    install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
            DESTINATION bin)
-  endif(NOT WIN32 OR CYGWIN OR MINGW)
+  endif()
 endif()
-# On versions of CMake that support it, create an export file CMake
+# Create an export file that CMake users can include() to import our targets.
-# users can include() to import our targets
+if(NOT SKIP_INSTALL_EXPORT AND NOT SKIP_INSTALL_ALL)
 if(PNG_EXPORT_RULE AND NOT SKIP_INSTALL_EXPORT AND NOT SKIP_INSTALL_ALL )
  install(EXPORT libpng DESTINATION lib/libpng FILE lib${PNG_LIB_NAME}.cmake)
 endif()
@ -801,4 +929,3 @@ endif()
 # to create msvc import lib for mingw compiled shared lib
 # pexports libpng.dll > libpng.def
 # lib /def:libpng.def /machine:x86
--- a/source/Irrlicht/libpng/INSTALL
+++ b/source/Irrlicht/libpng/INSTALL
@ -1,389 +0,0 @@
 Installing libpng
 Contents
   I. Simple installation
  II. Rebuilding the configure scripts
 III. Using scripts/makefile*
  IV. Using cmake
   V. Directory structure
  VI. Building with project files
 VII. Building with makefiles
 VIII. Configuring libpng for 16-bit platforms
  IX. Configuring for DOS
   X. Configuring for Medium Model
  XI. Prepending a prefix to exported symbols
 XII. Configuring for compiler xxx:
 XIII. Removing unwanted object code
 XIV. Changes to the build and configuration of libpng in libpng-1.5.x
  XV. Setjmp/longjmp issues
 XVI. Other sources of information about libpng
 I. Simple installation
 On Unix/Linux and similar systems, you can simply type
    ./configure [--prefix=/path]
    make check
    make install
 and ignore the rest of this document.  "/path" is the path to the directory
 where you want to install the libpng "lib", "include", and "bin"
 subdirectories.
 If you downloaded a GIT clone, you will need to run ./autogen.sh before
 running ./configure, to create "configure" and "Makefile.in" which are
 not included in the GIT repository.
 Note that "configure" is only included in the "*.tar" distributions and not
 in the "*.zip" or "*.7z" distributions. If you downloaded one of those
 distributions, see "Building with project files" or "Building with makefiles",
 below.
 II. Rebuilding the configure scripts
 If configure does not work on your system, or if you have a need to
 change configure.ac or Makefile.am, and you have a reasonably
 up-to-date set of tools, running ./autogen.sh in a git clone before
 running ./configure may fix the problem.  To be really sure that you
 aren't using any of the included pre-built scripts, especially if you
 are building from a tar distribution instead of a git distribution,
 do this:
    ./configure --enable-maintainer-mode
    make maintainer-clean
    ./autogen.sh --maintainer --clean
    ./autogen.sh --maintainer
    ./configure [--prefix=/path] [other options]
    make
    make install
    make check
 III. Using scripts/makefile*
 Instead, you can use one of the custom-built makefiles in the
 "scripts" directory
    cp scripts/pnglibconf.h.prebuilt pnglibconf.h
    cp scripts/makefile.system makefile
    make test
    make install
 The files that are presently available in the scripts directory
 are listed and described in scripts/README.txt.
 Or you can use one of the "projects" in the "projects" directory.
 Before installing libpng, you must first install zlib, if it
 is not already on your system.  zlib can usually be found
 wherever you got libpng; otherwise go to http://zlib.net.  You can place
 zlib in in the same directory as libpng or in another directory.
 If your system already has a preinstalled zlib you will still need
 to have access to the zlib.h and zconf.h include files that
 correspond to the version of zlib that's installed.
 If you wish to test with a particular zlib that is not first in the
 standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
 and LD_LIBRARY_PATH in your environment before running "make test"
 or "make distcheck":
 ZLIBLIB=/path/to/lib export ZLIBLIB
 ZLIBINC=/path/to/include export ZLIBINC
 CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
 LDFLAGS="-L$ZLIBLIB" export LDFLAGS
 LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH
 If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
 in your environment and type "make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test".
 IV. Using cmake
 If you want to use "cmake" (see www.cmake.org), type
   cmake . -DCMAKE_INSTALL_PREFIX=/path
   make
   make install
 As when using the simple configure method described above, "/path" points to
 the installation directory where you want to put the libpng "lib", "include",
 and "bin" subdirectories.
 V. Directory structure
 You can rename the directories that you downloaded (they
 might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.8"
 or "zlib128") so that you have directories called "zlib" and "libpng".
 Your directory structure should look like this:
   ..       (the parent directory)
      libpng  (this directory)
          INSTALL (this file)
          README
          *.h, *.c  => libpng source files
          CMakeLists.txt    =>  "cmake" script
          configuration files:
             configure.ac, configure, Makefile.am, Makefile.in,
             autogen.sh, config.guess, ltmain.sh, missing, libpng.pc.in,
             libpng-config.in, aclocal.m4, config.h.in, config.sub,
             depcomp, install-sh, mkinstalldirs, test-pngtest.sh
          contrib
             arm-neon, conftest, examples, gregbook, libtests, pngminim,
             pngminus, pngsuite, tools, visupng
          projects
             cbuilder5, owatcom, visualc71, vstudio, xcode
          scripts
             makefile.*
             *.def (module definition files)
             etc.
          pngtest.png
          etc.
      zlib
          README, *.h, *.c contrib, etc.
 If the line endings in the files look funny, you may wish to get the other
 distribution of libpng.  It is available in both tar.gz (UNIX style line
 endings) and zip (DOS style line endings) formats.
 VI. Building with project files
 If you are building libpng with MSVC, you can enter the
 libpng projects\visualc71 or vstudio directory and follow the instructions
 in README.txt.
 Otherwise enter the zlib directory and follow the instructions in zlib/README,
 then come back here and run "configure" or choose the appropriate
 makefile.sys in the scripts directory.
 VII. Building with makefiles
 Copy the file (or files) that you need from the
 scripts directory into this directory, for example
   MSDOS example: copy scripts\makefile.msc makefile
                  copy scripts\pnglibconf.h.prebuilt pnglibconf.h
   UNIX example:  cp scripts/makefile.std makefile
                  cp scripts/pnglibconf.h.prebuilt pnglibconf.h
 Read the makefile to see if you need to change any source or
 target directories to match your preferences.
 Then read pnglibconf.dfa to see if you want to make any configuration
 changes.
 Then just run "make" which will create the libpng library in
 this directory and "make test" which will run a quick test that reads
 the "pngtest.png" file and writes a "pngout.png" file that should be
 identical to it.  Look for "9782 zero samples" in the output of the
 test.  For more confidence, you can run another test by typing
 "pngtest pngnow.png" and looking for "289 zero samples" in the output.
 Also, you can run "pngtest -m contrib/pngsuite/*.png" and compare
 your output with the result shown in contrib/pngsuite/README.
 Most of the makefiles will allow you to run "make install" to
 put the library in its final resting place (if you want to
 do that, run "make install" in the zlib directory first if necessary).
 Some also allow you to run "make test-installed" after you have
 run "make install".
 VIII. Configuring libpng for 16-bit platforms
 You will want to look into zconf.h to tell zlib (and thus libpng) that
 it cannot allocate more than 64K at a time.  Even if you can, the memory
 won't be accessible.  So limit zlib and libpng to 64K by defining MAXSEG_64K.
 IX. Configuring for DOS
 For DOS users who only have access to the lower 640K, you will
 have to limit zlib's memory usage via a png_set_compression_mem_level()
 call.  See zlib.h or zconf.h in the zlib library for more information.
 X. Configuring for Medium Model
 Libpng's support for medium model has been tested on most of the popular
 compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
 defined, and FAR gets defined to far in pngconf.h, and you should be
 all set.  Everything in the library (except for zlib's structure) is
 expecting far data.  You must use the typedefs with the p or pp on
 the end for pointers (or at least look at them and be careful).  Make
 note that the rows of data are defined as png_bytepp, which is
 an "unsigned char far * far *".
 XI. Prepending a prefix to exported symbols
 Starting with libpng-1.6.0, you can configure libpng (when using the
 "configure" script) to prefix all exported symbols by means of the
 configuration option "--with-libpng-prefix=FOO_", where FOO_ can be any
 string beginning with a letter and containing only uppercase
 and lowercase letters, digits, and the underscore (i.e., a C language
 identifier).  This creates a set of macros in pnglibconf.h, so this is
 transparent to applications; their function calls get transformed by
 the macros to use the modified names.
 XII. Configuring for compiler xxx:
 All includes for libpng are in pngconf.h.  If you need to add, change
 or delete an include, this is the place to do it.
 The includes that are not needed outside libpng are placed in pngpriv.h,
 which is only used by the routines inside libpng itself.
 The files in libpng proper only include pngpriv.h and png.h, which
 in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
 As of libpng-1.5.0, pngpriv.h also includes three other private header
 files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
 that previously appeared in the public headers.
 XIII. Removing unwanted object code
 There are a bunch of #define's in pngconf.h that control what parts of
 libpng are compiled.  All the defines end in _SUPPORTED.  If you are
 never going to use a capability, you can change the #define to #undef
 before recompiling libpng and save yourself code and data space, or
 you can turn off individual capabilities with defines that begin with
 PNG_NO_.
 In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
 You can also turn all of the transforms and ancillary chunk capabilities
 off en masse with compiler directives that define
 PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
 or all four, along with directives to turn on any of the capabilities that
 you do want.  The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the
 extra transformations but still leave the library fully capable of reading
 and writing PNG files with all known public chunks. Use of the
 PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
 that is incapable of reading or writing ancillary chunks.  If you are
 not using the progressive reading capability, you can turn that off
 with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
 capability, which you'll still have).
 All the reading and writing specific code are in separate files, so the
 linker should only grab the files it needs.  However, if you want to
 make sure, or if you are building a stand alone library, all the
 reading files start with "pngr" and all the writing files start with "pngw".
 The files that don't match either (like png.c, pngtrans.c, etc.)
 are used for both reading and writing, and always need to be included.
 The progressive reader is in pngpread.c
 If you are creating or distributing a dynamically linked library (a .so
 or DLL file), you should not remove or disable any parts of the library,
 as this will cause applications linked with different versions of the
 library to fail if they call functions not available in your library.
 The size of the library itself should not be an issue, because only
 those sections that are actually used will be loaded into memory.
 XIV. Changes to the build and configuration of libpng in libpng-1.5.x
 Details of internal changes to the library code can be found in the CHANGES
 file and in the GIT repository logs.  These will be of no concern to the vast
 majority of library users or builders; however, the few who configure libpng
 to a non-default feature set may need to change how this is done.
 There should be no need for library builders to alter build scripts if
 these use the distributed build support - configure or the makefiles -
 however, users of the makefiles may care to update their build scripts
 to build pnglibconf.h where the corresponding makefile does not do so.
 Building libpng with a non-default configuration has changed completely.
 The old method using pngusr.h should still work correctly even though the
 way pngusr.h is used in the build has been changed; however, library
 builders will probably want to examine the changes to take advantage of
 new capabilities and to simplify their build system.
 A. Specific changes to library configuration capabilities
 The exact mechanism used to control attributes of API functions has
 changed.  A single set of operating system independent macro definitions
 is used and operating system specific directives are defined in
 pnglibconf.h
 As part of this the mechanism used to choose procedure call standards on
 those systems that allow a choice has been changed.  At present this only
 affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
 running on Intel processors.  As before, PNGAPI is defined where required
 to control the exported API functions; however, two new macros, PNGCBAPI
 and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
 (PNGCAPI) for functions that must match a C library prototype (currently
 only png_longjmp_ptr, which must match the C longjmp function.)  The new
 approach is documented in pngconf.h
 Despite these changes, libpng 1.5.0 only supports the native C function
 calling standard on those platforms tested so far (__cdecl on Microsoft
 Windows).  This is because the support requirements for alternative
 calling conventions seem to no longer exist.  Developers who find it
 necessary to set PNG_API_RULE to 1 should advise the mailing list
 (png-mng-implement) of this and library builders who use Openwatcom and
 therefore set PNG_API_RULE to 2 should also contact the mailing list.
 B. Changes to the configuration mechanism
 Prior to libpng-1.5.0 library builders who needed to configure libpng
 had either to modify the exported pngconf.h header file to add system
 specific configuration or had to write feature selection macros into
 pngusr.h and cause this to be included into pngconf.h by defining
 PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
 application built without PNG_USER_CONFIG defined would see the
 unmodified, default, libpng API and thus would probably fail to link.
 These mechanisms still work in the configure build and in any makefile
 build that builds pnglibconf.h, although the feature selection macros
 have changed somewhat as described above.  In 1.5.0, however, pngusr.h is
 processed only once, at the time the exported header file pnglibconf.h is
 built.  pngconf.h no longer includes pngusr.h; therefore, pngusr.h is ignored
 after the build of pnglibconf.h and it is never included in an application
 build.
 The formerly used alternative of adding a list of feature macros to the
 CPPFLAGS setting in the build also still works; however, the macros will be
 copied to pnglibconf.h and this may produce macro redefinition warnings
 when the individual C files are compiled.
 All configuration now only works if pnglibconf.h is built from
 scripts/pnglibconf.dfa.  This requires the program awk.  Brian Kernighan
 (the original author of awk) maintains C source code of that awk and this
 and all known later implementations (often called by subtly different
 names - nawk and gawk for example) are adequate to build pnglibconf.h.
 The Sun Microsystems (now Oracle) program 'awk' is an earlier version
 and does not work; this may also apply to other systems that have a
 functioning awk called 'nawk'.
 Configuration options are now documented in scripts/pnglibconf.dfa.  This
 file also includes dependency information that ensures a configuration is
 consistent; that is, if a feature is switched off, dependent features are
 also switched off.  As a recommended alternative to using feature macros in
 pngusr.h a system builder may also define equivalent options in pngusr.dfa
 (or, indeed, any file) and add that to the configuration by setting
 DFA_XTRA to the file name.  The makefiles in contrib/pngminim illustrate
 how to do this, and also illustrate a case where pngusr.h is still required.
 After you have built libpng, the definitions that were recorded in
 pnglibconf.h are available to your application (pnglibconf.h is included
 in png.h and gets installed alongside png.h and pngconf.h in your
 $PREFIX/include directory).  Do not edit pnglibconf.h after you have built
 libpng, because than the settings would not accurately reflect the settings
 that were used to build libpng.
 XV. Setjmp/longjmp issues
 Libpng uses setjmp()/longjmp() for error handling.  Unfortunately setjmp()
 is known to be not thread-safe on some platforms and we don't know of
 any platform where it is guaranteed to be thread-safe.  Therefore, if
 your application is going to be using multiple threads, you should
 configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
 -DPNG_NO_SETJMP on your compile line, or with
  #undef PNG_SETJMP_SUPPORTED
 in your pnglibconf.h or pngusr.h.
 Starting with libpng-1.6.0, the library included a "simplified API".
 This requires setjmp/longjmp, so you must either build the library
 with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
 and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.
 XVI. Other sources of information about libpng:
 Further information can be found in the README and libpng-manual.txt
 files, in the individual makefiles, in png.h, and the manual pages
 libpng.3 and png.5.
--- a/source/Irrlicht/libpng/LICENSE
+++ b/source/Irrlicht/libpng/LICENSE
@ -1,17 +1,46 @@
 COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
 =========================================
-This copy of the libpng notices is provided for your convenience.  In case of
+PNG Reference Library License version 2
-any discrepancy between this copy and the notices in the file png.h that is
+---------------------------------------
 included in the libpng distribution, the latter shall prevail.
-COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ * Copyright (c) 1995-2019 The PNG Reference Library Authors.
 * Copyright (c) 2018-2019 Cosmin Truta.
 * Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson.
 * Copyright (c) 1996-1997 Andreas Dilger.
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
-If you modify libpng you may insert additional notices immediately following
+The software is supplied "as is", without warranty of any kind,
-this sentence.
+express or implied, including, without limitation, the warranties
 of merchantability, fitness for a particular purpose, title, and
 non-infringement.  In no event shall the Copyright owners, or
 anyone distributing the software, be liable for any damages or
 other liability, whether in contract, tort or otherwise, arising
 from, out of, or in connection with the software, or the use or
 other dealings in the software, even if advised of the possibility
 of such damage.
-This code is released under the libpng license.
+Permission is hereby granted to use, copy, modify, and distribute
 this software, or portions hereof, for any purpose, without fee,
 subject to the following restrictions:
-libpng versions 1.0.7, July 1, 2000 through 1.6.23, June 9, 2016 are
+ 1. The origin of this software must not be misrepresented; you
-Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
+    must not claim that you wrote the original software.  If you
    use this software in a product, an acknowledgment in the product
    documentation would be appreciated, but is not required.
 2. Altered source versions must be plainly marked as such, and must
    not be misrepresented as being the original software.
 3. This Copyright notice may not be removed or altered from any
    source or altered source distribution.
 PNG Reference Library License version 1 (for libpng 0.5 through 1.6.35)
 -----------------------------------------------------------------------
 libpng versions 1.0.7, July 1, 2000, through 1.6.35, July 15, 2018 are
 Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
 added to the list of Contributing Authors:
@ -22,25 +51,28 @@ added to the list of Contributing Authors:
    Cosmin Truta
    Gilles Vollant
    James Yu
    Mandar Sahastrabuddhe
    Google Inc.
    Vadim Barkov
 and with the following additions to the disclaimer:
-   There is no warranty against interference with your enjoyment of the
+    There is no warranty against interference with your enjoyment of
-   library or against infringement.  There is no warranty that our
+    the library or against infringement.  There is no warranty that our
    efforts or the library will fulfill any of your particular purposes
    or needs.  This library is provided with all faults, and the entire
-   risk of satisfactory quality, performance, accuracy, and effort is with
+    risk of satisfactory quality, performance, accuracy, and effort is
-   the user.
+    with the user.
 Some files in the "contrib" directory and some configure-generated
-files that are distributed with libpng have other copyright owners and
+files that are distributed with libpng have other copyright owners, and
 are released under other open source licenses.
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
-license as libpng-0.96, with the following individuals added to the list
+license as libpng-0.96, with the following individuals added to the
-of Contributing Authors:
+list of Contributing Authors:
    Tom Lane
    Glenn Randers-Pehrson
@ -59,7 +91,7 @@ Contributing Authors:
    Greg Roelofs
    Tom Tanner
-Some files in the "scripts" directory have other copyright owners
+Some files in the "scripts" directory have other copyright owners,
 but are released under this license.
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
@ -74,13 +106,14 @@ is defined as the following set of individuals:
    Paul Schmidt
    Tim Wegner
-The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+The PNG Reference Library is supplied "AS IS".  The Contributing
-and Group 42, Inc. disclaim all warranties, expressed or implied,
+Authors and Group 42, Inc. disclaim all warranties, expressed or
-including, without limitation, the warranties of merchantability and of
+implied, including, without limitation, the warranties of
-fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+merchantability and of fitness for any purpose.  The Contributing
-assume no liability for direct, indirect, incidental, special, exemplary,
+Authors and Group 42, Inc. assume no liability for direct, indirect,
-or consequential damages, which may result from the use of the PNG
+incidental, special, exemplary, or consequential damages, which may
-Reference Library, even if advised of the possibility of such damage.
+result from the use of the PNG Reference Library, even if advised of
 the possibility of such damage.
 Permission is hereby granted to use, copy, modify, and distribute this
 source code, or portions hereof, for any purpose, without fee, subject
@ -94,37 +127,8 @@ to the following restrictions:
 3. This Copyright notice may not be removed or altered from any
    source or altered source distribution.
-The Contributing Authors and Group 42, Inc. specifically permit, without
+The Contributing Authors and Group 42, Inc. specifically permit,
-fee, and encourage the use of this source code as a component to
+without fee, and encourage the use of this source code as a component
-supporting the PNG file format in commercial products.  If you use this
+to supporting the PNG file format in commercial products.  If you use
-source code in a product, acknowledgment is not required but would be
+this source code in a product, acknowledgment is not required but would
-appreciated.
+be appreciated.
 END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
 TRADEMARK:
 The name "libpng" has not been registered by the Copyright owner
 as a trademark in any jurisdiction.  However, because libpng has
 been distributed and maintained world-wide, continually since 1995,
 the Copyright owner claims "common-law trademark protection" in any
 jurisdiction where common-law trademark is recognized.
 OSI CERTIFICATION:
 Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
 a certification mark of the Open Source Initiative. OSI has not addressed
 the additional disclaimers inserted at version 1.0.7.
 EXPORT CONTROL:
 The Copyright owner believes that the Export Control Classification
 Number (ECCN) for libpng is EAR99, which means not subject to export
 controls or International Traffic in Arms Regulations (ITAR) because
 it is open source, publicly available software, that does not contain
 any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
 734.7(b).
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
 June 9, 2016
--- a/source/Irrlicht/libpng/README
+++ b/source/Irrlicht/libpng/README
@ -1,15 +1,16 @@
-README for libpng version 1.6.23 - June 9, 2016 (shared library 16.0)
+README for libpng version 1.6.37 - April 14, 2019
-See the note about version numbers near the top of png.h
+=================================================
 See the note about version numbers near the top of png.h.
 See INSTALL for instructions on how to install libpng.
 Libpng comes in several distribution formats.  Get libpng-*.tar.gz or
-libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
+libpng-*.tar.xz or if you want UNIX-style line endings in the text
-or lpng*.7z or lpng*.zip if you want DOS-style line endings.
+files, or lpng*.7z or lpng*.zip if you want DOS-style line endings.
 Version 0.89 was the first official release of libpng.  Don't let the
-fact that it's the first release fool you.  The libpng library has been in
+fact that it's the first release fool you.  The libpng library has been
-extensive use and testing since mid-1995.  By late 1997 it had
+in extensive use and testing since mid-1995.  By late 1997 it had
 finally gotten to the stage where there hadn't been significant
 changes to the API in some time, and people have a bad feeling about
 libraries with versions < 1.0.  Version 1.0.0 was released in
@ -23,7 +24,7 @@ earlier versions if you are using a shared library.  The type of the
 png_uint_32, which will affect shared-library applications that use
 this function.
-To avoid problems with changes to the internals of png info_struct,
+To avoid problems with changes to the internals of the png info_struct,
 new APIs have been made available in 0.95 to avoid direct application
 access to info_ptr.  These functions are the png_set_<chunk> and
 png_get_<chunk> functions.  These functions should be used when
@ -60,94 +61,59 @@ the library action on the detection of chunk CRC errors.  It is possible
 to set different actions based on whether the CRC error occurred in a
 critical or an ancillary chunk.
-The changes made to the library, and bugs fixed are based on discussions
+For a detailed description on using libpng, read libpng-manual.txt.
-on the PNG-implement mailing list and not on material submitted
+For examples of libpng in a program, see example.c and pngtest.c.  For
-privately to Guy, Andreas, or Glenn.  They will forward any good
+usage information and restrictions (what little they are) on libpng,
-suggestions to the list.
+see png.h.  For a description on using zlib (the compression library
-
+used by libpng) and zlib's restrictions, see zlib.h
 For a detailed description on using libpng, read libpng-manual.txt.  For
 examples of libpng in a program, see example.c and pngtest.c.  For usage
 information and restrictions (what little they are) on libpng, see
 png.h.  For a description on using zlib (the compression library used by
 libpng) and zlib's restrictions, see zlib.h
 I have included a general makefile, as well as several machine and
-compiler specific ones, but you may have to modify one for your own needs.
+compiler specific ones, but you may have to modify one for your own
 needs.
 You should use zlib 1.0.4 or later to run this, but it MAY work with
 versions as old as zlib 0.95.  Even so, there are bugs in older zlib
 versions which can cause the output of invalid compression streams for
-some images.  You will definitely need zlib 1.0.4 or later if you are
+some images.
 taking advantage of the MS-DOS "far" structure allocation for the small
 and medium memory models.  You should also note that zlib is a
 compression library that is useful for more things than just PNG files.
 You can use zlib as a drop-in replacement for fread() and fwrite() if
 you are so inclined.
-zlib should be available at the same place that libpng is, or at zlib.net.
+You should also note that zlib is a compression library that is useful
 for more things than just PNG files.  You can use zlib as a drop-in
 replacement for fread() and fwrite(), if you are so inclined.
 zlib should be available at the same place that libpng is, or at
 https://zlib.net.
 You may also want a copy of the PNG specification.  It is available
 as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
-these at http://www.libpng.org/pub/png/documents/
+these at http://www.libpng.org/pub/png/pngdocs.html .
-This code is currently being archived at libpng.sf.net in the
+This code is currently being archived at libpng.sourceforge.io in the
-[DOWNLOAD] area, and at ftp://ftp.simplesystems.org.  If you can't find it
+[DOWNLOAD] area, and at http://libpng.download/src .
 in any of those places, e-mail me, and I'll help you find it.
-I am not a lawyer, but I believe that the Export Control Classification
+This release, based in a large way on Glenn's, Guy's and Andreas'
-Number (ECCN) for libpng is EAR99, which means not subject to export
+earlier work, was created and will be supported by myself and the PNG
 controls or International Traffic in Arms Regulations (ITAR) because it
 is open source, publicly available software, that does not contain any
 encryption software.  See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
 If you have any code changes, requests, problems, etc., please e-mail
 them to me.  Also, I'd appreciate any make files or project files,
 and any modifications you needed to make to get libpng to compile,
 along with a #define variable to tell what compiler/system you are on.
 If you needed to add transformations to libpng, or wish libpng would
 provide the image in a different way, drop me a note (and code, if
 possible), so I can consider supporting the transformation.
 Finally, if you get any warning messages when compiling libpng
 (note: not zlib), and they are easy to fix, I'd appreciate the
 fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
 This release was created and will be supported by myself (of course
 based in a large way on Guy's and Andreas' earlier work), and the PNG
 development group.
 Send comments/corrections/commendations to png-mng-implement at
 lists.sourceforge.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
-to subscribe) or to glennrp at users.sourceforge.net
+to subscribe).
-You can't reach Guy, the original libpng author, at the addresses
+Send general questions about the PNG specification to png-mng-misc
-given in previous versions of this document.  He and Andreas will
+at lists.sourceforge.net (subscription required; visit
 read mail addressed to the png-implement list, however.
 Please do not send general questions about PNG.  Send them to
 png-mng-misc at lists.sf.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
-subscribe).  If you have a question about something
+subscribe).
 in the PNG specification that is related to using libpng, send it
 to me.  Send me any questions that start with "I was using libpng,
 and ...".  If in doubt, send questions to me.  I'll bounce them
 to others, if necessary.
 Please do not send suggestions on how to change PNG.  We have
 been discussing PNG for twenty years now, and it is official and
 finished.  If you have suggestions for libpng, however, I'll
 gladly listen.  Even if your suggestion is not used immediately,
 it may be used later.
 Files in this distribution:
      ANNOUNCE      =>  Announcement of this version, with recent changes
      AUTHORS       =>  List of contributing authors
      CHANGES       =>  Description of changes between libpng versions
      KNOWNBUG      =>  List of known bugs and deficiencies
      LICENSE       =>  License to use and redistribute libpng
      README        =>  This file
      TODO          =>  Things not implemented in the current library
-      Y2KINFO       =>  Statement of Y2K compliance
+      TRADEMARK     =>  Trademark information
      example.c     =>  Example code for using libpng functions
      libpng.3      =>  manual page for libpng (includes libpng-manual.txt)
      libpng-manual.txt  =>  Description of libpng and its functions
@ -179,18 +145,25 @@ Files in this distribution:
      pngwtran.c    =>  Write data transformations
      pngwutil.c    =>  Write utility functions
      arm           =>  Contains optimized code for the ARM platform
      powerpc       =>  Contains optimized code for the PowerPC platform
      contrib       =>  Contributions
       arm-neon         =>  Optimized code for ARM-NEON platform
       powerpc-vsx      =>  Optimized code for POWERPC-VSX platform
       examples         =>  Example programs
       gregbook         =>  source code for PNG reading and writing, from
                            Greg Roelofs' "PNG: The Definitive Guide",
                            O'Reilly, 1999
       libtests         =>  Test programs
       mips-msa         =>  Optimized code for MIPS-MSA platform
       pngminim         =>  Minimal decoder, encoder, and progressive decoder
                            programs demonstrating use of pngusr.dfa
       pngminus         =>  Simple pnm2png and png2pnm programs
       pngsuite         =>  Test images
       testpngs
       tools            =>  Various tools
       visupng          =>  Contains a MSVC workspace for VisualPng
      intel             =>  Optimized code for INTEL-SSE2 platform
      mips              =>  Optimized code for MIPS platform
      projects      =>  Contains project files and workspaces for
                        building a DLL
       owatcom          =>  Contains a WATCOM project for building libpng
@ -201,15 +174,10 @@ Files in this distribution:
      scripts       =>  Directory containing scripts for building libpng:
                            (see scripts/README.txt for the list of scripts)
-Good luck, and happy coding.
+Good luck, and happy coding!
-Glenn Randers-Pehrson (current maintainer, since 1998)
+ * Cosmin Truta (current maintainer, since 2018)
- Internet: glennrp at users.sourceforge.net
+ * Glenn Randers-Pehrson (former maintainer, 1998-2018)
-
+ * Andreas Eric Dilger (former maintainer, 1996-1997)
-Andreas Eric Dilger (former maintainer, 1996-1997)
+ * Guy Eric Schalnat (original author and former maintainer, 1995-1996)
- Internet: adilger at enel.ucalgary.ca
+   (formerly of Group 42, Inc.)
 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
 -Guy Eric Schalnat (original author and former maintainer, 1995-1996)
 (formerly of Group 42, Inc)
 Internet: gschal at infinet.com
--- a/source/Irrlicht/libpng/TODO
+++ b/source/Irrlicht/libpng/TODO
@ -1,29 +1,23 @@
 /*
 TODO - list of things to do for libpng:
-Final bug fixes.
+* Fix all defects (duh!)
-Better C++ wrapper/full C++ implementation?
+* Better C++ wrapper / full C++ implementation (?)
-Fix problem with C++ and EXTERN "C".
+* Fix the problems with C++ and 'extern "C"'.
-cHRM transformation.
+* cHRM transformation.
-Remove setjmp/longjmp usage in favor of returning error codes.
+* Palette creation.
-Palette creation.
+* "grayscale->palette" transformation and "palette->grayscale" detection.
-Add "grayscale->palette" transformation and "palette->grayscale" detection.
+* Improved dithering.
-Improved dithering.
+* Multi-lingual error and warning message support.
-Multi-lingual error and warning message support.
+* Complete sRGB transformation.  (Currently it simply uses gamma=0.45455.)
-Complete sRGB transformation (presently it simply uses gamma=0.45455).
+* Man pages for function calls.
-Make profile checking optional via a png_set_something() call.
+* Better documentation.
-Man pages for function calls.
+* Better filter selection
-Better documentation.
+  (e.g., counting huffman bits/precompression; filter inertia; filter costs).
-Better filter selection
+* Histogram creation.
-   (counting huffman bits/precompression?  filter inertia?  filter costs?).
+* Text conversion between different code pages (e.g., Latin-1 -> Mac).
-Histogram creation.
+* Avoid building gamma tables whenever possible.
-Text conversion between different code pages (Latin-1 -> Mac and DOS).
+* Greater precision in changing to linear gamma for compositing against
-Avoid building gamma tables whenever possible.
+  background, and in doing rgb-to-gray transformations.
-Use greater precision when changing to linear gamma for compositing against
+* Investigate pre-incremented loop counters and other loop constructions.
-  background and doing rgb-to-gray transformation.
+* Interpolated method of handling interlacing.
-Investigate pre-incremented loop counters and other loop constructions.
+* More validations for libpng transformations.
 Add interpolated method of handling interlacing.
 Switch to the simpler zlib (zlib/libpng) license if legally possible.
 Extend pngvalid.c to validate more of the libpng transformations.
 */
--- a/source/Irrlicht/libpng/TRADEMARK
+++ b/source/Irrlicht/libpng/TRADEMARK
@ -0,0 +1,8 @@
 TRADEMARK
 =========
 The name "libpng" has not been registered by the Copyright owners
 as a trademark in any jurisdiction.  However, because libpng has
 been distributed and maintained world-wide, continually since 1995,
 the Copyright owners claim "common-law trademark protection" in any
 jurisdiction where common-law trademark is recognized.
--- a/source/Irrlicht/libpng/configure
+++ b/source/Irrlicht/libpng/configure
@ -1,19 +0,0 @@
 echo "
  There is no \"configure\" script in this distribution (*.zip or *.7z) of
  libpng-1.6.23.
  Instead, please copy the appropriate makefile for your system from the
  \"scripts\" directory.  Read the INSTALL file for more details.
  Update, July 2004: you can get a \"configure\" based distribution
  from the libpng distribution sites.  Download the file
  libpng-1.6.23.tar.gz or libpng-1.6.23.tar.xz.
  If the line endings in the files look funny, which is likely to be the
  case if you were trying to run \"configure\" on a Linux machine, you may
  wish to get the other distribution of libpng.  It is available in both
  tar.gz/tar.xz (UNIX style line endings, with \"configure\") and .7z/.zip
  (DOS style line endings, without \"configure\") formats.
 "
--- a/source/Irrlicht/libpng/example.c
+++ b/source/Irrlicht/libpng/example.c
@ -2,18 +2,20 @@
 #if 0 /* in case someone actually tries to compile this */
 /* example.c - an example of using libpng
- * Last changed in libpng 1.6.15 [November 20, 2014]
+ *
- * Maintained 1998-2014 Glenn Randers-Pehrson
+ * Maintained 2018 Cosmin Truta
- * Maintained 1996, 1997 Andreas Dilger)
+ * Maintained 1998-2016 Glenn Randers-Pehrson
- * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Maintained 1996-1997 Andreas Dilger
 * Written 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * To the extent possible under law, the authors have waived
 * all copyright and related or neighboring rights to this file.
- * This work is published from: United States.
+ * This work is published from: United States, Canada.
 */
 /* This is an example of how to use libpng to read and write PNG files.
- * The file libpng-manual.txt is much more verbose then this.  If you have not
+ * The file libpng-manual.txt is much more verbose then this.  If you have
- * read it, do so first.  This was designed to be a starting point of an
+ * not read it, do so first.  This was designed to be a starting point of an
 * implementation.  This is not officially part of libpng, is hereby placed
 * in the public domain, and therefore does not require a copyright notice.
 *
@ -24,16 +26,17 @@
 * see also the programs in the contrib directory.
 */
-/* The simple, but restricted, approach to reading a PNG file or data stream
+/* The simple, but restricted approach to reading a PNG file or data stream
- * just requires two function calls, as in the following complete program.
+ * requires just two function calls, as in the following complete program.
- * Writing a file just needs one function call, so long as the data has an
+ * Writing a file needs just one function call, so long as the data has an
 * appropriate layout.
 *
 * The following code reads PNG image data from a file and writes it, in a
- * potentially new format, to a new file.  While this code will compile there is
+ * potentially new format, to a new file.  While this code will compile, there
- * minimal (insufficient) error checking; for a more realistic version look at
+ * is minimal (insufficient) error checking.  For a more realistic version,
- * contrib/examples/pngtopng.c
+ * see contrib/examples/pngtopng.c
 */
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@ -68,28 +71,28 @@ int main(int argc, const char **argv)
          */
         buffer = malloc(PNG_IMAGE_SIZE(image));
-         /* If enough memory was available read the image in the desired format
+         /* If enough memory was available, read the image in the desired
-          * then write the result out to the new file.  'background' is not
+          * format, then write the result out to the new file.  'background' is
-          * necessary when reading the image because the alpha channel is
+          * not necessary when reading the image, because the alpha channel is
          * preserved; if it were to be removed, for example if we requested
          * PNG_FORMAT_RGB, then either a solid background color would have to
-          * be supplied or the output buffer would have to be initialized to the
+          * be supplied, or the output buffer would have to be initialized to
-          * actual background of the image.
+          * the actual background of the image.
          *
          * The fourth argument to png_image_finish_read is the 'row_stride' -
          * this is the number of components allocated for the image in each
          * row.  It has to be at least as big as the value returned by
          * PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
-          * default, minimum, size using PNG_IMAGE_SIZE as above you can pass
+          * default, minimum size, using PNG_IMAGE_SIZE as above, you can pass
          * zero.
          *
          * The final argument is a pointer to a buffer for the colormap;
-          * colormaps have exactly the same format as a row of image pixels (so
+          * colormaps have exactly the same format as a row of image pixels
-          * you choose what format to make the colormap by setting
+          * (so you choose what format to make the colormap by setting
          * image.format).  A colormap is only returned if
          * PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
          * case NULL is passed as the final argument.  If you do want to force
-          * all images into an index/color-mapped format then you can use:
+          * all images into an index/color-mapped format, then you can use:
          *
          *    PNG_IMAGE_COLORMAP_SIZE(image)
          *
@ -111,17 +114,15 @@ int main(int argc, const char **argv)
               exit(0);
            }
         }
         else
         {
-            /* Calling png_free_image is optional unless the simplified API was
+            /* Calling png_image_free is optional unless the simplified API was
-             * not run to completion.  In this case if there wasn't enough
+             * not run to completion.  In this case, if there wasn't enough
-             * memory for 'buffer' we didn't complete the read, so we must free
+             * memory for 'buffer', we didn't complete the read, so we must
-             * the image:
+             * free the image:
             */
            if (buffer == NULL)
-               png_free_image(&image);
+               png_image_free(&image);
            else
               free(buffer);
      }
@ -130,65 +131,67 @@ int main(int argc, const char **argv)
       * textual message in the 'png_image' structure:
       */
      fprintf(stderr, "pngtopng: error: %s\n", image.message);
-      exit (1);
+      exit(1);
   }
   fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
-   exit(1);
+   exit(2);
 }
 /* That's it ;-)  Of course you probably want to do more with PNG files than
 * just converting them all to 32-bit RGBA PNG files; you can do that between
 * the call to png_image_finish_read and png_image_write_to_file.  You can also
- * ask for the image data to be presented in a number of different formats.  You
+ * ask for the image data to be presented in a number of different formats.
- * do this by simply changing the 'format' parameter set before allocating the
+ * You do this by simply changing the 'format' parameter set before allocating
- * buffer.
+ * the buffer.
 *
 * The format parameter consists of five flags that define various aspects of
- * the image, you can simply add these together to get the format or you can use
+ * the image.  You can simply add these together to get the format, or you can
- * one of the predefined macros from png.h (as above):
+ * use one of the predefined macros from png.h (as above):
 *
- * PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per
+ * PNG_FORMAT_FLAG_COLOR: if set, the image will have three color components
- *    pixel (red, green and blue), if not set the image will just have one
+ *    per pixel (red, green and blue); if not set, the image will just have one
 *    luminance (grayscale) component.
 *
- * PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional
+ * PNG_FORMAT_FLAG_ALPHA: if set, each pixel in the image will have an
- *    alpha value; a linear value that describes the degree the image pixel
+ *    additional alpha value; a linear value that describes the degree the
- *    covers (overwrites) the contents of the existing pixel on the display.
+ *    image pixel covers (overwrites) the contents of the existing pixel on the
 *    display.
 *
- * PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned
+ * PNG_FORMAT_FLAG_LINEAR: if set, the components of each pixel will be
- *    as a series of 16-bit linear values, if not set the components will be
+ *    returned as a series of 16-bit linear values; if not set, the components
- *    returned as a series of 8-bit values encoded according to the 'sRGB'
+ *    will be returned as a series of 8-bit values encoded according to the
- *    standard.  The 8-bit format is the normal format for images intended for
+ *    sRGB standard.  The 8-bit format is the normal format for images intended
- *    direct display, because almost all display devices do the inverse of the
+ *    for direct display, because almost all display devices do the inverse of
- *    sRGB transformation to the data they receive.  The 16-bit format is more
+ *    the sRGB transformation to the data they receive.  The 16-bit format is
- *    common for scientific data and image data that must be further processed;
+ *    more common for scientific data and image data that must be further
- *    because it is linear simple math can be done on the component values.
+ *    processed; because it is linear, simple math can be done on the component
- *    Regardless of the setting of this flag the alpha channel is always linear,
+ *    values.  Regardless of the setting of this flag, the alpha channel is
- *    although it will be 8 bits or 16 bits wide as specified by the flag.
+ *    always linear, although it will be 8 bits or 16 bits wide as specified by
 *    the flag.
 *
- * PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned
+ * PNG_FORMAT_FLAG_BGR: if set, the components of a color pixel will be
- *    in the order blue, then green, then red.  If not set the pixel components
+ *    returned in the order blue, then green, then red.  If not set, the pixel
- *    are in the order red, then green, then blue.
+ *    components are in the order red, then green, then blue.
 *
- * PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the
+ * PNG_FORMAT_FLAG_AFIRST: if set, the alpha channel (if present) precedes the
- *    color or grayscale components.  If not set the alpha channel follows the
+ *    color or grayscale components.  If not set, the alpha channel follows the
 *    components.
 *
 * You do not have to read directly from a file.  You can read from memory or,
 * on systems that support it, from a <stdio.h> FILE*.  This is controlled by
- * the particular png_image_read_from_ function you call at the start.  Likewise
+ * the particular png_image_read_from_ function you call at the start.
- * on write you can write to a FILE* if your system supports it.  Check the
+ * Likewise, on write, you can write to a FILE* if your system supports it.
- * macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your
+ * Check the macro PNG_STDIO_SUPPORTED to see if stdio support has been
- * libpng build.
+ * included in your libpng build.
 *
- * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in
+ * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data, you may need to write it
- * the 8-bit format for display.  You do this by setting the convert_to_8bit
+ * in the 8-bit format for display.  You do this by setting the convert_to_8bit
 * flag to 'true'.
 *
 * Don't repeatedly convert between the 8-bit and 16-bit forms.  There is
- * significant data loss when 16-bit data is converted to the 8-bit encoding and
+ * significant data loss when 16-bit data is converted to the 8-bit encoding,
- * the current libpng implementation of conversion to 16-bit is also
+ * and the current libpng implementation of conversion to 16-bit is also
 * significantly lossy.  The latter will be fixed in the future, but the former
 * is unavoidable - the 8-bit format just doesn't have enough resolution.
 */
@ -199,10 +202,10 @@ int main(int argc, const char **argv)
 * interfaces.
 *
 * All these interfaces require that you do your own error handling - your
- * program must be able to arrange for control to return to your own code any
+ * program must be able to arrange for control to return to your own code, any
- * time libpng encounters a problem.  There are several ways to do this, but the
+ * time libpng encounters a problem.  There are several ways to do this, but
- * standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a
+ * the standard way is to use the <setjmp.h> interface to establish a return
- * return point within your own code.  You must do this if you do not use the
+ * point within your own code.  You must do this if you do not use the
 * simplified interface (above).
 *
 * The first step is to include the header files you need, including the libpng
@ -214,7 +217,7 @@ int main(int argc, const char **argv)
 /* The png_jmpbuf() macro, used in error handling, became available in
  * libpng version 1.0.6.  If you want to be able to run your code with older
  * versions of libpng, you must define the macro yourself (but only if it
-  * is not already defined by libpng!).
+  * is not already defined by libpng!)
  */
 #ifndef png_jmpbuf
@ -222,10 +225,10 @@ int main(int argc, const char **argv)
 #endif
 /* Check to see if a file is a PNG file using png_sig_cmp().  png_sig_cmp()
- * returns zero if the image is a PNG and nonzero if it isn't a PNG.
+ * returns zero if the image is a PNG, and nonzero otherwise.
 *
 * The function check_if_png() shown here, but not used, returns nonzero (true)
- * if the file can be opened and is a PNG, 0 (false) otherwise.
+ * if the file can be opened and is a PNG, and 0 (false) otherwise.
 *
 * If this call is successful, and you are going to keep the file open,
 * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
@ -238,7 +241,7 @@ int main(int argc, const char **argv)
 *
 * Many applications already read the first 2 or 4 bytes from the start
 * of the image to determine the file type, so it would be easiest just
- * to pass the bytes to png_sig_cmp() or even skip that if you know
+ * to pass the bytes to png_sig_cmp(), or even skip that if you know
 * you have a PNG file, and call png_set_sig_bytes().
 */
 #define PNG_BYTES_TO_CHECK 4
@ -250,14 +253,14 @@ int check_if_png(char *file_name, FILE **fp)
   if ((*fp = fopen(file_name, "rb")) == NULL)
      return 0;
-   /* Read in some of the signature bytes */
+   /* Read in some of the signature bytes. */
   if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
      return 0;
   /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
-      Return nonzero (true) if they match */
+    * Return nonzero (true) if they match.
-
+    */
-   return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
+   return(!png_sig_cmp(buf, 0, PNG_BYTES_TO_CHECK));
 }
 /* Read a PNG file.  You may want to return an error code if the read
@ -292,7 +295,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    * functions.  If you want to use the default stderr and longjump method,
    * you can supply NULL for the last three parameters.  We also supply the
    * the compiler header file version, so that we know if the application
-    * was compiled with a compatible version of the library.  REQUIRED
+    * was compiled with a compatible version of the library.  REQUIRED.
    */
   png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
       png_voidp user_error_ptr, user_error_fn, user_warning_fn);
@ -316,35 +319,33 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    * the normal method of doing things with libpng).  REQUIRED unless you
    * set up your own error handlers in the png_create_read_struct() earlier.
    */
   if (setjmp(png_jmpbuf(png_ptr)))
   {
-      /* Free all of the memory associated with the png_ptr and info_ptr */
+      /* Free all of the memory associated with the png_ptr and info_ptr. */
      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
      fclose(fp);
-      /* If we get here, we had a problem reading the file */
+      /* If we get here, we had a problem reading the file. */
      return (ERROR);
   }
-   /* One of the following I/O initialization methods is REQUIRED */
+   /* One of the following I/O initialization methods is REQUIRED. */
 #ifdef streams /* PNG file I/O method 1 */
-   /* Set up the input control if you are using standard C streams */
+   /* Set up the input control if you are using standard C streams. */
   png_init_io(png_ptr, fp);
 #else no_streams /* PNG file I/O method 2 */
   /* If you are using replacement read functions, instead of calling
-    * png_init_io() here you would call:
+    * png_init_io(), you would call:
    */
   png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
-   /* where user_io_ptr is a structure you want available to the callbacks */
+   /* where user_io_ptr is a structure you want available to the callbacks. */
 #endif no_streams /* Use only one I/O method! */
   /* If we have already read some of the signature */
   png_set_sig_bytes(png_ptr, sig_read);
 #ifdef hilevel
-   /*
+   /* If you have enough memory to read in the entire image at once,
    * If you have enough memory to read in the entire image at once,
    * and you need to specify only transforms that can be controlled
    * with one of the PNG_TRANSFORM_* bits (this presently excludes
    * quantizing, filling, setting background, and doing gamma
@ -354,10 +355,10 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
   png_read_png(png_ptr, info_ptr, png_transforms, NULL);
 #else
-   /* OK, you're doing it the hard way, with the lower-level functions */
+   /* OK, you're doing it the hard way, with the lower-level functions. */
   /* The call to png_read_info() gives us all of the information from the
-    * PNG file before the first IDAT (image data chunk).  REQUIRED
+    * PNG file before the first IDAT (image data chunk).  REQUIRED.
    */
   png_read_info(png_ptr, info_ptr);
@ -385,20 +386,21 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    */
   png_set_strip_alpha(png_ptr);
-   /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
+   /* Extract multiple pixels with bit depths of 1, 2 or 4 from a single
    * byte into separate bytes (useful for paletted and grayscale images).
    */
   png_set_packing(png_ptr);
   /* Change the order of packed pixels to least significant bit first
-    * (not useful if you are using png_set_packing). */
+    * (not useful if you are using png_set_packing).
    */
   png_set_packswap(png_ptr);
-   /* Expand paletted colors into true RGB triplets */
+   /* Expand paletted colors into true RGB triplets. */
   if (color_type == PNG_COLOR_TYPE_PALETTE)
      png_set_palette_to_rgb(png_ptr);
-   /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
+   /* Expand grayscale images to the full 8 bits from 1, 2 or 4 bits/pixel. */
   if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
      png_set_expand_gray_1_2_4_to_8(png_ptr);
@ -409,12 +411,11 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
      png_set_tRNS_to_alpha(png_ptr);
   /* Set the background color to draw transparent and alpha images over.
-    * It is possible to set the red, green, and blue components directly
+    * It is possible to set the red, green and blue components directly
-    * for paletted images instead of supplying a palette index.  Note that
+    * for paletted images, instead of supplying a palette index.  Note that,
    * even if the PNG file supplies a background, you are not required to
    * use it - you should use the (solid) application background if it has one.
    */
   png_color_16 my_background, *image_background;
   if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
@ -424,32 +425,29 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
      png_set_background(png_ptr, &my_background,
          PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
-   /* Some suggestions as to how to get a screen gamma value
+   /* Some suggestions as to how to get a screen gamma value.
    *
    * Note that screen gamma is the display_exponent, which includes
-    * the CRT_exponent and any correction for viewing conditions
+    * the CRT_exponent and any correction for viewing conditions.
    */
   if (/* We have a user-defined screen gamma value */)
   {
      screen_gamma = user-defined screen_gamma;
-   }
+   /* This is one way that applications share the same screen gamma value. */
   /* This is one way that applications share the same screen gamma value */
   else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
   {
      screen_gamma = atof(gamma_str);
   }
   /* If we don't have another value */
   else
   {
      screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor
                                          in a dimly lit room */
-      screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */
+      screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac
                                                 systems */
   }
   /* Tell libpng to handle the gamma conversion for you.  The final call
    * is a good guess for PC generated images, but it should be configurable
-    * by the user at run time by the user.  It is strongly suggested that
+    * by the user at run time.  Gamma correction support in your application
-    * your application support gamma correction.
+    * is strongly recommended.
    */
   int intent;
@ -466,7 +464,7 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
   }
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-   /* Quantize RGB files down to 8-bit palette or reduce palettes
+   /* Quantize RGB files down to 8-bit palette, or reduce palettes
    * to the number of colors available on your screen.
    */
   if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
@ -474,29 +472,26 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
      int num_palette;
      png_colorp palette;
-      /* This reduces the image to the application supplied palette */
+      /* This reduces the image to the application-supplied palette. */
      if (/* We have our own palette */)
      {
-         /* An array of colors to which the image should be quantized */
+         /* An array of colors to which the image should be quantized. */
         png_color std_color_cube[MAX_SCREEN_COLORS];
         png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
             MAX_SCREEN_COLORS, NULL, 0);
      }
-      /* This reduces the image to the palette supplied in the file */
+      /* This reduces the image to the palette supplied in the file. */
      else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
      {
         png_uint_16p histogram = NULL;
         png_get_hIST(png_ptr, info_ptr, &histogram);
         png_set_quantize(png_ptr, palette, num_palette,
             max_screen_colors, histogram, 0);
      }
   }
 #endif /* READ_QUANTIZE */
-   /* Invert monochrome files to have 0 as white and 1 as black */
+   /* Invert monochrome files to have 0 as white and 1 as black. */
   png_set_invert_mono(png_ptr);
   /* If you want to shift the pixel values from the range [0,255] or
@ -506,22 +501,21 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT) != 0)
   {
      png_color_8p sig_bit_p;
      png_get_sBIT(png_ptr, info_ptr, &sig_bit_p);
      png_set_shift(png_ptr, sig_bit_p);
   }
-   /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
+   /* Flip the RGB pixels to BGR (or RGBA to BGRA). */
   if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
      png_set_bgr(png_ptr);
-   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
+   /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR). */
   png_set_swap_alpha(png_ptr);
-   /* Swap bytes of 16-bit files to least significant byte first */
+   /* Swap bytes of 16-bit files to least significant byte first. */
   png_set_swap(png_ptr);
-   /* Add filler (or alpha) byte (before/after each RGB triplet) */
+   /* Add filler (or alpha) byte (before/after each RGB triplet). */
   png_set_filler(png_ptr, 0xffff, PNG_FILLER_AFTER);
 #ifdef PNG_READ_INTERLACING_SUPPORTED
@ -530,44 +524,35 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
    * see the png_read_row() method below:
    */
   number_passes = png_set_interlace_handling(png_ptr);
-#else
+#else /* !READ_INTERLACING */
   number_passes = 1;
 #endif /* READ_INTERLACING */
   /* Optional call to gamma correct and add the background to the palette
    * and update info structure.  REQUIRED if you are expecting libpng to
-    * update the palette for you (ie you selected such a transform above).
+    * update the palette for you (i.e. you selected such a transform above).
    */
   png_read_update_info(png_ptr, info_ptr);
   /* Allocate the memory to hold the image using the fields of info_ptr. */
   /* The easiest way to read the image: */
   png_bytep row_pointers[height];
   /* Clear the pointer array */
   for (row = 0; row < height; row++)
-      row_pointers[row] = NULL;
+      row_pointers[row] = NULL; /* Clear the pointer array */
   for (row = 0; row < height; row++)
      row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
          info_ptr));
-   /* Now it's time to read the image.  One of these methods is REQUIRED */
+   /* Now it's time to read the image.  One of these methods is REQUIRED. */
 #ifdef entire /* Read the entire image in one go */
   png_read_image(png_ptr, row_pointers);
 #else no_entire /* Read the image one or more scanlines at a time */
   /* The other way to read images - deal with interlacing: */
   for (pass = 0; pass < number_passes; pass++)
   {
 #ifdef single /* Read the image a single row at a time */
      for (y = 0; y < height; y++)
      {
         png_read_rows(png_ptr, &row_pointers[y], NULL, 1);
      }
 #else no_single /* Read the image several rows at a time */
      for (y = 0; y < height; y += number_of_rows)
@ -581,24 +566,24 @@ void read_png(FILE *fp, int sig_read)  /* File is already open */
 #endif no_sparkle /* Use only one of these two methods */
      }
-      /* If you want to display the image after every pass, do so here */
+      /* If you want to display the image after every pass, do so here. */
 #endif no_single /* Use only one of these two methods */
   }
 #endif no_entire /* Use only one of these two methods */
-   /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
+   /* Read rest of file, and get additional chunks in info_ptr.  REQUIRED. */
   png_read_end(png_ptr, info_ptr);
 #endif hilevel
-   /* At this point you have read the entire image */
+   /* At this point you have read the entire image. */
-   /* Clean up after the read, and free any memory allocated - REQUIRED */
+   /* Clean up after the read, and free any memory allocated.  REQUIRED. */
   png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
-   /* Close the file */
+   /* Close the file. */
   fclose(fp);
-   /* That's it */
+   /* That's it! */
   return (OK);
 }
@ -610,34 +595,30 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
   /* Create and initialize the png_struct with the desired error handler
    * functions.  If you want to use the default stderr and longjump method,
    * you can supply NULL for the last three parameters.  We also check that
-    * the library version is compatible in case we are using dynamically
+    * the library version is compatible, in case we are using dynamically
    * linked libraries.
    */
   *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
        png_voidp user_error_ptr, user_error_fn, user_warning_fn);
   if (*png_ptr == NULL)
   {
      *info_ptr = NULL;
      return (ERROR);
   }
   *info_ptr = png_create_info_struct(png_ptr);
   if (*info_ptr == NULL)
   {
      png_destroy_read_struct(png_ptr, info_ptr, NULL);
      return (ERROR);
   }
   if (setjmp(png_jmpbuf((*png_ptr))))
   {
      png_destroy_read_struct(png_ptr, info_ptr, NULL);
      return (ERROR);
   }
-   /* This one's new.  You will need to provide all three
+   /* You will need to provide all three function callbacks,
-    * function callbacks, even if you aren't using them all.
+    * even if you aren't using all of them.
    * If you aren't using all functions, you can specify NULL
    * parameters.  Even when all three functions are NULL,
    * you need to call png_set_progressive_read_fn().
@ -650,7 +631,6 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
    */
   png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
       info_callback, row_callback, end_callback);
   return (OK);
 }
@ -660,18 +640,18 @@ process_data(png_structp *png_ptr, png_infop *info_ptr,
 {
   if (setjmp(png_jmpbuf((*png_ptr))))
   {
-      /* Free the png_ptr and info_ptr memory on error */
+      /* Free the png_ptr and info_ptr memory on error. */
      png_destroy_read_struct(png_ptr, info_ptr, NULL);
      return (ERROR);
   }
-   /* This one's new also.  Simply give it chunks of data as
+   /* Give chunks of data as they arrive from the data stream
-    * they arrive from the data stream (in order, of course).
+    * (in order, of course).
    * On segmented machines, don't give it any more than 64K.
    * The library seems to run fine with sizes of 4K, although
-    * you can give it much less if necessary (I assume you can
+    * you can give it much less if necessary. (I assume you can
    * give it chunks of 1 byte, but I haven't tried with less
-    * than 256 bytes yet).  When this function returns, you may
+    * than 256 bytes yet.)  When this function returns, you may
    * want to display any rows that were generated in the row
    * callback, if you aren't already displaying them there.
    */
@ -693,8 +673,7 @@ info_callback(png_structp png_ptr, png_infop info)
 row_callback(png_structp png_ptr, png_bytep new_row,
    png_uint_32 row_num, int pass)
 {
-   /*
+   /* This function is called for every row in the image.  If the
    * This function is called for every row in the image.  If the
    * image is interlaced, and you turned on the interlace handler,
    * this function will be called for every row in every pass.
    *
@ -705,25 +684,22 @@ row_callback(png_structp png_ptr, png_bytep new_row,
    * The new row data pointer "new_row" may be NULL, indicating there is
    * no new data to be replaced (in cases of interlace loading).
    *
-    * If new_row is not NULL then you need to call
+    * If new_row is not NULL, then you need to call
-    * png_progressive_combine_row() to replace the corresponding row as
+    * png_progressive_combine_row(), to replace the corresponding row as
    * shown below:
    */
-   /* Get pointer to corresponding row in our
+   /* Get pointer to corresponding row in our PNG read buffer. */
    * PNG read buffer.
    */
   png_bytep old_row = ((png_bytep *)our_data)[row_num];
 #ifdef PNG_READ_INTERLACING_SUPPORTED
-   /* If both rows are allocated then copy the new row
+   /* If both rows are allocated, then copy the new row
    * data to the corresponding row data.
    */
-   if ((old_row != NULL) && (new_row != NULL))
+   if (old_row != NULL && new_row != NULL)
      png_progressive_combine_row(png_ptr, old_row, new_row);
-   /*
+   /* The rows and passes are called in order, so you don't really
    * The rows and passes are called in order, so you don't really
    * need the row_num and pass, but I'm supplying them because it
    * may make your life easier.
    *
@ -734,7 +710,6 @@ row_callback(png_structp png_ptr, png_bytep new_row,
    * (it just does the memcpy for you) if it will make the code
    * easier.  Thus, you can just do this for all cases:
    */
   png_progressive_combine_row(png_ptr, old_row, new_row);
   /* where old_row is what was displayed for previous rows.  Note
@ -781,14 +756,13 @@ void write_png(char *file_name /* , ... other image information ... */)
    */
   png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
       png_voidp user_error_ptr, user_error_fn, user_warning_fn);
   if (png_ptr == NULL)
   {
      fclose(fp);
      return (ERROR);
   }
-   /* Allocate/initialize the image information data.  REQUIRED */
+   /* Allocate/initialize the image information data.  REQUIRED. */
   info_ptr = png_create_info_struct(png_ptr);
   if (info_ptr == NULL)
   {
@ -797,30 +771,30 @@ void write_png(char *file_name /* , ... other image information ... */)
      return (ERROR);
   }
-   /* Set error handling.  REQUIRED if you aren't supplying your own
+   /* Set up error handling.  REQUIRED if you aren't supplying your own
    * error handling functions in the png_create_write_struct() call.
    */
   if (setjmp(png_jmpbuf(png_ptr)))
   {
-      /* If we get here, we had a problem writing the file */
+      /* If we get here, we had a problem writing the file. */
      fclose(fp);
      png_destroy_write_struct(&png_ptr, &info_ptr);
      return (ERROR);
   }
-   /* One of the following I/O initialization functions is REQUIRED */
+   /* One of the following I/O initialization functions is REQUIRED. */
 #ifdef streams /* I/O initialization method 1 */
-   /* Set up the output control if you are using standard C streams */
+   /* Set up the output control if you are using standard C streams. */
   png_init_io(png_ptr, fp);
 #else no_streams /* I/O initialization method 2 */
   /* If you are using replacement write functions, instead of calling
-    * png_init_io() here you would call
+    * png_init_io(), you would call:
    */
   png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
       user_IO_flush_function);
-   /* where user_io_ptr is a structure you want available to the callbacks */
+   /* where user_io_ptr is a structure you want available to the callbacks. */
 #endif no_streams /* Only use one initialization method */
 #ifdef hilevel
@ -831,30 +805,32 @@ void write_png(char *file_name /* , ... other image information ... */)
   png_write_png(png_ptr, info_ptr, png_transforms, NULL);
 #else
-   /* This is the hard way */
+   /* This is the hard way. */
   /* Set the image information here.  Width and height are up to 2^31,
-    * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
+    * bit_depth is one of 1, 2, 4, 8 or 16, but valid values also depend on
    * the color_type selected.  color_type is one of PNG_COLOR_TYPE_GRAY,
    * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
    * or PNG_COLOR_TYPE_RGB_ALPHA.  interlace is either PNG_INTERLACE_NONE or
    * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
-    * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
+    * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE.
    * REQUIRED.
    */
-   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
+   png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
-      PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+       PNG_COLOR_TYPE_???, PNG_INTERLACE_????,
       PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
-   /* Set the palette if there is one.  REQUIRED for indexed-color images */
+   /* Set the palette if there is one.  REQUIRED for indexed-color images. */
-   palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
+   palette = (png_colorp)png_malloc(png_ptr,
-             * (sizeof (png_color)));
+       PNG_MAX_PALETTE_LENGTH * (sizeof (png_color)));
   /* ... Set palette colors ... */
   png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
-   /* You must not free palette here, because png_set_PLTE only makes a link to
+   /* You must not free palette here, because png_set_PLTE only makes a link
-    * the palette that you malloced.  Wait until you are about to destroy
+    * to the palette that you allocated.  Wait until you are about to destroy
    * the png structure.
    */
-   /* Optional significant bit (sBIT) chunk */
+   /* Optional significant bit (sBIT) chunk. */
   png_color_8 sig_bit;
   /* If we are dealing with a grayscale image then */
@ -870,18 +846,17 @@ void write_png(char *file_name /* , ... other image information ... */)
   png_set_sBIT(png_ptr, info_ptr, &sig_bit);
   /* Optional gamma chunk is strongly suggested if you have any guess
    * as to the correct gamma of the image.
    */
   png_set_gAMA(png_ptr, info_ptr, gamma);
-   /* Optionally write comments into the image */
+   /* Optionally write comments into the image. */
   {
      png_text text_ptr[3];
-      char key0[]="Title";
+      char key0[] = "Title";
-      char text0[]="Mona Lisa";
+      char text0[] = "Mona Lisa";
      text_ptr[0].key = key0;
      text_ptr[0].text = text0;
      text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
@ -889,8 +864,8 @@ void write_png(char *file_name /* , ... other image information ... */)
      text_ptr[0].lang = NULL;
      text_ptr[0].lang_key = NULL;
-      char key1[]="Author";
+      char key1[] = "Author";
-      char text1[]="Leonardo DaVinci";
+      char text1[] = "Leonardo DaVinci";
      text_ptr[1].key = key1;
      text_ptr[1].text = text1;
      text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
@ -898,8 +873,8 @@ void write_png(char *file_name /* , ... other image information ... */)
      text_ptr[1].lang = NULL;
      text_ptr[1].lang_key = NULL;
-      char key2[]="Description";
+      char key2[] = "Description";
-      char text2[]="<long text>";
+      char text2[] = "<long text>";
      text_ptr[2].key = key2;
      text_ptr[2].text = text2;
      text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
@ -910,14 +885,14 @@ void write_png(char *file_name /* , ... other image information ... */)
      png_set_text(write_ptr, write_info_ptr, text_ptr, 3);
   }
-   /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */
+   /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs. */
-   /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored
+   /* Note that if sRGB is present, the gAMA and cHRM chunks must be ignored
    * on read and, if your application chooses to write them, they must
-    * be written in accordance with the sRGB profile
+    * be written in accordance with the sRGB profile.
    */
-   /* Write the file header information.  REQUIRED */
+   /* Write the file header information.  REQUIRED. */
   png_write_info(png_ptr, info_ptr);
   /* If you want, you can write the info in two steps, in case you need to
@ -941,7 +916,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    * all optional.  Only call them if you want them.
    */
-   /* Invert monochrome pixels */
+   /* Invert monochrome pixels. */
   png_set_invert_mono(png_ptr);
   /* Shift the pixels up to a legal bit depth and fill in
@ -949,10 +924,10 @@ void write_png(char *file_name /* , ... other image information ... */)
    */
   png_set_shift(png_ptr, &sig_bit);
-   /* Pack pixels into bytes */
+   /* Pack pixels into bytes. */
   png_set_packing(png_ptr);
-   /* Swap location of alpha bytes from ARGB to RGBA */
+   /* Swap location of alpha bytes from ARGB to RGBA. */
   png_set_swap_alpha(png_ptr);
   /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
@ -960,19 +935,18 @@ void write_png(char *file_name /* , ... other image information ... */)
    */
   png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
-   /* Flip BGR pixels to RGB */
+   /* Flip BGR pixels to RGB. */
   png_set_bgr(png_ptr);
-   /* Swap bytes of 16-bit files to most significant byte first */
+   /* Swap bytes of 16-bit files to most significant byte first. */
   png_set_swap(png_ptr);
-   /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
+   /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats. */
   png_set_packswap(png_ptr);
-   /* Turn on interlace handling if you are not using png_write_image() */
+   /* Turn on interlace handling if you are not using png_write_image(). */
   if (interlacing != 0)
      number_passes = png_set_interlace_handling(png_ptr);
   else
      number_passes = 1;
@ -982,24 +956,28 @@ void write_png(char *file_name /* , ... other image information ... */)
    */
   png_uint_32 k, height, width;
-   /* In this example, "image" is a one-dimensional array of bytes */
+   /* In this example, "image" is a one-dimensional array of bytes. */
   png_byte image[height*width*bytes_per_pixel];
   /* Guard against integer overflow. */
   if (height > PNG_SIZE_MAX / (width * bytes_per_pixel))
      png_error(png_ptr, "Image data buffer would be too large");
   png_byte image[height * width * bytes_per_pixel];
   png_bytep row_pointers[height];
-   if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
+   if (height > PNG_UINT_32_MAX / (sizeof (png_bytep)))
-     png_error (png_ptr, "Image is too tall to process in memory");
+      png_error(png_ptr, "Image is too tall to process in memory");
-   /* Set up pointers into your "image" byte array */
+   /* Set up pointers into your "image" byte array. */
   for (k = 0; k < height; k++)
-     row_pointers[k] = image + k*width*bytes_per_pixel;
+      row_pointers[k] = image + k * width * bytes_per_pixel;
-   /* One of the following output methods is REQUIRED */
+   /* One of the following output methods is REQUIRED. */
 #ifdef entire /* Write out the entire image data in one call */
   png_write_image(png_ptr, row_pointers);
-   /* The other way to write the image - deal with interlacing */
+   /* The other way to write the image - deal with interlacing. */
 #else no_entire /* Write out the image data by one or more scanlines */
@ -1011,27 +989,27 @@ void write_png(char *file_name /* , ... other image information ... */)
      /* Write a few rows at a time. */
      png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
-      /* If you are only writing one row at a time, this works */
+      /* If you are only writing one row at a time, this works. */
      for (y = 0; y < height; y++)
         png_write_rows(png_ptr, &row_pointers[y], 1);
   }
 #endif no_entire /* Use only one output method */
   /* You can write optional chunks like tEXt, zTXt, and tIME at the end
-    * as well.  Shouldn't be necessary in 1.2.0 and up as all the public
+    * as well.  Shouldn't be necessary in 1.2.0 and up, as all the public
-    * chunks are supported and you can use png_set_unknown_chunks() to
+    * chunks are supported, and you can use png_set_unknown_chunks() to
    * register unknown chunks into the info structure to be written out.
    */
-   /* It is REQUIRED to call this to finish writing the rest of the file */
+   /* It is REQUIRED to call this to finish writing the rest of the file. */
   png_write_end(png_ptr, info_ptr);
 #endif hilevel
-   /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
+   /* If you png_malloced a palette, free it here.
-    * as recommended in versions 1.0.5m and earlier of this example; if
+    * (Don't free info_ptr->palette, as shown in versions 1.0.5m and earlier of
-    * libpng mallocs info_ptr->palette, libpng will free it).  If you
+    * this example; if libpng mallocs info_ptr->palette, libpng will free it).
-    * allocated it with malloc() instead of png_malloc(), use free() instead
+    * If you allocated it with malloc() instead of png_malloc(), use free()
-    * of png_free().
+    * instead of png_free().
    */
   png_free(png_ptr, palette);
   palette = NULL;
@ -1042,19 +1020,20 @@ void write_png(char *file_name /* , ... other image information ... */)
    */
   png_free(png_ptr, trans);
   trans = NULL;
-   /* Whenever you use png_free() it is a good idea to set the pointer to
+
   /* Whenever you use png_free(), it is a good idea to set the pointer to
    * NULL in case your application inadvertently tries to png_free() it
-    * again.  When png_free() sees a NULL it returns without action, thus
+    * again.  When png_free() sees a NULL it returns without action, avoiding
-    * avoiding the double-free security problem.
+    * the double-free problem.
    */
-   /* Clean up after the write, and free any memory allocated */
+   /* Clean up after the write, and free any allocated memory. */
   png_destroy_write_struct(&png_ptr, &info_ptr);
-   /* Close the file */
+   /* Close the file. */
   fclose(fp);
-   /* That's it */
+   /* That's it! */
   return (OK);
 }
--- a/source/Irrlicht/libpng/libpng-config.in
+++ b/source/Irrlicht/libpng/libpng-config.in
@ -1,127 +0,0 @@
 #! /bin/sh
 # libpng-config
 # provides configuration info for libpng.
 # Copyright (C) 2002, 2004, 2006, 2007 Glenn Randers-Pehrson
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
 # and license in png.h
 # Modeled after libxml-config.
 version="@PNGLIB_VERSION@"
 prefix="@prefix@"
 exec_prefix="@exec_prefix@"
 libdir="@libdir@"
 includedir="@includedir@/libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@"
 libs="-lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@"
 all_libs="-lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@ @LIBS@"
 I_opts="-I${includedir}"
 L_opts="-L${libdir}"
 R_opts=""
 cppflags=""
 ccopts=""
 ldopts=""
 usage()
 {
    cat <<EOF
 Usage: $0 [OPTION] ...
 Known values for OPTION are:
  --prefix        print libpng prefix
  --libdir        print path to directory containing library
  --libs          print library linking information
  --ccopts        print compiler options
  --cppflags      print pre-processor flags
  --cflags        print preprocessor flags, I_opts, and compiler options
  --I_opts        print "-I" include options
  --L_opts        print linker "-L" flags for dynamic linking
  --R_opts        print dynamic linker "-R" or "-rpath" flags
  --ldopts        print linker options
  --ldflags       print linker flags (ldopts, L_opts, R_opts, and libs)
  --static        revise subsequent outputs for static linking
  --help          print this help and exit
  --version       print version information
 EOF
    exit $1
 }
 if test $# -eq 0; then
    usage 1
 fi
 while test $# -gt 0; do
    case "$1" in
    --prefix)
        echo ${prefix}
        ;;
    --version)
        echo ${version}
        exit 0
        ;;
    --help)
        usage 0
        ;;
    --ccopts)
        echo ${ccopts}
        ;;
    --cppflags)
        echo ${cppflags}
        ;;
    --cflags)
        echo ${I_opts} ${cppflags} ${ccopts}
        ;;
    --libdir)
        echo ${libdir}
        ;;
    --libs)
        echo ${libs}
        ;;
    --I_opts)
        echo ${I_opts}
        ;;
    --L_opts)
        echo ${L_opts}
        ;;
    --R_opts)
        echo ${R_opts}
        ;;
    --ldopts)
        echo ${ldopts}
        ;;
    --ldflags)
        echo ${ldopts} ${L_opts} ${R_opts} ${libs}
        ;;
    --static)
        R_opts=""
        libs=${all_libs}
        ;;
    *)
        usage
        exit 1
        ;;
    esac
    shift
 done
 exit 0
--- a/source/Irrlicht/libpng/libpng-manual.txt
+++ b/source/Irrlicht/libpng/libpng-manual.txt
@ -1,9 +1,7 @@
 libpng-manual.txt - A description on how to use and modify libpng
- libpng version 1.6.23 - June 9, 2016
+ Copyright (c) 2018-2019 Cosmin Truta
- Updated and distributed by Glenn Randers-Pehrson
+ Copyright (c) 1998-2018 Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2016 Glenn Randers-Pehrson
 This document is released under the libpng license.
 For conditions of distribution and use, see the disclaimer
@ -11,9 +9,13 @@ libpng-manual.txt - A description on how to use and modify libpng
 Based on:
- libpng versions 0.97, January 1998, through 1.6.23 - June 9, 2016
+ libpng version 1.6.36, December 2018, through 1.6.37 - April 2019
 Updated and distributed by Cosmin Truta
 Copyright (c) 2018-2019 Cosmin Truta
 libpng versions 0.97, January 1998, through 1.6.35 - July 2018
 Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2016 Glenn Randers-Pehrson
+ Copyright (c) 1998-2018 Glenn Randers-Pehrson
 libpng 1.0 beta 6 - version 0.96 - May 28, 1997
 Updated and distributed by Andreas Dilger
@ -45,7 +47,6 @@ libpng-manual.txt - A description on how to use and modify libpng
 XIII. Detecting libpng
  XIV. Source code repository
   XV. Coding style
  XVI. Y2K Compliance in libpng
 I. Introduction
@ -66,17 +67,17 @@ file format in application programs.
 The PNG specification (second edition), November 2003, is available as
 a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
-<http://www.w3.org/TR/2003/REC-PNG-20031110/
+<https://www.w3.org/TR/2003/REC-PNG-20031110/>.
 The W3C and ISO documents have identical technical content.
 The PNG-1.2 specification is available at
-<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
+<https://png-mng.sourceforge.io/pub/png/spec/1.2/>.
 It is technically equivalent
 to the PNG specification (second edition) but has some additional material.
-The PNG-1.0 specification is available as RFC 2083 
+The PNG-1.0 specification is available as RFC 2083 at
-<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+<https://png-mng.sourceforge.io/pub/png/spec/1.0/> and as a
-W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
+W3C Recommendation at <https://www.w3.org/TR/REC-png-961001>.
 Some additional chunks are described in the special-purpose public chunks
 documents at <http://www.libpng.org/pub/png/spec/register/>
@ -101,7 +102,7 @@ majority of the needs of its users.
 Libpng uses zlib for its compression and decompression of PNG files.
 Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <http://zlib.net/>.
+be found at the zlib home page, <https://zlib.net/>.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
@ -348,18 +349,18 @@ Customizing libpng.
    FILE *fp = fopen(file_name, "rb");
    if (!fp)
    {
-       return (ERROR);
+       return ERROR;
    }
    if (fread(header, 1, number, fp) != number)
    {
-       return (ERROR);
+       return ERROR;
    }
    is_png = !png_sig_cmp(header, 0, number);
    if (!is_png)
    {
-       return (NOT_PNG);
+       return NOT_PNG;
    }
 Next, png_struct and png_info need to be allocated and initialized.  In
@ -378,7 +379,7 @@ create the structure, so your application should check for that.
        user_error_fn, user_warning_fn);
    if (!png_ptr)
-       return (ERROR);
+       return ERROR;
    png_infop info_ptr = png_create_info_struct(png_ptr);
@ -386,7 +387,7 @@ create the structure, so your application should check for that.
    {
       png_destroy_read_struct(&png_ptr,
           (png_infopp)NULL, (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
 If you want to use your own memory allocation routines,
@ -421,7 +422,7 @@ free any memory.
       png_destroy_read_struct(&png_ptr, &info_ptr,
           &end_info);
       fclose(fp);
-       return (ERROR);
+       return ERROR;
    }
 Pass (png_infopp)NULL instead of &end_info if you didn't create
@ -467,8 +468,9 @@ the default, use
 The values for png_set_crc_action() say how libpng is to handle CRC errors in
 ancillary and critical chunks, and whether to use the data contained
-therein.  Note that it is impossible to "discard" data in a critical
+therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
-chunk.
+is handled while reading the IDAT chunk. Note that it is impossible to
 "discard" data in a critical chunk.
 Choices for (int) crit_action are
   PNG_CRC_DEFAULT      0  error/quit
@ -485,6 +487,9 @@ Choices for (int) ancil_action are
   PNG_CRC_QUIET_USE    4  quiet/use data
   PNG_CRC_NO_CHANGE    5  use the current value
 When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
 checksums are not only ignored, but they are not evaluated.
 Setting up callback code
 You can set up a callback function to handle any unknown chunks in the
@ -499,7 +504,7 @@ input stream. You must supply the function
           png_byte name[5];
           png_byte *data;
-           png_size_t size;
+           size_t size;
       /* Note that libpng has already taken care of
          the CRC handling */
@ -508,9 +513,9 @@ input stream. You must supply the function
          unknown chunk structure, process it, and return one
          of the following: */
-       return (-n); /* chunk had an error */
+       return -n; /* chunk had an error */
-       return (0); /* did not recognize */
+       return 0; /* did not recognize */
-       return (n); /* success */
+       return n; /* success */
    }
 (You can give your function another name that you like instead of
@ -559,7 +564,7 @@ non-interlaced case the row that was just handled is simply one less than the
 passed in row number, and pass will always be 0.  For the interlaced case the
 same applies unless the row value is 0, in which case the row just handled was
 the last one from one of the preceding passes.  Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass-1', if you really
+pass you cannot be sure that the preceding pass is just 'pass-1'; if you really
 need to know what the last pass is record (row,pass) from the callback and use
 the last recorded value each time.
@ -684,8 +689,9 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
   chunk_cache_max = png_get_chunk_cache_max(png_ptr);
 Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
-memory that a compressed chunk other than IDAT can occupy, when decompressed.
+memory that any chunk other than IDAT can occupy, originally or when
-You can change this limit with
+decompressed (prior to libpng-1.6.32 the limit was only applied to compressed
 chunks after decompression). You can change this limit with
   png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
@ -981,7 +987,16 @@ premultiplication.
    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
-This is the default libpng handling of the alpha channel - it is not
+Choices for the alpha_mode are
    PNG_ALPHA_PNG           0 /* according to the PNG standard */
    PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
    PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
    PNG_ALPHA_PREMULTIPLIED 1 /* as above */
    PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
    PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
 PNG_ALPHA_PNG is the default libpng handling of the alpha channel. It is not
 pre-multiplied into the color components. In addition the call states
 that the output is for a sRGB system and causes all PNG files without gAMA
 chunks to be assumed to be encoded using sRGB.
@ -989,7 +1004,7 @@ chunks to be assumed to be encoded using sRGB.
    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
 In this case the output is assumed to be something like an sRGB conformant
-display preceeded by a power-law lookup table of power 1.45.  This is how
+display preceded by a power-law lookup table of power 1.45.  This is how
 early Mac systems behaved.
    png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
@ -997,7 +1012,7 @@ early Mac systems behaved.
 This is the classic Jim Blinn approach and will work in academic
 environments where everything is done by the book.  It has the shortcoming
 of assuming that input PNG data with no gamma information is linear - this
-is unlikely to be correct unless the PNG files where generated locally.
+is unlikely to be correct unless the PNG files were generated locally.
 Most of the time the output precision will be so low as to show
 significant banding in dark areas of the image.
@ -1041,7 +1056,7 @@ faster.)
 When the default gamma of PNG files doesn't match the output gamma.
 If you have PNG files with no gamma information png_set_alpha_mode allows
-you to provide a default gamma, but it also sets the ouput gamma to the
+you to provide a default gamma, but it also sets the output gamma to the
 matching value.  If you know your PNG files have a gamma that doesn't
 match the output you can take advantage of the fact that
 png_set_alpha_mode always sets the output gamma but only sets the PNG
@ -1186,7 +1201,20 @@ row_pointers prior to calling png_read_png() with
   png_set_rows(png_ptr, info_ptr, &row_pointers);
 Alternatively you could allocate your image in one big block and define
-row_pointers[i] to point into the proper places in your block.
+row_pointers[i] to point into the proper places in your block, but first
 be sure that your platform is able to allocate such a large buffer:
   /* Guard against integer overflow */
   if (height > PNG_SIZE_MAX/(width*pixel_size)) {
        png_error(png_ptr,"image_data buffer would be too large");
   }
   png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
   for (int i=0; i<height, i++)
      row_pointers[i]=buffer+i*width*pixel_size;
   png_set_rows(png_ptr, info_ptr, &row_pointers);
 If you use png_set_rows(), the application is responsible for freeing
 row_pointers (and row_pointers[i], if they were separately allocated).
@ -1313,6 +1341,11 @@ in until png_read_end() has read the chunk data following the image.
    rowbytes = png_get_rowbytes(png_ptr, info_ptr);
    rowbytes       - number of bytes needed to hold a row
                     This value, the bit_depth, color_type,
                     and the number of channels can change
                     if you use transforms such as
                     png_set_expand(). See
                     png_read_update_info(), below.
    signature = png_get_signature(png_ptr, info_ptr);
@ -1431,6 +1464,11 @@ png_set_rgb_to_gray()).
                     the single transparent color for
                     non-paletted images (PNG_INFO_tRNS)
    png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
                     (PNG_INFO_eXIf)
    exif           - Exif profile (array of png_byte)
    png_get_hIST(png_ptr, info_ptr, &hist);
                     (PNG_INFO_hIST)
@ -2142,6 +2180,16 @@ are allocating one large chunk, you will need to build an
 array of pointers to each row, as it will be needed for some
 of the functions below.
 Be sure that your platform can allocate the buffer that you'll need.
 libpng internally checks for oversize width, but you'll need to
 do your own check for number_of_rows*width*pixel_size if you are using
 a multiple-row buffer:
   /* Guard against integer overflow */
   if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
        png_error(png_ptr,"image_data buffer would be too large");
   }
 Remember: Before you call png_read_update_info(), the png_get_*()
 functions return the values corresponding to the original PNG image.
 After you call png_read_update_info the values refer to the image
@ -2230,7 +2278,8 @@ is exactly the same.  If you are planning on displaying the image
 after each pass, the "rectangle" effect is generally considered the
 better looking one.
-If you only want the "sparkle" effect, just call png_read_rows() as
+If you only want the "sparkle" effect, just call png_read_row() or
 png_read_rows() as
 normal, with the third parameter NULL.  Make sure you make pass over
 the image number_of_passes times, and you don't change the data in the
 rows between calls.  You can change the locations of the data, just
@ -2239,6 +2288,8 @@ pass, and assumes the data from previous passes is still valid.
    png_read_rows(png_ptr, row_pointers, NULL,
        number_of_rows);
    or
    png_read_row(png_ptr, row_pointers, NULL);
 If you only want the first effect (the rectangles), do the same as
 before except pass the row buffer in the third parameter, and leave
@ -2246,6 +2297,8 @@ the second parameter NULL.
    png_read_rows(png_ptr, NULL, row_pointers,
        number_of_rows);
    or
    png_read_row(png_ptr, NULL, row_pointers);
 If you don't want libpng to handle the interlacing details, just call
 png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
@ -2357,7 +2410,7 @@ separate.
    {
       png_destroy_read_struct(&png_ptr, &info_ptr,
           (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
   png_read_end(png_ptr, end_info);
@ -2461,6 +2514,7 @@ your application instead of by libpng, you can use
             PNG_INFO_gAMA, PNG_INFO_sBIT,
             PNG_INFO_cHRM, PNG_INFO_PLTE,
             PNG_INFO_tRNS, PNG_INFO_bKGD,
             PNG_INFO_eXIf,
             PNG_INFO_hIST, PNG_INFO_pHYs,
             PNG_INFO_oFFs, PNG_INFO_tIME,
             PNG_INFO_pCAL, PNG_INFO_sRGB,
@ -2496,7 +2550,7 @@ png_infop info_ptr;
         user_error_fn, user_warning_fn);
    if (!png_ptr)
-        return (ERROR);
+        return ERROR;
    info_ptr = png_create_info_struct(png_ptr);
@ -2504,14 +2558,14 @@ png_infop info_ptr;
    {
       png_destroy_read_struct(&png_ptr,
          (png_infopp)NULL, (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
    if (setjmp(png_jmpbuf(png_ptr)))
    {
       png_destroy_read_struct(&png_ptr, &info_ptr,
          (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
    /* This one's new.  You can provide functions
@ -2545,7 +2599,7 @@ png_infop info_ptr;
    {
       png_destroy_read_struct(&png_ptr, &info_ptr,
           (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
    /* This one's new also.  Simply give it a chunk
@ -2689,7 +2743,7 @@ custom writing functions.  See the discussion under Customizing libpng.
    FILE *fp = fopen(file_name, "wb");
    if (!fp)
-       return (ERROR);
+       return ERROR;
 Next, png_struct and png_info need to be allocated and initialized.
 As these can be both relatively large, you may not want to store these
@ -2704,14 +2758,14 @@ both "png_ptr"; you can call them anything you like, such as
        user_error_fn, user_warning_fn);
    if (!png_ptr)
-       return (ERROR);
+       return ERROR;
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr)
    {
       png_destroy_write_struct(&png_ptr,
           (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
 If you want to use your own memory allocation routines,
@ -2738,7 +2792,7 @@ section below for more information on the libpng error handling.
    {
    png_destroy_write_struct(&png_ptr, &info_ptr);
       fclose(fp);
-       return (ERROR);
+       return ERROR;
    }
    ...
    return;
@ -3060,6 +3114,11 @@ width, height, bit_depth, and color_type must be the same in each call.
                     single transparent color for
                     non-paletted images (PNG_INFO_tRNS)
    png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
    exif           - Exif profile (array of
                     png_byte) (PNG_INFO_eXIf)
    png_set_hIST(png_ptr, info_ptr, hist);
    hist           - histogram of palette (array of
@ -3721,7 +3780,7 @@ in-memory bitmap formats or to be written from the same formats.  If these
 formats do not accommodate your needs then you can, and should, use the more
 sophisticated APIs above - these support a wide variety of in-memory formats
 and a wide variety of sophisticated transformations to those formats as well
-as a wide variety of APIs to manipulate ancilliary information.
+as a wide variety of APIs to manipulate ancillary information.
 To read a PNG file using the simplified API:
@ -3815,7 +3874,7 @@ PNG_FORMAT_FLAG_LINEAR flag below.
 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.
 When an alpha channel is present it is expected to denote pixel coverage
@ -3997,7 +4056,7 @@ Flags containing additional information about the image are held in
 the 'flags' field of png_image.
  PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
-    This indicates the the RGB values of the in-memory bitmap do not
+    This indicates that the RGB values of the in-memory bitmap do not
    correspond to the red, green and blue end-points defined by sRGB.
  PNG_IMAGE_FLAG_FAST == 0x02
@ -4044,7 +4103,7 @@ READ APIs
      The PNG header is read from the stdio FILE object.
   int png_image_begin_read_from_memory(png_imagep image,
-      png_const_voidp memory, png_size_t size)
+      png_const_voidp memory, size_t size)
      The PNG header is read from the given memory buffer.
@ -4079,7 +4138,7 @@ READ APIs
 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.
 WRITE APIS
@ -4197,10 +4256,10 @@ png_get_io_ptr().  For example:
 The replacement I/O functions must have prototypes as follows:
    void user_read_data(png_structp png_ptr,
-        png_bytep data, png_size_t length);
+        png_bytep data, size_t length);
    void user_write_data(png_structp png_ptr,
-        png_bytep data, png_size_t length);
+        png_bytep data, size_t length);
    void user_flush_data(png_structp png_ptr);
@ -4237,8 +4296,6 @@ functions after png_create_*_struct() has been called by calling:
        png_voidp error_ptr, png_error_ptr error_fn,
        png_error_ptr warning_fn);
    png_voidp error_ptr = png_get_error_ptr(png_ptr);
 If NULL is supplied for either error_fn or warning_fn, then the libpng
 default function will be used, calling fprintf() and/or longjmp() if a
 problem is encountered.  The replacement error functions should have
@ -4250,6 +4307,11 @@ parameters as follows:
    void user_warning_fn(png_structp png_ptr,
        png_const_charp warning_msg);
 Then, within your user_error_fn or user_warning_fn, you can retrieve
 the error_ptr if you need it, by calling
    png_voidp error_ptr = png_get_error_ptr(png_ptr);
 The motivation behind using setjmp() and longjmp() is the C++ throw and
 catch exception handling methods.  This makes the code much easier to write,
 as there is no need to check every return code of every function call.
@ -4257,7 +4319,7 @@ However, there are some uncertainties about the status of local variables
 after a longjmp, so the user may want to be careful about doing anything
 after setjmp returns non-zero besides returning itself.  Consult your
 compiler documentation for more details.  For an alternative approach, you
-may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
+may wish to use the "cexcept" facility (see https://cexcept.sourceforge.io/),
 which is illustrated in pngvalid.c and in contrib/visupng.
 Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
@ -4485,7 +4547,7 @@ in a MNG datastream.  As a minimum, it must have the MNG 8-byte signature
 and the MHDR and MEND chunks.  Libpng does not provide support for these
 or any other MNG chunks; your application must provide its own support for
 them.  You may wish to consider using libmng (available at
-http://www.libmng.com) instead.
+https://www.libmng.com/) instead.
 VIII. Changes to Libpng from version 0.88
@ -4723,7 +4785,7 @@ behavior in case the application runs out of memory part-way through
 the process.
 We changed the prototypes of png_get_compression_buffer_size() and
-png_set_compression_buffer_size() to work with png_size_t instead of
+png_set_compression_buffer_size() to work with size_t instead of
 png_uint_32.
 Support for numbered error messages was removed by default, since we
@ -4812,7 +4874,7 @@ to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
 There are changes of form in png.h, including new and changed macros to
 declare parts of the API.  Some API functions with arguments that are
 pointers to data not modified within the function have been corrected to
-declare these arguments with PNG_CONST.
+declare these arguments with const.
 Much of the internal use of C macros to control the library build has also
 changed and some of this is visible in the exported header files, in
@ -4908,18 +4970,14 @@ PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
 that it could be used to override them.  Now this function will reduce or
 increase the limits.
-Starting in libpng-1.5.10, the user limits can be set en masse with the
+Starting in libpng-1.5.22, default user limits were established. These
-configuration option PNG_SAFE_LIMITS_SUPPORTED.  If this option is enabled,
+can be overridden by application calls to png_set_user_limits(),
-a set of "safe" limits is applied in pngpriv.h.  These can be overridden by
+png_set_user_chunk_cache_max(), and/or png_set_user_malloc_max().
-application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
+The limits are now
-and/or png_set_user_malloc_max() that increase or decrease the limits.  Also,
+                             max possible  default
 in libpng-1.5.10 the default width and height limits were increased
 from 1,000,000 to 0x7fffffff (i.e., made unlimited).  Therefore, the
 limits are now
                               default      safe
   png_user_width_max        0x7fffffff    1,000,000
   png_user_height_max       0x7fffffff    1,000,000
-   png_user_chunk_cache_max  0 (unlimited)   128
+   png_user_chunk_cache_max  0 (unlimited) 1000
   png_user_chunk_malloc_max 0 (unlimited) 8,000,000
 The png_set_option() function (and the "options" member of the png struct) was
@ -5169,6 +5227,11 @@ is an error. Previously this requirement of the PNG specification was not
 enforced, and the palette was always limited to 256 entries. An over-length
 PLTE chunk found in an input PNG is silently truncated.
 Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
 attempt to decode the Exif profile; it simply returns a byte array
 containing the profile to the calling application which must do its own
 decoding.
 XIII. Detecting libpng
 The png_get_io_ptr() function has been present since libpng-0.88, has never
@ -5185,27 +5248,32 @@ control.  The git repository was built from old libpng-x.y.z.tar.gz files
 going back to version 0.70.  You can access the git repository (read only)
 at
-    git://git.code.sf.net/p/libpng/code
+    https://github.com/glennrp/libpng or
    https://git.code.sf.net/p/libpng/code.git
-or you can browse it with a web browser by selecting the "code" button at
+or you can browse it with a web browser at
-    https://sourceforge.net/projects/libpng
+    https://github.com/glennrp/libpng or
    https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
-Patches can be sent to glennrp at users.sourceforge.net or to
+Patches can be sent to png-mng-implement at lists.sourceforge.net or
-png-mng-implement at lists.sourceforge.net or you can upload them to
+uploaded to the libpng bug tracker at
 the libpng bug tracker at
-    http://libpng.sourceforge.net
+    https://libpng.sourceforge.io/
 or as a "pull request" to
    https://github.com/glennrp/libpng/pulls
 We also accept patches built from the tar or zip distributions, and
-simple verbal discriptions of bug fixes, reported either to the
+simple verbal descriptions of bug fixes, reported either to the
 SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list, or directly to glennrp.
+mailing list, as github issues.
 XV. Coding style
 Our coding style is similar to the "Allman" style
-(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
+(See https://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
 braces on separate lines:
    if (condition)
@ -5221,7 +5289,7 @@ braces on separate lines:
 The braces can be omitted from simple one-line actions:
    if (condition)
-       return (0);
+       return 0;
 We use 3-space indentation, except for continued statements which
 are usually indented the same as the first line of the statement
@ -5330,66 +5398,12 @@ with an even number of lower-case hex digits, and to make them unsigned
 We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.
-We prefer "if (something != 0)" and "if (something == 0)"
+We prefer "if (something != 0)" and "if (something == 0)" over
-over "if (something)" and if "(!something)", respectively.
+"if (something)" and if "(!something)", respectively, and for pointers
 we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)".
 We do not use the TAB character for indentation in the C sources.
 Lines do not exceed 80 characters.
 Other rules can be inferred by inspecting the libpng source.
 XVI. Y2K Compliance in libpng
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 This is your unofficial assurance that libpng from version 0.71 and
 upward through 1.6.23 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 Libpng only has two year fields.  One is a 2-byte unsigned integer
 that will hold years up to 65535.  The other, which is deprecated,
 holds the date in text format, and will hold years up to 9999.
 The integer is
    "png_uint_16 year" in png_time_struct.
 The string is
    "char time_buffer[29]" in png_struct.  This is no longer used
 in libpng-1.6.x and will be removed from libpng-1.7.0.
 There are seven time-related functions:
    png_convert_to_rfc_1123_buffer() in png.c
      (formerly png_convert_to_rfc_1152() in error, and
      also formerly png_convert_to_rfc_1123())
    png_convert_from_struct_tm() in pngwrite.c, called
      in pngwrite.c
    png_convert_from_time_t() in pngwrite.c
    png_get_tIME() in pngget.c
    png_handle_tIME() in pngrutil.c, called in pngread.c
    png_set_tIME() in pngset.c
    png_write_tIME() in pngwutil.c, called in pngwrite.c
 All appear to handle dates properly in a Y2K environment.  The
 png_convert_from_time_t() function calls gmtime() to convert from system
 clock time, which returns (year - 1900), which we properly convert to
 the full 4-digit year.  There is a possibility that applications using
 libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
 function, or that they are incorrectly passing only a 2-digit year
 instead of "year - 1900" into the png_convert_from_struct_tm() function,
 but this is not under our control.  The libpng documentation has always
 stated that it works with 4-digit years, and the APIs have been
 documented as such.
 The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
 integer to hold the year, and can hold years as large as 65535.
 zlib, upon which libpng depends, is also Y2K compliant.  It contains
 no date-related code.
   Glenn Randers-Pehrson
   libpng maintainer
   PNG Development Group
--- a/source/Irrlicht/libpng/libpng.3
+++ b/source/Irrlicht/libpng/libpng.3
@ -1,11 +1,11 @@
-.TH LIBPNG 3 "June 9, 2016"
+.TH LIBPNG 3 "April 14, 2019"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.37
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
-\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
+.SH SYNOPSIS
 \fB#include <png.h>\fP
 \fBpng_uint_32 png_access_version_number (void);\fP
 \fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
@ -35,7 +35,7 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
-\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP
+\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask\fP\fB);\fP
 \fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
@ -97,6 +97,10 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
 \fBpng_uint_32 png_get_eXIf (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fI*exif\fP\fB);\fP
 \fBpng_uint_32 png_get_eXIf_1 (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unit_32 \fP\fI*num_exif\fP\fB, png_bytep \fI*exif\fP\fB);\fP
 \fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
 \fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
@ -221,7 +225,7 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBint png_image_begin_read_from_stdio (png_imagep \fP\fIimage\fP\fB, FILE* \fIfile\fP\fB);\fP
-\fBint, png_image_begin_read_from_memory (png_imagep \fP\fIimage\fP\fB, png_const_voidp \fP\fImemory\fP\fB, png_size_t \fIsize\fP\fB);\fP
+\fBint, png_image_begin_read_from_memory (png_imagep \fP\fIimage\fP\fB, png_const_voidp \fP\fImemory\fP\fB, size_t \fIsize\fP\fB);\fP
 \fBint png_image_finish_read (png_imagep \fP\fIimage\fP\fB, png_colorp \fP\fIbackground\fP\fB, void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
@ -229,11 +233,11 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
-\fBint png_image_write_to_memory (png_imagep \fP\fIimage\fP\fB, void \fP\fI*memory\fP\fB, png_alloc_size_t * PNG_RESTRICT \fP\fImemory_bytes\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, const void \fI*colormap)\fP\fB);\fP
+\fBint png_image_write_to_memory (png_imagep \fP\fIimage\fP\fB, void \fP\fI*memory\fP\fB, png_alloc_size_t * PNG_RESTRICT \fP\fImemory_bytes\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, const void \fI*colormap\fP\fB);\fP
-\fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP
+\fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
-\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
+\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, size_t \fIpng_info_struct_size\fP\fB);\fP
 \fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
@ -247,11 +251,11 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP
-\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
+\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, size_t \fIbuffer_size\fP\fB);\fP
-\fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP
+\fBsize_t png_process_data_pause (png_structp \fP\fIpng_ptr\fP\fB, int \fIsave\fP\fB);\fP
-\fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP
+\fBpng_uint_32 png_process_data_skip (png_structp \fP\fIpng_ptr\fP\fB);\fP
 \fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
@ -293,7 +297,7 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
-\fBvoid png_set_check_for_invalid_index(png_structrp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
+\fBvoid png_set_check_for_invalid_index (png_structrp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
 \fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
@ -347,6 +351,10 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
 \fBvoid png_set_eXIf (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fIexif\fP\fB);\fP
 \fBvoid png_set_eXIf_1 (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fInum_exif\fP\fB, png_bytep \fIexif\fP\fB);\fP
 \fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
 \fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
@ -445,7 +453,7 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBvoid png_set_text_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
-\fBvoid \fP\fIpng_set_text_compression_method\fP\fB, (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod)\fP\fB);\fP
+\fBvoid png_set_text_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
 \fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
@ -467,15 +475,15 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
 \fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
-\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
+\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, size_t \fP\fIstart\fP\fB, size_t \fInum_to_check\fP\fB);\fP
 \fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
 \fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
-\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, size_t \fIlength\fP\fB);\fP
-\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, size_t \fIlength\fP\fB);\fP
 \fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
@ -507,13 +515,12 @@ the Portable Network Graphics (PNG) format image files.  It uses the
 .IR zlib(3)
 compression library.
 Following is a copy of the libpng-manual.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng
- libpng version 1.6.23 - June 9, 2016
+ Copyright (c) 2018-2019 Cosmin Truta
- Updated and distributed by Glenn Randers-Pehrson
+ Copyright (c) 1998-2018 Glenn Randers-Pehrson
 <glennrp at users.sourceforge.net>
 Copyright (c) 1998-2016 Glenn Randers-Pehrson
 This document is released under the libpng license.
 For conditions of distribution and use, see the disclaimer
@ -521,9 +528,13 @@ libpng-manual.txt - A description on how to use and modify libpng
 Based on:
- libpng versions 0.97, January 1998, through 1.6.23 - June 9, 2016
+ libpng version 1.6.36, December 2018, through 1.6.37 - April 2019
 Updated and distributed by Cosmin Truta
 Copyright (c) 2018-2019 Cosmin Truta
 libpng versions 0.97, January 1998, through 1.6.35 - July 2018
 Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2016 Glenn Randers-Pehrson
+ Copyright (c) 1998-2018 Glenn Randers-Pehrson
 libpng 1.0 beta 6 - version 0.96 - May 28, 1997
 Updated and distributed by Andreas Dilger
@ -555,7 +566,6 @@ libpng-manual.txt - A description on how to use and modify libpng
 XIII. Detecting libpng
  XIV. Source code repository
   XV. Coding style
  XVI. Y2K Compliance in libpng
 .SH I. Introduction
@ -576,17 +586,17 @@ file format in application programs.
 The PNG specification (second edition), November 2003, is available as
 a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
-<http://www.w3.org/TR/2003/REC-PNG-20031110/
+<https://www.w3.org/TR/2003/REC-PNG-20031110/>.
 The W3C and ISO documents have identical technical content.
 The PNG-1.2 specification is available at
-<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
+<https://png-mng.sourceforge.io/pub/png/spec/1.2/>.
 It is technically equivalent
 to the PNG specification (second edition) but has some additional material.
-The PNG-1.0 specification is available as RFC 2083 
+The PNG-1.0 specification is available as RFC 2083 at
-<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+<https://png-mng.sourceforge.io/pub/png/spec/1.0/> and as a
-W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
+W3C Recommendation at <https://www.w3.org/TR/REC-png-961001>.
 Some additional chunks are described in the special-purpose public chunks
 documents at <http://www.libpng.org/pub/png/spec/register/>
@ -611,7 +621,7 @@ majority of the needs of its users.
 Libpng uses zlib for its compression and decompression of PNG files.
 Further information about zlib, and the latest version of zlib, can
-be found at the zlib home page, <http://zlib.net/>.
+be found at the zlib home page, <https://zlib.net/>.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
@ -858,18 +868,18 @@ Customizing libpng.
    FILE *fp = fopen(file_name, "rb");
    if (!fp)
    {
-       return (ERROR);
+       return ERROR;
    }
    if (fread(header, 1, number, fp) != number)
    {
-       return (ERROR);
+       return ERROR;
    }
    is_png = !png_sig_cmp(header, 0, number);
    if (!is_png)
    {
-       return (NOT_PNG);
+       return NOT_PNG;
    }
 Next, png_struct and png_info need to be allocated and initialized.  In
@ -888,7 +898,7 @@ create the structure, so your application should check for that.
        user_error_fn, user_warning_fn);
    if (!png_ptr)
-       return (ERROR);
+       return ERROR;
    png_infop info_ptr = png_create_info_struct(png_ptr);
@ -896,7 +906,7 @@ create the structure, so your application should check for that.
    {
       png_destroy_read_struct(&png_ptr,
           (png_infopp)NULL, (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
 If you want to use your own memory allocation routines,
@ -931,7 +941,7 @@ free any memory.
       png_destroy_read_struct(&png_ptr, &info_ptr,
           &end_info);
       fclose(fp);
-       return (ERROR);
+       return ERROR;
    }
 Pass (png_infopp)NULL instead of &end_info if you didn't create
@ -977,8 +987,9 @@ the default, use
 The values for png_set_crc_action() say how libpng is to handle CRC errors in
 ancillary and critical chunks, and whether to use the data contained
-therein.  Note that it is impossible to "discard" data in a critical
+therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
-chunk.
+is handled while reading the IDAT chunk. Note that it is impossible to
 "discard" data in a critical chunk.
 Choices for (int) crit_action are
   PNG_CRC_DEFAULT      0  error/quit
@ -995,6 +1006,9 @@ Choices for (int) ancil_action are
   PNG_CRC_QUIET_USE    4  quiet/use data
   PNG_CRC_NO_CHANGE    5  use the current value
 When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
 checksums are not only ignored, but they are not evaluated.
 .SS Setting up callback code
 You can set up a callback function to handle any unknown chunks in the
@ -1009,7 +1023,7 @@ input stream. You must supply the function
           png_byte name[5];
           png_byte *data;
-           png_size_t size;
+           size_t size;
       /* Note that libpng has already taken care of
          the CRC handling */
@ -1018,9 +1032,9 @@ input stream. You must supply the function
          unknown chunk structure, process it, and return one
          of the following: */
-       return (\-n); /* chunk had an error */
+       return \-n; /* chunk had an error */
-       return (0); /* did not recognize */
+       return 0; /* did not recognize */
-       return (n); /* success */
+       return n; /* success */
    }
 (You can give your function another name that you like instead of
@ -1069,7 +1083,7 @@ non-interlaced case the row that was just handled is simply one less than the
 passed in row number, and pass will always be 0.  For the interlaced case the
 same applies unless the row value is 0, in which case the row just handled was
 the last one from one of the preceding passes.  Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
+pass you cannot be sure that the preceding pass is just 'pass\-1'; if you really
 need to know what the last pass is record (row,pass) from the callback and use
 the last recorded value each time.
@ -1194,8 +1208,9 @@ where 0x7fffffffL means unlimited.  You can retrieve this limit with
   chunk_cache_max = png_get_chunk_cache_max(png_ptr);
 Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
-memory that a compressed chunk other than IDAT can occupy, when decompressed.
+memory that any chunk other than IDAT can occupy, originally or when
-You can change this limit with
+decompressed (prior to libpng-1.6.32 the limit was only applied to compressed
 chunks after decompression). You can change this limit with
   png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
@ -1491,7 +1506,16 @@ premultiplication.
    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
-This is the default libpng handling of the alpha channel - it is not
+Choices for the alpha_mode are
    PNG_ALPHA_PNG           0 /* according to the PNG standard */
    PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
    PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
    PNG_ALPHA_PREMULTIPLIED 1 /* as above */
    PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
    PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
 PNG_ALPHA_PNG is the default libpng handling of the alpha channel. It is not
 pre-multiplied into the color components. In addition the call states
 that the output is for a sRGB system and causes all PNG files without gAMA
 chunks to be assumed to be encoded using sRGB.
@ -1499,7 +1523,7 @@ chunks to be assumed to be encoded using sRGB.
    png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
 In this case the output is assumed to be something like an sRGB conformant
-display preceeded by a power-law lookup table of power 1.45.  This is how
+display preceded by a power-law lookup table of power 1.45.  This is how
 early Mac systems behaved.
    png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
@ -1507,7 +1531,7 @@ early Mac systems behaved.
 This is the classic Jim Blinn approach and will work in academic
 environments where everything is done by the book.  It has the shortcoming
 of assuming that input PNG data with no gamma information is linear - this
-is unlikely to be correct unless the PNG files where generated locally.
+is unlikely to be correct unless the PNG files were generated locally.
 Most of the time the output precision will be so low as to show
 significant banding in dark areas of the image.
@ -1551,7 +1575,7 @@ faster.)
 When the default gamma of PNG files doesn't match the output gamma.
 If you have PNG files with no gamma information png_set_alpha_mode allows
-you to provide a default gamma, but it also sets the ouput gamma to the
+you to provide a default gamma, but it also sets the output gamma to the
 matching value.  If you know your PNG files have a gamma that doesn't
 match the output you can take advantage of the fact that
 png_set_alpha_mode always sets the output gamma but only sets the PNG
@ -1696,7 +1720,20 @@ row_pointers prior to calling png_read_png() with
   png_set_rows(png_ptr, info_ptr, &row_pointers);
 Alternatively you could allocate your image in one big block and define
-row_pointers[i] to point into the proper places in your block.
+row_pointers[i] to point into the proper places in your block, but first
 be sure that your platform is able to allocate such a large buffer:
   /* Guard against integer overflow */
   if (height > PNG_SIZE_MAX/(width*pixel_size)) {
        png_error(png_ptr,"image_data buffer would be too large");
   }
   png_bytep buffer=png_malloc(png_ptr,height*width*pixel_size);
   for (int i=0; i<height, i++)
      row_pointers[i]=buffer+i*width*pixel_size;
   png_set_rows(png_ptr, info_ptr, &row_pointers);
 If you use png_set_rows(), the application is responsible for freeing
 row_pointers (and row_pointers[i], if they were separately allocated).
@ -1823,6 +1860,11 @@ in until png_read_end() has read the chunk data following the image.
    rowbytes = png_get_rowbytes(png_ptr, info_ptr);
    rowbytes       - number of bytes needed to hold a row
                     This value, the bit_depth, color_type,
                     and the number of channels can change
                     if you use transforms such as
                     png_set_expand(). See
                     png_read_update_info(), below.
    signature = png_get_signature(png_ptr, info_ptr);
@ -1941,6 +1983,11 @@ png_set_rgb_to_gray()).
                     the single transparent color for
                     non-paletted images (PNG_INFO_tRNS)
    png_get_eXIf_1(png_ptr, info_ptr, &num_exif, &exif);
                     (PNG_INFO_eXIf)
    exif           - Exif profile (array of png_byte)
    png_get_hIST(png_ptr, info_ptr, &hist);
                     (PNG_INFO_hIST)
@ -2652,6 +2699,16 @@ are allocating one large chunk, you will need to build an
 array of pointers to each row, as it will be needed for some
 of the functions below.
 Be sure that your platform can allocate the buffer that you'll need.
 libpng internally checks for oversize width, but you'll need to
 do your own check for number_of_rows*width*pixel_size if you are using
 a multiple-row buffer:
   /* Guard against integer overflow */
   if (number_of_rows > PNG_SIZE_MAX/(width*pixel_size)) {
        png_error(png_ptr,"image_data buffer would be too large");
   }
 Remember: Before you call png_read_update_info(), the png_get_*()
 functions return the values corresponding to the original PNG image.
 After you call png_read_update_info the values refer to the image
@ -2740,7 +2797,8 @@ is exactly the same.  If you are planning on displaying the image
 after each pass, the "rectangle" effect is generally considered the
 better looking one.
-If you only want the "sparkle" effect, just call png_read_rows() as
+If you only want the "sparkle" effect, just call png_read_row() or
 png_read_rows() as
 normal, with the third parameter NULL.  Make sure you make pass over
 the image number_of_passes times, and you don't change the data in the
 rows between calls.  You can change the locations of the data, just
@ -2749,6 +2807,8 @@ pass, and assumes the data from previous passes is still valid.
    png_read_rows(png_ptr, row_pointers, NULL,
        number_of_rows);
    or
    png_read_row(png_ptr, row_pointers, NULL);
 If you only want the first effect (the rectangles), do the same as
 before except pass the row buffer in the third parameter, and leave
@ -2756,6 +2816,8 @@ the second parameter NULL.
    png_read_rows(png_ptr, NULL, row_pointers,
        number_of_rows);
    or
    png_read_row(png_ptr, NULL, row_pointers);
 If you don't want libpng to handle the interlacing details, just call
 png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
@ -2867,7 +2929,7 @@ separate.
    {
       png_destroy_read_struct(&png_ptr, &info_ptr,
           (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
   png_read_end(png_ptr, end_info);
@ -2971,6 +3033,7 @@ your application instead of by libpng, you can use
             PNG_INFO_gAMA, PNG_INFO_sBIT,
             PNG_INFO_cHRM, PNG_INFO_PLTE,
             PNG_INFO_tRNS, PNG_INFO_bKGD,
             PNG_INFO_eXIf,
             PNG_INFO_hIST, PNG_INFO_pHYs,
             PNG_INFO_oFFs, PNG_INFO_tIME,
             PNG_INFO_pCAL, PNG_INFO_sRGB,
@ -3006,7 +3069,7 @@ png_infop info_ptr;
         user_error_fn, user_warning_fn);
    if (!png_ptr)
-        return (ERROR);
+        return ERROR;
    info_ptr = png_create_info_struct(png_ptr);
@ -3014,14 +3077,14 @@ png_infop info_ptr;
    {
       png_destroy_read_struct(&png_ptr,
          (png_infopp)NULL, (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
    if (setjmp(png_jmpbuf(png_ptr)))
    {
       png_destroy_read_struct(&png_ptr, &info_ptr,
          (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
    /* This one's new.  You can provide functions
@ -3055,7 +3118,7 @@ png_infop info_ptr;
    {
       png_destroy_read_struct(&png_ptr, &info_ptr,
           (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
    /* This one's new also.  Simply give it a chunk
@ -3199,7 +3262,7 @@ custom writing functions.  See the discussion under Customizing libpng.
    FILE *fp = fopen(file_name, "wb");
    if (!fp)
-       return (ERROR);
+       return ERROR;
 Next, png_struct and png_info need to be allocated and initialized.
 As these can be both relatively large, you may not want to store these
@ -3214,14 +3277,14 @@ both "png_ptr"; you can call them anything you like, such as
        user_error_fn, user_warning_fn);
    if (!png_ptr)
-       return (ERROR);
+       return ERROR;
    png_infop info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr)
    {
       png_destroy_write_struct(&png_ptr,
           (png_infopp)NULL);
-       return (ERROR);
+       return ERROR;
    }
 If you want to use your own memory allocation routines,
@ -3248,7 +3311,7 @@ section below for more information on the libpng error handling.
    {
    png_destroy_write_struct(&png_ptr, &info_ptr);
       fclose(fp);
-       return (ERROR);
+       return ERROR;
    }
    ...
    return;
@ -3570,6 +3633,11 @@ width, height, bit_depth, and color_type must be the same in each call.
                     single transparent color for
                     non-paletted images (PNG_INFO_tRNS)
    png_set_eXIf_1(png_ptr, info_ptr, num_exif, exif);
    exif           - Exif profile (array of
                     png_byte) (PNG_INFO_eXIf)
    png_set_hIST(png_ptr, info_ptr, hist);
    hist           - histogram of palette (array of
@ -4231,7 +4299,7 @@ in-memory bitmap formats or to be written from the same formats.  If these
 formats do not accommodate your needs then you can, and should, use the more
 sophisticated APIs above - these support a wide variety of in-memory formats
 and a wide variety of sophisticated transformations to those formats as well
-as a wide variety of APIs to manipulate ancilliary information.
+as a wide variety of APIs to manipulate ancillary information.
 To read a PNG file using the simplified API:
@ -4325,7 +4393,7 @@ PNG_FORMAT_FLAG_LINEAR flag below.
 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.
 When an alpha channel is present it is expected to denote pixel coverage
@ -4507,7 +4575,7 @@ Flags containing additional information about the image are held in
 the 'flags' field of png_image.
  PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
-    This indicates the the RGB values of the in-memory bitmap do not
+    This indicates that the RGB values of the in-memory bitmap do not
    correspond to the red, green and blue end-points defined by sRGB.
  PNG_IMAGE_FLAG_FAST == 0x02
@ -4554,7 +4622,7 @@ READ APIs
      The PNG header is read from the stdio FILE object.
   int png_image_begin_read_from_memory(png_imagep image,
-      png_const_voidp memory, png_size_t size)
+      png_const_voidp memory, size_t size)
      The PNG header is read from the given memory buffer.
@ -4589,7 +4657,7 @@ READ APIs
 When the simplified API needs to convert between sRGB and linear colorspaces,
 the actual sRGB transfer curve defined in the sRGB specification (see the
-article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
 approximation used elsewhere in libpng.
 WRITE APIS
@ -4707,10 +4775,10 @@ png_get_io_ptr().  For example:
 The replacement I/O functions must have prototypes as follows:
    void user_read_data(png_structp png_ptr,
-        png_bytep data, png_size_t length);
+        png_bytep data, size_t length);
    void user_write_data(png_structp png_ptr,
-        png_bytep data, png_size_t length);
+        png_bytep data, size_t length);
    void user_flush_data(png_structp png_ptr);
@ -4747,8 +4815,6 @@ functions after png_create_*_struct() has been called by calling:
        png_voidp error_ptr, png_error_ptr error_fn,
        png_error_ptr warning_fn);
    png_voidp error_ptr = png_get_error_ptr(png_ptr);
 If NULL is supplied for either error_fn or warning_fn, then the libpng
 default function will be used, calling fprintf() and/or longjmp() if a
 problem is encountered.  The replacement error functions should have
@ -4760,6 +4826,11 @@ parameters as follows:
    void user_warning_fn(png_structp png_ptr,
        png_const_charp warning_msg);
 Then, within your user_error_fn or user_warning_fn, you can retrieve
 the error_ptr if you need it, by calling
    png_voidp error_ptr = png_get_error_ptr(png_ptr);
 The motivation behind using setjmp() and longjmp() is the C++ throw and
 catch exception handling methods.  This makes the code much easier to write,
 as there is no need to check every return code of every function call.
@ -4767,7 +4838,7 @@ However, there are some uncertainties about the status of local variables
 after a longjmp, so the user may want to be careful about doing anything
 after setjmp returns non-zero besides returning itself.  Consult your
 compiler documentation for more details.  For an alternative approach, you
-may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
+may wish to use the "cexcept" facility (see https://cexcept.sourceforge.io/),
 which is illustrated in pngvalid.c and in contrib/visupng.
 Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
@ -4995,7 +5066,7 @@ in a MNG datastream.  As a minimum, it must have the MNG 8-byte signature
 and the MHDR and MEND chunks.  Libpng does not provide support for these
 or any other MNG chunks; your application must provide its own support for
 them.  You may wish to consider using libmng (available at
-http://www.libmng.com) instead.
+https://www.libmng.com/) instead.
 .SH VIII. Changes to Libpng from version 0.88
@ -5233,7 +5304,7 @@ behavior in case the application runs out of memory part-way through
 the process.
 We changed the prototypes of png_get_compression_buffer_size() and
-png_set_compression_buffer_size() to work with png_size_t instead of
+png_set_compression_buffer_size() to work with size_t instead of
 png_uint_32.
 Support for numbered error messages was removed by default, since we
@ -5322,7 +5393,7 @@ to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
 There are changes of form in png.h, including new and changed macros to
 declare parts of the API.  Some API functions with arguments that are
 pointers to data not modified within the function have been corrected to
-declare these arguments with PNG_CONST.
+declare these arguments with const.
 Much of the internal use of C macros to control the library build has also
 changed and some of this is visible in the exported header files, in
@ -5418,18 +5489,14 @@ PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
 that it could be used to override them.  Now this function will reduce or
 increase the limits.
-Starting in libpng-1.5.10, the user limits can be set en masse with the
+Starting in libpng-1.5.22, default user limits were established. These
-configuration option PNG_SAFE_LIMITS_SUPPORTED.  If this option is enabled,
+can be overridden by application calls to png_set_user_limits(),
-a set of "safe" limits is applied in pngpriv.h.  These can be overridden by
+png_set_user_chunk_cache_max(), and/or png_set_user_malloc_max().
-application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
+The limits are now
-and/or png_set_user_malloc_max() that increase or decrease the limits.  Also,
+                             max possible  default
 in libpng-1.5.10 the default width and height limits were increased
 from 1,000,000 to 0x7fffffff (i.e., made unlimited).  Therefore, the
 limits are now
                               default      safe
   png_user_width_max        0x7fffffff    1,000,000
   png_user_height_max       0x7fffffff    1,000,000
-   png_user_chunk_cache_max  0 (unlimited)   128
+   png_user_chunk_cache_max  0 (unlimited) 1000
   png_user_chunk_malloc_max 0 (unlimited) 8,000,000
 The png_set_option() function (and the "options" member of the png struct) was
@ -5679,6 +5746,11 @@ is an error. Previously this requirement of the PNG specification was not
 enforced, and the palette was always limited to 256 entries. An over-length
 PLTE chunk found in an input PNG is silently truncated.
 Starting with libpng-1.6.31, the eXIf chunk is supported. Libpng does not
 attempt to decode the Exif profile; it simply returns a byte array
 containing the profile to the calling application which must do its own
 decoding.
 .SH XIII. Detecting libpng
 The png_get_io_ptr() function has been present since libpng-0.88, has never
@ -5695,27 +5767,32 @@ control.  The git repository was built from old libpng-x.y.z.tar.gz files
 going back to version 0.70.  You can access the git repository (read only)
 at
-    git://git.code.sf.net/p/libpng/code
+    https://github.com/glennrp/libpng or
    https://git.code.sf.net/p/libpng/code.git
-or you can browse it with a web browser by selecting the "code" button at
+or you can browse it with a web browser at
-    https://sourceforge.net/projects/libpng
+    https://github.com/glennrp/libpng or
    https://sourceforge.net/p/libpng/code/ci/libpng16/tree/
-Patches can be sent to glennrp at users.sourceforge.net or to
+Patches can be sent to png-mng-implement at lists.sourceforge.net or
-png-mng-implement at lists.sourceforge.net or you can upload them to
+uploaded to the libpng bug tracker at
 the libpng bug tracker at
-    http://libpng.sourceforge.net
+    https://libpng.sourceforge.io/
 or as a "pull request" to
    https://github.com/glennrp/libpng/pulls
 We also accept patches built from the tar or zip distributions, and
-simple verbal discriptions of bug fixes, reported either to the
+simple verbal descriptions of bug fixes, reported either to the
 SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list, or directly to glennrp.
+mailing list, as github issues.
 .SH XV. Coding style
 Our coding style is similar to the "Allman" style
-(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
+(See https://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
 braces on separate lines:
    if (condition)
@ -5731,7 +5808,7 @@ braces on separate lines:
 The braces can be omitted from simple one-line actions:
    if (condition)
-       return (0);
+       return 0;
 We use 3-space indentation, except for continued statements which
 are usually indented the same as the first line of the statement
@ -5840,8 +5917,9 @@ with an even number of lower-case hex digits, and to make them unsigned
 We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.
-We prefer "if (something != 0)" and "if (something == 0)"
+We prefer "if (something != 0)" and "if (something == 0)" over
-over "if (something)" and if "(!something)", respectively.
+"if (something)" and if "(!something)", respectively, and for pointers
 we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)".
 We do not use the TAB character for indentation in the C sources.
@ -5849,61 +5927,6 @@ Lines do not exceed 80 characters.
 Other rules can be inferred by inspecting the libpng source.
 .SH XVI. Y2K Compliance in libpng
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
 This is your unofficial assurance that libpng from version 0.71 and
 upward through 1.6.23 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 Libpng only has two year fields.  One is a 2-byte unsigned integer
 that will hold years up to 65535.  The other, which is deprecated,
 holds the date in text format, and will hold years up to 9999.
 The integer is
    "png_uint_16 year" in png_time_struct.
 The string is
    "char time_buffer[29]" in png_struct.  This is no longer used
 in libpng-1.6.x and will be removed from libpng-1.7.0.
 There are seven time-related functions:
    png_convert_to_rfc_1123_buffer() in png.c
      (formerly png_convert_to_rfc_1152() in error, and
      also formerly png_convert_to_rfc_1123())
    png_convert_from_struct_tm() in pngwrite.c, called
      in pngwrite.c
    png_convert_from_time_t() in pngwrite.c
    png_get_tIME() in pngget.c
    png_handle_tIME() in pngrutil.c, called in pngread.c
    png_set_tIME() in pngset.c
    png_write_tIME() in pngwutil.c, called in pngwrite.c
 All appear to handle dates properly in a Y2K environment.  The
 png_convert_from_time_t() function calls gmtime() to convert from system
 clock time, which returns (year - 1900), which we properly convert to
 the full 4-digit year.  There is a possibility that applications using
 libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
 function, or that they are incorrectly passing only a 2-digit year
 instead of "year - 1900" into the png_convert_from_struct_tm() function,
 but this is not under our control.  The libpng documentation has always
 stated that it works with 4-digit years, and the APIs have been
 documented as such.
 The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
 integer to hold the year, and can hold years as large as 65535.
 zlib, upon which libpng depends, is also Y2K compliant.  It contains
 no date-related code.
   Glenn Randers-Pehrson
   libpng maintainer
   PNG Development Group
 .SH NOTE
 Note about libpng version numbers:
@ -5951,30 +5974,32 @@ the first widely used release:
 1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
 1.0.7                    1    10007  (still compatible)
 ...
- 1.0.19                  10    10019  10.so.0.19[.0]
+ 1.0.69                  10    10069  10.so.0.69[.0]
 ...
- 1.2.56                  13    10256  12.so.0.56[.0]
+ 1.2.59                  13    10259  12.so.0.59[.0]
 ...
- 1.5.27                  15    10527  15.so.15.27[.0]
+ 1.4.20                  14    10420  14.so.0.20[.0]
 ...
- 1.6.23                  16    10623  16.so.16.23[.0]
+ 1.5.30                  15    10530  15.so.15.30[.0]
 ...
 1.6.35                  16    10635  16.so.16.35[.0]
-Henceforth the source version will match the shared-library minor
+Henceforth the source version will match the shared-library minor and
-and patch numbers; the shared-library major version number will be
+patch numbers; the shared-library major version number will be used for
-used for changes in backward compatibility, as it is intended.  The
+changes in backward compatibility, as it is intended.
-PNG_PNGLIB_VER macro, which is not used within libpng but is available
+The PNG_PNGLIB_VER macro, which is not used within libpng but is
-for applications, is an unsigned integer of the form xyyzz corresponding
+available for applications, is an unsigned integer of the form XYYZZ
-to the source version x.y.z (leading zeros in y and z).  Beta versions
+corresponding to the source version X.Y.Z (leading zeros in Y and Z).
-were given the previous public release number plus a letter, until
+Beta versions were given the previous public release number plus a
-version 1.0.6j; from then on they were given the upcoming public
+letter, until version 1.0.6j; from then on they were given the upcoming
-release number plus "betaNN" or "rcNN".
+public release number plus "betaNN" or "rcNN".
 .SH "SEE ALSO"
 .IR libpngpf(3) ", " png(5)
 .LP
 .IR libpng :
 .IP
-http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
+https://libpng.sourceforge.io/ (follow the [DOWNLOAD] link)
 http://www.libpng.org/pub/png
 .LP
@ -5984,7 +6009,7 @@ http://www.libpng.org/pub/png
 .I libpng
 or at
 .br
-ftp://ftp.info-zip.org/pub/infozip/zlib
+https://zlib.net/
 .LP
 .IR PNG specification: RFC 2083
@ -5993,19 +6018,20 @@ ftp://ftp.info-zip.org/pub/infozip/zlib
 .I libpng
 or at
 .br
-ftp://ftp.rfc-editor.org:/in-notes/rfc2083.txt
+https://www.ietf.org/rfc/rfc2083.txt
 .br
 or (as a W3C Recommendation) at
 .br
-http://www.w3.org/TR/REC-png.html
+https://www.w3.org/TR/REC-png.html
 .LP
 In the case of any inconsistency between the PNG specification
 and this library, the specification takes precedence.
 .SH AUTHORS
-This man page: Glenn Randers-Pehrson
+This man page:
-<glennrp at users.sourceforge.net>
+Initially created by Glenn Randers-Pehrson.
 Maintained by Cosmin Truta.
 The contributing authors would like to thank all those who helped
 with testing, bug fixes, and patience.  This wouldn't have been
@ -6013,157 +6039,14 @@ possible without all of you.
 Thanks to Frank J. T. Wojcik for helping with the documentation.
-Libpng version 1.6.23 - June 9, 2016:
+Libpng:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
-Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
+Maintained by Cosmin Truta.
 Supported by the PNG development group
 .br
 png-mng-implement at lists.sf.net
 (subscription required; visit
 png-mng-implement at lists.sourceforge.net (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe).
 .SH NOTICES:
 This copy of the libpng notices is provided for your convenience.  In case of
 any discrepancy between this copy and the notices in the file png.h that is
 included in the libpng distribution, the latter shall prevail.
 COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
 If you modify libpng you may insert additional notices immediately following
 this sentence.
 This code is released under the libpng license.
 libpng versions 1.0.7, July 1, 2000 through 1.6.23, June 9, 2016 are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
 added to the list of Contributing Authors:
   Simon-Pierre Cadieux
   Eric S. Raymond
   Mans Rullgard
   Cosmin Truta
   Gilles Vollant
   James Yu
 and with the following additions to the disclaimer:
   There is no warranty against interference with your enjoyment of the
   library or against infringement.  There is no warranty that our
   efforts or the library will fulfill any of your particular purposes
   or needs.  This library is provided with all faults, and the entire
   risk of satisfactory quality, performance, accuracy, and effort is with
   the user.
 Some files in the "contrib" directory and some configure-generated
 files that are distributed with libpng have other copyright owners and
 are released under other open source licenses.
 libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 libpng-0.96, and are distributed according to the same disclaimer and
 license as libpng-0.96, with the following individuals added to the list
 of Contributing Authors:
   Tom Lane
   Glenn Randers-Pehrson
   Willem van Schaik
 libpng versions 0.89, June 1996, through 0.96, May 1997, are
 Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
 and are distributed according to the same disclaimer and license as
 libpng-0.88, with the following individuals added to the list of
 Contributing Authors:
   John Bowler
   Kevin Bracey
   Sam Bushell
   Magnus Holmgren
   Greg Roelofs
   Tom Tanner
 Some files in the "scripts" directory have other copyright owners
 but are released under this license.
 libpng versions 0.5, May 1995, through 0.88, January 1996, are
 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 For the purposes of this copyright and license, "Contributing Authors"
 is defined as the following set of individuals:
   Andreas Dilger
   Dave Martindale
   Guy Eric Schalnat
   Paul Schmidt
   Tim Wegner
 The PNG Reference Library is supplied "AS IS".  The Contributing Authors
 and Group 42, Inc. disclaim all warranties, expressed or implied,
 including, without limitation, the warranties of merchantability and of
 fitness for any purpose.  The Contributing Authors and Group 42, Inc.
 assume no liability for direct, indirect, incidental, special, exemplary,
 or consequential damages, which may result from the use of the PNG
 Reference Library, even if advised of the possibility of such damage.
 Permission is hereby granted to use, copy, modify, and distribute this
 source code, or portions hereof, for any purpose, without fee, subject
 to the following restrictions:
  1. The origin of this source code must not be misrepresented.
  2. Altered versions must be plainly marked as such and must not
     be misrepresented as being the original source.
  3. This Copyright notice may not be removed or altered from any
     source or altered source distribution.
 The Contributing Authors and Group 42, Inc. specifically permit, without
 fee, and encourage the use of this source code as a component to
 supporting the PNG file format in commercial products.  If you use this
 source code in a product, acknowledgment is not required but would be
 appreciated.
 END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
 TRADEMARK:
 The name "libpng" has not been registered by the Copyright owner
 as a trademark in any jurisdiction.  However, because libpng has
 been distributed and maintained world-wide, continually since 1995,
 the Copyright owner claims "common-law trademark protection" in any
 jurisdiction where common-law trademark is recognized.
 OSI CERTIFICATION:
 Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
 a certification mark of the Open Source Initiative. OSI has not addressed
 the additional disclaimers inserted at version 1.0.7.
 EXPORT CONTROL:
 The Copyright owner believes that the Export Control Classification
 Number (ECCN) for libpng is EAR99, which means not subject to export
 controls or International Traffic in Arms Regulations (ITAR) because
 it is open source, publicly available software, that does not contain
 any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
 734.7(b).
 A "png_get_copyright" function is available, for convenient use in "about"
 boxes and the like:
   printf("%s", png_get_copyright(NULL));
 Also, the PNG logo (in PNG format, of course) is supplied in the
 files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
 June 9, 2016
 .\" end of man page
--- a/source/Irrlicht/libpng/libpng.pc.in
+++ b/source/Irrlicht/libpng/libpng.pc.in
@ -1,11 +0,0 @@
 prefix=@prefix@
 exec_prefix=@exec_prefix@
 libdir=@libdir@
 includedir=@includedir@/libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
 Name: libpng
 Description: Loads and saves PNG files
 Version: @PNGLIB_VERSION@
 Libs: -L${libdir} -lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
 Libs.private: @LIBS@
 Cflags: -I${includedir}
--- a/source/Irrlicht/libpng/libpngpf.3
+++ b/source/Irrlicht/libpng/libpngpf.3
@ -1,18 +1,24 @@
-.TH LIBPNGPF 3 "June 9, 2016"
+.TH LIBPNGPF 3 "April 14, 2019"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.23
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.37
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
-\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer \fP\fImaintained\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short description of each \fIfunction.
+\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer
 \fP\fImaintained\fP\fB, now that the private function prototypes are hidden in
 \fP\fIpngpriv.h\fP\fB and not accessible to applications. Look in
 \fP\fIpngpriv.h\fP\fB for the prototypes and a short description of each
 function.
 .SH DESCRIPTION
 The functions previously listed here are used privately by libpng and are not
 available for use by applications.  They are not "exported" to applications
 using shared libraries.
-.SH SEE ALSO
+.SH "SEE ALSO"
 .BR "png"(5), " libpng"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
-.SH AUTHOR
+
-Glenn Randers-Pehrson
+.SH AUTHORS
 Cosmin Truta, Glenn Randers-Pehrson
--- a/source/Irrlicht/libpng/png.5
+++ b/source/Irrlicht/libpng/png.5
@ -1,47 +1,49 @@
-.TH PNG 5 "June 9, 2016"
+.TH PNG 5 "April 14, 2019"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
 PNG (Portable Network Graphics) is an extensible file format for the
-lossless, portable, well-compressed storage of raster images. PNG provides
+lossless, portable, well-compressed storage of raster images.  PNG
-a patent-free replacement for GIF and can also replace many
+provides a patent-free replacement for GIF, and can also replace many
 common uses of TIFF. Indexed-color, grayscale, and truecolor images are
 supported, plus an optional alpha channel.  Sample depths range from
 1 to 16 bits.
 .br
-
+PNG is designed to work well in online viewing applications, such
-PNG is designed to work well in online viewing applications, such as the
+as the World Wide Web, so it is fully streamable with a progressive
-World Wide Web, so it is fully streamable with a progressive display
+display option.  PNG is robust, providing both full file integrity
-option. PNG is robust, providing both full file integrity checking and
+checking and fast, simple detection of common transmission errors.
-fast, simple detection of common transmission errors. Also, PNG can store
+Also, PNG can store gamma and chromaticity data for improved color
-gamma and chromaticity data for improved color matching on heterogeneous
+matching on heterogeneous platforms.
 platforms.
 .SH "SEE ALSO"
 .BR "libpng"(3), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
 .LP
-PNG specification (second edition), November 2003:
+PNG Specification (Second Edition), November 2003:
 .IP
 .br
-  <http://www.w3.org/TR/2003/REC-PNG-20031110/
+https://www.w3.org/TR/2003/REC-PNG-20031110/
 PNG 1.2 specification, July 1999:
 .IP
 .br
 http://png-mng.sourceforge.net/pub/png/spec/1.2/
 .LP
-PNG 1.0 specification, October 1996:
+PNG 1.2 Specification, July 1999:
 .IP
 .br
 https://png-mng.sourceforge.io/pub/png/spec/1.2/
 .LP
 PNG 1.0 Specification, October 1996:
 .IP
 .br
 RFC 2083
 .br
 https://www.ietf.org/rfc/rfc2083.txt
 .IP
 .br
-http://www.ietf.org/rfc/rfc2083.txt
+or W3C Recommendation
 .br
-or (as a W3C Recommendation) at
+https://www.w3.org/TR/REC-png-961001
-.br
+
 http://www.w3.org/TR/REC-png-961001
 .SH AUTHORS
-This man page: Glenn Randers-Pehrson
+This man page: Cosmin Truta, Glenn Randers-Pehrson
 .LP
 Portable Network Graphics (PNG) Specification (Second Edition)
 Information technology - Computer graphics and image processing -
@ -53,22 +55,30 @@ Glenn Randers-Pehrson and others (png-list).
 .LP
 Portable Network Graphics (PNG) Specification Version 1.0 (October 1, 1996):
 Thomas Boutell and others (png-list).
 .LP
-
+.SH COPYRIGHT
 .SH COPYRIGHT NOTICE
 .LP
-This man page is Copyright (c) 1998-2006 Glenn Randers-Pehrson.  See png.h
+This man page is
-for conditions of use and distribution.
+.br
 Copyright (c) 2018-2019 Cosmin Truta.
 .br
 Copyright (c) 1998-2006 Glenn Randers-Pehrson.
 .br
 See png.h for conditions of use and distribution.
 .LP
 The PNG Specification (Second Edition) is
 .br
 Copyright (c) 2003 W3C. (MIT, ERCIM, Keio), All Rights Reserved.
 .LP
-The PNG-1.2 specification is copyright (c) 1999 Glenn Randers-Pehrson.
+The PNG-1.2 Specification is
 .br
 Copyright (c) 1999 Glenn Randers-Pehrson.
 .br
 See the specification for conditions of use and distribution.
 .LP
-The PNG-1.0 specification is copyright (c) 1996 Massachusetts Institute of
+The PNG-1.0 Specification is
-Technology.  See the specification for conditions of use and distribution.
+.br
-.LP
+Copyright (c) 1996 Massachusetts Institute of Technology.
 .br
 See the specification for conditions of use and distribution.
 .\" end of man page
--- a/source/Irrlicht/libpng/png.c
+++ b/source/Irrlicht/libpng/png.c
@ -1,10 +1,10 @@
 /* png.c - location for general purpose libpng functions
 *
- * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -14,7 +14,27 @@
 #include "pngpriv.h"
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_23 Your_png_h_is_not_version_1_6_23;
+typedef png_libpng_version_1_6_37 Your_png_h_is_not_version_1_6_37;
 #ifdef __GNUC__
 /* The version tests may need to be added to, but the problem warning has
 * consistently been fixed in GCC versions which obtain wide-spread release.
 * The problem is that many versions of GCC rearrange comparison expressions in
 * the optimizer in such a way that the results of the comparison will change
 * if signed integer overflow occurs.  Such comparisons are not permitted in
 * ANSI C90, however GCC isn't clever enough to work out that that do not occur
 * below in png_ascii_from_fp and png_muldiv, so it produces a warning with
 * -Wextra.  Unfortunately this is highly dependent on the optimizer and the
 * machine architecture so the warning comes and goes unpredictably and is
 * impossible to "fix", even were that a good idea.
 */
 #if __GNUC__ == 7 && __GNUC_MINOR__ == 1
 #define GCC_STRICT_OVERFLOW 1
 #endif /* GNU 7.1.x */
 #endif /* GNU */
 #ifndef GCC_STRICT_OVERFLOW
 #define GCC_STRICT_OVERFLOW 0
 #endif
 /* Tells libpng that we have already handled the first "num_bytes" bytes
 * of the PNG file signature.  If the PNG data is embedded into another
@ -51,7 +71,7 @@ png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
 * PNG signature (this is the same behavior as strcmp, memcmp, etc).
 */
 int PNGAPI
-png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
+png_sig_cmp(png_const_bytep sig, size_t start, size_t num_to_check)
 {
   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
@ -116,7 +136,7 @@ png_reset_crc(png_structrp png_ptr)
 * trouble of calculating it.
 */
 void /* PRIVATE */
-png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
+png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, size_t length)
 {
   int need_crc = 1;
@ -401,7 +421,7 @@ png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
 * those cases where it does anything other than a memset.
 */
 PNG_FUNCTION(void,PNGAPI
-png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
+png_info_init_3,(png_infopp ptr_ptr, size_t png_info_struct_size),
    PNG_DEPRECATED)
 {
   png_inforp info_ptr = *ptr_ptr;
@ -458,7 +478,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
 #ifdef PNG_TEXT_SUPPORTED
   /* Free text item num or (if num == -1) all text items */
-   if (info_ptr->text != 0 &&
+   if (info_ptr->text != NULL &&
       ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
   {
      if (num != -1)
@ -477,6 +497,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
         png_free(png_ptr, info_ptr->text);
         info_ptr->text = NULL;
         info_ptr->num_text = 0;
         info_ptr->max_text = 0;
      }
   }
 #endif
@ -541,7 +562,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
 #ifdef PNG_sPLT_SUPPORTED
   /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
-   if (info_ptr->splt_palettes != 0 &&
+   if (info_ptr->splt_palettes != NULL &&
       ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
   {
      if (num != -1)
@ -571,7 +592,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
 #endif
 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
-   if (info_ptr->unknown_chunks != 0 &&
+   if (info_ptr->unknown_chunks != NULL &&
       ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
   {
      if (num != -1)
@ -594,6 +615,26 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
   }
 #endif
 #ifdef PNG_eXIf_SUPPORTED
   /* Free any eXIf entry */
   if (((mask & PNG_FREE_EXIF) & info_ptr->free_me) != 0)
   {
 # ifdef PNG_READ_eXIf_SUPPORTED
      if (info_ptr->eXIf_buf)
      {
         png_free(png_ptr, info_ptr->eXIf_buf);
         info_ptr->eXIf_buf = NULL;
      }
 # endif
      if (info_ptr->exif)
      {
         png_free(png_ptr, info_ptr->exif);
         info_ptr->exif = NULL;
      }
      info_ptr->valid &= ~PNG_INFO_eXIf;
   }
 #endif
 #ifdef PNG_hIST_SUPPORTED
   /* Free any hIST entry */
   if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
@ -617,7 +658,7 @@ png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
   /* Free any image bits attached to the info structure */
   if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
   {
-      if (info_ptr->row_pointers != 0)
+      if (info_ptr->row_pointers != NULL)
      {
         png_uint_32 row;
         for (row = 0; row < info_ptr->height; row++)
@ -684,7 +725,7 @@ png_init_io(png_structrp png_ptr, png_FILE_p fp)
 void PNGAPI
 png_save_int_32(png_bytep buf, png_int_32 i)
 {
-   png_save_uint_32(buf, i);
+   png_save_uint_32(buf, (png_uint_32)i);
 }
 #  endif
@ -695,7 +736,7 @@ png_save_int_32(png_bytep buf, png_int_32 i)
 int PNGAPI
 png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
 {
-   static PNG_CONST char short_months[12][4] =
+   static const char short_months[12][4] =
        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
@ -773,20 +814,14 @@ png_get_copyright(png_const_structrp png_ptr)
 #ifdef PNG_STRING_COPYRIGHT
   return PNG_STRING_COPYRIGHT
 #else
 #  ifdef __STDC__
   return PNG_STRING_NEWLINE \
-      "libpng version 1.6.23 - June 9, 2016" PNG_STRING_NEWLINE \
+      "libpng version 1.6.37" PNG_STRING_NEWLINE \
-      "Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \
+      "Copyright (c) 2018-2019 Cosmin Truta" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson" \
      PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE;
 #  else
   return "libpng version 1.6.23 - June 9, 2016\
      Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
      Copyright (c) 1996-1997 Andreas Dilger\
      Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
 #  endif
 #endif
 }
@ -901,7 +936,7 @@ png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
   /* The code is the fifth byte after each four byte string.  Historically this
    * code was always searched from the end of the list, this is no longer
-    * necessary because the 'set' routine handles duplicate entries correcty.
+    * necessary because the 'set' routine handles duplicate entries correctly.
    */
   do /* num_chunk_list > 0, so at least one */
   {
@ -1080,7 +1115,7 @@ png_colorspace_set_gamma(png_const_structrp png_ptr,
    png_colorspacerp colorspace, png_fixed_point gAMA)
 {
   /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
-    * occur.  Since the fixed point representation is asymetrical it is
+    * occur.  Since the fixed point representation is asymmetrical it is
    * possible for 1/gamma to overflow the limit of 21474 and this means the
    * gamma value must be at least 5/100000 and hence at most 20000.0.  For
    * safety the limits here are a little narrower.  The values are 0.00016 to
@ -1872,12 +1907,12 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
    */
   if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
      return png_icc_profile_error(png_ptr, colorspace, "sRGB",
-         (unsigned)intent, "invalid sRGB rendering intent");
+          (png_alloc_size_t)intent, "invalid sRGB rendering intent");
   if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
       colorspace->rendering_intent != intent)
      return png_icc_profile_error(png_ptr, colorspace, "sRGB",
-         (unsigned)intent, "inconsistent rendering intents");
+         (png_alloc_size_t)intent, "inconsistent rendering intents");
   if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
   {
@ -1931,16 +1966,49 @@ png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
 static const png_byte D50_nCIEXYZ[12] =
   { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
-int /* PRIVATE */
+static int /* bool */
-png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
+icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
    png_const_charp name, png_uint_32 profile_length)
 {
   if (profile_length < 132)
      return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
          "too short");
   return 1;
 }
 #ifdef PNG_READ_iCCP_SUPPORTED
 int /* PRIVATE */
 png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
    png_const_charp name, png_uint_32 profile_length)
 {
   if (!icc_check_length(png_ptr, colorspace, name, profile_length))
      return 0;
   /* This needs to be here because the 'normal' check is in
    * png_decompress_chunk, yet this happens after the attempt to
    * png_malloc_base the required data.  We only need this on read; on write
    * the caller supplies the profile buffer so libpng doesn't allocate it.  See
    * the call to icc_check_length below (the write case).
    */
 #  ifdef PNG_SET_USER_LIMITS_SUPPORTED
      else if (png_ptr->user_chunk_malloc_max > 0 &&
               png_ptr->user_chunk_malloc_max < profile_length)
         return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
             "exceeds application limits");
 #  elif PNG_USER_CHUNK_MALLOC_MAX > 0
      else if (PNG_USER_CHUNK_MALLOC_MAX < profile_length)
         return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
             "exceeds libpng limits");
 #  else /* !SET_USER_LIMITS */
      /* This will get compiled out on all 32-bit and better systems. */
      else if (PNG_SIZE_MAX < profile_length)
         return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
             "exceeds system limits");
 #  endif /* !SET_USER_LIMITS */
   return 1;
 }
 #endif /* READ_iCCP */
 int /* PRIVATE */
 png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
@ -1993,7 +2061,7 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
    */
   /* Data checks (could be skipped).  These checks must be independent of the
-    * version number; however, the version number doesn't accomodate changes in
+    * version number; however, the version number doesn't accommodate changes in
    * the header fields (just the known tags and the interpretation of the
    * data.)
    */
@ -2149,15 +2217,6 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
       * being in range.  All defined tag types have an 8 byte header - a 4 byte
       * type signature then 0.
       */
      if ((tag_start & 3) != 0)
      {
         /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
          * only a warning here because libpng does not care about the
          * alignment.
          */
         (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
            "ICC profile tag start not a multiple of 4");
      }
      /* This is a hard error; potentially it can cause read outside the
       * profile.
@ -2165,6 +2224,16 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
      if (tag_start > profile_length || tag_length > profile_length - tag_start)
         return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
             "ICC profile tag outside profile");
      if ((tag_start & 3) != 0)
      {
         /* CNHP730S.icc shipped with Microsoft Windows 64 violates this; it is
          * only a warning here because libpng does not care about the
          * alignment.
          */
         (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
             "ICC profile tag start not a multiple of 4");
      }
   }
   return 1; /* success, maybe with warnings */
@ -2354,7 +2423,6 @@ png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
   return 0; /* no match */
 }
 #endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
 void /* PRIVATE */
 png_icc_set_sRGB(png_const_structrp png_ptr,
@ -2363,12 +2431,11 @@ png_icc_set_sRGB(png_const_structrp png_ptr,
   /* Is this profile one of the known ICC sRGB profiles?  If it is, just set
    * the sRGB information.
    */
 #if PNG_sRGB_PROFILE_CHECKS >= 0
   if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
 #endif
      (void)png_colorspace_set_sRGB(png_ptr, colorspace,
         (int)/*already checked*/png_get_uint_32(profile+64));
 }
 #endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
 #endif /* sRGB */
 int /* PRIVATE */
@ -2379,13 +2446,13 @@ png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
   if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
      return 0;
-   if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
+   if (icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
       png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
           color_type) != 0 &&
       png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
           profile) != 0)
   {
-#     ifdef PNG_sRGB_SUPPORTED
+#     if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
         /* If no sRGB support, don't try storing sRGB information */
         png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
 #     endif
@ -2497,7 +2564,7 @@ png_check_IHDR(png_const_structrp png_ptr,
      error = 1;
   }
-   if (png_gt(((width + 7) & (~7)),
+   if (png_gt(((width + 7) & (~7U)),
       ((PNG_SIZE_MAX
           - 48        /* big_row_buf hack */
           - 1)        /* filter byte */
@ -2634,7 +2701,7 @@ png_check_IHDR(png_const_structrp png_ptr,
 #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
 /* ASCII to fp functions */
-/* Check an ASCII formated floating point value, see the more detailed
+/* Check an ASCII formatted floating point value, see the more detailed
 * comments in pngpriv.h
 */
 /* The following is used internally to preserve the sticky flags */
@ -2642,11 +2709,11 @@ png_check_IHDR(png_const_structrp png_ptr,
 #define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
 int /* PRIVATE */
-png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
+png_check_fp_number(png_const_charp string, size_t size, int *statep,
    png_size_tp whereami)
 {
   int state = *statep;
-   png_size_t i = *whereami;
+   size_t i = *whereami;
   while (i < size)
   {
@ -2769,10 +2836,10 @@ PNG_FP_End:
 /* The same but for a complete string. */
 int
-png_check_fp_string(png_const_charp string, png_size_t size)
+png_check_fp_string(png_const_charp string, size_t size)
 {
   int        state=0;
-   png_size_t char_index=0;
+   size_t char_index=0;
   if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
      (char_index == size || string[char_index] == 0))
@ -2799,7 +2866,7 @@ png_pow10(int power)
   if (power < 0)
   {
      if (power < DBL_MIN_10_EXP) return 0;
-      recip = 1, power = -power;
+      recip = 1; power = -power;
   }
   if (power > 0)
@ -2824,8 +2891,16 @@ png_pow10(int power)
 /* Function to format a floating point value in ASCII with a given
 * precision.
 */
 #if GCC_STRICT_OVERFLOW
 #pragma GCC diagnostic push
 /* The problem arises below with exp_b10, which can never overflow because it
 * comes, originally, from frexp and is therefore limited to a range which is
 * typically +/-710 (log2(DBL_MAX)/log2(DBL_MIN)).
 */
 #pragma GCC diagnostic warning "-Wstrict-overflow=2"
 #endif /* GCC_STRICT_OVERFLOW */
 void /* PRIVATE */
-png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
+png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, size_t size,
    double fp, unsigned int precision)
 {
   /* We use standard functions from math.h, but not printf because
@ -2877,7 +2952,9 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
            double test = png_pow10(exp_b10+1);
            if (test <= DBL_MAX)
-               ++exp_b10, base = test;
+            {
               ++exp_b10; base = test;
            }
            else
               break;
@ -2891,7 +2968,10 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
          * test on DBL_MAX above.
          */
         fp /= base;
-         while (fp >= 1) fp /= 10, ++exp_b10;
+         while (fp >= 1)
         {
            fp /= 10; ++exp_b10;
         }
         /* Because of the code above fp may, at this point, be
          * less than .1, this is ok because the code below can
@ -2908,7 +2988,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
             */
            if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
            {
-               czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
+               czero = 0U-exp_b10; /* PLUS 2 digits: TOTAL 3 */
               exp_b10 = 0;      /* Dot added below before first output. */
            }
            else
@ -2942,7 +3022,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
                     /* Rounding up to 10, handle that here. */
                     if (czero > 0)
                     {
-                        --czero, d = 1;
+                        --czero; d = 1;
                        if (cdigits == 0) --clead;
                     }
                     else
@ -2956,7 +3036,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
                           else if (ch == 46)
                           {
-                              ch = *--ascii, ++size;
+                              ch = *--ascii; ++size;
                              /* Advance exp_b10 to '1', so that the
                               * decimal point happens after the
                               * previous digit.
@ -2983,7 +3063,9 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
                              int ch = *--ascii;
                              if (ch == 46)
-                                 ++size, exp_b10 = 1;
+                              {
                                 ++size; exp_b10 = 1;
                              }
                              /* Else lost a leading zero, so 'exp_b10' is
                               * still ok at (-1)
@ -3019,21 +3101,26 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
                      */
                     if (exp_b10 != (-1))
                     {
-                        if (exp_b10 == 0) *ascii++ = 46, --size;
+                        if (exp_b10 == 0)
                        {
                           *ascii++ = 46; --size;
                        }
                        /* PLUS 1: TOTAL 4 */
                        --exp_b10;
                     }
-                     *ascii++ = 48, --czero;
+                     *ascii++ = 48; --czero;
                  }
                  if (exp_b10 != (-1))
                  {
                     if (exp_b10 == 0)
-                        *ascii++ = 46, --size; /* counted above */
+                     {
                        *ascii++ = 46; --size; /* counted above */
                     }
                     --exp_b10;
                  }
-                  *ascii++ = (char)(48 + (int)d), ++cdigits;
+                  *ascii++ = (char)(48 + (int)d); ++cdigits;
               }
            }
            while (cdigits+czero < precision+clead && fp > DBL_MIN);
@ -3041,11 +3128,11 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
            /* The total output count (max) is now 4+precision */
            /* Check for an exponent, if we don't need one we are
-             * done and just need to terminate the string.  At
+             * done and just need to terminate the string.  At this
-             * this point exp_b10==(-1) is effectively if flag - it got
+             * point, exp_b10==(-1) is effectively a flag: it got
-             * to '-1' because of the decrement after outputting
+             * to '-1' because of the decrement, after outputting
-             * the decimal point above (the exponent required is
+             * the decimal point above. (The exponent required is
-             * *not* -1!)
+             * *not* -1.)
             */
            if (exp_b10 >= (-1) && exp_b10 <= 2)
            {
@ -3056,7 +3143,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
                * zeros were *not* output, so this doesn't increase
                * the output count.
                */
-               while (--exp_b10 >= 0) *ascii++ = 48;
+               while (exp_b10-- > 0) *ascii++ = 48;
               *ascii = 0;
@ -3074,7 +3161,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
             */
            size -= cdigits;
-            *ascii++ = 69, --size;    /* 'E': PLUS 1 TOTAL 2+precision */
+            *ascii++ = 69; --size;    /* 'E': PLUS 1 TOTAL 2+precision */
            /* The following use of an unsigned temporary avoids ambiguities in
             * the signed arithmetic on exp_b10 and permits GCC at least to do
@ -3085,12 +3172,12 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
               if (exp_b10 < 0)
               {
-                  *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
+                  *ascii++ = 45; --size; /* '-': PLUS 1 TOTAL 3+precision */
-                  uexp_b10 = -exp_b10;
+                  uexp_b10 = 0U-exp_b10;
               }
               else
-                  uexp_b10 = exp_b10;
+                  uexp_b10 = 0U+exp_b10;
               cdigits = 0;
@ -3133,6 +3220,9 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
   /* Here on buffer too small. */
   png_error(png_ptr, "ASCII conversion buffer too small");
 }
 #if GCC_STRICT_OVERFLOW
 #pragma GCC diagnostic pop
 #endif /* GCC_STRICT_OVERFLOW */
 #  endif /* FLOATING_POINT */
@ -3141,7 +3231,7 @@ png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
 */
 void /* PRIVATE */
 png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
-    png_size_t size, png_fixed_point fp)
+    size_t size, png_fixed_point fp)
 {
   /* Require space for 10 decimal digits, a decimal point, a minus sign and a
    * trailing \0, 13 characters:
@ -3152,9 +3242,11 @@ png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
      /* Avoid overflow here on the minimum integer. */
      if (fp < 0)
-         *ascii++ = 45, num = -fp;
+      {
         *ascii++ = 45; num = (png_uint_32)(-fp);
      }
      else
-         num = fp;
+         num = (png_uint_32)fp;
      if (num <= 0x80000000) /* else overflowed */
      {
@ -3190,7 +3282,10 @@ png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
                * then ndigits digits to first:
                */
               i = 5;
-               while (ndigits < i) *ascii++ = 48, --i;
+               while (ndigits < i)
               {
                  *ascii++ = 48; --i;
               }
               while (ndigits >= first) *ascii++ = digits[--ndigits];
               /* Don't output the trailing zeros! */
            }
@ -3241,6 +3336,15 @@ png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
 * the nearest .00001).  Overflow and divide by zero are signalled in
 * the result, a boolean - true on success, false on overflow.
 */
 #if GCC_STRICT_OVERFLOW /* from above */
 /* It is not obvious which comparison below gets optimized in such a way that
 * signed overflow would change the result; looking through the code does not
 * reveal any tests which have the form GCC complains about, so presumably the
 * optimizer is moving an add or subtract into the 'if' somewhere.
 */
 #pragma GCC diagnostic push
 #pragma GCC diagnostic warning "-Wstrict-overflow=2"
 #endif /* GCC_STRICT_OVERFLOW */
 int
 png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
    png_int_32 divisor)
@ -3355,6 +3459,9 @@ png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
   return 0;
 }
 #if GCC_STRICT_OVERFLOW
 #pragma GCC diagnostic pop
 #endif /* GCC_STRICT_OVERFLOW */
 #endif /* READ_GAMMA || INCH_CONVERSIONS */
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
@ -3648,7 +3755,7 @@ png_log16bit(png_uint_32 x)
 * of getting this accuracy in practice.
 *
 * To deal with this the following exp() function works out the exponent of the
- * frational part of the logarithm by using an accurate 32-bit value from the
+ * fractional part of the logarithm by using an accurate 32-bit value from the
 * top four fractional bits then multiplying in the remaining bits.
 */
 static const png_uint_32
@ -3863,18 +3970,18 @@ png_gamma_correct(png_structrp png_ptr, unsigned int value,
 */
 static void
 png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
-   PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+    unsigned int shift, png_fixed_point gamma_val)
 {
   /* Various values derived from 'shift': */
-   PNG_CONST unsigned int num = 1U << (8U - shift);
+   unsigned int num = 1U << (8U - shift);
 #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
   /* CSE the division and work round wacky GCC warnings (see the comments
    * in png_gamma_8bit_correct for where these come from.)
    */
-   PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1);
+   double fmax = 1.0 / (((png_int_32)1 << (16U - shift)) - 1);
 #endif
-   PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
+   unsigned int max = (1U << (16U - shift)) - 1U;
-   PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
+   unsigned int max_by_2 = 1U << (15U - shift);
   unsigned int i;
   png_uint_16pp table = *ptable =
@ -3940,10 +4047,10 @@ png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
 */
 static void
 png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
-   PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+    unsigned int shift, png_fixed_point gamma_val)
 {
-   PNG_CONST unsigned int num = 1U << (8U - shift);
+   unsigned int num = 1U << (8U - shift);
-   PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
+   unsigned int max = (1U << (16U - shift))-1U;
   unsigned int i;
   png_uint_32 last;
@ -4008,7 +4115,7 @@ png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
 */
 static void
 png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
-   PNG_CONST png_fixed_point gamma_val)
+    png_fixed_point gamma_val)
 {
   unsigned int i;
   png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
@ -4092,9 +4199,9 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
   /* Remove any existing table; this copes with multiple calls to
    * png_read_update_info. The warning is because building the gamma tables
-   * multiple times is a performance hit - it's harmless but the ability to call
+    * multiple times is a performance hit - it's harmless but the ability to
-   * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
+    * call png_read_update_info() multiple times is new in 1.5.6 so it seems
-   * to warn if the app introduces such a hit.
+    * sensible to warn if the app introduces such a hit.
    */
   if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
   {
@ -4105,7 +4212,8 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
   if (bit_depth <= 8)
   {
      png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
-         png_ptr->screen_gamma > 0 ?  png_reciprocal2(png_ptr->colorspace.gamma,
+          png_ptr->screen_gamma > 0 ?
          png_reciprocal2(png_ptr->colorspace.gamma,
          png_ptr->screen_gamma) : PNG_FP_1);
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
@ -4117,7 +4225,8 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
             png_reciprocal(png_ptr->colorspace.gamma));
         png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
-            png_ptr->screen_gamma > 0 ?  png_reciprocal(png_ptr->screen_gamma) :
+             png_ptr->screen_gamma > 0 ?
             png_reciprocal(png_ptr->screen_gamma) :
             png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
      }
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
@ -4148,8 +4257,8 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
       * pow(iv, gamma).
       *
       * Thus the gamma table consists of up to 256 256-entry tables.  The table
-      * is selected by the (8-gamma_shift) most significant of the low 8 bits of
+       * is selected by the (8-gamma_shift) most significant of the low 8 bits
-      * the color value then indexed by the upper 8 bits:
+       * of the color value then indexed by the upper 8 bits:
       *
       *   table[low bits][high 8 bits]
       *
@ -4182,8 +4291,8 @@ png_build_gamma_table(png_structrp png_ptr, int bit_depth)
      /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
       * PNG_COMPOSE).  This effectively smashed the background calculation for
-      * 16-bit output because the 8-bit table assumes the result will be reduced
+       * 16-bit output because the 8-bit table assumes the result will be
-      * to 8 bits.
+       * reduced to 8 bits.
       */
      if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
          png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
@ -4225,13 +4334,13 @@ png_set_option(png_structrp png_ptr, int option, int onoff)
   if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
      (option & 1) == 0)
   {
-      int mask = 3 << option;
+      png_uint_32 mask = 3U << option;
-      int setting = (2 + (onoff != 0)) << option;
+      png_uint_32 setting = (2U + (onoff != 0)) << option;
-      int current = png_ptr->options;
+      png_uint_32 current = png_ptr->options;
-      png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff);
+      png_ptr->options = (png_uint_32)((current & ~mask) | setting);
-      return (current & mask) >> option;
+      return (int)(current & mask) >> option;
   }
   return PNG_OPTION_INVALID;
@ -4243,7 +4352,7 @@ png_set_option(png_structrp png_ptr, int option, int onoff)
   defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
 /* sRGB conversion tables; these are machine generated with the code in
 * contrib/tools/makesRGB.c.  The actual sRGB transfer curve defined in the
- * specification (see the article at http://en.wikipedia.org/wiki/SRGB)
+ * specification (see the article at https://en.wikipedia.org/wiki/SRGB)
 * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
 * The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
 * The inverse (linear to sRGB) table has accuracies as follows:
@ -4479,8 +4588,7 @@ png_image_free(png_imagep image)
   if (image != NULL && image->opaque != NULL &&
      image->opaque->error_buf == NULL)
   {
-      /* Ignore errors here: */
+      png_image_free_function(image);
      (void)png_safe_execute(image, png_image_free_function, image);
      image->opaque = NULL;
   }
 }
--- a/source/Irrlicht/libpng/png.h
+++ b/source/Irrlicht/libpng/png.h
@ -1,36 +1,69 @@
 /* png.h - header file for PNG reference library
 *
- * libpng version 1.6.23, June 9, 2016
+ * libpng version 1.6.37 - April 14, 2019
 *
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 2018-2019 Cosmin Truta
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
- * This code is released under the libpng license (See LICENSE, below)
+ * This code is released under the libpng license. (See LICENSE, below.)
 *
 * Authors and maintainers:
 *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
 *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.23, June 9, 2016:
+ *   libpng versions 0.97, January 1998, through 1.6.35, July 2018:
- *     Glenn Randers-Pehrson.
+ *     Glenn Randers-Pehrson
 *   libpng versions 1.6.36, December 2018, through 1.6.37, April 2019:
 *     Cosmin Truta
 *   See also "Contributing Authors", below.
 */
 /*
- * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
 * =========================================
 *
- * If you modify libpng you may insert additional notices immediately following
+ * PNG Reference Library License version 2
- * this sentence.
+ * ---------------------------------------
 *
- * This code is released under the libpng license.
+ *  * Copyright (c) 1995-2019 The PNG Reference Library Authors.
 *  * Copyright (c) 2018-2019 Cosmin Truta.
 *  * Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson.
 *  * Copyright (c) 1996-1997 Andreas Dilger.
 *  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
- * Some files in the "contrib" directory and some configure-generated
+ * The software is supplied "as is", without warranty of any kind,
- * files that are distributed with libpng have other copyright owners and
+ * express or implied, including, without limitation, the warranties
- * are released under other open source licenses.
+ * of merchantability, fitness for a particular purpose, title, and
 * non-infringement.  In no event shall the Copyright owners, or
 * anyone distributing the software, be liable for any damages or
 * other liability, whether in contract, tort or otherwise, arising
 * from, out of, or in connection with the software, or the use or
 * other dealings in the software, even if advised of the possibility
 * of such damage.
 *
- * libpng versions 1.0.7, July 1, 2000 through 1.6.23, June 9, 2016 are
+ * Permission is hereby granted to use, copy, modify, and distribute
- * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
+ * this software, or portions hereof, for any purpose, without fee,
 * subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you
 *     must not claim that you wrote the original software.  If you
 *     use this software in a product, an acknowledgment in the product
 *     documentation would be appreciated, but is not required.
 *
 *  2. Altered source versions must be plainly marked as such, and must
 *     not be misrepresented as being the original software.
 *
 *  3. This Copyright notice may not be removed or altered from any
 *     source or altered source distribution.
 *
 *
 * PNG Reference Library License version 1 (for libpng 0.5 through 1.6.35)
 * -----------------------------------------------------------------------
 *
 * libpng versions 1.0.7, July 1, 2000, through 1.6.35, July 15, 2018 are
 * Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson, are
 * derived from libpng-1.0.6, and are distributed according to the same
 * disclaimer and license as libpng-1.0.6 with the following individuals
 * added to the list of Contributing Authors:
@ -41,33 +74,33 @@
 *     Cosmin Truta
 *     Gilles Vollant
 *     James Yu
 *     Mandar Sahastrabuddhe
 *     Google Inc.
 *     Vadim Barkov
 *
 * and with the following additions to the disclaimer:
 *
- *    There is no warranty against interference with your enjoyment of the
+ *     There is no warranty against interference with your enjoyment of
- *    library or against infringement.  There is no warranty that our
+ *     the library or against infringement.  There is no warranty that our
 *     efforts or the library will fulfill any of your particular purposes
 *     or needs.  This library is provided with all faults, and the entire
- *    risk of satisfactory quality, performance, accuracy, and effort is with
+ *     risk of satisfactory quality, performance, accuracy, and effort is
- *    the user.
+ *     with the user.
 *
- * Some files in the "contrib" directory have other copyright owners and
+ * Some files in the "contrib" directory and some configure-generated
 * files that are distributed with libpng have other copyright owners, and
 * are released under other open source licenses.
 *
 *
 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
 * libpng-0.96, and are distributed according to the same disclaimer and
- * license as libpng-0.96, with the following individuals added to the list
+ * license as libpng-0.96, with the following individuals added to the
- * of Contributing Authors:
+ * list of Contributing Authors:
 *
 *     Tom Lane
 *     Glenn Randers-Pehrson
 *     Willem van Schaik
 *
 * Some files in the "scripts" directory have different copyright owners
 * but are also released under this license.
 *
 * libpng versions 0.89, June 1996, through 0.96, May 1997, are
 * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
 * and are distributed according to the same disclaimer and license as
@ -81,7 +114,7 @@
 *     Greg Roelofs
 *     Tom Tanner
 *
- * Some files in the "scripts" directory have other copyright owners
+ * Some files in the "scripts" directory have other copyright owners,
 * but are released under this license.
 *
 * libpng versions 0.5, May 1995, through 0.88, January 1996, are
@ -96,13 +129,14 @@
 *     Paul Schmidt
 *     Tim Wegner
 *
- * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+ * The PNG Reference Library is supplied "AS IS".  The Contributing
- * and Group 42, Inc. disclaim all warranties, expressed or implied,
+ * Authors and Group 42, Inc. disclaim all warranties, expressed or
- * including, without limitation, the warranties of merchantability and of
+ * implied, including, without limitation, the warranties of
- * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+ * merchantability and of fitness for any purpose.  The Contributing
- * assume no liability for direct, indirect, incidental, special, exemplary,
+ * Authors and Group 42, Inc. assume no liability for direct, indirect,
- * or consequential damages, which may result from the use of the PNG
+ * incidental, special, exemplary, or consequential damages, which may
- * Reference Library, even if advised of the possibility of such damage.
+ * result from the use of the PNG Reference Library, even if advised of
 * the possibility of such damage.
 *
 * Permission is hereby granted to use, copy, modify, and distribute this
 * source code, or portions hereof, for any purpose, without fee, subject
@ -116,36 +150,22 @@
 *  3. This Copyright notice may not be removed or altered from any
 *     source or altered source distribution.
 *
- * The Contributing Authors and Group 42, Inc. specifically permit, without
+ * The Contributing Authors and Group 42, Inc. specifically permit,
- * fee, and encourage the use of this source code as a component to
+ * without fee, and encourage the use of this source code as a component
- * supporting the PNG file format in commercial products.  If you use this
+ * to supporting the PNG file format in commercial products.  If you use
- * source code in a product, acknowledgment is not required but would be
+ * this source code in a product, acknowledgment is not required but would
- * appreciated.
+ * be appreciated.
 *
 * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
 *
- * TRADEMARK:
+ * TRADEMARK
 * =========
 *
- * The name "libpng" has not been registered by the Copyright owner
+ * The name "libpng" has not been registered by the Copyright owners
 * as a trademark in any jurisdiction.  However, because libpng has
 * been distributed and maintained world-wide, continually since 1995,
- * the Copyright owner claims "common-law trademark protection" in any
+ * the Copyright owners claim "common-law trademark protection" in any
 * jurisdiction where common-law trademark is recognized.
 *
 * OSI CERTIFICATION:
 *
 * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
 * a certification mark of the Open Source Initiative. OSI has not addressed
 * the additional disclaimers inserted at version 1.0.7.
 *
 * EXPORT CONTROL:
 *
 * The Copyright owner believes that the Export Control Classification
 * Number (ECCN) for libpng is EAR99, which means not subject to export
 * controls or International Traffic in Arms Regulations (ITAR) because
 * it is open source, publicly available software, that does not contain
 * any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
 * 734.7(b).
 */
 /*
@ -211,23 +231,25 @@
 *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
 *    1.0.7                    1    10007  (still compatible)
 *    ...
- *    1.0.19                  10    10019  10.so.0.19[.0]
+ *    1.0.69                  10    10069  10.so.0.69[.0]
 *    ...
- *    1.2.56                  13    10256  12.so.0.56[.0]
+ *    1.2.59                  13    10259  12.so.0.59[.0]
 *    ...
- *    1.5.27                  15    10527  15.so.15.27[.0]
+ *    1.4.20                  14    10420  14.so.0.20[.0]
 *    ...
- *    1.6.23                  16    10623  16.so.16.23[.0]
+ *    1.5.30                  15    10530  15.so.15.30[.0]
 *    ...
 *    1.6.37                  16    10637  16.so.16.37[.0]
 *
- *    Henceforth the source version will match the shared-library major
+ *    Henceforth the source version will match the shared-library major and
- *    and minor numbers; the shared-library major version number will be
+ *    minor numbers; the shared-library major version number will be used for
- *    used for changes in backward compatibility, as it is intended.  The
+ *    changes in backward compatibility, as it is intended.
- *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
+ *    The PNG_LIBPNG_VER macro, which is not used within libpng but is
- *    for applications, is an unsigned integer of the form xyyzz corresponding
+ *    available for applications, is an unsigned integer of the form XYYZZ
- *    to the source version x.y.z (leading zeros in y and z).  Beta versions
+ *    corresponding to the source version X.Y.Z (leading zeros in Y and Z).
- *    were given the previous public release number plus a letter, until
+ *    Beta versions were given the previous public release number plus a
- *    version 1.0.6j; from then on they were given the upcoming public
+ *    letter, until version 1.0.6j; from then on they were given the upcoming
- *    release number plus "betaNN" or "rcNN".
+ *    public release number plus "betaNN" or "rcNN".
 *
 *    Binary incompatibility exists only when applications make direct access
 *    to the info_ptr or png_ptr members through png.h, and the compiled
@ -237,65 +259,8 @@
 *    in binary compatibility (e.g., when a new feature is added).
 *
 * See libpng.txt or libpng.3 for more information.  The PNG specification
- * is available as a W3C Recommendation and as an ISO Specification,
+ * is available as a W3C Recommendation and as an ISO/IEC Standard; see
- * <http://www.w3.org/TR/2003/REC-PNG-20031110/
+ * <https://www.w3.org/TR/2003/REC-PNG-20031110/>
 */
 /*
 * Y2K compliance in libpng:
 * =========================
 *
 *    June 9, 2016
 *
 *    Since the PNG Development group is an ad-hoc body, we can't make
 *    an official declaration.
 *
 *    This is your unofficial assurance that libpng from version 0.71 and
 *    upward through 1.6.23 are Y2K compliant.  It is my belief that
 *    earlier versions were also Y2K compliant.
 *
 *    Libpng only has two year fields.  One is a 2-byte unsigned integer
 *    that will hold years up to 65535.  The other, which is deprecated,
 *    holds the date in text format, and will hold years up to 9999.
 *
 *    The integer is
 *        "png_uint_16 year" in png_time_struct.
 *
 *    The string is
 *        "char time_buffer[29]" in png_struct.  This is no longer used
 *    in libpng-1.6.x and will be removed from libpng-1.7.0.
 *
 *    There are seven time-related functions:
 *        png.c: png_convert_to_rfc_1123_buffer() in png.c
 *          (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
 *          png_convert_to_rfc_1152() in error prior to libpng-0.98)
 *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
 *        png_convert_from_time_t() in pngwrite.c
 *        png_get_tIME() in pngget.c
 *        png_handle_tIME() in pngrutil.c, called in pngread.c
 *        png_set_tIME() in pngset.c
 *        png_write_tIME() in pngwutil.c, called in pngwrite.c
 *
 *    All handle dates properly in a Y2K environment.  The
 *    png_convert_from_time_t() function calls gmtime() to convert from system
 *    clock time, which returns (year - 1900), which we properly convert to
 *    the full 4-digit year.  There is a possibility that libpng applications
 *    are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
 *    function, or that they are incorrectly passing only a 2-digit year
 *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
 *    but this is not under our control.  The libpng documentation has always
 *    stated that it works with 4-digit years, and the APIs have been
 *    documented as such.
 *
 *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
 *    integer to hold the year, and can hold years as large as 65535.
 *
 *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
 *    no date-related code.
 *
 *       Glenn Randers-Pehrson
 *       libpng maintainer
 *       PNG Development Group
 */
 #ifndef PNG_H
@ -313,9 +278,8 @@
 */
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.23"
+#define PNG_LIBPNG_VER_STRING "1.6.37"
-#define PNG_HEADER_VERSION_STRING \
+#define PNG_HEADER_VERSION_STRING " libpng version 1.6.37 - April 14, 2019\n"
     " libpng version 1.6.23 - June 9, 2016\n"
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@ -323,12 +287,11 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   6
-#define PNG_LIBPNG_VER_RELEASE 23
+#define PNG_LIBPNG_VER_RELEASE 37
-/* This should match the numeric part of the final component of
+/* This should be zero for a public release, or non-zero for a
- * PNG_LIBPNG_VER_STRING, omitting any leading zero:
+ * development version.  [Deprecated]
 */
 #define PNG_LIBPNG_VER_BUILD  0
 /* Release Status */
@ -348,26 +311,27 @@
 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
-/* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
+/* Careful here.  At one time, Guy wanted to use 082, but that
- * We must not include leading zeros.
+ * would be octal.  We must not include leading zeros.
- * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
+ * Versions 0.7 through 1.0.0 were in the range 0 to 100 here
- * version 1.0.0 was mis-numbered 100 instead of 10000).  From
+ * (only version 1.0.0 was mis-numbered 100 instead of 10000).
- * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
+ * From version 1.0.1 it is:
 * XXYYZZ, where XX=major, YY=minor, ZZ=release
 */
-#define PNG_LIBPNG_VER 10623 /* 1.6.23 */
+#define PNG_LIBPNG_VER 10637 /* 1.6.37 */
 /* Library configuration: these options cannot be changed after
 * the library has been built.
 */
 #ifndef PNGLCONF_H
-    /* If pnglibconf.h is missing, you can
+/* If pnglibconf.h is missing, you can
 * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
 */
 #   include "pnglibconf.h"
 #endif
 #ifndef PNG_VERSION_INFO_ONLY
-   /* Machine specific configuration. */
+/* Machine specific configuration. */
 #  include "pngconf.h"
 #endif
@ -464,7 +428,7 @@ extern "C" {
 /* This triggers a compiler error in png.c, if png.c and png.h
 * do not agree upon the version number.
 */
-typedef char* png_libpng_version_1_6_23;
+typedef char* png_libpng_version_1_6_37;
 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 *
@ -605,8 +569,8 @@ typedef struct png_text_struct
   png_charp key;          /* keyword, 1-79 character description of "text" */
   png_charp text;         /* comment, may be an empty string (ie "")
                              or a NULL pointer */
-   png_size_t text_length; /* length of the text string */
+   size_t text_length;     /* length of the text string */
-   png_size_t itxt_length; /* length of the itxt string */
+   size_t itxt_length;     /* length of the itxt string */
   png_charp lang;         /* language code, 0-79 characters
                              or a NULL pointer */
   png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
@ -659,7 +623,7 @@ typedef struct png_unknown_chunk_t
 {
   png_byte name[5]; /* Textual chunk name with '\0' terminator */
   png_byte *data;   /* Data, should not be modified on read! */
-    png_size_t size;
+   size_t size;
   /* On write 'location' must be set using the flag values listed below.
    * Notice that on read it is set by libpng however the values stored have
@ -684,7 +648,7 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
 /* Maximum positive integer used in PNG is (2^31)-1 */
 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
-#define PNG_SIZE_MAX ((png_size_t)(-1))
+#define PNG_SIZE_MAX ((size_t)(-1))
 /* These are constants for fixed point values encoded in the
 * PNG specification manner (x100000)
@ -781,6 +745,7 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
 #define PNG_INFO_sPLT 0x2000U  /* ESR, 1.0.6 */
 #define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
 #define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
 #define PNG_INFO_eXIf 0x10000U /* GR-P, 1.6.31 */
 /* This is used for the transformation routines, as some of them
 * change these values for the row.  It also should enable using
@ -789,7 +754,7 @@ typedef png_unknown_chunk * * png_unknown_chunkpp;
 typedef struct png_row_info_struct
 {
   png_uint_32 width;    /* width of row */
-   png_size_t rowbytes;  /* number of bytes in row */
+   size_t rowbytes;      /* number of bytes in row */
   png_byte color_type;  /* color type of row */
   png_byte bit_depth;   /* bit depth of row */
   png_byte channels;    /* number of channels (1, 2, 3, or 4) */
@ -808,7 +773,7 @@ typedef png_row_info * * png_row_infopp;
 * expected to return the read data in the buffer.
 */
 typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
-typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
+typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, size_t));
 typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
 typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
    int));
@ -945,8 +910,8 @@ PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
 * signature, and non-zero otherwise.  Having num_to_check == 0 or
 * start > 7 will always fail (ie return non-zero).
 */
-PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
+PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, size_t start,
-    png_size_t num_to_check));
+    size_t num_to_check));
 /* Simple signature checking function.  This is the same as calling
 * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
@ -965,11 +930,11 @@ PNG_EXPORTA(5, png_structp, png_create_write_struct,
    png_error_ptr warn_fn),
    PNG_ALLOCATED);
-PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
+PNG_EXPORT(6, size_t, png_get_compression_buffer_size,
    (png_const_structrp png_ptr));
 PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
-    png_size_t size));
+    size_t size));
 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
 * match up.
@ -1022,7 +987,7 @@ PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
 /* Write a PNG chunk - size, type, (optional) data, CRC. */
 PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
-    chunk_name, png_const_bytep data, png_size_t length));
+    chunk_name, png_const_bytep data, size_t length));
 /* Write the start of a PNG chunk - length and chunk name. */
 PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
@ -1030,7 +995,7 @@ PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
 PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
-    png_const_bytep data, png_size_t length));
+    png_const_bytep data, size_t length));
 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
 PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
@ -1044,7 +1009,7 @@ PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
 * the API will be removed in the future.
 */
 PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
-    png_size_t png_info_struct_size), PNG_DEPRECATED);
+    size_t png_info_struct_size), PNG_DEPRECATED);
 /* Writes all the PNG information before the image. */
 PNG_EXPORT(20, void, png_write_info_before_PLTE,
@ -1141,7 +1106,7 @@ PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
 * corresponding composited pixel, and the color channels are unassociated
 * (not premultiplied).  The gamma encoded color channels must be scaled
 * according to the contribution and to do this it is necessary to undo
- * the encoding, scale the color values, perform the composition and reencode
+ * the encoding, scale the color values, perform the composition and re-encode
 * the values.  This is the 'PNG' mode.
 *
 * The alternative is to 'associate' the alpha with the color information by
@ -1197,7 +1162,7 @@ PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
 *
 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
 *    In this case the output is assumed to be something like an sRGB conformant
- *    display preceeded by a power-law lookup table of power 1.45.  This is how
+ *    display preceded by a power-law lookup table of power 1.45.  This is how
 *    early Mac systems behaved.
 *
 * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
@ -1244,7 +1209,7 @@ PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
 *
 * When the default gamma of PNG files doesn't match the output gamma.
 *    If you have PNG files with no gamma information png_set_alpha_mode allows
- *    you to provide a default gamma, but it also sets the ouput gamma to the
+ *    you to provide a default gamma, but it also sets the output gamma to the
 *    matching value.  If you know your PNG files have a gamma that doesn't
 *    match the output you can take advantage of the fact that
 *    png_set_alpha_mode always sets the output gamma but only sets the PNG
@ -1695,7 +1660,7 @@ PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
 *           chunk will cause an error at this point unless it is to be saved.
 * positive: The chunk was handled, libpng will ignore/discard it.
 *
- * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
+ * See "INTERACTION WITH USER CHUNK CALLBACKS" below for important notes about
 * how this behavior will change in libpng 1.7
 */
 PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
@ -1720,7 +1685,7 @@ PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
 /* Function to be called when data becomes available */
 PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
-    png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
+    png_inforp info_ptr, png_bytep buffer, size_t buffer_size));
 /* A function which may be called *only* within png_process_data to stop the
 * processing of any more data.  The function returns the number of bytes
@ -1729,7 +1694,7 @@ PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
 * 'save' is set to true the routine will first save all the pending data and
 * will always return 0.
 */
-PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
+PNG_EXPORT(219, size_t, png_process_data_pause, (png_structrp, int save));
 /* A function which may be called *only* outside (after) a call to
 * png_process_data.  It returns the number of bytes of data to skip in the
@ -1793,7 +1758,8 @@ PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
 #define PNG_FREE_PLTE 0x1000U
 #define PNG_FREE_TRNS 0x2000U
 #define PNG_FREE_TEXT 0x4000U
-#define PNG_FREE_ALL  0x7fffU
+#define PNG_FREE_EXIF 0x8000U /* Added at libpng-1.6.31 */
 #define PNG_FREE_ALL  0xffffU
 #define PNG_FREE_MUL  0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
 #ifdef PNG_USER_MEM_SUPPORTED
@ -1873,7 +1839,7 @@ PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
    png_const_inforp info_ptr, png_uint_32 flag));
 /* Returns number of bytes needed to hold a transformed row. */
-PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
+PNG_EXPORT(111, size_t, png_get_rowbytes, (png_const_structrp png_ptr,
    png_const_inforp info_ptr));
 #ifdef PNG_INFO_IMAGE_SUPPORTED
@ -2012,6 +1978,18 @@ PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
    png_fixed_point int_blue_Z))
 #endif
 #ifdef PNG_eXIf_SUPPORTED
 PNG_EXPORT(246, png_uint_32, png_get_eXIf, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_bytep *exif));
 PNG_EXPORT(247, void, png_set_eXIf, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_bytep exif));
 PNG_EXPORT(248, png_uint_32, png_get_eXIf_1, (png_const_structrp png_ptr,
    png_const_inforp info_ptr, png_uint_32 *num_exif, png_bytep *exif));
 PNG_EXPORT(249, void, png_set_eXIf_1, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 num_exif, png_bytep exif));
 #endif
 #ifdef PNG_gAMA_SUPPORTED
 PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
    png_const_inforp info_ptr, double *file_gamma))
@ -2030,9 +2008,6 @@ PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
 #ifdef PNG_hIST_SUPPORTED
 PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_uint_16p *hist));
 #endif
 #ifdef PNG_hIST_SUPPORTED
 PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
    png_inforp info_ptr, png_const_uint_16p hist));
 #endif
@ -2233,7 +2208,7 @@ PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
 * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
 * it simply resets the behavior to the libpng default.
 *
- * INTERACTION WTIH USER CHUNK CALLBACKS:
+ * INTERACTION WITH USER CHUNK CALLBACKS:
 * The per-chunk handling is always used when there is a png_user_chunk_ptr
 * callback and the callback returns 0; the chunk is then always stored *unless*
 * it is critical and the per-chunk setting is other than ALWAYS.  Notice that
@ -2300,8 +2275,10 @@ PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
 *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
 *    be processed by libpng.
 */
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
    int keep, png_const_bytep chunk_list, int num_chunks));
 #endif /* HANDLE_AS_UNKNOWN */
 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
 * the result is therefore true (non-zero) if special handling is required,
@ -2309,7 +2286,7 @@ PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
 */
 PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
    png_const_bytep chunk_name));
-#endif
+#endif /* SET_UNKNOWN_CHUNKS */
 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
 PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
@ -2531,18 +2508,22 @@ PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
 /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
 #  define png_composite(composite, fg, alpha, bg)        \
-     { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
+   {                                                     \
      png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
          * (png_uint_16)(alpha)                         \
          + (png_uint_16)(bg)*(png_uint_16)(255          \
          - (png_uint_16)(alpha)) + 128);                \
-       (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); }
+      (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); \
   }
 #  define png_composite_16(composite, fg, alpha, bg)     \
-     { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \
+   {                                                     \
      png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
          * (png_uint_32)(alpha)                         \
          + (png_uint_32)(bg)*(65535                     \
          - (png_uint_32)(alpha)) + 32768);              \
-       (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); }
+      (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); \
   }
 #else  /* Standard method using integer division */
@ -2610,7 +2591,7 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
    ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
    : (png_int_32)png_get_uint_32(buf)))
-   /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
+/* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
 * but defining a macro name prefixed with PNG_PREFIX.
 */
 #  ifndef PNG_PREFIX
@ -2646,7 +2627,7 @@ PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
 * The simplified API hides the details of both libpng and the PNG file format
 * itself.  It allows PNG files to be read into a very limited number of
 * in-memory bitmap formats or to be written from the same formats.  If these
- * formats do not accomodate your needs then you can, and should, use the more
+ * formats do not accommodate your needs then you can, and should, use the more
 * sophisticated APIs above - these support a wide variety of in-memory formats
 * and a wide variety of sophisticated transformations to those formats as well
 * as a wide variety of APIs to manipulate ancillary information.
@ -2752,7 +2733,7 @@ typedef struct
 *
 * When the simplified API needs to convert between sRGB and linear colorspaces,
 * the actual sRGB transfer curve defined in the sRGB specification (see the
- * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+ * article at <https://en.wikipedia.org/wiki/SRGB>) is used, not the gamma=1/2.2
 * approximation used elsewhere in libpng.
 *
 * When an alpha channel is present it is expected to denote pixel coverage
@ -2807,6 +2788,8 @@ typedef struct
 #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
 #endif
 #define PNG_FORMAT_FLAG_ASSOCIATED_ALPHA 0x40U /* alpha channel is associated */
 /* Commonly used formats have predefined macros.
 *
 * First the single byte (sRGB) formats:
@ -2953,7 +2936,7 @@ typedef struct
 * 'flags' field of png_image.
 */
 #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
-   /* This indicates the the RGB values of the in-memory bitmap do not
+   /* This indicates that the RGB values of the in-memory bitmap do not
    * correspond to the red, green and blue end-points defined by sRGB.
    */
@ -3006,7 +2989,7 @@ PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
 #endif /* STDIO */
 PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
-   png_const_voidp memory, png_size_t size));
+   png_const_voidp memory, size_t size));
   /* The PNG header is read from the given memory buffer. */
 PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
@ -3119,7 +3102,7 @@ PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
    * than or equal to the original value.
    *
    * If the function returns false and *memory_bytes was not changed an error
-    * occured during write.  If *memory_bytes was changed, or is not 0 if
+    * occurred during write.  If *memory_bytes was changed, or is not 0 if
    * 'memory' was NULL, the write would have succeeded but for the memory
    * buffer being too small.  *memory_bytes contains the required number of
    * bytes and will be bigger that the original value.
@ -3203,7 +3186,7 @@ PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
 * option and 'onoff' is 0 (off) or non-0 (on).  The value returned is given
 * by the PNG_OPTION_ defines below.
 *
- * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
+ * HARDWARE: normally hardware capabilities, such as the Intel SSE instructions,
 *           are detected at run time, however sometimes it may be impossible
 *           to do this in user mode, in which case it is necessary to discover
 *           the capabilities in an OS specific way.  Such capabilities are
@ -3221,7 +3204,14 @@ PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
 #endif
 #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
 #define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
-#define PNG_OPTION_NEXT  6 /* Next option - numbers must be even */
+#ifdef PNG_MIPS_MSA_API_SUPPORTED
 #  define PNG_MIPS_MSA   6 /* HARDWARE: MIPS Msa SIMD instructions supported */
 #endif
 #define PNG_IGNORE_ADLER32 8
 #ifdef PNG_POWERPC_VSX_API_SUPPORTED
 #  define PNG_POWERPC_VSX   10 /* HARDWARE: PowerPC VSX SIMD instructions supported */
 #endif
 #define PNG_OPTION_NEXT  12 /* Next option - numbers must be even */
 /* Return values: NOTE: there are four values and 'off' is *not* zero */
 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
@ -3245,7 +3235,7 @@ PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
 * one to use is one more than this.)
 */
 #ifdef PNG_EXPORT_LAST_ORDINAL
-  PNG_EXPORT_LAST_ORDINAL(245);
+  PNG_EXPORT_LAST_ORDINAL(249);
 #endif
 #ifdef __cplusplus
--- a/source/Irrlicht/libpng/pngconf.h
+++ b/source/Irrlicht/libpng/pngconf.h
@ -1,11 +1,12 @@
-/* pngconf.h - machine configurable file for libpng
+/* pngconf.h - machine-configurable file for libpng
 *
- * libpng version 1.6.23, June 9, 2016
+ * libpng version 1.6.37
 *
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 2018-2019 Cosmin Truta
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1996-1997 Andreas Dilger
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -57,14 +58,13 @@
 #endif /* PNG_BUILDING_SYMBOL_TABLE */
-/* Prior to 1.6.0 it was possible to turn off 'const' in declarations using
+/* Prior to 1.6.0, it was possible to turn off 'const' in declarations,
- * PNG_NO_CONST; this is no longer supported except for data declarations which
+ * using PNG_NO_CONST.  This is no longer supported.
 * apparently still cause problems in 2011 on some compilers.
 */
 #define PNG_CONST const /* backward compatibility only */
-/* This controls optimization of the reading of 16-bit and 32-bit values
+/* This controls optimization of the reading of 16-bit and 32-bit
- * from PNG files.  It can be set on a per-app-file basis - it
+ * values from PNG files.  It can be set on a per-app-file basis: it
 * just changes whether a macro is used when the function is called.
 * The library builder sets the default; if read functions are not
 * built into the library the macro implementation is forced on.
@ -127,7 +127,7 @@
 *
 * These cases only differ if the operating system does not use the C
 * calling convention, at present this just means the above cases
- * (x86 DOS/Windows sytems) and, even then, this does not apply to
+ * (x86 DOS/Windows systems) and, even then, this does not apply to
 * Cygwin running on those systems.
 *
 * Note that the value must be defined in pnglibconf.h so that what
@ -507,16 +507,18 @@
 #  error "libpng requires a signed 32-bit (or more) type"
 #endif
-#if UINT_MAX > 4294967294
+#if UINT_MAX > 4294967294U
   typedef unsigned int png_uint_32;
-#elif ULONG_MAX > 4294967294
+#elif ULONG_MAX > 4294967294U
   typedef unsigned long int png_uint_32;
 #else
 #  error "libpng requires an unsigned 32-bit (or more) type"
 #endif
-/* Prior to 1.6.0 it was possible to disable the use of size_t, 1.6.0, however,
+/* Prior to 1.6.0, it was possible to disable the use of size_t and ptrdiff_t.
- * requires an ISOC90 compiler and relies on consistent behavior of sizeof.
+ * From 1.6.0 onwards, an ISO C90 compiler, as well as a standard-compliant
 * behavior of sizeof and ptrdiff_t are required.
 * The legacy typedefs are provided here for backwards compatibility.
 */
 typedef size_t png_size_t;
 typedef ptrdiff_t png_ptrdiff_t;
@ -537,13 +539,12 @@ typedef ptrdiff_t png_ptrdiff_t;
 #  endif
 #endif
-/* png_alloc_size_t is guaranteed to be no smaller than png_size_t, and no
+/* png_alloc_size_t is guaranteed to be no smaller than size_t, and no smaller
- * smaller than png_uint_32.  Casts from png_size_t or png_uint_32 to
+ * than png_uint_32.  Casts from size_t or png_uint_32 to png_alloc_size_t are
- * png_alloc_size_t are not necessary; in fact, it is recommended not to use
+ * not necessary; in fact, it is recommended not to use them at all, so that
- * them at all so that the compiler can complain when something turns out to be
+ * the compiler can complain when something turns out to be problematic.
 * problematic.
 *
- * Casts in the other direction (from png_alloc_size_t to png_size_t or
+ * Casts in the other direction (from png_alloc_size_t to size_t or
 * png_uint_32) should be explicitly applied; however, we do not expect to
 * encounter practical situations that require such conversions.
 *
@ -553,7 +554,7 @@ typedef ptrdiff_t png_ptrdiff_t;
 #ifdef PNG_SMALL_SIZE_T
   typedef png_uint_32 png_alloc_size_t;
 #else
-   typedef png_size_t png_alloc_size_t;
+   typedef size_t png_alloc_size_t;
 #endif
 /* Prior to 1.6.0 libpng offered limited support for Microsoft C compiler
@ -589,8 +590,8 @@ typedef char                  * png_charp;
 typedef const char            * png_const_charp;
 typedef png_fixed_point       * png_fixed_point_p;
 typedef const png_fixed_point * png_const_fixed_point_p;
-typedef png_size_t            * png_size_tp;
+typedef size_t                * png_size_tp;
-typedef const png_size_t      * png_const_size_tp;
+typedef const size_t          * png_const_size_tp;
 #ifdef PNG_STDIO_SUPPORTED
 typedef FILE            * png_FILE_p;
--- a/source/Irrlicht/libpng/pngdebug.h
+++ b/source/Irrlicht/libpng/pngdebug.h
@ -1,10 +1,10 @@
 /* pngdebug.h - Debugging macros for libpng, also used in pngtest.c
 *
- * Last changed in libpng 1.6.8 [December 19, 2013]
+ * Copyright (c) 2018 Cosmin Truta
 * Copyright (c) 1998-2002,2004,2006-2013 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
--- a/source/Irrlicht/libpng/pngerror.c
+++ b/source/Irrlicht/libpng/pngerror.c
@ -1,10 +1,10 @@
 /* pngerror.c - stub functions for i/o and memory allocation
 *
- * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -163,7 +163,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
         case PNG_NUMBER_FORMAT_02u:
            /* Expects at least 2 digits. */
            mincount = 2;
-            /* FALL THROUGH */
+            /* FALLTHROUGH */
         case PNG_NUMBER_FORMAT_u:
            *--end = digits[number % 10];
@ -173,7 +173,7 @@ png_format_number(png_const_charp start, png_charp end, int format,
         case PNG_NUMBER_FORMAT_02x:
            /* This format expects at least two digits */
            mincount = 2;
-            /* FALL THROUGH */
+            /* FALLTHROUGH */
         case PNG_NUMBER_FORMAT_x:
            *--end = digits[number & 0xf];
@ -425,7 +425,7 @@ png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
 * if the character is invalid.
 */
 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
-static PNG_CONST char png_digit[16] = {
+static const char png_digit[16] = {
   '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
   'A', 'B', 'C', 'D', 'E', 'F'
 };
@ -573,7 +573,7 @@ png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
 {
 #  define fixed_message "fixed point overflow in "
 #  define fixed_message_ln ((sizeof fixed_message)-1)
-   int  iin;
+   unsigned int  iin;
   char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
   memcpy(msg, fixed_message, fixed_message_ln);
   iin = 0;
@ -885,7 +885,7 @@ PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
 png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
    PNG_NORETURN)
 {
-   const png_const_structrp png_ptr = png_nonconst_ptr;
+   png_const_structrp png_ptr = png_nonconst_ptr;
   png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
   /* An error is always logged here, overwriting anything (typically a warning)
@ -920,7 +920,7 @@ png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
 void /* PRIVATE */ PNGCBAPI
 png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
 {
-   const png_const_structrp png_ptr = png_nonconst_ptr;
+   png_const_structrp png_ptr = png_nonconst_ptr;
   png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
   /* A warning is only logged if there is no prior warning or error. */
--- a/source/Irrlicht/libpng/pngget.c
+++ b/source/Irrlicht/libpng/pngget.c
@ -1,10 +1,10 @@
 /* pngget.c - retrieval of values from info struct
 *
- * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -26,7 +26,7 @@ png_get_valid(png_const_structrp png_ptr, png_const_inforp info_ptr,
   return(0);
 }
-png_size_t PNGAPI
+size_t PNGAPI
 png_get_rowbytes(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
   if (png_ptr != NULL && info_ptr != NULL)
@ -338,7 +338,7 @@ ppi_from_ppm(png_uint_32 ppm)
   png_fixed_point result;
   if (ppm <= PNG_UINT_31_MAX && png_muldiv(&result, (png_int_32)ppm, 127,
       5000) != 0)
-      return result;
+      return (png_uint_32)result;
   /* Overflow. */
   return 0;
@ -367,7 +367,7 @@ png_get_y_pixels_per_inch(png_const_structrp png_ptr, png_const_inforp info_ptr)
 static png_fixed_point
 png_fixed_inches_from_microns(png_const_structrp png_ptr, png_int_32 microns)
 {
-   /* Convert from metres * 1,000,000 to inches * 100,000, meters to
+   /* Convert from meters * 1,000,000 to inches * 100,000, meters to
    * inches is simply *(100/2.54), so we want *(10/2.54) == 500/127.
    * Notice that this can overflow - a warning is output and 0 is
    * returned.
@ -741,8 +741,7 @@ png_get_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
   if (png_ptr != NULL && info_ptr != NULL &&
       (info_ptr->valid & PNG_INFO_iCCP) != 0 &&
-       name != NULL && compression_type != NULL && profile != NULL &&
+       name != NULL && profile != NULL && proflen != NULL)
           proflen != NULL)
   {
      *name = info_ptr->iccp_name;
      *profile = info_ptr->iccp_profile;
@ -750,11 +749,13 @@ png_get_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
      /* This is somewhat irrelevant since the profile data returned has
       * actually been uncompressed.
       */
      if (compression_type != NULL)
         *compression_type = PNG_COMPRESSION_TYPE_BASE;
      return (PNG_INFO_iCCP);
   }
   return (0);
 }
 #endif
@ -773,6 +774,35 @@ png_get_sPLT(png_const_structrp png_ptr, png_inforp info_ptr,
 }
 #endif
 #ifdef PNG_eXIf_SUPPORTED
 png_uint_32 PNGAPI
 png_get_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
    png_bytep *exif)
 {
  png_warning(png_ptr, "png_get_eXIf does not work; use png_get_eXIf_1");
  PNG_UNUSED(info_ptr)
  PNG_UNUSED(exif)
  return 0;
 }
 png_uint_32 PNGAPI
 png_get_eXIf_1(png_const_structrp png_ptr, png_const_inforp info_ptr,
    png_uint_32 *num_exif, png_bytep *exif)
 {
   png_debug1(1, "in %s retrieval function", "eXIf");
   if (png_ptr != NULL && info_ptr != NULL &&
       (info_ptr->valid & PNG_INFO_eXIf) != 0 && exif != NULL)
   {
      *num_exif = info_ptr->num_exif;
      *exif = info_ptr->exif;
      return (PNG_INFO_eXIf);
   }
   return (0);
 }
 #endif
 #ifdef PNG_hIST_SUPPORTED
 png_uint_32 PNGAPI
 png_get_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
@ -1135,7 +1165,7 @@ png_get_user_chunk_ptr(png_const_structrp png_ptr)
 }
 #endif
-png_size_t PNGAPI
+size_t PNGAPI
 png_get_compression_buffer_size(png_const_structrp png_ptr)
 {
   if (png_ptr == NULL)
--- a/source/Irrlicht/libpng/pnginfo.h
+++ b/source/Irrlicht/libpng/pnginfo.h
@ -1,10 +1,10 @@
 /* pnginfo.h - header file for PNG reference library
 *
- * Last changed in libpng 1.6.1 [March 28, 2013]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2013 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2013,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -58,7 +58,7 @@ struct png_info_def
   png_uint_32 width;       /* width of image in pixels (from IHDR) */
   png_uint_32 height;      /* height of image in pixels (from IHDR) */
   png_uint_32 valid;       /* valid chunk data (see PNG_INFO_ below) */
-   png_size_t rowbytes; /* bytes needed to hold an untransformed row */
+   size_t rowbytes;         /* bytes needed to hold an untransformed row */
   png_colorp palette;      /* array of color values (valid & PNG_INFO_PLTE) */
   png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */
   png_uint_16 num_trans;   /* number of transparent palette color (tRNS) */
@ -185,6 +185,14 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
   png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
 #endif
 #ifdef PNG_eXIf_SUPPORTED
   int num_exif;  /* Added at libpng-1.6.31 */
   png_bytep exif;
 # ifdef PNG_READ_eXIf_SUPPORTED
   png_bytep eXIf_buf;  /* Added at libpng-1.6.32 */
 # endif
 #endif
 #ifdef PNG_hIST_SUPPORTED
   /* The hIST chunk contains the relative frequency or importance of the
    * various palette entries, so that a viewer can intelligently select a
@ -239,7 +247,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
   /* The sCAL chunk describes the actual physical dimensions of the
    * subject matter of the graphic.  The chunk contains a unit specification
    * a byte value, and two ASCII strings representing floating-point
-    * values.  The values are width and height corresponsing to one pixel
+    * values.  The values are width and height corresponding to one pixel
    * in the image.  Data values are valid if (valid & PNG_INFO_sCAL) is
    * non-zero.
    */
--- a/source/Irrlicht/libpng/pnglibconf.h
+++ b/source/Irrlicht/libpng/pnglibconf.h
@ -1,8 +1,9 @@
 /* pnglibconf.h - library build configuration */
-/* libpng version 1.6.23, June 9, 2016 */
+/* libpng version 1.6.37 */
-/* Copyright (c) 1998-2016 Glenn Randers-Pehrson */
+/* Copyright (c) 2018-2019 Cosmin Truta */
 /* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson */
 /* This code is released under the libpng license. */
 /* For conditions of distribution and use, see the disclaimer */
@ -42,6 +43,8 @@
 #define PNG_IO_STATE_SUPPORTED
 #define PNG_MNG_FEATURES_SUPPORTED
 #define PNG_POINTER_INDEXING_SUPPORTED
 /*#undef PNG_POWERPC_VSX_API_SUPPORTED*/
 /*#undef PNG_POWERPC_VSX_CHECK_SUPPORTED*/
 #define PNG_PROGRESSIVE_READ_SUPPORTED
 #define PNG_READ_16BIT_SUPPORTED
 #define PNG_READ_ALPHA_MODE_SUPPORTED
@ -80,6 +83,7 @@
 #define PNG_READ_USER_TRANSFORM_SUPPORTED
 #define PNG_READ_bKGD_SUPPORTED
 #define PNG_READ_cHRM_SUPPORTED
 #define PNG_READ_eXIf_SUPPORTED
 #define PNG_READ_gAMA_SUPPORTED
 #define PNG_READ_hIST_SUPPORTED
 #define PNG_READ_iCCP_SUPPORTED
@ -149,6 +153,7 @@
 #define PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
 #define PNG_WRITE_bKGD_SUPPORTED
 #define PNG_WRITE_cHRM_SUPPORTED
 #define PNG_WRITE_eXIf_SUPPORTED
 #define PNG_WRITE_gAMA_SUPPORTED
 #define PNG_WRITE_hIST_SUPPORTED
 #define PNG_WRITE_iCCP_SUPPORTED
@ -166,6 +171,7 @@
 #define PNG_WRITE_zTXt_SUPPORTED
 #define PNG_bKGD_SUPPORTED
 #define PNG_cHRM_SUPPORTED
 #define PNG_eXIf_SUPPORTED
 #define PNG_gAMA_SUPPORTED
 #define PNG_hIST_SUPPORTED
 #define PNG_iCCP_SUPPORTED
@ -203,7 +209,7 @@
 #define PNG_USER_HEIGHT_MAX 1000000
 #define PNG_USER_WIDTH_MAX 1000000
 #define PNG_ZBUF_SIZE 8192
-#define PNG_ZLIB_VERNUM 0x1280
+#define PNG_ZLIB_VERNUM 0 /* unknown */
 #define PNG_Z_DEFAULT_COMPRESSION (-1)
 #define PNG_Z_DEFAULT_NOFILTER_STRATEGY 0
 #define PNG_Z_DEFAULT_STRATEGY 1
--- a/source/Irrlicht/libpng/pngmem.c
+++ b/source/Irrlicht/libpng/pngmem.c
@ -1,10 +1,10 @@
 /* pngmem.c - stub functions for memory allocation
 *
- * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -109,7 +109,7 @@ static png_voidp
 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
    size_t element_size)
 {
-   png_alloc_size_t req = nelements; /* known to be > 0 */
+   png_alloc_size_t req = (png_alloc_size_t)nelements; /* known to be > 0 */
   if (req <= PNG_SIZE_MAX/element_size)
      return png_malloc_base(png_ptr, req * element_size);
--- a/source/Irrlicht/libpng/pngpread.c
+++ b/source/Irrlicht/libpng/pngpread.c
@ -1,10 +1,10 @@
 /* pngpread.c - read a png file in push mode
 *
- * Last changed in libpng 1.6.23 [June 9, 2016]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -34,7 +34,7 @@ if (png_ptr->buffer_size < N) \
 void PNGAPI
 png_process_data(png_structrp png_ptr, png_inforp info_ptr,
-    png_bytep buffer, png_size_t buffer_size)
+    png_bytep buffer, size_t buffer_size)
 {
   if (png_ptr == NULL || info_ptr == NULL)
      return;
@ -47,7 +47,7 @@ png_process_data(png_structrp png_ptr, png_inforp info_ptr,
   }
 }
-png_size_t PNGAPI
+size_t PNGAPI
 png_process_data_pause(png_structrp png_ptr, int save)
 {
   if (png_ptr != NULL)
@ -60,7 +60,7 @@ png_process_data_pause(png_structrp png_ptr, int save)
      else
      {
         /* This includes any pending saved bytes: */
-         png_size_t remaining = png_ptr->buffer_size;
+         size_t remaining = png_ptr->buffer_size;
         png_ptr->buffer_size = 0;
         /* So subtract the saved buffer size, unless all the data
@ -77,7 +77,7 @@ png_process_data_pause(png_structrp png_ptr, int save)
 png_uint_32 PNGAPI
 png_process_data_skip(png_structrp png_ptr)
 {
-  /* TODO: Deprecate and remove this API.
+/* TODO: Deprecate and remove this API.
 * Somewhere the implementation of this seems to have been lost,
 * or abandoned.  It was only to support some internal back-door access
 * to png_struct) in libpng-1.4.x.
@ -133,8 +133,8 @@ png_process_some_data(png_structrp png_ptr, png_inforp info_ptr)
 void /* PRIVATE */
 png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 {
-   png_size_t num_checked = png_ptr->sig_bytes, /* SAFE, does not exceed 8 */
+   size_t num_checked = png_ptr->sig_bytes; /* SAFE, does not exceed 8 */
-       num_to_check = 8 - num_checked;
+   size_t num_to_check = 8 - num_checked;
   if (png_ptr->buffer_size < num_to_check)
   {
@ -189,6 +189,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
      png_crc_read(png_ptr, chunk_tag, 4);
      png_ptr->chunk_name = PNG_CHUNK_FROM_STRING(chunk_tag);
      png_check_chunk_name(png_ptr, png_ptr->chunk_name);
      png_check_chunk_length(png_ptr, png_ptr->push_length);
      png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
   }
@ -417,7 +418,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
 }
 void PNGCBAPI
-png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
+png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, size_t length)
 {
   png_bytep ptr;
@ -427,7 +428,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
   ptr = buffer;
   if (png_ptr->save_buffer_size != 0)
   {
-      png_size_t save_size;
+      size_t save_size;
      if (length < png_ptr->save_buffer_size)
         save_size = length;
@ -444,7 +445,7 @@ png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
   }
   if (length != 0 && png_ptr->current_buffer_size != 0)
   {
-      png_size_t save_size;
+      size_t save_size;
      if (length < png_ptr->current_buffer_size)
         save_size = length;
@ -466,7 +467,7 @@ png_push_save_buffer(png_structrp png_ptr)
   {
      if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
      {
-         png_size_t i, istop;
+         size_t i, istop;
         png_bytep sp;
         png_bytep dp;
@ -481,7 +482,7 @@ png_push_save_buffer(png_structrp png_ptr)
   if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
       png_ptr->save_buffer_max)
   {
-      png_size_t new_max;
+      size_t new_max;
      png_bytep old_buffer;
      if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
@ -493,7 +494,7 @@ png_push_save_buffer(png_structrp png_ptr)
      new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
      old_buffer = png_ptr->save_buffer;
      png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
-          (png_size_t)new_max);
+          (size_t)new_max);
      if (png_ptr->save_buffer == NULL)
      {
@ -521,7 +522,7 @@ png_push_save_buffer(png_structrp png_ptr)
 void /* PRIVATE */
 png_push_restore_buffer(png_structrp png_ptr, png_bytep buffer,
-   png_size_t buffer_length)
+    size_t buffer_length)
 {
   png_ptr->current_buffer = buffer;
   png_ptr->current_buffer_size = buffer_length;
@ -561,7 +562,7 @@ png_push_read_IDAT(png_structrp png_ptr)
   if (png_ptr->idat_size != 0 && png_ptr->save_buffer_size != 0)
   {
-      png_size_t save_size = png_ptr->save_buffer_size;
+      size_t save_size = png_ptr->save_buffer_size;
      png_uint_32 idat_size = png_ptr->idat_size;
      /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
@ -571,7 +572,7 @@ png_push_read_IDAT(png_structrp png_ptr)
       * will break on either 16-bit or 64-bit platforms.
       */
      if (idat_size < save_size)
-         save_size = (png_size_t)idat_size;
+         save_size = (size_t)idat_size;
      else
         idat_size = (png_uint_32)save_size;
@ -588,7 +589,7 @@ png_push_read_IDAT(png_structrp png_ptr)
   if (png_ptr->idat_size != 0 && png_ptr->current_buffer_size != 0)
   {
-      png_size_t save_size = png_ptr->current_buffer_size;
+      size_t save_size = png_ptr->current_buffer_size;
      png_uint_32 idat_size = png_ptr->idat_size;
      /* We want the smaller of 'idat_size' and 'current_buffer_size', but they
@ -597,7 +598,7 @@ png_push_read_IDAT(png_structrp png_ptr)
       * larger - this cannot overflow.
       */
      if (idat_size < save_size)
-         save_size = (png_size_t)idat_size;
+         save_size = (size_t)idat_size;
      else
         idat_size = (png_uint_32)save_size;
@ -624,7 +625,7 @@ png_push_read_IDAT(png_structrp png_ptr)
 void /* PRIVATE */
 png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
-   png_size_t buffer_length)
+    size_t buffer_length)
 {
   /* The caller checks for a non-zero buffer length. */
   if (!(buffer_length > 0) || buffer == NULL)
@ -683,8 +684,13 @@ png_process_IDAT_data(png_structrp png_ptr, png_bytep buffer,
             png_ptr->pass > 6)
            png_warning(png_ptr, "Truncated compressed data in IDAT");
         else
         {
            if (ret == Z_DATA_ERROR)
               png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
            else
               png_error(png_ptr, "Decompression error in IDAT");
         }
         /* Skip the check on unprocessed input */
         return;
@ -966,20 +972,20 @@ png_read_push_finish_row(png_structrp png_ptr)
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
+   static const png_byte png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};
   /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};
   /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
+   static const png_byte png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
   /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
+   static const png_byte png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
   /* Height of interlace block.  This is not currently used - if you need
    * it, uncomment it here and in png.h
-   static PNG_CONST png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
   */
 #endif
--- a/source/Irrlicht/libpng/pngpriv.h
+++ b/source/Irrlicht/libpng/pngpriv.h
@ -1,10 +1,10 @@
 /* pngpriv.h - private declarations for use inside libpng
 *
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -35,7 +35,9 @@
 * Windows/Visual Studio) there is no effect; the OS specific tests below are
 * still required (as of 2011-05-02.)
 */
-#define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
+#ifndef _POSIX_SOURCE
 # define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
 #endif
 #ifndef PNG_VERSION_INFO_ONLY
 /* Standard library headers not required by png.h: */
@ -172,7 +174,10 @@
 #     else /* !defined __ARM_NEON__ */
         /* The 'intrinsics' code simply won't compile without this -mfpu=neon:
          */
 #        if !defined(__aarch64__)
            /* The assembler code currently does not work on ARM64 */
 #          define PNG_ARM_NEON_IMPLEMENTATION 2
 #        endif /* __aarch64__ */
 #     endif /* __ARM_NEON__ */
 #  endif /* !PNG_ARM_NEON_IMPLEMENTATION */
@ -182,6 +187,90 @@
 #  endif
 #endif /* PNG_ARM_NEON_OPT > 0 */
 #ifndef PNG_MIPS_MSA_OPT
 #  if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
 #     define PNG_MIPS_MSA_OPT 2
 #  else
 #     define PNG_MIPS_MSA_OPT 0
 #  endif
 #endif
 #ifndef PNG_POWERPC_VSX_OPT
 #  if defined(__PPC64__) && defined(__ALTIVEC__) && defined(__VSX__)
 #     define PNG_POWERPC_VSX_OPT 2
 #  else
 #     define PNG_POWERPC_VSX_OPT 0
 #  endif
 #endif
 #ifndef PNG_INTEL_SSE_OPT
 #   ifdef PNG_INTEL_SSE
      /* Only check for SSE if the build configuration has been modified to
       * enable SSE optimizations.  This means that these optimizations will
       * be off by default.  See contrib/intel for more details.
       */
 #     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
 #         define PNG_INTEL_SSE_OPT 1
 #      else
 #         define PNG_INTEL_SSE_OPT 0
 #      endif
 #   else
 #      define PNG_INTEL_SSE_OPT 0
 #   endif
 #endif
 #if PNG_INTEL_SSE_OPT > 0
 #   ifndef PNG_INTEL_SSE_IMPLEMENTATION
 #      if defined(__SSE4_1__) || defined(__AVX__)
          /* We are not actually using AVX, but checking for AVX is the best
             way we can detect SSE4.1 and SSSE3 on MSVC.
          */
 #         define PNG_INTEL_SSE_IMPLEMENTATION 3
 #      elif defined(__SSSE3__)
 #         define PNG_INTEL_SSE_IMPLEMENTATION 2
 #      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
 #         define PNG_INTEL_SSE_IMPLEMENTATION 1
 #      else
 #         define PNG_INTEL_SSE_IMPLEMENTATION 0
 #      endif
 #   endif
 #   if PNG_INTEL_SSE_IMPLEMENTATION > 0
 #      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
 #   endif
 #else
 #   define PNG_INTEL_SSE_IMPLEMENTATION 0
 #endif
 #if PNG_MIPS_MSA_OPT > 0
 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
 #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
 #     if defined(__mips_msa)
 #        if defined(__clang__)
 #        elif defined(__GNUC__)
 #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
 #              define PNG_MIPS_MSA_IMPLEMENTATION 2
 #           endif /* no GNUC support */
 #        endif /* __GNUC__ */
 #     else /* !defined __mips_msa */
 #        define PNG_MIPS_MSA_IMPLEMENTATION 2
 #     endif /* __mips_msa */
 #  endif /* !PNG_MIPS_MSA_IMPLEMENTATION */
 #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
 #     define PNG_MIPS_MSA_IMPLEMENTATION 1
 #  endif
 #endif /* PNG_MIPS_MSA_OPT > 0 */
 #if PNG_POWERPC_VSX_OPT > 0
 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_vsx
 #  define PNG_POWERPC_VSX_IMPLEMENTATION 1
 #endif
 /* Is this a build of a DLL where compilation of the object modules requires
 * different preprocessor settings to those required for a simple library?  If
 * so PNG_BUILD_DLL must be set.
@ -374,25 +463,6 @@
 #  define png_fixed_error(s1,s2) png_err(s1)
 #endif
 /* C allows up-casts from (void*) to any pointer and (const void*) to any
 * pointer to a const object.  C++ regards this as a type error and requires an
 * explicit, static, cast and provides the static_cast<> rune to ensure that
 * const is not cast away.
 */
 #ifdef __cplusplus
 #  define png_voidcast(type, value) static_cast<type>(value)
 #  define png_constcast(type, value) const_cast<type>(value)
 #  define png_aligncast(type, value) \
   static_cast<type>(static_cast<void*>(value))
 #  define png_aligncastconst(type, value) \
   static_cast<type>(static_cast<const void*>(value))
 #else
 #  define png_voidcast(type, value) (value)
 #  define png_constcast(type, value) ((type)(value))
 #  define png_aligncast(type, value) ((void*)(value))
 #  define png_aligncastconst(type, value) ((const void*)(value))
 #endif /* __cplusplus */
 /* Some fixed point APIs are still required even if not exported because
 * they get used by the corresponding floating point APIs.  This magic
 * deals with this:
@ -407,6 +477,35 @@
 /* Other defines specific to compilers can go here.  Try to keep
 * them inside an appropriate ifdef/endif pair for portability.
 */
 /* C allows up-casts from (void*) to any pointer and (const void*) to any
 * pointer to a const object.  C++ regards this as a type error and requires an
 * explicit, static, cast and provides the static_cast<> rune to ensure that
 * const is not cast away.
 */
 #ifdef __cplusplus
 #  define png_voidcast(type, value) static_cast<type>(value)
 #  define png_constcast(type, value) const_cast<type>(value)
 #  define png_aligncast(type, value) \
   static_cast<type>(static_cast<void*>(value))
 #  define png_aligncastconst(type, value) \
   static_cast<type>(static_cast<const void*>(value))
 #else
 #  define png_voidcast(type, value) (value)
 #  ifdef _WIN64
 #     ifdef __GNUC__
         typedef unsigned long long png_ptruint;
 #     else
         typedef unsigned __int64 png_ptruint;
 #     endif
 #  else
      typedef unsigned long png_ptruint;
 #  endif
 #  define png_constcast(type, value) ((type)(png_ptruint)(const void*)(value))
 #  define png_aligncast(type, value) ((void*)(value))
 #  define png_aligncastconst(type, value) ((const void*)(value))
 #endif /* __cplusplus */
 #if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
    defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
   /* png.c requires the following ANSI-C constants if the conversion of
@ -504,7 +603,8 @@
 /* This implicitly assumes alignment is always to a power of 2. */
 #ifdef png_alignof
 #  define png_isaligned(ptr, type)\
-   ((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
+   (((type)((const char*)ptr-(const char*)0) & \
   (type)(png_alignof(type)-1)) == 0)
 #else
 #  define png_isaligned(ptr, type) 0
 #endif
@ -521,92 +621,92 @@
 * are defined in png.h because they need to be visible to applications
 * that call png_set_unknown_chunk().
 */
-/* #define PNG_HAVE_IHDR            0x01 (defined in png.h) */
+/* #define PNG_HAVE_IHDR            0x01U (defined in png.h) */
-/* #define PNG_HAVE_PLTE            0x02 (defined in png.h) */
+/* #define PNG_HAVE_PLTE            0x02U (defined in png.h) */
-#define PNG_HAVE_IDAT               0x04
+#define PNG_HAVE_IDAT               0x04U
-/* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
+/* #define PNG_AFTER_IDAT           0x08U (defined in png.h) */
-#define PNG_HAVE_IEND               0x10
+#define PNG_HAVE_IEND               0x10U
-                   /*               0x20 (unused) */
+                   /*               0x20U (unused) */
-                   /*               0x40 (unused) */
+                   /*               0x40U (unused) */
-                   /*               0x80 (unused) */
+                   /*               0x80U (unused) */
-#define PNG_HAVE_CHUNK_HEADER      0x100
+#define PNG_HAVE_CHUNK_HEADER      0x100U
-#define PNG_WROTE_tIME             0x200
+#define PNG_WROTE_tIME             0x200U
-#define PNG_WROTE_INFO_BEFORE_PLTE 0x400
+#define PNG_WROTE_INFO_BEFORE_PLTE 0x400U
-#define PNG_BACKGROUND_IS_GRAY     0x800
+#define PNG_BACKGROUND_IS_GRAY     0x800U
-#define PNG_HAVE_PNG_SIGNATURE    0x1000
+#define PNG_HAVE_PNG_SIGNATURE    0x1000U
-#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
+#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
-                   /*             0x4000 (unused) */
+                   /*             0x4000U (unused) */
-#define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */
+#define PNG_IS_READ_STRUCT        0x8000U /* Else is a write struct */
 /* Flags for the transformations the PNG library does on the image data */
-#define PNG_BGR                 0x0001
+#define PNG_BGR                 0x0001U
-#define PNG_INTERLACE           0x0002
+#define PNG_INTERLACE           0x0002U
-#define PNG_PACK                0x0004
+#define PNG_PACK                0x0004U
-#define PNG_SHIFT               0x0008
+#define PNG_SHIFT               0x0008U
-#define PNG_SWAP_BYTES          0x0010
+#define PNG_SWAP_BYTES          0x0010U
-#define PNG_INVERT_MONO         0x0020
+#define PNG_INVERT_MONO         0x0020U
-#define PNG_QUANTIZE            0x0040
+#define PNG_QUANTIZE            0x0040U
-#define PNG_COMPOSE             0x0080     /* Was PNG_BACKGROUND */
+#define PNG_COMPOSE             0x0080U    /* Was PNG_BACKGROUND */
-#define PNG_BACKGROUND_EXPAND   0x0100
+#define PNG_BACKGROUND_EXPAND   0x0100U
-#define PNG_EXPAND_16           0x0200     /* Added to libpng 1.5.2 */
+#define PNG_EXPAND_16           0x0200U    /* Added to libpng 1.5.2 */
-#define PNG_16_TO_8             0x0400     /* Becomes 'chop' in 1.5.4 */
+#define PNG_16_TO_8             0x0400U    /* Becomes 'chop' in 1.5.4 */
-#define PNG_RGBA                0x0800
+#define PNG_RGBA                0x0800U
-#define PNG_EXPAND              0x1000
+#define PNG_EXPAND              0x1000U
-#define PNG_GAMMA               0x2000
+#define PNG_GAMMA               0x2000U
-#define PNG_GRAY_TO_RGB         0x4000
+#define PNG_GRAY_TO_RGB         0x4000U
-#define PNG_FILLER              0x8000
+#define PNG_FILLER              0x8000U
-#define PNG_PACKSWAP           0x10000
+#define PNG_PACKSWAP           0x10000U
-#define PNG_SWAP_ALPHA         0x20000
+#define PNG_SWAP_ALPHA         0x20000U
-#define PNG_STRIP_ALPHA        0x40000
+#define PNG_STRIP_ALPHA        0x40000U
-#define PNG_INVERT_ALPHA       0x80000
+#define PNG_INVERT_ALPHA       0x80000U
-#define PNG_USER_TRANSFORM    0x100000
+#define PNG_USER_TRANSFORM    0x100000U
-#define PNG_RGB_TO_GRAY_ERR   0x200000
+#define PNG_RGB_TO_GRAY_ERR   0x200000U
-#define PNG_RGB_TO_GRAY_WARN  0x400000
+#define PNG_RGB_TO_GRAY_WARN  0x400000U
-#define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
+#define PNG_RGB_TO_GRAY       0x600000U /* two bits, RGB_TO_GRAY_ERR|WARN */
-#define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
+#define PNG_ENCODE_ALPHA      0x800000U /* Added to libpng-1.5.4 */
-#define PNG_ADD_ALPHA        0x1000000 /* Added to libpng-1.2.7 */
+#define PNG_ADD_ALPHA        0x1000000U /* Added to libpng-1.2.7 */
-#define PNG_EXPAND_tRNS      0x2000000 /* Added to libpng-1.2.9 */
+#define PNG_EXPAND_tRNS      0x2000000U /* Added to libpng-1.2.9 */
-#define PNG_SCALE_16_TO_8    0x4000000 /* Added to libpng-1.5.4 */
+#define PNG_SCALE_16_TO_8    0x4000000U /* Added to libpng-1.5.4 */
-                       /*    0x8000000 unused */
+                       /*    0x8000000U unused */
-                       /*   0x10000000 unused */
+                       /*   0x10000000U unused */
-                       /*   0x20000000 unused */
+                       /*   0x20000000U unused */
-                       /*   0x40000000 unused */
+                       /*   0x40000000U unused */
 /* Flags for png_create_struct */
-#define PNG_STRUCT_PNG   0x0001
+#define PNG_STRUCT_PNG   0x0001U
-#define PNG_STRUCT_INFO  0x0002
+#define PNG_STRUCT_INFO  0x0002U
 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
-#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
+#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001U
-#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
+#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002U /* Added to libpng-1.6.0 */
-                                  /*      0x0004    unused */
+                                  /*      0x0004U    unused */
-#define PNG_FLAG_ZSTREAM_ENDED            0x0008 /* Added to libpng-1.6.0 */
+#define PNG_FLAG_ZSTREAM_ENDED            0x0008U /* Added to libpng-1.6.0 */
-                                  /*      0x0010    unused */
+                                  /*      0x0010U    unused */
-                                  /*      0x0020    unused */
+                                  /*      0x0020U    unused */
-#define PNG_FLAG_ROW_INIT                 0x0040
+#define PNG_FLAG_ROW_INIT                 0x0040U
-#define PNG_FLAG_FILLER_AFTER             0x0080
+#define PNG_FLAG_FILLER_AFTER             0x0080U
-#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
+#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100U
-#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
+#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200U
-#define PNG_FLAG_CRC_CRITICAL_USE         0x0400
+#define PNG_FLAG_CRC_CRITICAL_USE         0x0400U
-#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
+#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800U
-#define PNG_FLAG_ASSUME_sRGB              0x1000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_ASSUME_sRGB              0x1000U /* Added to libpng-1.5.4 */
-#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000U /* Added to libpng-1.5.4 */
-#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000 /* Added to libpng-1.5.4 */
+#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000U /* Added to libpng-1.5.4 */
-/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000 */
+/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000U */
-/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000 */
+/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000U */
-#define PNG_FLAG_LIBRARY_MISMATCH        0x20000
+#define PNG_FLAG_LIBRARY_MISMATCH        0x20000U
-#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000
+#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000U
-#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000
+#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000U
-#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000 /* Added to libpng-1.4.0 */
+#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000U /* Added to libpng-1.4.0 */
-#define PNG_FLAG_APP_WARNINGS_WARN      0x200000 /* Added to libpng-1.6.0 */
+#define PNG_FLAG_APP_WARNINGS_WARN      0x200000U /* Added to libpng-1.6.0 */
-#define PNG_FLAG_APP_ERRORS_WARN        0x400000 /* Added to libpng-1.6.0 */
+#define PNG_FLAG_APP_ERRORS_WARN        0x400000U /* Added to libpng-1.6.0 */
-                                  /*    0x800000    unused */
+                                  /*    0x800000U    unused */
-                                  /*   0x1000000    unused */
+                                  /*   0x1000000U    unused */
-                                  /*   0x2000000    unused */
+                                  /*   0x2000000U    unused */
-                                  /*   0x4000000    unused */
+                                  /*   0x4000000U    unused */
-                                  /*   0x8000000    unused */
+                                  /*   0x8000000U    unused */
-                                  /*  0x10000000    unused */
+                                  /*  0x10000000U    unused */
-                                  /*  0x20000000    unused */
+                                  /*  0x20000000U    unused */
-                                  /*  0x40000000    unused */
+                                  /*  0x40000000U    unused */
 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                     PNG_FLAG_CRC_ANCILLARY_NOWARN)
@ -637,8 +737,26 @@
 /* Added to libpng-1.2.6 JB */
 #define PNG_ROWBYTES(pixel_bits, width) \
    ((pixel_bits) >= 8 ? \
-    ((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
+    ((size_t)(width) * (((size_t)(pixel_bits)) >> 3)) : \
-    (( ((png_size_t)(width) * ((png_size_t)(pixel_bits))) + 7) >> 3) )
+    (( ((size_t)(width) * ((size_t)(pixel_bits))) + 7) >> 3) )
 /* This returns the number of trailing bits in the last byte of a row, 0 if the
 * last byte is completely full of pixels.  It is, in principle, (pixel_bits x
 * width) % 8, but that would overflow for large 'width'.  The second macro is
 * the same except that it returns the number of unused bits in the last byte;
 * (8-TRAILBITS), but 0 when TRAILBITS is 0.
 *
 * NOTE: these macros are intended to be self-evidently correct and never
 * overflow on the assumption that pixel_bits is in the range 0..255.  The
 * arguments are evaluated only once and they can be signed (e.g. as a result of
 * the integral promotions).  The result of the expression always has type
 * (png_uint_32), however the compiler always knows it is in the range 0..7.
 */
 #define PNG_TRAILBITS(pixel_bits, width) \
    (((pixel_bits) * ((width) % (png_uint_32)8)) % 8)
 #define PNG_PADBITS(pixel_bits, width) \
    ((8 - PNG_TRAILBITS(pixel_bits, width)) % 8)
 /* PNG_OUT_OF_RANGE returns true if value is outside the range
 * ideal-delta..ideal+delta.  Each argument is evaluated twice.
@ -733,6 +851,7 @@
 #define png_PLTE PNG_U32( 80,  76,  84,  69)
 #define png_bKGD PNG_U32( 98,  75,  71,  68)
 #define png_cHRM PNG_U32( 99,  72,  82,  77)
 #define png_eXIf PNG_U32(101,  88,  73, 102) /* registered July 2017 */
 #define png_fRAc PNG_U32(102,  82,  65,  99) /* registered, not defined */
 #define png_gAMA PNG_U32(103,  65,  77,  65)
 #define png_gIFg PNG_U32(103,  73,  70, 103)
@ -807,7 +926,7 @@
    * PNG files the -I directives must match.
    *
    * The most likely explanation is that you passed a -I in CFLAGS. This will
-    * not work; all the preprocessor directories and in particular all the -I
+    * not work; all the preprocessor directives and in particular all the -I
    * directives must be in CPPFLAGS.
    */
 #endif
@ -936,15 +1055,15 @@ PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);
 */
 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
-    png_bytep data, png_size_t length),PNG_EMPTY);
+    png_bytep data, size_t length),PNG_EMPTY);
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_push_fill_buffer,(png_structp png_ptr,
-    png_bytep buffer, png_size_t length),PNG_EMPTY);
+    png_bytep buffer, size_t length),PNG_EMPTY);
 #endif
 PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
-    png_bytep data, png_size_t length),PNG_EMPTY);
+    png_bytep data, size_t length),PNG_EMPTY);
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 #  ifdef PNG_STDIO_SUPPORTED
@ -958,7 +1077,7 @@ PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr),PNG_EMPTY);
 /* Write the "data" buffer to whatever output you are using */
 PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
-    png_const_bytep data, png_size_t length),PNG_EMPTY);
+    png_const_bytep data, size_t length),PNG_EMPTY);
 /* Read and check the PNG file signature */
 PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
@ -970,7 +1089,7 @@ PNG_INTERNAL_FUNCTION(png_uint_32,png_read_chunk_header,(png_structrp png_ptr),
 /* Read data from whatever input you are using into the "data" buffer */
 PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_bytep data,
-    png_size_t length),PNG_EMPTY);
+    size_t length),PNG_EMPTY);
 /* Read bytes into buf, and update png_ptr->crc */
 PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_bytep buf,
@ -988,7 +1107,7 @@ PNG_INTERNAL_FUNCTION(int,png_crc_error,(png_structrp png_ptr),PNG_EMPTY);
 * since this is the maximum buffer size we can specify.
 */
 PNG_INTERNAL_FUNCTION(void,png_calculate_crc,(png_structrp png_ptr,
-   png_const_bytep ptr, png_size_t length),PNG_EMPTY);
+   png_const_bytep ptr, size_t length),PNG_EMPTY);
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_flush,(png_structrp png_ptr),PNG_EMPTY);
@ -1033,6 +1152,11 @@ PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
    int intent),PNG_EMPTY);
 #endif
 #ifdef PNG_WRITE_eXIf_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_write_eXIf,(png_structrp png_ptr,
    png_bytep exif, int num_exif),PNG_EMPTY);
 #endif
 #ifdef PNG_WRITE_iCCP_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
   png_const_charp name, png_const_bytep profile), PNG_EMPTY);
@ -1066,7 +1190,7 @@ PNG_INTERNAL_FUNCTION(void,png_write_hIST,(png_structrp png_ptr,
 /* Chunks that have keywords */
 #ifdef PNG_WRITE_tEXt_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_write_tEXt,(png_structrp png_ptr,
-   png_const_charp key, png_const_charp text, png_size_t text_len),PNG_EMPTY);
+   png_const_charp key, png_const_charp text, size_t text_len),PNG_EMPTY);
 #endif
 #ifdef PNG_WRITE_zTXt_SUPPORTED
@ -1174,6 +1298,7 @@ PNG_INTERNAL_FUNCTION(void,png_do_write_interlace,(png_row_infop row_info,
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row,(png_structrp pp, png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row, int filter),PNG_EMPTY);
 #if PNG_ARM_NEON_OPT > 0
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_neon,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_neon,(png_row_infop
@ -1188,6 +1313,56 @@ PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_neon,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 #endif
 #if PNG_MIPS_MSA_OPT > 0
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_msa,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 #endif
 #if PNG_POWERPC_VSX_OPT > 0
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_vsx,(png_row_infop row_info,
    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_vsx,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 #endif
 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 #endif
 /* Choose the best filter to use and filter the row data */
 PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
@ -1215,7 +1390,7 @@ PNG_INTERNAL_FUNCTION(void,png_read_finish_row,(png_structrp png_ptr),
 /* Initialize the row buffers, etc. */
 PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
 PNG_INTERNAL_FUNCTION(int,png_zlib_inflate,(png_structrp png_ptr, int flush),
      PNG_EMPTY);
 #  define PNG_INFLATE(pp, flush) png_zlib_inflate(pp, flush)
@ -1281,6 +1456,11 @@ PNG_INTERNAL_FUNCTION(void,png_handle_cHRM,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 #ifdef PNG_READ_eXIf_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_handle_eXIf,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
 #ifdef PNG_READ_gAMA_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_handle_gAMA,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
@ -1356,9 +1536,12 @@ PNG_INTERNAL_FUNCTION(void,png_handle_zTXt,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length),PNG_EMPTY);
 #endif
-PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_structrp png_ptr,
+PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_const_structrp png_ptr,
    png_uint_32 chunk_name),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_check_chunk_length,(png_const_structrp png_ptr,
    png_uint_32 chunk_length),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
    png_inforp info_ptr, png_uint_32 length, int keep),PNG_EMPTY);
   /* This is the function that gets called for unknown chunks.  The 'keep'
@ -1400,10 +1583,10 @@ PNG_INTERNAL_FUNCTION(void,png_push_check_crc,(png_structrp png_ptr),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_save_buffer,(png_structrp png_ptr),
    PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_restore_buffer,(png_structrp png_ptr,
-    png_bytep buffer, png_size_t buffer_length),PNG_EMPTY);
+    png_bytep buffer, size_t buffer_length),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_read_IDAT,(png_structrp png_ptr),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_process_IDAT_data,(png_structrp png_ptr,
-    png_bytep buffer, png_size_t buffer_length),PNG_EMPTY);
+    png_bytep buffer, size_t buffer_length),PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_process_row,(png_structrp png_ptr),
    PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(void,png_push_handle_unknown,(png_structrp png_ptr,
@ -1492,9 +1675,11 @@ PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
   /* The 'name' is used for information only */
 /* Routines for checking parts of an ICC profile. */
 #ifdef PNG_READ_iCCP_SUPPORTED
 PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length), PNG_EMPTY);
 #endif /* READ_iCCP */
 PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
   png_colorspacerp colorspace, png_const_charp name,
   png_uint_32 profile_length,
@ -1671,13 +1856,13 @@ PNG_INTERNAL_FUNCTION(void,png_chunk_report,(png_const_structrp png_ptr,
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_ascii_from_fp,(png_const_structrp png_ptr,
-   png_charp ascii, png_size_t size, double fp, unsigned int precision),
+   png_charp ascii, size_t size, double fp, unsigned int precision),
   PNG_EMPTY);
 #endif /* FLOATING_POINT */
 #ifdef PNG_FIXED_POINT_SUPPORTED
 PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
-   png_charp ascii, png_size_t size, png_fixed_point fp),PNG_EMPTY);
+   png_charp ascii, size_t size, png_fixed_point fp),PNG_EMPTY);
 #endif /* FIXED_POINT */
 #endif /* sCAL */
@ -1770,7 +1955,7 @@ PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
 * the problem character.)  This has not been tested within libpng.
 */
 PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
-   png_size_t size, int *statep, png_size_tp whereami),PNG_EMPTY);
+   size_t size, int *statep, png_size_tp whereami),PNG_EMPTY);
 /* This is the same but it checks a complete string and returns true
 * only if it just contains a floating point number.  As of 1.5.4 this
@ -1779,7 +1964,7 @@ PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
 * for negative or zero values using the sticky flag.
 */
 PNG_INTERNAL_FUNCTION(int,png_check_fp_string,(png_const_charp string,
-   png_size_t size),PNG_EMPTY);
+   size_t size),PNG_EMPTY);
 #endif /* pCAL || sCAL */
 #if defined(PNG_GAMMA_SUPPORTED) ||\
@ -1854,7 +2039,7 @@ typedef struct png_control
   png_voidp   error_buf;           /* Always a jmp_buf at present. */
   png_const_bytep memory;          /* Memory buffer. */
-   png_size_t      size;            /* Size of the memory buffer. */
+   size_t          size;            /* Size of the memory buffer. */
   unsigned int for_write       :1; /* Otherwise it is a read structure */
   unsigned int owned_file      :1; /* We own the file in io_ptr */
@ -1913,13 +2098,48 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structp png_ptr,
    * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
    * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
    */
 #  if PNG_ARM_NEON_OPT > 0
 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #endif
 #if PNG_MIPS_MSA_OPT > 0
 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_msa,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #endif
 #  if PNG_INTEL_SSE_IMPLEMENTATION > 0
 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #  endif
 #endif
 PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
   png_const_charp key, png_bytep new_key), PNG_EMPTY);
 #if PNG_ARM_NEON_IMPLEMENTATION == 1
 PNG_INTERNAL_FUNCTION(void,
                      png_riffle_palette_neon,
                      (png_structrp),
                      PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(int,
                      png_do_expand_palette_rgba8_neon,
                      (png_structrp,
                       png_row_infop,
                       png_const_bytep,
                       const png_bytepp,
                       const png_bytepp),
                      PNG_EMPTY);
 PNG_INTERNAL_FUNCTION(int,
                      png_do_expand_palette_rgb8_neon,
                      (png_structrp,
                       png_row_infop,
                       png_const_bytep,
                       const png_bytepp,
                       const png_bytepp),
                      PNG_EMPTY);
 #endif
 /* Maintainer: Put new private prototypes here ^ */
 #include "pngdebug.h"
--- a/source/Irrlicht/libpng/pngread.c
+++ b/source/Irrlicht/libpng/pngread.c
@ -1,10 +1,10 @@
 /* pngread.c - read a PNG file
 *
- * Last changed in libpng 1.6.23 [June 9, 2016]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -175,6 +175,11 @@ png_read_info(png_structrp png_ptr, png_inforp info_ptr)
         png_handle_cHRM(png_ptr, info_ptr, length);
 #endif
 #ifdef PNG_READ_eXIf_SUPPORTED
      else if (chunk_name == png_eXIf)
         png_handle_eXIf(png_ptr, info_ptr, length);
 #endif
 #ifdef PNG_READ_gAMA_SUPPORTED
      else if (chunk_name == png_gAMA)
         png_handle_gAMA(png_ptr, info_ptr, length);
@ -359,9 +364,9 @@ png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
         {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
+            png_uint_32 s0   = (png_uint_32)(*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
+            png_uint_32 s1   = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 s2   = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
            png_uint_32 red  = (s0 + s1 + 65536) & 0xffff;
            png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
            *(rp    ) = (png_byte)((red >> 8) & 0xff);
@ -534,6 +539,7 @@ png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
      png_error(png_ptr, "Invalid attempt to read row data");
   /* Fill the row with IDAT data: */
   png_ptr->row_buf[0]=255; /* to force error if no data was found */
   png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
   if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
@ -842,6 +848,11 @@ png_read_end(png_structrp png_ptr, png_inforp info_ptr)
         png_handle_cHRM(png_ptr, info_ptr, length);
 #endif
 #ifdef PNG_READ_eXIf_SUPPORTED
      else if (chunk_name == png_eXIf)
         png_handle_eXIf(png_ptr, info_ptr, length);
 #endif
 #ifdef PNG_READ_gAMA_SUPPORTED
      else if (chunk_name == png_gAMA)
         png_handle_gAMA(png_ptr, info_ptr, length);
@ -983,6 +994,12 @@ png_read_destroy(png_structrp png_ptr)
   png_ptr->chunk_list = NULL;
 #endif
 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
    defined(PNG_ARM_NEON_IMPLEMENTATION)
   png_free(png_ptr, png_ptr->riffled_palette);
   png_ptr->riffled_palette = NULL;
 #endif
   /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
    * callbacks are still set at this point.  They are required to complete the
    * destruction of the png_struct itself.
@ -1030,8 +1047,7 @@ png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 void PNGAPI
 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
-                           int transforms,
+    int transforms, voidp params)
                           voidp params)
 {
   if (png_ptr == NULL || info_ptr == NULL)
      return;
@ -1394,7 +1410,9 @@ png_image_read_header(png_voidp argument)
   png_structrp png_ptr = image->opaque->png_ptr;
   png_inforp info_ptr = image->opaque->info_ptr;
 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
   png_set_benign_errors(png_ptr, 1/*warn*/);
 #endif
   png_read_info(png_ptr, info_ptr);
   /* Do this the fast way; just read directly out of png_struct. */
@ -1432,7 +1450,7 @@ png_image_read_header(png_voidp argument)
            break;
         case PNG_COLOR_TYPE_PALETTE:
-            cmap_entries = png_ptr->num_palette;
+            cmap_entries = (png_uint_32)png_ptr->num_palette;
            break;
         default:
@ -1520,7 +1538,7 @@ png_image_begin_read_from_file(png_imagep image, const char *file_name)
 #endif /* STDIO */
 static void PNGCBAPI
-png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
+png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need)
 {
   if (png_ptr != NULL)
   {
@ -1531,7 +1549,7 @@ png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
         if (cp != NULL)
         {
            png_const_bytep memory = cp->memory;
-            png_size_t size = cp->size;
+            size_t size = cp->size;
            if (memory != NULL && size >= need)
            {
@ -1550,7 +1568,7 @@ png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
 }
 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
-   png_const_voidp memory, png_size_t size)
+    png_const_voidp memory, size_t size)
 {
   if (image != NULL && image->version == PNG_IMAGE_VERSION)
   {
@ -1609,7 +1627,7 @@ png_image_skip_unused_chunks(png_structrp png_ptr)
    * errors (which are unfortunately quite common.)
    */
   {
-         static PNG_CONST png_byte chunks_to_process[] = {
+         static const png_byte chunks_to_process[] = {
            98,  75,  71,  68, '\0',  /* bKGD */
            99,  72,  82,  77, '\0',  /* cHRM */
           103,  65,  77,  65, '\0',  /* gAMA */
@ -1746,9 +1764,9 @@ png_create_colormap_entry(png_image_read_control *display,
    png_uint_32 alpha, int encoding)
 {
   png_imagep image = display->image;
-   const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
+   int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
       P_LINEAR : P_sRGB;
-   const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
+   int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
       (red != green || green != blue);
   if (ip > 255)
@ -1857,13 +1875,13 @@ png_create_colormap_entry(png_image_read_control *display,
   /* Store the value. */
   {
 #     ifdef PNG_FORMAT_AFIRST_SUPPORTED
-         const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
+         int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
            (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
 #     else
 #        define afirst 0
 #     endif
 #     ifdef PNG_FORMAT_BGR_SUPPORTED
-         const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
+         int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
 #     else
 #        define bgr 0
 #     endif
@ -1882,7 +1900,7 @@ png_create_colormap_entry(png_image_read_control *display,
         {
            case 4:
               entry[afirst ? 0 : 3] = (png_uint_16)alpha;
-               /* FALL THROUGH */
+               /* FALLTHROUGH */
            case 3:
               if (alpha < 65535)
@ -1904,7 +1922,7 @@ png_create_colormap_entry(png_image_read_control *display,
            case 2:
               entry[1 ^ afirst] = (png_uint_16)alpha;
-               /* FALL THROUGH */
+               /* FALLTHROUGH */
            case 1:
               if (alpha < 65535)
@ -1933,6 +1951,7 @@ png_create_colormap_entry(png_image_read_control *display,
         {
            case 4:
               entry[afirst ? 0 : 3] = (png_byte)alpha;
               /* FALLTHROUGH */
            case 3:
               entry[afirst + (2 ^ bgr)] = (png_byte)blue;
               entry[afirst + 1] = (png_byte)green;
@ -1941,6 +1960,7 @@ png_create_colormap_entry(png_image_read_control *display,
            case 2:
               entry[1 ^ afirst] = (png_byte)alpha;
               /* FALLTHROUGH */
            case 1:
               entry[afirst] = (png_byte)green;
               break;
@ -1967,7 +1987,7 @@ make_gray_file_colormap(png_image_read_control *display)
   for (i=0; i<256; ++i)
      png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
-   return i;
+   return (int)i;
 }
 static int
@ -1978,7 +1998,7 @@ make_gray_colormap(png_image_read_control *display)
   for (i=0; i<256; ++i)
      png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
-   return i;
+   return (int)i;
 }
 #define PNG_GRAY_COLORMAP_ENTRIES 256
@ -2032,7 +2052,7 @@ make_ga_colormap(png_image_read_control *display)
             P_sRGB);
   }
-   return i;
+   return (int)i;
 }
 #define PNG_GA_COLORMAP_ENTRIES 256
@ -2057,7 +2077,7 @@ make_rgb_colormap(png_image_read_control *display)
      }
   }
-   return i;
+   return (int)i;
 }
 #define PNG_RGB_COLORMAP_ENTRIES 216
@ -2071,11 +2091,11 @@ png_image_read_colormap(png_voidp argument)
 {
   png_image_read_control *display =
      png_voidcast(png_image_read_control*, argument);
-   const png_imagep image = display->image;
+   png_imagep image = display->image;
-   const png_structrp png_ptr = image->opaque->png_ptr;
+   png_structrp png_ptr = image->opaque->png_ptr;
-   const png_uint_32 output_format = image->format;
+   png_uint_32 output_format = image->format;
-   const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
+   int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
      P_LINEAR : P_sRGB;
   unsigned int cmap_entries;
@ -2105,7 +2125,7 @@ png_image_read_colormap(png_voidp argument)
      else if (display->background == NULL /* no way to remove it */)
         png_error(png_ptr,
-            "a background color must be supplied to remove alpha/transparency");
+             "background color must be supplied to remove alpha/transparency");
      /* Get a copy of the background color (this avoids repeating the checks
       * below.)  The encoding is 8-bit sRGB or 16-bit linear, depending on the
@ -2250,7 +2270,7 @@ png_image_read_colormap(png_voidp argument)
            if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
               png_error(png_ptr, "gray[16] color-map: too few entries");
-            cmap_entries = make_gray_colormap(display);
+            cmap_entries = (unsigned int)make_gray_colormap(display);
            if (png_ptr->num_trans > 0)
            {
@ -2348,7 +2368,7 @@ png_image_read_colormap(png_voidp argument)
            if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
               png_error(png_ptr, "gray+alpha color-map: too few entries");
-            cmap_entries = make_ga_colormap(display);
+            cmap_entries = (unsigned int)make_ga_colormap(display);
            background_index = PNG_CMAP_GA_BACKGROUND;
            output_processing = PNG_CMAP_GA;
@ -2382,7 +2402,7 @@ png_image_read_colormap(png_voidp argument)
               if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
                  png_error(png_ptr, "gray-alpha color-map: too few entries");
-               cmap_entries = make_gray_colormap(display);
+               cmap_entries = (unsigned int)make_gray_colormap(display);
               if (output_encoding == P_LINEAR)
               {
@ -2430,8 +2450,8 @@ png_image_read_colormap(png_voidp argument)
               background_index = i;
               png_create_colormap_entry(display, i++, back_r, back_g, back_b,
 #ifdef __COVERITY__
-                 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
+                   /* Coverity claims that output_encoding
-                  * here.
+                    * cannot be 2 (P_LINEAR) here.
                    */ 255U,
 #else
                    output_encoding == P_LINEAR ? 65535U : 255U,
@ -2521,7 +2541,7 @@ png_image_read_colormap(png_voidp argument)
               if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
                  png_error(png_ptr, "rgb[ga] color-map: too few entries");
-               cmap_entries = make_ga_colormap(display);
+               cmap_entries = (unsigned int)make_ga_colormap(display);
               background_index = PNG_CMAP_GA_BACKGROUND;
               output_processing = PNG_CMAP_GA;
            }
@ -2547,12 +2567,12 @@ png_image_read_colormap(png_voidp argument)
                  png_ptr->num_trans > 0) &&
                  png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
               {
-                  cmap_entries = make_gray_file_colormap(display);
+                  cmap_entries = (unsigned int)make_gray_file_colormap(display);
                  data_encoding = P_FILE;
               }
               else
-                  cmap_entries = make_gray_colormap(display);
+                  cmap_entries = (unsigned int)make_gray_colormap(display);
               /* But if the input has alpha or transparency it must be removed
                */
@ -2640,7 +2660,7 @@ png_image_read_colormap(png_voidp argument)
                  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
                     png_error(png_ptr, "rgb+alpha color-map: too few entries");
-                  cmap_entries = make_rgb_colormap(display);
+                  cmap_entries = (unsigned int)make_rgb_colormap(display);
                  /* Add a transparent entry. */
                  png_create_colormap_entry(display, cmap_entries, 255, 255,
@ -2689,7 +2709,7 @@ png_image_read_colormap(png_voidp argument)
                  if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
                     png_error(png_ptr, "rgb-alpha color-map: too few entries");
-                  cmap_entries = make_rgb_colormap(display);
+                  cmap_entries = (unsigned int)make_rgb_colormap(display);
                  png_create_colormap_entry(display, cmap_entries, back_r,
                      back_g, back_b, 0/*unused*/, output_encoding);
@ -2774,7 +2794,7 @@ png_image_read_colormap(png_voidp argument)
               if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
                  png_error(png_ptr, "rgb color-map: too few entries");
-               cmap_entries = make_rgb_colormap(display);
+               cmap_entries = (unsigned int)make_rgb_colormap(display);
               output_processing = PNG_CMAP_RGB;
            }
         }
@ -2788,7 +2808,7 @@ png_image_read_colormap(png_voidp argument)
            unsigned int num_trans = png_ptr->num_trans;
            png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
            png_const_colorp colormap = png_ptr->palette;
-            const int do_background = trans != NULL &&
+            int do_background = trans != NULL &&
               (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
            unsigned int i;
@ -2798,11 +2818,11 @@ png_image_read_colormap(png_voidp argument)
            output_processing = PNG_CMAP_NONE;
            data_encoding = P_FILE; /* Don't change from color-map indices */
-            cmap_entries = png_ptr->num_palette;
+            cmap_entries = (unsigned int)png_ptr->num_palette;
            if (cmap_entries > 256)
               cmap_entries = 256;
-            if (cmap_entries > image->colormap_entries)
+            if (cmap_entries > (unsigned int)image->colormap_entries)
               png_error(png_ptr, "palette color-map: too few entries");
            for (i=0; i < cmap_entries; ++i)
@ -2819,12 +2839,12 @@ png_image_read_colormap(png_voidp argument)
                      * on the sRGB color in 'back'.
                      */
                     png_create_colormap_entry(display, i,
-                        png_colormap_compose(display, colormap[i].red, P_FILE,
+                         png_colormap_compose(display, colormap[i].red,
-                           trans[i], back_r, output_encoding),
+                             P_FILE, trans[i], back_r, output_encoding),
-                        png_colormap_compose(display, colormap[i].green, P_FILE,
+                         png_colormap_compose(display, colormap[i].green,
-                           trans[i], back_g, output_encoding),
+                             P_FILE, trans[i], back_g, output_encoding),
-                        png_colormap_compose(display, colormap[i].blue, P_FILE,
+                         png_colormap_compose(display, colormap[i].blue,
-                           trans[i], back_b, output_encoding),
+                             P_FILE, trans[i], back_b, output_encoding),
                         output_encoding == P_LINEAR ? trans[i] * 257U :
                             trans[i],
                         output_encoding);
@ -2860,7 +2880,7 @@ png_image_read_colormap(png_voidp argument)
      case P_sRGB:
         /* Change to 8-bit sRGB */
         png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
-         /* FALL THROUGH */
+         /* FALLTHROUGH */
      case P_FILE:
         if (png_ptr->bit_depth > 8)
@ -2914,7 +2934,7 @@ png_image_read_colormap(png_voidp argument)
         png_error(png_ptr, "bad background index (internal error)");
   }
-   display->colormap_processing = output_processing;
+   display->colormap_processing = (int)output_processing;
   return 1/*ok*/;
 }
@ -3178,8 +3198,7 @@ png_image_read_colormapped(png_voidp argument)
            image->colormap_entries == 244 /* 216 + 1 + 27 */)
            break;
-         /* goto bad_output; */
+         goto bad_output;
         /* FALL THROUGH */
      default:
      bad_output:
@ -3223,14 +3242,14 @@ png_image_read_colormapped(png_voidp argument)
   else
   {
-      png_alloc_size_t row_bytes = display->row_bytes;
+      png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
      while (--passes >= 0)
      {
         png_uint_32      y = image->height;
         png_bytep        row = png_voidcast(png_bytep, display->first_row);
-         while (y-- > 0)
+         for (; y > 0; --y)
         {
            png_read_row(png_ptr, row, NULL);
            row += row_bytes;
@ -3433,8 +3452,7 @@ png_image_read_background(png_voidp argument)
            for (pass = 0; pass < passes; ++pass)
            {
-               png_bytep        row = png_voidcast(png_bytep,
+               png_bytep row = png_voidcast(png_bytep, display->first_row);
                                                   display->first_row);
               unsigned int     startx, stepx, stepy;
               png_uint_32      y;
@ -3559,8 +3577,9 @@ png_image_read_background(png_voidp argument)
             * stride which was multiplied by 2 (below) to get row_bytes.
             */
            ptrdiff_t    step_row = display->row_bytes / 2;
-            int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
+            unsigned int preserve_alpha = (image->format &
-            unsigned int outchannels = 1+preserve_alpha;
+                PNG_FORMAT_FLAG_ALPHA) != 0;
            unsigned int outchannels = 1U+preserve_alpha;
            int swap_alpha = 0;
 #           ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
@ -3747,6 +3766,12 @@ png_image_read_direct(png_voidp argument)
         output_gamma = PNG_DEFAULT_sRGB;
      }
      if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0)
      {
         mode = PNG_ALPHA_OPTIMIZED;
         change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
      }
      /* If 'do_local_background' is set check for the presence of gamma
       * correction; this is part of the work-round for the libpng bug
       * described above.
@ -3927,7 +3952,7 @@ png_image_read_direct(png_voidp argument)
       */
      if (linear != 0)
      {
-         PNG_CONST png_uint_16 le = 0x0001;
+         png_uint_16 le = 0x0001;
         if ((*(png_const_bytep) & le) != 0)
            png_set_swap(png_ptr);
@ -3972,6 +3997,10 @@ png_image_read_direct(png_voidp argument)
      else if (do_local_compose != 0) /* internal error */
         png_error(png_ptr, "png_image_read: alpha channel lost");
      if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) {
         info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
      }
      if (info_ptr->bit_depth == 16)
         info_format |= PNG_FORMAT_FLAG_LINEAR;
@ -4057,14 +4086,14 @@ png_image_read_direct(png_voidp argument)
   else
   {
-      png_alloc_size_t row_bytes = display->row_bytes;
+      png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
      while (--passes >= 0)
      {
         png_uint_32      y = image->height;
         png_bytep        row = png_voidcast(png_bytep, display->first_row);
-         while (y-- > 0)
+         for (; y > 0; --y)
         {
            png_read_row(png_ptr, row, NULL);
            row += row_bytes;
@ -4085,29 +4114,52 @@ png_image_finish_read(png_imagep image, png_const_colorp background,
       * original PNG format because it may not occur in the output PNG format
       * and libpng deals with the issues of reading the original.
       */
-      const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
+      unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
+      /* The following checks just the 'row_stride' calculation to ensure it
       * fits in a signed 32-bit value.  Because channels/components can be
       * either 1 or 2 bytes in size the length of a row can still overflow 32
       * bits; this is just to verify that the 'row_stride' argument can be
       * represented.
       */
      if (image->width <= 0x7fffffffU/channels) /* no overflow */
      {
         png_uint_32 check;
-         const png_uint_32 png_row_stride = image->width * channels;
+         png_uint_32 png_row_stride = image->width * channels;
         if (row_stride == 0)
            row_stride = (png_int_32)/*SAFE*/png_row_stride;
         if (row_stride < 0)
-            check = -row_stride;
+            check = (png_uint_32)(-row_stride);
         else
-            check = row_stride;
+            check = (png_uint_32)row_stride;
         /* This verifies 'check', the absolute value of the actual stride
          * passed in and detects overflow in the application calculation (i.e.
          * if the app did actually pass in a non-zero 'row_stride'.
          */
         if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
         {
            /* Now check for overflow of the image buffer calculation; this
             * limits the whole image size to 32 bits for API compatibility with
             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
             *
             * The PNG_IMAGE_BUFFER_SIZE macro is:
             *
             *    (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
             *
             * And the component size is always 1 or 2, so make sure that the
             * number of *bytes* that the application is saying are available
             * does actually fit into a 32-bit number.
             *
             * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
             * will be changed to use png_alloc_size_t; bigger images can be
             * accommodated on 64-bit systems.
             */
-            if (image->height <= 0xFFFFFFFF/png_row_stride)
+            if (image->height <=
                0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
            {
               if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
                  (image->colormap_entries > 0 && colormap != NULL))
@ -4127,7 +4179,8 @@ png_image_finish_read(png_imagep image, png_const_colorp background,
                   * all the setup has already been done.
                   */
                  if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
-                     result = png_safe_execute(image,
+                     result =
                         png_safe_execute(image,
                             png_image_read_colormap, &display) &&
                             png_safe_execute(image,
                             png_image_read_colormapped, &display);
--- a/source/Irrlicht/libpng/pngrio.c
+++ b/source/Irrlicht/libpng/pngrio.c
@ -1,10 +1,10 @@
 /* pngrio.c - functions for data input
 *
- * Last changed in libpng 1.6.17 [March 26, 2015]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -29,7 +29,7 @@
 * to read more than 64K on a 16-bit machine.
 */
 void /* PRIVATE */
-png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length)
+png_read_data(png_structrp png_ptr, png_bytep data, size_t length)
 {
   png_debug1(4, "reading %d bytes", (int)length);
@ -47,14 +47,14 @@ png_read_data(png_structrp png_ptr, png_bytep data, png_size_t length)
 * than changing the library.
 */
 void PNGCBAPI
-png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
+png_default_read_data(png_structp png_ptr, png_bytep data, size_t length)
 {
-   png_size_t check;
+   size_t check;
   if (png_ptr == NULL)
      return;
-   /* fread() returns 0 on error, so it is OK to store this in a png_size_t
+   /* fread() returns 0 on error, so it is OK to store this in a size_t
    * instead of an int, which is what fread() actually returns.
    */
   check = fread(data, 1, length, png_voidcast(png_FILE_p, png_ptr->io_ptr));
--- a/source/Irrlicht/libpng/pngrtran.c
+++ b/source/Irrlicht/libpng/pngrtran.c
@ -1,10 +1,10 @@
 /* pngrtran.c - transforms the data in a row for PNG readers
 *
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -18,6 +18,17 @@
 #include "pngpriv.h"
 #ifdef PNG_ARM_NEON_IMPLEMENTATION
 #  if PNG_ARM_NEON_IMPLEMENTATION == 1
 #    define PNG_ARM_NEON_INTRINSICS_AVAILABLE
 #    if defined(_MSC_VER) && defined(_M_ARM64)
 #      include <arm64_neon.h>
 #    else
 #      include <arm_neon.h>
 #    endif
 #  endif
 #endif
 #ifdef PNG_READ_SUPPORTED
 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
@ -49,6 +60,7 @@ png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
      case PNG_CRC_WARN_DISCARD:    /* Not a valid action for critical data */
         png_warning(png_ptr,
             "Can't discard critical data on CRC error");
         /* FALLTHROUGH */
      case PNG_CRC_ERROR_QUIT:                                /* Error/quit */
      case PNG_CRC_DEFAULT:
@ -291,7 +303,7 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
    * who use the inverse of the gamma value accidentally!  Since some of these
    * values are reasonable this may have to be changed:
    *
-    * 1.6.x: changed from 0.07..3 to 0.01..100 (to accomodate the optimal 16-bit
+    * 1.6.x: changed from 0.07..3 to 0.01..100 (to accommodate the optimal 16-bit
    * gamma of 36, and its reciprocal.)
    */
   if (output_gamma < 1000 || output_gamma > 10000000)
@ -429,7 +441,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
      int i;
      png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
-          (png_uint_32)(num_palette * (sizeof (png_byte))));
+          (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
      for (i = 0; i < num_palette; i++)
         png_ptr->quantize_index[i] = (png_byte)i;
   }
@ -446,7 +458,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
         /* Initialize an array to sort colors */
         png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * (sizeof (png_byte))));
+             (png_alloc_size_t)((png_uint_32)num_palette * (sizeof (png_byte))));
         /* Initialize the quantize_sort array */
         for (i = 0; i < num_palette; i++)
@ -580,9 +592,11 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
         /* Initialize palette index arrays */
         png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * (sizeof (png_byte))));
+             (png_alloc_size_t)((png_uint_32)num_palette *
             (sizeof (png_byte))));
         png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * (sizeof (png_byte))));
+             (png_alloc_size_t)((png_uint_32)num_palette *
             (sizeof (png_byte))));
         /* Initialize the sort array */
         for (i = 0; i < num_palette; i++)
@ -591,7 +605,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
            png_ptr->palette_to_index[i] = (png_byte)i;
         }
-         hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
+         hash = (png_dsortpp)png_calloc(png_ptr, (png_alloc_size_t)(769 *
             (sizeof (png_dsortp))));
         num_new_palette = num_palette;
@ -622,7 +636,7 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
                  {
                     t = (png_dsortp)png_malloc_warn(png_ptr,
-                         (png_uint_32)(sizeof (png_dsort)));
+                         (png_alloc_size_t)(sizeof (png_dsort)));
                     if (t == NULL)
                         break;
@ -744,12 +758,12 @@ png_set_quantize(png_structrp png_ptr, png_colorp palette,
      int num_red = (1 << PNG_QUANTIZE_RED_BITS);
      int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
      int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
-      png_size_t num_entries = ((png_size_t)1 << total_bits);
+      size_t num_entries = ((size_t)1 << total_bits);
      png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
-          (png_uint_32)(num_entries * (sizeof (png_byte))));
+          (png_alloc_size_t)(num_entries * (sizeof (png_byte))));
-      distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
+      distance = (png_bytep)png_malloc(png_ptr, (png_alloc_size_t)(num_entries *
          (sizeof (png_byte))));
      memset(distance, 0xff, num_entries * (sizeof (png_byte)));
@ -1177,9 +1191,9 @@ png_init_palette_transformations(png_structrp png_ptr)
                */
               int i, istop = png_ptr->num_trans;
-              for (i=0; i<istop; i++)
+               for (i = 0; i < istop; i++)
-                 png_ptr->trans_alpha[i] = (png_byte)(255 -
+                  png_ptr->trans_alpha[i] =
-                    png_ptr->trans_alpha[i]);
+                      (png_byte)(255 - png_ptr->trans_alpha[i]);
            }
         }
 #endif /* READ_INVERT_ALPHA */
@ -1253,7 +1267,7 @@ png_init_rgb_transformations(png_structrp png_ptr)
            default:
            case 8:
-               /* FALL THROUGH (Already 8 bits) */
+               /* FALLTHROUGH */ /*  (Already 8 bits) */
            case 16:
               /* Already a full 16 bits */
@ -1314,7 +1328,7 @@ png_init_read_transformations(png_structrp png_ptr)
      else if (png_ptr->screen_gamma != 0)
         /* The converse - assume the file matches the screen, note that this
-          * perhaps undesireable default can (from 1.5.4) be changed by calling
+          * perhaps undesirable default can (from 1.5.4) be changed by calling
          * png_set_alpha_mode (even if the alpha handling mode isn't required
          * or isn't changed from the default.)
          */
@ -1882,7 +1896,7 @@ png_init_read_transformations(png_structrp png_ptr)
      png_ptr->transformations &= ~PNG_SHIFT;
-      /* significant bits can be in the range 1 to 7 for a meaninful result, if
+      /* significant bits can be in the range 1 to 7 for a meaningful result, if
       * the number of significant bits is 0 then no shift is done (this is an
       * error condition which is silently ignored.)
       */
@ -2148,9 +2162,9 @@ png_do_unpack(png_row_infop row_info, png_bytep row)
      {
         case 1:
         {
-            png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
+            png_bytep sp = row + (size_t)((row_width - 1) >> 3);
-            png_bytep dp = row + (png_size_t)row_width - 1;
+            png_bytep dp = row + (size_t)row_width - 1;
-            png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
+            png_uint_32 shift = 7U - ((row_width + 7U) & 0x07);
            for (i = 0; i < row_width; i++)
            {
               *dp = (png_byte)((*sp >> shift) & 0x01);
@ -2172,9 +2186,9 @@ png_do_unpack(png_row_infop row_info, png_bytep row)
         case 2:
         {
-            png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
+            png_bytep sp = row + (size_t)((row_width - 1) >> 2);
-            png_bytep dp = row + (png_size_t)row_width - 1;
+            png_bytep dp = row + (size_t)row_width - 1;
-            png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
+            png_uint_32 shift = ((3U - ((row_width + 3U) & 0x03)) << 1);
            for (i = 0; i < row_width; i++)
            {
               *dp = (png_byte)((*sp >> shift) & 0x03);
@ -2195,9 +2209,9 @@ png_do_unpack(png_row_infop row_info, png_bytep row)
         case 4:
         {
-            png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
+            png_bytep sp = row + (size_t)((row_width - 1) >> 1);
-            png_bytep dp = row + (png_size_t)row_width - 1;
+            png_bytep dp = row + (size_t)row_width - 1;
-            png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
+            png_uint_32 shift = ((1U - ((row_width + 1U) & 0x01)) << 2);
            for (i = 0; i < row_width; i++)
            {
               *dp = (png_byte)((*sp >> shift) & 0x0f);
@ -2460,10 +2474,10 @@ png_do_chop(png_row_infop row_info, png_bytep row)
 static void
 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
 {
   png_uint_32 row_width = row_info->width;
   png_debug(1, "in png_do_read_swap_alpha");
   {
      png_uint_32 row_width = row_info->width;
   if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
   {
      /* This converts from RGBA to ARGB */
@ -2549,7 +2563,6 @@ png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
      }
 #endif
   }
   }
 }
 #endif
@ -2678,8 +2691,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from G to GX */
-            png_bytep sp = row + (png_size_t)row_width;
+            png_bytep sp = row + (size_t)row_width;
-            png_bytep dp =  sp + (png_size_t)row_width;
+            png_bytep dp =  sp + (size_t)row_width;
            for (i = 1; i < row_width; i++)
            {
               *(--dp) = lo_filler;
@ -2694,8 +2707,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         else
         {
            /* This changes the data from G to XG */
-            png_bytep sp = row + (png_size_t)row_width;
+            png_bytep sp = row + (size_t)row_width;
-            png_bytep dp = sp  + (png_size_t)row_width;
+            png_bytep dp = sp  + (size_t)row_width;
            for (i = 0; i < row_width; i++)
            {
               *(--dp) = *(--sp);
@ -2713,8 +2726,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from GG to GGXX */
-            png_bytep sp = row + (png_size_t)row_width * 2;
+            png_bytep sp = row + (size_t)row_width * 2;
-            png_bytep dp = sp  + (png_size_t)row_width * 2;
+            png_bytep dp = sp  + (size_t)row_width * 2;
            for (i = 1; i < row_width; i++)
            {
               *(--dp) = lo_filler;
@ -2732,8 +2745,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         else
         {
            /* This changes the data from GG to XXGG */
-            png_bytep sp = row + (png_size_t)row_width * 2;
+            png_bytep sp = row + (size_t)row_width * 2;
-            png_bytep dp = sp  + (png_size_t)row_width * 2;
+            png_bytep dp = sp  + (size_t)row_width * 2;
            for (i = 0; i < row_width; i++)
            {
               *(--dp) = *(--sp);
@ -2755,8 +2768,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from RGB to RGBX */
-            png_bytep sp = row + (png_size_t)row_width * 3;
+            png_bytep sp = row + (size_t)row_width * 3;
-            png_bytep dp = sp  + (png_size_t)row_width;
+            png_bytep dp = sp  + (size_t)row_width;
            for (i = 1; i < row_width; i++)
            {
               *(--dp) = lo_filler;
@ -2773,8 +2786,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         else
         {
            /* This changes the data from RGB to XRGB */
-            png_bytep sp = row + (png_size_t)row_width * 3;
+            png_bytep sp = row + (size_t)row_width * 3;
-            png_bytep dp = sp + (png_size_t)row_width;
+            png_bytep dp = sp + (size_t)row_width;
            for (i = 0; i < row_width; i++)
            {
               *(--dp) = *(--sp);
@ -2794,8 +2807,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         if ((flags & PNG_FLAG_FILLER_AFTER) != 0)
         {
            /* This changes the data from RRGGBB to RRGGBBXX */
-            png_bytep sp = row + (png_size_t)row_width * 6;
+            png_bytep sp = row + (size_t)row_width * 6;
-            png_bytep dp = sp  + (png_size_t)row_width * 2;
+            png_bytep dp = sp  + (size_t)row_width * 2;
            for (i = 1; i < row_width; i++)
            {
               *(--dp) = lo_filler;
@ -2817,8 +2830,8 @@ png_do_read_filler(png_row_infop row_info, png_bytep row,
         else
         {
            /* This changes the data from RRGGBB to XXRRGGBB */
-            png_bytep sp = row + (png_size_t)row_width * 6;
+            png_bytep sp = row + (size_t)row_width * 6;
-            png_bytep dp = sp  + (png_size_t)row_width * 2;
+            png_bytep dp = sp  + (size_t)row_width * 2;
            for (i = 0; i < row_width; i++)
            {
               *(--dp) = *(--sp);
@ -2859,8 +2872,8 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
         if (row_info->bit_depth == 8)
         {
            /* This changes G to RGB */
-            png_bytep sp = row + (png_size_t)row_width - 1;
+            png_bytep sp = row + (size_t)row_width - 1;
-            png_bytep dp = sp  + (png_size_t)row_width * 2;
+            png_bytep dp = sp  + (size_t)row_width * 2;
            for (i = 0; i < row_width; i++)
            {
               *(dp--) = *sp;
@ -2872,8 +2885,8 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
         else
         {
            /* This changes GG to RRGGBB */
-            png_bytep sp = row + (png_size_t)row_width * 2 - 1;
+            png_bytep sp = row + (size_t)row_width * 2 - 1;
-            png_bytep dp = sp  + (png_size_t)row_width * 4;
+            png_bytep dp = sp  + (size_t)row_width * 4;
            for (i = 0; i < row_width; i++)
            {
               *(dp--) = *sp;
@ -2891,8 +2904,8 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
         if (row_info->bit_depth == 8)
         {
            /* This changes GA to RGBA */
-            png_bytep sp = row + (png_size_t)row_width * 2 - 1;
+            png_bytep sp = row + (size_t)row_width * 2 - 1;
-            png_bytep dp = sp  + (png_size_t)row_width * 2;
+            png_bytep dp = sp  + (size_t)row_width * 2;
            for (i = 0; i < row_width; i++)
            {
               *(dp--) = *(sp--);
@ -2905,8 +2918,8 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
         else
         {
            /* This changes GGAA to RRGGBBAA */
-            png_bytep sp = row + (png_size_t)row_width * 4 - 1;
+            png_bytep sp = row + (size_t)row_width * 4 - 1;
-            png_bytep dp = sp  + (png_size_t)row_width * 4;
+            png_bytep dp = sp  + (size_t)row_width * 4;
            for (i = 0; i < row_width; i++)
            {
               *(dp--) = *(sp--);
@ -2934,7 +2947,7 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
 * <http://www.inforamp.net/~poynton/>  (THIS LINK IS DEAD June 2008 but
 * versions dated 1998 through November 2002 have been archived at
- * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
+ * https://web.archive.org/web/20000816232553/www.inforamp.net/
 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
 * Charles Poynton poynton at poynton.com
 *
@ -2977,14 +2990,13 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 *  values this results in an implicit assumption that the original PNG RGB
 *  values were linear.
 *
- *  Other integer coefficents can be used via png_set_rgb_to_gray().  Because
+ *  Other integer coefficients can be used via png_set_rgb_to_gray().  Because
 *  the API takes just red and green coefficients the blue coefficient is
 *  calculated to make the sum 32768.  This will result in different rounding
 *  to that used above.
 */
 static int
 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
 {
   int rgb_error = 0;
@ -2993,12 +3005,11 @@ png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
   if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 &&
       (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
   {
-      PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
+      png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
-      PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
+      png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
-      PNG_CONST png_uint_32 bc = 32768 - rc - gc;
+      png_uint_32 bc = 32768 - rc - gc;
-      PNG_CONST png_uint_32 row_width = row_info->width;
+      png_uint_32 row_width = row_info->width;
-      PNG_CONST int have_alpha =
+      int have_alpha = (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
         (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
      if (row_info->bit_depth == 8)
      {
@ -3206,7 +3217,6 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
   png_debug(1, "in png_do_compose");
   {
   switch (row_info->color_type)
   {
      case PNG_COLOR_TYPE_GRAY:
@ -3223,7 +3233,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                     == png_ptr->trans_color.gray)
                  {
                     unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
-                        tmp |= png_ptr->background.gray << shift;
+                     tmp |=
                         (unsigned int)(png_ptr->background.gray << shift);
                     *sp = (png_byte)(tmp & 0xff);
                  }
@ -3252,7 +3263,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         == png_ptr->trans_color.gray)
                     {
                        unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                        tmp |=
                           (unsigned int)png_ptr->background.gray << shift;
                        *sp = (png_byte)(tmp & 0xff);
                     }
@ -3262,7 +3274,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                        unsigned int g = (gamma_table [p | (p << 2) |
                            (p << 4) | (p << 6)] >> 6) & 0x03;
                        unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
-                           tmp |= g << shift;
+                        tmp |= (unsigned int)(g << shift);
                        *sp = (png_byte)(tmp & 0xff);
                     }
@ -3288,7 +3300,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         == png_ptr->trans_color.gray)
                     {
                        unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                        tmp |=
                            (unsigned int)png_ptr->background.gray << shift;
                        *sp = (png_byte)(tmp & 0xff);
                     }
@ -3318,7 +3331,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         == png_ptr->trans_color.gray)
                     {
                        unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                        tmp |=
                           (unsigned int)(png_ptr->background.gray << shift);
                        *sp = (png_byte)(tmp & 0xff);
                     }
@ -3328,7 +3342,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                        unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
                           0x0f;
                        unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
-                           tmp |= g << shift;
+                        tmp |= (unsigned int)(g << shift);
                        *sp = (png_byte)(tmp & 0xff);
                     }
@ -3354,7 +3368,8 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
                         == png_ptr->trans_color.gray)
                     {
                        unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                        tmp |=
                           (unsigned int)(png_ptr->background.gray << shift);
                        *sp = (png_byte)(tmp & 0xff);
                     }
@ -3915,7 +3930,6 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
      default:
         break;
   }
   }
 }
 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
@ -4138,12 +4152,11 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
   {
      if (row_info->bit_depth == 8)
      {
-         PNG_CONST png_bytep table = png_ptr->gamma_from_1;
+         png_bytep table = png_ptr->gamma_from_1;
         if (table != NULL)
         {
-            PNG_CONST int step =
+            int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
               (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
            /* The alpha channel is the last component: */
            row += step - 1;
@ -4157,13 +4170,12 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
      else if (row_info->bit_depth == 16)
      {
-         PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
+         png_uint_16pp table = png_ptr->gamma_16_from_1;
-         PNG_CONST int gamma_shift = png_ptr->gamma_shift;
+         int gamma_shift = png_ptr->gamma_shift;
         if (table != NULL)
         {
-            PNG_CONST int step =
+            int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
               (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
            /* The alpha channel is the last component: */
            row += step - 2;
@ -4194,8 +4206,9 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 * upon whether you supply trans and num_trans.
 */
 static void
-png_do_expand_palette(png_row_infop row_info, png_bytep row,
+png_do_expand_palette(png_structrp png_ptr, png_row_infop row_info,
-   png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
+    png_bytep row, png_const_colorp palette, png_const_bytep trans_alpha,
    int num_trans)
 {
   int shift, value;
   png_bytep sp, dp;
@ -4212,8 +4225,8 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
         {
            case 1:
            {
-               sp = row + (png_size_t)((row_width - 1) >> 3);
+               sp = row + (size_t)((row_width - 1) >> 3);
-               dp = row + (png_size_t)row_width - 1;
+               dp = row + (size_t)row_width - 1;
               shift = 7 - (int)((row_width + 7) & 0x07);
               for (i = 0; i < row_width; i++)
               {
@ -4239,8 +4252,8 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
            case 2:
            {
-               sp = row + (png_size_t)((row_width - 1) >> 2);
+               sp = row + (size_t)((row_width - 1) >> 2);
-               dp = row + (png_size_t)row_width - 1;
+               dp = row + (size_t)row_width - 1;
               shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
               for (i = 0; i < row_width; i++)
               {
@ -4262,8 +4275,8 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
            case 4:
            {
-               sp = row + (png_size_t)((row_width - 1) >> 1);
+               sp = row + (size_t)((row_width - 1) >> 1);
-               dp = row + (png_size_t)row_width - 1;
+               dp = row + (size_t)row_width - 1;
               shift = (int)((row_width & 0x01) << 2);
               for (i = 0; i < row_width; i++)
               {
@ -4296,17 +4309,30 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
         {
            if (num_trans > 0)
            {
-               sp = row + (png_size_t)row_width - 1;
+               sp = row + (size_t)row_width - 1;
-               dp = row + (png_size_t)(row_width << 2) - 1;
+               dp = row + ((size_t)row_width << 2) - 1;
-               for (i = 0; i < row_width; i++)
+               i = 0;
 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
               if (png_ptr->riffled_palette != NULL)
               {
                  /* The RGBA optimization works with png_ptr->bit_depth == 8
                   * but sometimes row_info->bit_depth has been changed to 8.
                   * In these cases, the palette hasn't been riffled.
                   */
                  i = png_do_expand_palette_rgba8_neon(png_ptr, row_info, row,
                      &sp, &dp);
               }
 #else
               PNG_UNUSED(png_ptr)
 #endif
               for (; i < row_width; i++)
               {
                  if ((int)(*sp) >= num_trans)
                     *dp-- = 0xff;
                  else
                     *dp-- = trans_alpha[*sp];
                  *dp-- = palette[*sp].blue;
                  *dp-- = palette[*sp].green;
                  *dp-- = palette[*sp].red;
@ -4321,10 +4347,17 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
            else
            {
-               sp = row + (png_size_t)row_width - 1;
+               sp = row + (size_t)row_width - 1;
-               dp = row + (png_size_t)(row_width * 3) - 1;
+               dp = row + (size_t)(row_width * 3) - 1;
               i = 0;
 #ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
               i = png_do_expand_palette_rgb8_neon(png_ptr, row_info, row,
                   &sp, &dp);
 #else
               PNG_UNUSED(png_ptr)
 #endif
-               for (i = 0; i < row_width; i++)
+               for (; i < row_width; i++)
               {
                  *dp-- = palette[*sp].blue;
                  *dp-- = palette[*sp].green;
@ -4357,7 +4390,6 @@ png_do_expand(png_row_infop row_info, png_bytep row,
   png_debug(1, "in png_do_expand");
   {
   if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
   {
      unsigned int gray = trans_color != NULL ? trans_color->gray : 0;
@ -4369,8 +4401,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
            case 1:
            {
               gray = (gray & 0x01) * 0xff;
-                  sp = row + (png_size_t)((row_width - 1) >> 3);
+               sp = row + (size_t)((row_width - 1) >> 3);
-                  dp = row + (png_size_t)row_width - 1;
+               dp = row + (size_t)row_width - 1;
               shift = 7 - (int)((row_width + 7) & 0x07);
               for (i = 0; i < row_width; i++)
               {
@ -4397,8 +4429,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
            case 2:
            {
               gray = (gray & 0x03) * 0x55;
-                  sp = row + (png_size_t)((row_width - 1) >> 2);
+               sp = row + (size_t)((row_width - 1) >> 2);
-                  dp = row + (png_size_t)row_width - 1;
+               dp = row + (size_t)row_width - 1;
               shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
               for (i = 0; i < row_width; i++)
               {
@ -4422,8 +4454,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
            case 4:
            {
               gray = (gray & 0x0f) * 0x11;
-                  sp = row + (png_size_t)((row_width - 1) >> 1);
+               sp = row + (size_t)((row_width - 1) >> 1);
-                  dp = row + (png_size_t)row_width - 1;
+               dp = row + (size_t)row_width - 1;
               shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
               for (i = 0; i < row_width; i++)
               {
@ -4457,8 +4489,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
         if (row_info->bit_depth == 8)
         {
            gray = gray & 0xff;
-               sp = row + (png_size_t)row_width - 1;
+            sp = row + (size_t)row_width - 1;
-               dp = row + (png_size_t)(row_width << 1) - 1;
+            dp = row + ((size_t)row_width << 1) - 1;
            for (i = 0; i < row_width; i++)
            {
@ -4513,8 +4545,8 @@ png_do_expand(png_row_infop row_info, png_bytep row,
         png_byte red = (png_byte)(trans_color->red & 0xff);
         png_byte green = (png_byte)(trans_color->green & 0xff);
         png_byte blue = (png_byte)(trans_color->blue & 0xff);
-            sp = row + (png_size_t)row_info->rowbytes - 1;
+         sp = row + (size_t)row_info->rowbytes - 1;
-            dp = row + (png_size_t)(row_width << 2) - 1;
+         dp = row + ((size_t)row_width << 2) - 1;
         for (i = 0; i < row_width; i++)
         {
            if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
@ -4537,7 +4569,7 @@ png_do_expand(png_row_infop row_info, png_bytep row,
         png_byte green_low = (png_byte)(trans_color->green & 0xff);
         png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
         sp = row + row_info->rowbytes - 1;
-            dp = row + (png_size_t)(row_width << 3) - 1;
+         dp = row + ((size_t)row_width << 3) - 1;
         for (i = 0; i < row_width; i++)
         {
            if (*(sp - 5) == red_high &&
@ -4570,7 +4602,6 @@ png_do_expand(png_row_infop row_info, png_bytep row,
      row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
      row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
   }
   }
 }
 #endif
@ -4596,7 +4627,9 @@ png_do_expand_16(png_row_infop row_info, png_bytep row)
      png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
      png_byte *dp = sp + row_info->rowbytes;  /* destination, end + 1 */
      while (dp > sp)
-         dp[-2] = dp[-1] = *--sp, dp -= 2;
+      {
         dp[-2] = dp[-1] = *--sp; dp -= 2;
      }
      row_info->rowbytes *= 2;
      row_info->bit_depth = 16;
@ -4738,7 +4771,19 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
   {
      if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
      {
-         png_do_expand_palette(row_info, png_ptr->row_buf + 1,
+#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
         if ((png_ptr->num_trans > 0) && (png_ptr->bit_depth == 8))
         {
            if (png_ptr->riffled_palette == NULL)
            {
               /* Initialize the accelerated palette expansion. */
               png_ptr->riffled_palette =
                   (png_bytep)png_malloc(png_ptr, 256 * 4);
               png_riffle_palette_neon(png_ptr);
            }
         }
 #endif
         png_do_expand_palette(png_ptr, row_info, png_ptr->row_buf + 1,
             png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
      }
@ -4750,8 +4795,7 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
                &(png_ptr->trans_color));
         else
-            png_do_expand(row_info, png_ptr->row_buf + 1,
+            png_do_expand(row_info, png_ptr->row_buf + 1, NULL);
                NULL);
      }
   }
 #endif
@ -4975,7 +5019,7 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
             (png_ptr,     /* png_ptr */
             row_info,     /* row_info: */
                /*  png_uint_32 width;       width of row */
-                /*  png_size_t rowbytes;     number of bytes in row */
+                /*  size_t rowbytes;         number of bytes in row */
                /*  png_byte color_type;     color type of pixels */
                /*  png_byte bit_depth;      bit depth of samples */
                /*  png_byte channels;       number of channels (1-4) */
--- a/source/Irrlicht/libpng/pngrutil.c
+++ b/source/Irrlicht/libpng/pngrutil.c
@ -1,10 +1,10 @@
 /* pngrutil.c - utilities to read a PNG file
 *
- * Last changed in libpng 1.6.20 [December 3, 2014]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -86,7 +86,7 @@ png_get_int_32)(png_const_bytep buf)
 {
   png_uint_32 uval = png_get_uint_32(buf);
   if ((uval & 0x80000000) == 0) /* non-negative */
-      return uval;
+      return (png_int_32)uval;
   uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
   if ((uval & 0x80000000) == 0) /* no overflow */
@ -102,7 +102,7 @@ png_get_int_32)(png_const_bytep buf)
 png_uint_16 (PNGAPI
 png_get_uint_16)(png_const_bytep buf)
 {
-   /* ANSI-C requires an int value to accomodate at least 16 bits so this
+   /* ANSI-C requires an int value to accommodate at least 16 bits so this
    * works and allows the compiler not to worry about possible narrowing
    * on 32-bit systems.  (Pre-ANSI systems did not make integers smaller
    * than 16 bits either.)
@ -120,7 +120,7 @@ png_get_uint_16)(png_const_bytep buf)
 void /* PRIVATE */
 png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
 {
-   png_size_t num_checked, num_to_check;
+   size_t num_checked, num_to_check;
   /* Exit if the user application does not expect a signature. */
   if (png_ptr->sig_bytes >= 8)
@ -181,6 +181,9 @@ png_read_chunk_header(png_structrp png_ptr)
   /* Check to see if chunk name is valid. */
   png_check_chunk_name(png_ptr, png_ptr->chunk_name);
   /* Check for too-large chunk length */
   png_check_chunk_length(png_ptr, length);
 #ifdef PNG_IO_STATE_SUPPORTED
   png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
 #endif
@ -311,6 +314,7 @@ png_read_buffer(png_structrp png_ptr, png_alloc_size_t new_size, int warn)
      if (buffer != NULL)
      {
         memset(buffer, 0, new_size); /* just in case */
         png_ptr->read_buffer = buffer;
         png_ptr->read_buffer_size = new_size;
      }
@ -370,11 +374,10 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
    */
   {
      int ret; /* zlib return code */
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
      int window_bits = 0;
 # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
      int window_bits;
      if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
          PNG_OPTION_ON)
      {
@ -384,13 +387,11 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
      else
      {
         window_bits = 0;
         png_ptr->zstream_start = 1;
      }
 # else
 #   define window_bits 0
 # endif
-#endif
+
 #endif /* ZLIB_VERNUM >= 0x1240 */
      /* Set this for safety, just in case the previous owner left pointers to
       * memory allocations.
@ -402,25 +403,32 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
      {
-#if PNG_ZLIB_VERNUM < 0x1240
+#if ZLIB_VERNUM >= 0x1240
         ret = inflateReset(&png_ptr->zstream);
 #else
         ret = inflateReset2(&png_ptr->zstream, window_bits);
 #else
         ret = inflateReset(&png_ptr->zstream);
 #endif
      }
      else
      {
-#if PNG_ZLIB_VERNUM < 0x1240
+#if ZLIB_VERNUM >= 0x1240
         ret = inflateInit(&png_ptr->zstream);
 #else
         ret = inflateInit2(&png_ptr->zstream, window_bits);
 #else
         ret = inflateInit(&png_ptr->zstream);
 #endif
         if (ret == Z_OK)
            png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
      }
 #if ZLIB_VERNUM >= 0x1290 && \
   defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_IGNORE_ADLER32)
      if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
         /* Turn off validation of the ADLER32 checksum in IDAT chunks */
         ret = inflateValidate(&png_ptr->zstream, 0);
 #endif
      if (ret == Z_OK)
         png_ptr->zowner = owner;
@ -435,7 +443,7 @@ png_inflate_claim(png_structrp png_ptr, png_uint_32 owner)
 #endif
 }
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
 /* Handle the start of the inflate stream if we called inflateInit2(strm,0);
 * in this case some zlib versions skip validation of the CINFO field and, in
 * certain circumstances, libpng may end up displaying an invalid image, in
@ -461,6 +469,7 @@ png_zlib_inflate(png_structrp png_ptr, int flush)
 #endif /* Zlib >= 1.2.4 */
 #ifdef PNG_READ_COMPRESSED_TEXT_SUPPORTED
 #if defined(PNG_READ_zTXt_SUPPORTED) || defined (PNG_READ_iTXt_SUPPORTED)
 /* png_inflate now returns zlib error codes including Z_OK and Z_STREAM_END to
 * allow the caller to do multiple calls if required.  If the 'finish' flag is
 * set Z_FINISH will be passed to the final inflate() call and Z_STREAM_END must
@ -665,6 +674,8 @@ png_decompress_chunk(png_structrp png_ptr,
               if (text != NULL)
               {
                  memset(text, 0, buffer_size);
                  ret = png_inflate(png_ptr, png_ptr->chunk_name, 1/*finish*/,
                      png_ptr->read_buffer + prefix_size, &lzsize,
                      text + prefix_size, newlength);
@ -728,8 +739,6 @@ png_decompress_chunk(png_structrp png_ptr,
            {
               /* inflateReset failed, store the error message */
               png_zstream_error(png_ptr, ret);
               if (ret == Z_STREAM_END)
               ret = PNG_UNEXPECTED_ZLIB_RETURN;
            }
         }
@ -754,6 +763,7 @@ png_decompress_chunk(png_structrp png_ptr,
      return Z_MEM_ERROR;
   }
 }
 #endif /* READ_zTXt || READ_iTXt */
 #endif /* READ_COMPRESSED_TEXT */
 #ifdef PNG_READ_iCCP_SUPPORTED
@ -802,8 +812,8 @@ png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
          * the available output is produced; this allows reading of truncated
          * streams.
          */
-         ret = PNG_INFLATE(png_ptr,
+         ret = PNG_INFLATE(png_ptr, *chunk_bytes > 0 ?
-            *chunk_bytes > 0 ? Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
+             Z_NO_FLUSH : (finish ? Z_FINISH : Z_SYNC_FLUSH));
      }
      while (ret == Z_OK && (*out_size > 0 || png_ptr->zstream.avail_out > 0));
@ -821,7 +831,7 @@ png_inflate_read(png_structrp png_ptr, png_bytep read_buffer, uInt read_size,
      return Z_STREAM_ERROR;
   }
 }
-#endif
+#endif /* READ_iCCP */
 /* Read and check the IDHR chunk */
@ -1009,7 +1019,7 @@ png_handle_PLTE(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
   {
-      png_crc_finish(png_ptr, (int) length - num * 3);
+      png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
   }
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
@ -1371,11 +1381,13 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
    * chunk is just ignored, so does not invalidate the color space.  An
    * alternative is to set the 'invalid' flags at the start of this routine
    * and only clear them in they were not set before and all the tests pass.
    * The minimum 'deflate' stream is assumed to be just the 2 byte header and
    * 4 byte checksum.  The keyword must be at least one character and there is
    * a terminator (0) byte and the compression method.
    */
-   if (length < 9)
+
   /* The keyword must be at least one character and there is a
    * terminator (0) byte and the compression method byte, and the
    * 'zlib' datastream is at least 11 bytes.
    */
   if (length < 14)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "too short");
@ -1407,6 +1419,16 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      png_crc_read(png_ptr, (png_bytep)keyword, read_length);
      length -= read_length;
      /* The minimum 'zlib' stream is assumed to be just the 2 byte header,
       * 5 bytes minimum 'deflate' stream, and the 4 byte checksum.
       */
      if (length < 11)
      {
         png_crc_finish(png_ptr, length);
         png_chunk_benign_error(png_ptr, "too short");
         return;
      }
      keyword_length = 0;
      while (keyword_length < 80 && keyword_length < read_length &&
         keyword[keyword_length] != 0)
@ -1425,7 +1447,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
            if (png_inflate_claim(png_ptr, png_iCCP) == Z_OK)
            {
-               Byte profile_header[132];
+               Byte profile_header[132]={0};
               Byte local_buffer[PNG_INFLATE_BUF_SIZE];
               png_alloc_size_t size = (sizeof profile_header);
@ -1439,8 +1461,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
               {
                  /* We have the ICC profile header; do the basic header checks.
                   */
-                  const png_uint_32 profile_length =
+                  png_uint_32 profile_length = png_get_uint_32(profile_header);
                     png_get_uint_32(profile_header);
                  if (png_icc_check_length(png_ptr, &png_ptr->colorspace,
                      keyword, profile_length) != 0)
@ -1455,10 +1476,10 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                        /* Now read the tag table; a variable size buffer is
                         * needed at this point, allocate one for the whole
                         * profile.  The header check has already validated
-                         * that none of these stuff will overflow.
+                         * that none of this stuff will overflow.
                         */
-                        const png_uint_32 tag_count = png_get_uint_32(
+                        png_uint_32 tag_count =
-                           profile_header+128);
+                           png_get_uint_32(profile_header + 128);
                        png_bytep profile = png_read_buffer(png_ptr,
                            profile_length, 2/*silent*/);
@ -1512,7 +1533,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                                    png_crc_finish(png_ptr, length);
                                    finished = 1;
-#                                   ifdef PNG_sRGB_SUPPORTED
+# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
                                    /* Check for a match against sRGB */
                                    png_icc_set_sRGB(png_ptr,
                                        &png_ptr->colorspace, profile,
@ -1562,19 +1583,11 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                                       return;
                                    }
                                 }
-
+                                 if (errmsg == NULL)
                                 else if (size > 0)
                                    errmsg = "truncated";
 #ifndef __COVERITY__
                                 else
                                    errmsg = png_ptr->zstream.msg;
 #endif
                              }
                              /* else png_icc_check_tag_table output an error */
                           }
                           else /* profile truncated */
                              errmsg = png_ptr->zstream.msg;
                        }
@ -1634,7 +1647,7 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   int entry_size, i;
   png_uint_32 skip = 0;
   png_uint_32 dl;
-   png_size_t max_dl;
+   size_t max_dl;
   png_debug(1, "in png_handle_sPLT");
@ -1715,13 +1728,13 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   data_length = length - (png_uint_32)(entry_start - buffer);
   /* Integrity-check the data length */
-   if ((data_length % entry_size) != 0)
+   if ((data_length % (unsigned int)entry_size) != 0)
   {
      png_warning(png_ptr, "sPLT chunk has bad length");
      return;
   }
-   dl = (png_int_32)(data_length / entry_size);
+   dl = (png_uint_32)(data_length / (unsigned int)entry_size);
   max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
   if (dl > max_dl)
@ -1730,10 +1743,10 @@ png_handle_sPLT(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      return;
   }
-   new_palette.nentries = (png_int_32)(data_length / entry_size);
+   new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
-   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
+   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
-       png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
+       (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
   if (new_palette.entries == NULL)
   {
@ -1983,6 +1996,15 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
   {
      if (png_ptr->bit_depth <= 8)
      {
         if (buf[0] != 0 || buf[1] >= (unsigned int)(1 << png_ptr->bit_depth))
         {
            png_chunk_benign_error(png_ptr, "invalid gray level");
            return;
         }
      }
      background.index = 0;
      background.red =
      background.green =
@ -1992,6 +2014,15 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   else
   {
      if (png_ptr->bit_depth <= 8)
      {
         if (buf[0] != 0 || buf[2] != 0 || buf[4] != 0)
         {
            png_chunk_benign_error(png_ptr, "invalid color");
            return;
         }
      }
      background.index = 0;
      background.red = png_get_uint_16(buf);
      background.green = png_get_uint_16(buf + 2);
@ -2003,6 +2034,69 @@ png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 }
 #endif
 #ifdef PNG_READ_eXIf_SUPPORTED
 void /* PRIVATE */
 png_handle_eXIf(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
   unsigned int i;
   png_debug(1, "in png_handle_eXIf");
   if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
      png_chunk_error(png_ptr, "missing IHDR");
   if (length < 2)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "too short");
      return;
   }
   else if (info_ptr == NULL || (info_ptr->valid & PNG_INFO_eXIf) != 0)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "duplicate");
      return;
   }
   info_ptr->free_me |= PNG_FREE_EXIF;
   info_ptr->eXIf_buf = png_voidcast(png_bytep,
             png_malloc_warn(png_ptr, length));
   if (info_ptr->eXIf_buf == NULL)
   {
      png_crc_finish(png_ptr, length);
      png_chunk_benign_error(png_ptr, "out of memory");
      return;
   }
   for (i = 0; i < length; i++)
   {
      png_byte buf[1];
      png_crc_read(png_ptr, buf, 1);
      info_ptr->eXIf_buf[i] = buf[0];
      if (i == 1 && buf[0] != 'M' && buf[0] != 'I'
                 && info_ptr->eXIf_buf[0] != buf[0])
      {
         png_crc_finish(png_ptr, length);
         png_chunk_benign_error(png_ptr, "incorrect byte-order specifier");
         png_free(png_ptr, info_ptr->eXIf_buf);
         info_ptr->eXIf_buf = NULL;
         return;
      }
   }
   if (png_crc_finish(png_ptr, 0) != 0)
      return;
   png_set_eXIf_1(png_ptr, info_ptr, length, info_ptr->eXIf_buf);
   png_free(png_ptr, info_ptr->eXIf_buf);
   info_ptr->eXIf_buf = NULL;
 }
 #endif
 #ifdef PNG_READ_hIST_SUPPORTED
 void /* PRIVATE */
 png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
@ -2282,7 +2376,7 @@ void /* PRIVATE */
 png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
 {
   png_bytep buffer;
-   png_size_t i;
+   size_t i;
   int state;
   png_debug(1, "in png_handle_sCAL");
@ -2352,7 +2446,7 @@ png_handle_sCAL(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   else
   {
-      png_size_t heighti = i;
+      size_t heighti = i;
      state = 0;
      if (png_check_fp_number((png_const_charp)buffer, length,
@ -2531,6 +2625,9 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
   if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
      png_ptr->mode |= PNG_AFTER_IDAT;
   /* Note, "length" is sufficient here; we won't be adding
    * a null terminator later.
    */
   buffer = png_read_buffer(png_ptr, length, 2/*silent*/);
   if (buffer == NULL)
@ -2577,9 +2674,13 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
      {
         png_text text;
-         /* It worked; png_ptr->read_buffer now looks like a tEXt chunk except
+         if (png_ptr->read_buffer == NULL)
-          * for the extra compression type byte and the fact that it isn't
+           errmsg="Read failure in png_handle_zTXt";
-          * necessarily '\0' terminated.
+         else
         {
            /* It worked; png_ptr->read_buffer now looks like a tEXt chunk
             * except for the extra compression type byte and the fact that
             * it isn't necessarily '\0' terminated.
             */
            buffer = png_ptr->read_buffer;
            buffer[uncompressed_length+(keyword_length+2)] = 0;
@ -2595,6 +2696,7 @@ png_handle_zTXt(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
            if (png_set_text_2(png_ptr, info_ptr, &text, 1) != 0)
               errmsg = "insufficient memory";
         }
      }
      else
         errmsg = png_ptr->zstream.msg;
@ -2782,7 +2884,7 @@ png_cache_unknown_chunk(png_structrp png_ptr, png_uint_32 length)
   {
      PNG_CSTRING_FROM_CHUNK(png_ptr->unknown_chunk.name, png_ptr->chunk_name);
      /* The following is safe because of the PNG_SIZE_MAX init above */
-      png_ptr->unknown_chunk.size = (png_size_t)length/*SAFE*/;
+      png_ptr->unknown_chunk.size = (size_t)length/*SAFE*/;
      /* 'mode' is a flag array, only the bottom four bits matter here */
      png_ptr->unknown_chunk.location = (png_byte)png_ptr->mode/*SAFE*/;
@ -2969,7 +3071,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
         case 2:
            png_ptr->user_chunk_cache_max = 1;
            png_chunk_benign_error(png_ptr, "no space in chunk cache");
-            /* FALL THROUGH */
+            /* FALLTHROUGH */
         case 1:
            /* NOTE: prior to 1.6.0 this case resulted in an unknown critical
             * chunk being skipped, now there will be a hard error below.
@ -2978,7 +3080,7 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
         default: /* not at limit */
            --(png_ptr->user_chunk_cache_max);
-            /* FALL THROUGH */
+            /* FALLTHROUGH */
         case 0: /* no limit */
 #  endif /* USER_LIMITS */
            /* Here when the limit isn't reached or when limits are compiled
@ -3029,20 +3131,61 @@ png_handle_unknown(png_structrp png_ptr, png_inforp info_ptr,
 */
 void /* PRIVATE */
-png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
+png_check_chunk_name(png_const_structrp png_ptr, png_uint_32 chunk_name)
 {
   int i;
   png_uint_32 cn=chunk_name;
   png_debug(1, "in png_check_chunk_name");
   for (i=1; i<=4; ++i)
   {
-      int c = chunk_name & 0xff;
+      int c = cn & 0xff;
      if (c < 65 || c > 122 || (c > 90 && c < 97))
         png_chunk_error(png_ptr, "invalid chunk type");
-      chunk_name >>= 8;
+      cn >>= 8;
   }
 }
 void /* PRIVATE */
 png_check_chunk_length(png_const_structrp png_ptr, png_uint_32 length)
 {
   png_alloc_size_t limit = PNG_UINT_31_MAX;
 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
   if (png_ptr->user_chunk_malloc_max > 0 &&
       png_ptr->user_chunk_malloc_max < limit)
      limit = png_ptr->user_chunk_malloc_max;
 # elif PNG_USER_CHUNK_MALLOC_MAX > 0
   if (PNG_USER_CHUNK_MALLOC_MAX < limit)
      limit = PNG_USER_CHUNK_MALLOC_MAX;
 # endif
   if (png_ptr->chunk_name == png_IDAT)
   {
      png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
      size_t row_factor =
         (size_t)png_ptr->width
         * (size_t)png_ptr->channels
         * (png_ptr->bit_depth > 8? 2: 1)
         + 1
         + (png_ptr->interlaced? 6: 0);
      if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
         idat_limit = PNG_UINT_31_MAX;
      else
         idat_limit = png_ptr->height * row_factor;
      row_factor = row_factor > 32566? 32566 : row_factor;
      idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */
      idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX;
      limit = limit < idat_limit? idat_limit : limit;
   }
   if (length > limit)
   {
      png_debug2(0," length = %lu, limit = %lu",
         (unsigned long)length,(unsigned long)limit);
      png_chunk_error(png_ptr, "chunk data is too large");
   }
 }
@ -3097,7 +3240,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
 #     ifdef PNG_READ_PACKSWAP_SUPPORTED
      if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
         /* little-endian byte */
-         end_mask = 0xff << end_mask;
+         end_mask = (unsigned int)(0xff << end_mask);
      else /* big-endian byte */
 #     endif
@ -3219,7 +3362,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
         /* Hence the pre-compiled masks indexed by PACKSWAP (or not), depth and
          * then pass:
          */
-         static PNG_CONST png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
+         static const png_uint_32 row_mask[2/*PACKSWAP*/][3/*depth*/][6] =
         {
            /* Little-endian byte masks for PACKSWAP */
            { S_MASKS(1,0), S_MASKS(2,0), S_MASKS(4,0) },
@ -3230,7 +3373,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
         /* display_mask has only three entries for the odd passes, so index by
          * pass>>1.
          */
-         static PNG_CONST png_uint_32 display_mask[2][3][3] =
+         static const png_uint_32 display_mask[2][3][3] =
         {
            /* Little-endian byte masks for PACKSWAP */
            { B_MASKS(1,0), B_MASKS(2,0), B_MASKS(4,0) },
@ -3371,7 +3514,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
                */
               do
               {
-                  dp[0] = sp[0], dp[1] = sp[1];
+                  dp[0] = sp[0]; dp[1] = sp[1];
                  if (row_width <= bytes_to_jump)
                     return;
@ -3392,7 +3535,7 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
                */
               for (;;)
               {
-                  dp[0] = sp[0], dp[1] = sp[1], dp[2] = sp[2];
+                  dp[0] = sp[0]; dp[1] = sp[1]; dp[2] = sp[2];
                  if (row_width <= bytes_to_jump)
                     return;
@ -3418,8 +3561,8 @@ png_combine_row(png_const_structrp png_ptr, png_bytep dp, int display)
                  /* Everything is aligned for png_uint_16 copies, but try for
                   * png_uint_32 first.
                   */
-                  if (png_isaligned(dp, png_uint_32) != 0 &&
+                  if (png_isaligned(dp, png_uint_32) &&
-                      png_isaligned(sp, png_uint_32) != 0 &&
+                      png_isaligned(sp, png_uint_32) &&
                      bytes_to_copy % (sizeof (png_uint_32)) == 0 &&
                      bytes_to_jump % (sizeof (png_uint_32)) == 0)
                  {
@ -3543,7 +3686,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
 {
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Offset to next interlace block */
-   static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static const unsigned int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
   png_debug(1, "in png_do_read_interlace");
   if (row != NULL && row_info != NULL)
@ -3556,11 +3699,12 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
      {
         case 1:
         {
-            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
+            png_bytep sp = row + (size_t)((row_info->width - 1) >> 3);
-            png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
+            png_bytep dp = row + (size_t)((final_width - 1) >> 3);
-            int sshift, dshift;
+            unsigned int sshift, dshift;
-            int s_start, s_end, s_inc;
+            unsigned int s_start, s_end;
-            int jstop = png_pass_inc[pass];
+            int s_inc;
            int jstop = (int)png_pass_inc[pass];
            png_byte v;
            png_uint_32 i;
            int j;
@ -3568,8 +3712,8 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
            if ((transformations & PNG_PACKSWAP) != 0)
            {
-                sshift = (int)((row_info->width + 7) & 0x07);
+                sshift = ((row_info->width + 7) & 0x07);
-                dshift = (int)((final_width + 7) & 0x07);
+                dshift = ((final_width + 7) & 0x07);
                s_start = 7;
                s_end = 0;
                s_inc = -1;
@ -3578,8 +3722,8 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
            else
 #endif
            {
-                sshift = 7 - (int)((row_info->width + 7) & 0x07);
+                sshift = 7 - ((row_info->width + 7) & 0x07);
-                dshift = 7 - (int)((final_width + 7) & 0x07);
+                dshift = 7 - ((final_width + 7) & 0x07);
                s_start = 0;
                s_end = 7;
                s_inc = 1;
@ -3591,7 +3735,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
               for (j = 0; j < jstop; j++)
               {
                  unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
-                  tmp |= v << dshift;
+                  tmp |= (unsigned int)(v << dshift);
                  *dp = (png_byte)(tmp & 0xff);
                  if (dshift == s_end)
@ -3601,7 +3745,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
                  }
                  else
-                     dshift += s_inc;
+                     dshift = (unsigned int)((int)dshift + s_inc);
               }
               if (sshift == s_end)
@ -3611,7 +3755,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
               }
               else
-                  sshift += s_inc;
+                  sshift = (unsigned int)((int)sshift + s_inc);
            }
            break;
         }
@ -3620,16 +3764,17 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
         {
            png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
            png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
-            int sshift, dshift;
+            unsigned int sshift, dshift;
-            int s_start, s_end, s_inc;
+            unsigned int s_start, s_end;
-            int jstop = png_pass_inc[pass];
+            int s_inc;
            int jstop = (int)png_pass_inc[pass];
            png_uint_32 i;
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
            if ((transformations & PNG_PACKSWAP) != 0)
            {
-               sshift = (int)(((row_info->width + 3) & 0x03) << 1);
+               sshift = (((row_info->width + 3) & 0x03) << 1);
-               dshift = (int)(((final_width + 3) & 0x03) << 1);
+               dshift = (((final_width + 3) & 0x03) << 1);
               s_start = 6;
               s_end = 0;
               s_inc = -2;
@ -3638,8 +3783,8 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
            else
 #endif
            {
-               sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
+               sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1);
-               dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
+               dshift = ((3 - ((final_width + 3) & 0x03)) << 1);
               s_start = 0;
               s_end = 6;
               s_inc = 2;
@ -3654,7 +3799,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
               for (j = 0; j < jstop; j++)
               {
                  unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
-                  tmp |= v << dshift;
+                  tmp |= (unsigned int)(v << dshift);
                  *dp = (png_byte)(tmp & 0xff);
                  if (dshift == s_end)
@ -3664,7 +3809,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
                  }
                  else
-                     dshift += s_inc;
+                     dshift = (unsigned int)((int)dshift + s_inc);
               }
               if (sshift == s_end)
@ -3674,25 +3819,26 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
               }
               else
-                  sshift += s_inc;
+                  sshift = (unsigned int)((int)sshift + s_inc);
            }
            break;
         }
         case 4:
         {
-            png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
+            png_bytep sp = row + (size_t)((row_info->width - 1) >> 1);
-            png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
+            png_bytep dp = row + (size_t)((final_width - 1) >> 1);
-            int sshift, dshift;
+            unsigned int sshift, dshift;
-            int s_start, s_end, s_inc;
+            unsigned int s_start, s_end;
            int s_inc;
            png_uint_32 i;
-            int jstop = png_pass_inc[pass];
+            int jstop = (int)png_pass_inc[pass];
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
            if ((transformations & PNG_PACKSWAP) != 0)
            {
-               sshift = (int)(((row_info->width + 1) & 0x01) << 2);
+               sshift = (((row_info->width + 1) & 0x01) << 2);
-               dshift = (int)(((final_width + 1) & 0x01) << 2);
+               dshift = (((final_width + 1) & 0x01) << 2);
               s_start = 4;
               s_end = 0;
               s_inc = -4;
@ -3701,8 +3847,8 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
            else
 #endif
            {
-               sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
+               sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2);
-               dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
+               dshift = ((1 - ((final_width + 1) & 0x01)) << 2);
               s_start = 0;
               s_end = 4;
               s_inc = 4;
@ -3716,7 +3862,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
               for (j = 0; j < jstop; j++)
               {
                  unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
-                  tmp |= v << dshift;
+                  tmp |= (unsigned int)(v << dshift);
                  *dp = (png_byte)(tmp & 0xff);
                  if (dshift == s_end)
@ -3726,7 +3872,7 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
                  }
                  else
-                     dshift += s_inc;
+                     dshift = (unsigned int)((int)dshift + s_inc);
               }
               if (sshift == s_end)
@ -3736,21 +3882,21 @@ png_do_read_interlace(png_row_infop row_info, png_bytep row, int pass,
               }
               else
-                  sshift += s_inc;
+                  sshift = (unsigned int)((int)sshift + s_inc);
            }
            break;
         }
         default:
         {
-            png_size_t pixel_bytes = (row_info->pixel_depth >> 3);
+            size_t pixel_bytes = (row_info->pixel_depth >> 3);
-            png_bytep sp = row + (png_size_t)(row_info->width - 1)
+            png_bytep sp = row + (size_t)(row_info->width - 1)
                * pixel_bytes;
-            png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
+            png_bytep dp = row + (size_t)(final_width - 1) * pixel_bytes;
-            int jstop = png_pass_inc[pass];
+            int jstop = (int)png_pass_inc[pass];
            png_uint_32 i;
            for (i = 0; i < row_info->width; i++)
@ -3785,8 +3931,8 @@ static void
 png_read_filter_row_sub(png_row_infop row_info, png_bytep row,
    png_const_bytep prev_row)
 {
-   png_size_t i;
+   size_t i;
-   png_size_t istop = row_info->rowbytes;
+   size_t istop = row_info->rowbytes;
   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
   png_bytep rp = row + bpp;
@ -3803,8 +3949,8 @@ static void
 png_read_filter_row_up(png_row_infop row_info, png_bytep row,
    png_const_bytep prev_row)
 {
-   png_size_t i;
+   size_t i;
-   png_size_t istop = row_info->rowbytes;
+   size_t istop = row_info->rowbytes;
   png_bytep rp = row;
   png_const_bytep pp = prev_row;
@ -3819,11 +3965,11 @@ static void
 png_read_filter_row_avg(png_row_infop row_info, png_bytep row,
    png_const_bytep prev_row)
 {
-   png_size_t i;
+   size_t i;
   png_bytep rp = row;
   png_const_bytep pp = prev_row;
   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
-   png_size_t istop = row_info->rowbytes - bpp;
+   size_t istop = row_info->rowbytes - bpp;
   for (i = 0; i < bpp; i++)
   {
@ -3878,7 +4024,10 @@ png_read_filter_row_paeth_1byte_pixel(png_row_infop row_info, png_bytep row,
      /* Find the best predictor, the least of pa, pb, pc favoring the earlier
       * ones in the case of a tie.
       */
-      if (pb < pa) pa = pb, a = b;
+      if (pb < pa)
      {
         pa = pb; a = b;
      }
      if (pc < pa) a = c;
      /* Calculate the current pixel in a, and move the previous row pixel to c
@ -3894,7 +4043,7 @@ static void
 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
    png_const_bytep prev_row)
 {
-   int bpp = (row_info->pixel_depth + 7) >> 3;
+   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
   png_bytep rp_end = row + bpp;
   /* Process the first pixel in the row completely (this is the same as 'up'
@ -3907,7 +4056,7 @@ png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
   }
   /* Remainder */
-   rp_end += row_info->rowbytes - bpp;
+   rp_end = rp_end + (row_info->rowbytes - bpp);
   while (row < rp_end)
   {
@ -3930,7 +4079,10 @@ png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
      pc = (p + pc) < 0 ? -(p + pc) : p + pc;
 #endif
-      if (pb < pa) pa = pb, a = b;
+      if (pb < pa)
      {
         pa = pb; a = b;
      }
      if (pc < pa) a = c;
      a += *row;
@ -4176,16 +4328,16 @@ png_read_finish_row(png_structrp png_ptr)
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
   /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
   /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
   /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
   png_debug(1, "in png_read_finish_row");
   png_ptr->row_number++;
@ -4241,19 +4393,19 @@ png_read_start_row(png_structrp png_ptr)
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
   /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
   /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
   /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
-   int max_pixel_depth;
+   unsigned int max_pixel_depth;
-   png_size_t row_bytes;
+   size_t row_bytes;
   png_debug(1, "in png_read_start_row");
@ -4281,7 +4433,7 @@ png_read_start_row(png_structrp png_ptr)
      png_ptr->iwidth = png_ptr->width;
   }
-   max_pixel_depth = png_ptr->pixel_depth;
+   max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
   /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
    * calculations to calculate the final pixel depth, then
@ -4416,7 +4568,7 @@ png_read_start_row(png_structrp png_ptr)
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
   if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
   {
-      int user_pixel_depth = png_ptr->user_transform_depth *
+      unsigned int user_pixel_depth = png_ptr->user_transform_depth *
         png_ptr->user_transform_channels;
      if (user_pixel_depth > max_pixel_depth)
@ -4438,7 +4590,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    * for safety's sake
    */
   row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
-       1 + ((max_pixel_depth + 7) >> 3);
+       1 + ((max_pixel_depth + 7) >> 3U);
 #ifdef PNG_MAX_MALLOC_64K
   if (row_bytes > (png_uint_32)65536L)
@ -4507,7 +4659,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    * does not, so free the read buffer now regardless; the sequential reader
    * reallocates it on demand.
    */
-   if (png_ptr->read_buffer != 0)
+   if (png_ptr->read_buffer != NULL)
   {
      png_bytep buffer = png_ptr->read_buffer;
--- a/source/Irrlicht/libpng/pngset.c
+++ b/source/Irrlicht/libpng/pngset.c
@ -1,10 +1,10 @@
 /* pngset.c - storage of image information into info struct
 *
- * Last changed in libpng 1.6.23 [June 9, 2016]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -134,6 +134,53 @@ png_set_cHRM_XYZ(png_const_structrp png_ptr, png_inforp info_ptr, double red_X,
 #endif /* cHRM */
 #ifdef PNG_eXIf_SUPPORTED
 void PNGAPI
 png_set_eXIf(png_const_structrp png_ptr, png_inforp info_ptr,
    png_bytep eXIf_buf)
 {
  png_warning(png_ptr, "png_set_eXIf does not work; use png_set_eXIf_1");
  PNG_UNUSED(info_ptr)
  PNG_UNUSED(eXIf_buf)
 }
 void PNGAPI
 png_set_eXIf_1(png_const_structrp png_ptr, png_inforp info_ptr,
    png_uint_32 num_exif, png_bytep eXIf_buf)
 {
   int i;
   png_debug1(1, "in %s storage function", "eXIf");
   if (png_ptr == NULL || info_ptr == NULL)
      return;
   if (info_ptr->exif)
   {
      png_free(png_ptr, info_ptr->exif);
      info_ptr->exif = NULL;
   }
   info_ptr->num_exif = num_exif;
   info_ptr->exif = png_voidcast(png_bytep, png_malloc_warn(png_ptr,
       info_ptr->num_exif));
   if (info_ptr->exif == NULL)
   {
      png_warning(png_ptr, "Insufficient memory for eXIf chunk data");
      return;
   }
   info_ptr->free_me |= PNG_FREE_EXIF;
   for (i = 0; i < (int) info_ptr->num_exif; i++)
      info_ptr->exif[i] = eXIf_buf[i];
   info_ptr->valid |= PNG_INFO_eXIf;
 }
 #endif /* eXIf */
 #ifdef PNG_gAMA_SUPPORTED
 void PNGFAPI
 png_set_gAMA_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
@ -266,7 +313,7 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
    png_const_charp purpose, png_int_32 X0, png_int_32 X1, int type,
    int nparams, png_const_charp units, png_charpp params)
 {
-   png_size_t length;
+   size_t length;
   int i;
   png_debug1(1, "in %s storage function", "pCAL");
@ -283,17 +330,29 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
   /* Check that the type matches the specification. */
   if (type < 0 || type > 3)
-      png_error(png_ptr, "Invalid pCAL equation type");
+   {
      png_chunk_report(png_ptr, "Invalid pCAL equation type",
            PNG_CHUNK_WRITE_ERROR);
      return;
   }
   if (nparams < 0 || nparams > 255)
-      png_error(png_ptr, "Invalid pCAL parameter count");
+   {
      png_chunk_report(png_ptr, "Invalid pCAL parameter count",
            PNG_CHUNK_WRITE_ERROR);
      return;
   }
   /* Validate params[nparams] */
   for (i=0; i<nparams; ++i)
   {
      if (params[i] == NULL ||
          !png_check_fp_string(params[i], strlen(params[i])))
-         png_error(png_ptr, "Invalid format for pCAL parameter");
+      {
         png_chunk_report(png_ptr, "Invalid format for pCAL parameter",
               PNG_CHUNK_WRITE_ERROR);
         return;
      }
   }
   info_ptr->pcal_purpose = png_voidcast(png_charp,
@ -301,8 +360,8 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
   if (info_ptr->pcal_purpose == NULL)
   {
-      png_warning(png_ptr, "Insufficient memory for pCAL purpose");
+      png_chunk_report(png_ptr, "Insufficient memory for pCAL purpose",
-
+            PNG_CHUNK_WRITE_ERROR);
      return;
   }
@ -331,7 +390,7 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
   memcpy(info_ptr->pcal_units, units, length);
   info_ptr->pcal_params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
-       (png_size_t)((nparams + 1) * (sizeof (png_charp)))));
+       (size_t)(((unsigned int)nparams + 1) * (sizeof (png_charp)))));
   if (info_ptr->pcal_params == NULL)
   {
@ -340,7 +399,8 @@ png_set_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
      return;
   }
-   memset(info_ptr->pcal_params, 0, (nparams + 1) * (sizeof (png_charp)));
+   memset(info_ptr->pcal_params, 0, ((unsigned int)nparams + 1) *
       (sizeof (png_charp)));
   for (i = 0; i < nparams; i++)
   {
@ -370,7 +430,7 @@ void PNGAPI
 png_set_sCAL_s(png_const_structrp png_ptr, png_inforp info_ptr,
    int unit, png_const_charp swidth, png_const_charp sheight)
 {
-   png_size_t lengthw = 0, lengthh = 0;
+   size_t lengthw = 0, lengthh = 0;
   png_debug1(1, "in %s storage function", "sCAL");
@ -563,7 +623,8 @@ png_set_PLTE(png_structrp png_ptr, png_inforp info_ptr,
       PNG_MAX_PALETTE_LENGTH * (sizeof (png_color))));
   if (num_palette > 0)
-      memcpy(png_ptr->palette, palette, num_palette * (sizeof (png_color)));
+      memcpy(png_ptr->palette, palette, (unsigned int)num_palette *
          (sizeof (png_color)));
   info_ptr->palette = png_ptr->palette;
   info_ptr->num_palette = png_ptr->num_palette = (png_uint_16)num_palette;
@ -630,7 +691,7 @@ png_set_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
 {
   png_charp new_iccp_name;
   png_bytep new_iccp_profile;
-   png_size_t length;
+   size_t length;
   png_debug1(1, "in %s storage function", "iCCP");
@ -957,7 +1018,7 @@ png_set_tRNS(png_structrp png_ptr, png_inforp info_ptr,
         /* Changed from num_trans to PNG_MAX_PALETTE_LENGTH in version 1.2.1 */
          info_ptr->trans_alpha = png_voidcast(png_bytep,
              png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH));
-          memcpy(info_ptr->trans_alpha, trans_alpha, (png_size_t)num_trans);
+          memcpy(info_ptr->trans_alpha, trans_alpha, (size_t)num_trans);
       }
       png_ptr->trans_alpha = info_ptr->trans_alpha;
   }
@ -1037,7 +1098,7 @@ png_set_sPLT(png_const_structrp png_ptr,
   do
   {
-      png_size_t length;
+      size_t length;
      /* Skip invalid input entries */
      if (entries->name == NULL || entries->entries == NULL)
@ -1080,7 +1141,7 @@ png_set_sPLT(png_const_structrp png_ptr,
       * checked it when doing the allocation.
       */
      memcpy(np->entries, entries->entries,
-         entries->nentries * sizeof (png_sPLT_entry));
+          (unsigned int)entries->nentries * sizeof (png_sPLT_entry));
      /* Note that 'continue' skips the advance of the out pointer and out
       * count, so an invalid entry is not added.
@ -1088,8 +1149,9 @@ png_set_sPLT(png_const_structrp png_ptr,
      info_ptr->valid |= PNG_INFO_sPLT;
      ++(info_ptr->splt_palettes_num);
      ++np;
      ++entries;
   }
-   while (++entries, --nentries);
+   while (--nentries);
   if (nentries > 0)
      png_chunk_report(png_ptr, "sPLT out of memory", PNG_CHUNK_WRITE_ERROR);
@ -1249,7 +1311,7 @@ png_set_unknown_chunk_location(png_const_structrp png_ptr, png_inforp info_ptr,
      {
         png_app_error(png_ptr, "invalid unknown chunk location");
         /* Fake out the pre 1.6.0 behavior: */
-         if ((location & PNG_HAVE_IDAT) != 0) /* undocumented! */
+         if (((unsigned int)location & PNG_HAVE_IDAT) != 0) /* undocumented! */
            location = PNG_AFTER_IDAT;
         else
@ -1337,9 +1399,10 @@ png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
      /* Ignore all unknown chunks and all chunks recognized by
       * libpng except for IHDR, PLTE, tRNS, IDAT, and IEND
       */
-      static PNG_CONST png_byte chunks_to_ignore[] = {
+      static const png_byte chunks_to_ignore[] = {
         98,  75,  71,  68, '\0',  /* bKGD */
         99,  72,  82,  77, '\0',  /* cHRM */
        101,  88,  73, 102, '\0',  /* eXIf */
        103,  65,  77,  65, '\0',  /* gAMA */
        104,  73,  83,  84, '\0',  /* hIST */
        105,  67,  67,  80, '\0',  /* iCCP */
@ -1373,7 +1436,7 @@ png_set_keep_unknown_chunks(png_structrp png_ptr, int keep,
         return;
      }
-      num_chunks = num_chunks_in;
+      num_chunks = (unsigned int)num_chunks_in;
   }
   old_num_chunks = png_ptr->num_chunk_list;
@ -1500,7 +1563,7 @@ png_set_rows(png_const_structrp png_ptr, png_inforp info_ptr,
 #endif
 void PNGAPI
-png_set_compression_buffer_size(png_structrp png_ptr, png_size_t size)
+png_set_compression_buffer_size(png_structrp png_ptr, size_t size)
 {
   if (png_ptr == NULL)
      return;
@ -1563,7 +1626,7 @@ void PNGAPI
 png_set_invalid(png_const_structrp png_ptr, png_inforp info_ptr, int mask)
 {
   if (png_ptr != NULL && info_ptr != NULL)
-      info_ptr->valid &= ~mask;
+      info_ptr->valid &= (unsigned int)(~mask);
 }
@ -1662,7 +1725,9 @@ png_set_check_for_invalid_index(png_structrp png_ptr, int allowed)
 png_uint_32 /* PRIVATE */
 png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
 {
 #ifdef PNG_WARNINGS_SUPPORTED
   png_const_charp orig_key = key;
 #endif
   png_uint_32 key_len = 0;
   int bad_character = 0;
   int space = 1;
@ -1680,14 +1745,16 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
      png_byte ch = (png_byte)*key++;
      if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
-         *new_key++ = ch, ++key_len, space = 0;
+      {
         *new_key++ = ch; ++key_len; space = 0;
      }
      else if (space == 0)
      {
         /* A space or an invalid character when one wasn't seen immediately
          * before; output just a space.
          */
-         *new_key++ = 32, ++key_len, space = 1;
+         *new_key++ = 32; ++key_len; space = 1;
         /* If the character was not a space then it is invalid. */
         if (ch != 32)
@ -1700,7 +1767,7 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
   if (key_len > 0 && space != 0) /* trailing space */
   {
-      --key_len, --new_key;
+      --key_len; --new_key;
      if (bad_character == 0)
         bad_character = 32;
   }
@ -1725,7 +1792,9 @@ png_check_keyword(png_structrp png_ptr, png_const_charp key, png_bytep new_key)
      png_formatted_warning(png_ptr, p, "keyword \"@1\": bad character '0x@2'");
   }
-#endif /* WARNINGS */
+#else /* !WARNINGS */
   PNG_UNUSED(png_ptr)
 #endif /* !WARNINGS */
   return key_len;
 }
--- a/source/Irrlicht/libpng/pngstruct.h
+++ b/source/Irrlicht/libpng/pngstruct.h
@ -1,10 +1,10 @@
 /* pngstruct.h - header file for PNG reference library
 *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -47,7 +47,7 @@
 /* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
 * can handle at once.  This type need be no larger than 16 bits (so maximum of
 * 65535), this define allows us to discover how big it is, but limited by the
- * maximuum for png_size_t.  The value can be overriden in a library build
+ * maximum for size_t.  The value can be overridden in a library build
 * (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
 * lower value (e.g. 255 works).  A lower value may help memory usage (slightly)
 * and may even improve performance on some systems (and degrade it on others.)
@ -214,7 +214,7 @@ struct png_struct_def
   png_uint_32 height;        /* height of image in pixels */
   png_uint_32 num_rows;      /* number of rows in current pass */
   png_uint_32 usr_width;     /* width of row at start of write */
-   png_size_t rowbytes;       /* size of row in bytes */
+   size_t rowbytes;           /* size of row in bytes */
   png_uint_32 iwidth;        /* width of current interlaced row in pixels */
   png_uint_32 row_number;    /* current row in interlace pass */
   png_uint_32 chunk_name;    /* PNG_CHUNK() id of current chunk */
@ -232,7 +232,7 @@ struct png_struct_def
   png_bytep try_row;    /* buffer to save trial row when filtering */
   png_bytep tst_row;    /* buffer to save best trial row when filtering */
 #endif
-   png_size_t info_rowbytes;  /* Added in 1.5.4: cache of updated row bytes */
+   size_t info_rowbytes;      /* Added in 1.5.4: cache of updated row bytes */
   png_uint_32 idat_size;     /* current IDAT size for read */
   png_uint_32 crc;           /* current chunk CRC value */
@ -249,7 +249,7 @@ struct png_struct_def
   png_byte filter;           /* file filter type (always 0) */
   png_byte interlaced;       /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
   png_byte pass;             /* current interlace pass (0 - 6) */
-   png_byte do_filter;        /* row filter flags (see PNG_FILTER_ below ) */
+   png_byte do_filter;        /* row filter flags (see PNG_FILTER_ in png.h ) */
   png_byte color_type;       /* color type of file */
   png_byte bit_depth;        /* bit depth of file */
   png_byte usr_bit_depth;    /* bit depth of users row: write only */
@ -263,7 +263,7 @@ struct png_struct_def
                              /* pixel depth used for the row buffers */
   png_byte transformed_pixel_depth;
                              /* pixel depth after read/write transforms */
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
   png_byte zstream_start;    /* at start of an input zlib stream */
 #endif /* Zlib >= 1.2.4 */
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
@ -307,7 +307,7 @@ struct png_struct_def
 #endif
 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
-   png_color_8 shift;         /* shift for significant bit tranformation */
+   png_color_8 shift;         /* shift for significant bit transformation */
 #endif
 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
@ -328,10 +328,10 @@ struct png_struct_def
   png_bytep current_buffer;         /* buffer for recently used data */
   png_uint_32 push_length;          /* size of current input chunk */
   png_uint_32 skip_length;          /* bytes to skip in input data */
-   png_size_t save_buffer_size;      /* amount of data now in save_buffer */
+   size_t save_buffer_size;          /* amount of data now in save_buffer */
-   png_size_t save_buffer_max;       /* total size of save_buffer */
+   size_t save_buffer_max;           /* total size of save_buffer */
-   png_size_t buffer_size;           /* total amount of available input data */
+   size_t buffer_size;               /* total amount of available input data */
-   png_size_t current_buffer_size;   /* amount of data now in current_buffer */
+   size_t current_buffer_size;       /* amount of data now in current_buffer */
   int process_mode;                 /* what push library is currently doing */
   int cur_palette;                  /* current push library palette index */
@ -353,7 +353,7 @@ struct png_struct_def
 /* Options */
 #ifdef PNG_SET_OPTION_SUPPORTED
-   png_byte options;           /* On/off state (up to 4 options) */
+   png_uint_32 options;           /* On/off state (up to 16 options) */
 #endif
 #if PNG_LIBPNG_VER < 10700
@ -392,6 +392,12 @@ struct png_struct_def
   /* deleted in 1.5.5: rgb_to_gray_blue_coeff; */
 #endif
 /* New member added in libpng-1.6.36 */
 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
    defined(PNG_ARM_NEON_IMPLEMENTATION)
   png_bytep riffled_palette; /* buffer for accelerated palette expansion */
 #endif
 /* New member added in libpng-1.0.4 (renamed in 1.0.9) */
 #if defined(PNG_MNG_FEATURES_SUPPORTED)
 /* Changed from png_byte to png_uint_32 at version 1.2.0 */
@ -451,7 +457,7 @@ struct png_struct_def
 #endif
 /* New member added in libpng-1.2.26 */
-  png_size_t old_big_row_buf_size;
+   size_t old_big_row_buf_size;
 #ifdef PNG_READ_SUPPORTED
 /* New member added in libpng-1.2.30 */
--- a/source/Irrlicht/libpng/pngtest.c
+++ b/source/Irrlicht/libpng/pngtest.c
@ -1,10 +1,10 @@
 /* pngtest.c - a simple test program to test libpng
 *
- * Last changed in libpng 1.5.25 [December 3, 2015]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -43,15 +43,6 @@
 #include "png.h"
 /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
 * a skipped test, in earlier versions we need to succeed on a skipped test, so:
 */
 #if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
 #  define SKIP 77
 #else
 #  define SKIP 0
 #endif
 /* Known chunks that exist in pngtest.png must be supported or pngtest will fail
 * simply as a result of re-ordering them.  This may be fixed in 1.7
 *
@ -153,6 +144,7 @@ tIME_to_str(png_structp png_ptr, png_charp ts, png_const_timep t)
 static int verbose = 0;
 static int strict = 0;
 static int relaxed = 0;
 static int xfail = 0;
 static int unsupported_chunks = 0; /* chunk unsupported by libpng in input */
 static int error_count = 0; /* count calls to png_error */
 static int warning_count = 0; /* count calls to png_warning */
@ -353,10 +345,10 @@ count_zero_samples(png_structp png_ptr, png_row_infop row_info, png_bytep data)
 #ifdef PNG_IO_STATE_SUPPORTED
 void
-pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
+pngtest_check_io_state(png_structp png_ptr, size_t data_length,
    png_uint_32 io_op);
 void
-pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
+pngtest_check_io_state(png_structp png_ptr, size_t data_length,
    png_uint_32 io_op)
 {
   png_uint_32 io_state = png_get_io_state(png_ptr);
@ -394,12 +386,12 @@ pngtest_check_io_state(png_structp png_ptr, png_size_t data_length,
 #endif
 static void PNGCBAPI
-pngtest_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
+pngtest_read_data(png_structp png_ptr, png_bytep data, size_t length)
 {
-   png_size_t check = 0;
+   size_t check = 0;
   png_voidp io_ptr;
-   /* fread() returns 0 on error, so it is OK to store this in a png_size_t
+   /* fread() returns 0 on error, so it is OK to store this in a size_t
    * instead of an int, which is what fread() actually returns.
    */
   io_ptr = png_get_io_ptr(png_ptr);
@ -433,9 +425,9 @@ pngtest_flush(png_structp png_ptr)
 * than changing the library.
 */
 static void PNGCBAPI
-pngtest_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
+pngtest_write_data(png_structp png_ptr, png_bytep data, size_t length)
 {
-   png_size_t check;
+   size_t check;
   check = fwrite(data, 1, length, (png_FILE_p)png_get_io_ptr(png_ptr));
@ -457,13 +449,13 @@ pngtest_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
 */
 typedef struct
 {
-   PNG_CONST char *file_name;
+   const char *file_name;
 }  pngtest_error_parameters;
 static void PNGCBAPI
 pngtest_warning(png_structp png_ptr, png_const_charp message)
 {
-   PNG_CONST char *name = "UNKNOWN (ERROR!)";
+   const char *name = "UNKNOWN (ERROR!)";
   pngtest_error_parameters *test =
      (pngtest_error_parameters*)png_get_error_ptr(png_ptr);
@ -472,7 +464,7 @@ pngtest_warning(png_structp png_ptr, png_const_charp message)
   if (test != NULL && test->file_name != NULL)
      name = test->file_name;
-   fprintf(STDERR, "%s: libpng warning: %s\n", name, message);
+   fprintf(STDERR, "\n%s: libpng warning: %s\n", name, message);
 }
 /* This is the default error handling function.  Note that replacements for
@ -713,7 +705,7 @@ read_user_chunk_callback(png_struct *png_ptr, png_unknown_chunkp chunk)
    * The unknown chunk structure contains the chunk data:
    * png_byte name[5];
    * png_byte *data;
-    * png_size_t size;
+    * size_t size;
    *
    * Note that libpng has already taken care of the CRC handling.
    */
@ -858,7 +850,7 @@ pngtest_check_text_support(png_structp png_ptr, png_textp text_ptr,
 /* Test one file */
 static int
-test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
+test_one_file(const char *inname, const char *outname)
 {
   static png_FILE_p fpin;
   static png_FILE_p fpout;  /* "static" prevents setjmp corruption */
@ -945,8 +937,12 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      fprintf(STDERR, "%s -> %s: libpng read error\n", inname, outname);
      png_free(read_ptr, row_buf);
      row_buf = NULL;
      if (verbose != 0)
        fprintf(STDERR, "   destroy read structs\n");
      png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
 #ifdef PNG_WRITE_SUPPORTED
      if (verbose != 0)
        fprintf(STDERR, "   destroy write structs\n");
      png_destroy_info_struct(write_ptr, &write_end_info_ptr);
      png_destroy_write_struct(&write_ptr, &write_info_ptr);
 #endif
@ -961,11 +957,15 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   if (setjmp(png_jmpbuf(write_ptr)))
   {
      fprintf(STDERR, "%s -> %s: libpng write error\n", inname, outname);
      png_free(read_ptr, row_buf);
      row_buf = NULL;
      if (verbose != 0)
        fprintf(STDERR, "   destroying read structs\n");
      png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
      if (verbose != 0)
        fprintf(STDERR, "   destroying write structs\n");
      png_destroy_info_struct(write_ptr, &write_end_info_ptr);
 #ifdef PNG_WRITE_SUPPORTED
      png_destroy_write_struct(&write_ptr, &write_info_ptr);
 #endif
      FCLOSE(fpin);
      FCLOSE(fpout);
      return (1);
@ -973,15 +973,16 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 #endif
 #endif
 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
   if (strict != 0)
   {
      /* Treat png_benign_error() as errors on read */
      png_set_benign_errors(read_ptr, 0);
-#ifdef PNG_WRITE_SUPPORTED
+# ifdef PNG_WRITE_SUPPORTED
      /* Treat them as errors on write */
      png_set_benign_errors(write_ptr, 0);
-#endif
+# endif
      /* if strict is not set, then app warnings and errors are treated as
       * warnings in release builds, but not in unstable builds; this can be
@ -994,10 +995,20 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      /* Allow application (pngtest) errors and warnings to pass */
      png_set_benign_errors(read_ptr, 1);
-#ifdef PNG_WRITE_SUPPORTED
+      /* Turn off CRC checking while reading */
-      png_set_benign_errors(write_ptr, 1);
+      png_set_crc_action(read_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
 #ifdef PNG_IGNORE_ADLER32
      /* Turn off ADLER32 checking while reading */
      png_set_option(read_ptr, PNG_IGNORE_ADLER32, PNG_OPTION_ON);
 #endif
 # ifdef PNG_WRITE_SUPPORTED
      png_set_benign_errors(write_ptr, 1);
 # endif
   }
 #endif /* BENIGN_ERRORS */
   pngtest_debug("Initializing input and output streams");
 #ifdef PNG_STDIO_SUPPORTED
@ -1190,6 +1201,22 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      }
   }
 #endif
 #ifdef PNG_READ_eXIf_SUPPORTED
   {
      png_bytep exif=NULL;
      png_uint_32 exif_length;
      if (png_get_eXIf_1(read_ptr, read_info_ptr, &exif_length, &exif) != 0)
      {
         if (exif_length > 1)
            fprintf(STDERR," eXIf type %c%c, %lu bytes\n",exif[0],exif[1],
               (unsigned long)exif_length);
 # ifdef PNG_WRITE_eXIf_SUPPORTED
         png_set_eXIf_1(write_ptr, write_info_ptr, exif_length, exif);
 # endif
      }
   }
 #endif
 #ifdef PNG_hIST_SUPPORTED
   {
      png_uint_16p hist;
@ -1300,10 +1327,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         {
            int i;
-            printf("\n");
+            fprintf(STDERR,"\n");
            for (i=0; i<num_text; i++)
            {
-               printf("   Text compression[%d]=%d\n",
+               fprintf(STDERR,"   Text compression[%d]=%d\n",
                   i, text_ptr[i].compression);
            }
         }
@ -1395,6 +1422,15 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   png_write_info(write_ptr, write_info_ptr);
   write_chunks(write_ptr, before_IDAT); /* after PLTE */
   png_write_info(write_ptr, write_end_info_ptr);
   write_chunks(write_ptr, after_IDAT); /* after IDAT */
 #ifdef PNG_COMPRESSION_COMPAT
   /* Test the 'compatibility' setting here, if it is available. */
   png_set_compression(write_ptr, PNG_COMPRESSION_COMPAT);
 #endif
 #endif
 #ifdef SINGLE_ROWBUF_ALLOC
@ -1402,7 +1438,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
   row_buf = (png_bytep)png_malloc(read_ptr,
       png_get_rowbytes(read_ptr, read_info_ptr));
-   pngtest_debug1("\t0x%08lx", (unsigned long)row_buf);
+   pngtest_debug1("\t%p", row_buf);
 #endif /* SINGLE_ROWBUF_ALLOC */
   pngtest_debug("Writing row data");
@ -1456,7 +1492,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         row_buf = (png_bytep)png_malloc(read_ptr,
             png_get_rowbytes(read_ptr, read_info_ptr));
-         pngtest_debug2("\t0x%08lx (%lu bytes)", (unsigned long)row_buf,
+         pngtest_debug2("\t%p (%lu bytes)", row_buf,
             (unsigned long)png_get_rowbytes(read_ptr, read_info_ptr));
 #endif /* !SINGLE_ROWBUF_ALLOC */
@ -1511,10 +1547,10 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
         {
            int i;
-            printf("\n");
+            fprintf(STDERR,"\n");
            for (i=0; i<num_text; i++)
            {
-               printf("   Text compression[%d]=%d\n",
+               fprintf(STDERR,"   Text compression[%d]=%d\n",
                   i, text_ptr[i].compression);
            }
         }
@ -1523,6 +1559,22 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      }
   }
 #endif
 #ifdef PNG_READ_eXIf_SUPPORTED
   {
      png_bytep exif=NULL;
      png_uint_32 exif_length;
      if (png_get_eXIf_1(read_ptr, end_info_ptr, &exif_length, &exif) != 0)
      {
         if (exif_length > 1)
            fprintf(STDERR," eXIf type %c%c, %lu bytes\n",exif[0],exif[1],
               (unsigned long)exif_length);
 # ifdef PNG_WRITE_eXIf_SUPPORTED
         png_set_eXIf_1(write_ptr, write_end_info_ptr, exif_length, exif);
 # endif
      }
   }
 #endif
 #ifdef PNG_tIME_SUPPORTED
   {
      png_timep mod_time;
@ -1676,7 +1728,7 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
      for (;;)
      {
         static int wrote_question = 0;
-         png_size_t num_in, num_out;
+         size_t num_in, num_out;
         char inbuf[256], outbuf[256];
         num_in = fread(inbuf, 1, sizeof inbuf, fpin);
@ -1690,7 +1742,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
            if (wrote_question == 0 && unsupported_chunks == 0)
            {
               fprintf(STDERR,
-         "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
+                   "   Was %s written with the same maximum IDAT"
                   " chunk size (%d bytes),",
                   inname, PNG_ZBUF_SIZE);
               fprintf(STDERR,
                   "\n   filtering heuristic (libpng default), compression");
@ -1721,7 +1774,8 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
            if (wrote_question == 0 && unsupported_chunks == 0)
            {
               fprintf(STDERR,
-         "   Was %s written with the same maximum IDAT chunk size (%d bytes),",
+                   "   Was %s written with the same maximum"
                   " IDAT chunk size (%d bytes),",
                    inname, PNG_ZBUF_SIZE);
               fprintf(STDERR,
                   "\n   filtering heuristic (libpng default), compression");
@ -1757,11 +1811,11 @@ test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
 /* Input and output filenames */
 #ifdef RISCOS
-static PNG_CONST char *inname = "pngtest/png";
+static const char *inname = "pngtest/png";
-static PNG_CONST char *outname = "pngout/png";
+static const char *outname = "pngout/png";
 #else
-static PNG_CONST char *inname = "pngtest.png";
+static const char *inname = "pngtest.png";
-static PNG_CONST char *outname = "pngout.png";
+static const char *outname = "pngout.png";
 #endif
 int
@ -1836,6 +1890,7 @@ main(int argc, char *argv[])
         inname = argv[2];
         strict++;
         relaxed = 0;
         multiple=1;
      }
      else if (strcmp(argv[1], "--relaxed") == 0)
@ -1845,6 +1900,17 @@ main(int argc, char *argv[])
         inname = argv[2];
         strict = 0;
         relaxed++;
         multiple=1;
      }
      else if (strcmp(argv[1], "--xfail") == 0)
      {
         status_dots_requested = 0;
         verbose = 1;
         inname = argv[2];
         strict = 0;
         xfail++;
         relaxed++;
         multiple=1;
      }
      else
@ -1900,11 +1966,16 @@ main(int argc, char *argv[])
 #endif /* TIME_RFC1123 */
         }
         else
         {
            if (xfail)
              fprintf(STDERR, " XFAIL\n");
            else
            {
              fprintf(STDERR, " FAIL\n");
              ierror += kerror;
            }
         }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         if (allocation_now != current_allocation)
            fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
@ -1991,9 +2062,14 @@ main(int argc, char *argv[])
 #endif
            }
            if (xfail)
              fprintf(STDERR, " XFAIL\n");
            else
            {
              fprintf(STDERR, " FAIL\n");
              ierror += kerror;
            }
         }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
         if (allocation_now != current_allocation)
             fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
@ -2074,9 +2150,9 @@ main(void)
   fprintf(STDERR,
       " test ignored because libpng was not built with read support\n");
   /* And skip this test */
-   return SKIP;
+   return PNG_LIBPNG_VER < 10600 ? 0 : 77;
 }
 #endif
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_23 Your_png_h_is_not_version_1_6_23;
+typedef png_libpng_version_1_6_37 Your_png_h_is_not_version_1_6_37;
--- a/source/Irrlicht/libpng/pngtest.png
+++ b/source/Irrlicht/libpng/pngtest.png
--- a/source/Irrlicht/libpng/pngtrans.c
+++ b/source/Irrlicht/libpng/pngtrans.c
@ -1,10 +1,10 @@
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
 *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -172,7 +172,8 @@ png_set_filler(png_structrp png_ptr, png_uint_32 filler, int filler_loc)
                   * size!
                   */
                  png_app_error(png_ptr,
-                     "png_set_filler is invalid for low bit depth gray output");
+                      "png_set_filler is invalid for"
                      " low bit depth gray output");
                  return;
               }
@ -268,8 +269,8 @@ png_do_invert(png_row_infop row_info, png_bytep row)
   if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
   {
      png_bytep rp = row;
-      png_size_t i;
+      size_t i;
-      png_size_t istop = row_info->rowbytes;
+      size_t istop = row_info->rowbytes;
      for (i = 0; i < istop; i++)
      {
@ -282,8 +283,8 @@ png_do_invert(png_row_infop row_info, png_bytep row)
      row_info->bit_depth == 8)
   {
      png_bytep rp = row;
-      png_size_t i;
+      size_t i;
-      png_size_t istop = row_info->rowbytes;
+      size_t istop = row_info->rowbytes;
      for (i = 0; i < istop; i += 2)
      {
@ -297,8 +298,8 @@ png_do_invert(png_row_infop row_info, png_bytep row)
      row_info->bit_depth == 16)
   {
      png_bytep rp = row;
-      png_size_t i;
+      size_t i;
-      png_size_t istop = row_info->rowbytes;
+      size_t istop = row_info->rowbytes;
      for (i = 0; i < istop; i += 4)
      {
@ -344,7 +345,7 @@ png_do_swap(png_row_infop row_info, png_bytep row)
 #endif
 #if defined(PNG_READ_PACKSWAP_SUPPORTED)||defined(PNG_WRITE_PACKSWAP_SUPPORTED)
-static PNG_CONST png_byte onebppswaptable[256] = {
+static const png_byte onebppswaptable[256] = {
   0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0,
   0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
   0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,
@ -379,7 +380,7 @@ static PNG_CONST png_byte onebppswaptable[256] = {
   0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
 };
-static PNG_CONST png_byte twobppswaptable[256] = {
+static const png_byte twobppswaptable[256] = {
   0x00, 0x40, 0x80, 0xC0, 0x10, 0x50, 0x90, 0xD0,
   0x20, 0x60, 0xA0, 0xE0, 0x30, 0x70, 0xB0, 0xF0,
   0x04, 0x44, 0x84, 0xC4, 0x14, 0x54, 0x94, 0xD4,
@ -414,7 +415,7 @@ static PNG_CONST png_byte twobppswaptable[256] = {
   0x2F, 0x6F, 0xAF, 0xEF, 0x3F, 0x7F, 0xBF, 0xFF
 };
-static PNG_CONST png_byte fourbppswaptable[256] = {
+static const png_byte fourbppswaptable[256] = {
   0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
   0x80, 0x90, 0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0,
   0x01, 0x11, 0x21, 0x31, 0x41, 0x51, 0x61, 0x71,
@ -513,11 +514,15 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
         if (at_start != 0) /* Skip initial filler */
            ++sp;
         else          /* Skip initial channel and, for sp, the filler */
-            sp += 2, ++dp;
+         {
            sp += 2; ++dp;
         }
         /* For a 1 pixel wide image there is nothing to do */
         while (sp < ep)
-            *dp++ = *sp, sp += 2;
+         {
            *dp++ = *sp; sp += 2;
         }
         row_info->pixel_depth = 8;
      }
@ -527,10 +532,14 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
         if (at_start != 0) /* Skip initial filler */
            sp += 2;
         else          /* Skip initial channel and, for sp, the filler */
-            sp += 4, dp += 2;
+         {
            sp += 4; dp += 2;
         }
         while (sp < ep)
-            *dp++ = *sp++, *dp++ = *sp, sp += 3;
+         {
            *dp++ = *sp++; *dp++ = *sp; sp += 3;
         }
         row_info->pixel_depth = 16;
      }
@ -553,11 +562,15 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
         if (at_start != 0) /* Skip initial filler */
            ++sp;
         else          /* Skip initial channels and, for sp, the filler */
-            sp += 4, dp += 3;
+         {
            sp += 4; dp += 3;
         }
         /* Note that the loop adds 3 to dp and 4 to sp each time. */
         while (sp < ep)
-            *dp++ = *sp++, *dp++ = *sp++, *dp++ = *sp, sp += 2;
+         {
            *dp++ = *sp++; *dp++ = *sp++; *dp++ = *sp; sp += 2;
         }
         row_info->pixel_depth = 24;
      }
@ -567,14 +580,16 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
         if (at_start != 0) /* Skip initial filler */
            sp += 2;
         else          /* Skip initial channels and, for sp, the filler */
-            sp += 8, dp += 6;
+         {
            sp += 8; dp += 6;
         }
         while (sp < ep)
         {
            /* Copy 6 bytes, skip 2 */
-            *dp++ = *sp++, *dp++ = *sp++;
+            *dp++ = *sp++; *dp++ = *sp++;
-            *dp++ = *sp++, *dp++ = *sp++;
+            *dp++ = *sp++; *dp++ = *sp++;
-            *dp++ = *sp++, *dp++ = *sp, sp += 3;
+            *dp++ = *sp++; *dp++ = *sp; sp += 3;
         }
         row_info->pixel_depth = 48;
@ -594,7 +609,7 @@ png_do_strip_channel(png_row_infop row_info, png_bytep row, int at_start)
      return; /* The filler channel has gone already */
   /* Fix the rowbytes value. */
-   row_info->rowbytes = dp-row;
+   row_info->rowbytes = (size_t)(dp-row);
 }
 #endif
@ -692,8 +707,8 @@ png_do_check_palette_indexes(png_structrp png_ptr, png_row_infop row_info)
       * and this calculation is used because it avoids warnings that other
       * forms produced on either GCC or MSVC.
       */
-      int padding = (-row_info->pixel_depth * row_info->width) & 7;
+      int padding = PNG_PADBITS(row_info->pixel_depth, row_info->width);
-      png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
+      png_bytep rp = png_ptr->row_buf + row_info->rowbytes - 1;
      switch (row_info->bit_depth)
      {
--- a/source/Irrlicht/libpng/pngusr.dfa
+++ b/source/Irrlicht/libpng/pngusr.dfa
@ -0,0 +1,14 @@
 # pngusr.dfa
 #
 # Build time configuration of libpng
 #
 # Enter build configuration options in this file
 #
 # Security settings: by default these limits are unset, you can change them
 # here by entering the appropriate values as #defines preceded by '@' (to cause,
 # them to be passed through to the build of pnglibconf.h), for example:
 #
 # @# define PNG_USER_WIDTH_MAX 65535
 # @# define PNG_USER_HEIGHT_MAX 65535
 # @# define PNG_USER_CHUNK_CACHE_MAX 256
 # @# define PNG_USER_CHUNK_MALLOC_MAX 640000
--- a/source/Irrlicht/libpng/pngwio.c
+++ b/source/Irrlicht/libpng/pngwio.c
@ -1,10 +1,10 @@
 /* pngwio.c - functions for data output
 *
- * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2014 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2014,2016,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -30,7 +30,7 @@
 */
 void /* PRIVATE */
-png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
+png_write_data(png_structrp png_ptr, png_const_bytep data, size_t length)
 {
   /* NOTE: write_data_fn must not change the buffer! */
   if (png_ptr->write_data_fn != NULL )
@ -48,9 +48,9 @@ png_write_data(png_structrp png_ptr, png_const_bytep data, png_size_t length)
 * than changing the library.
 */
 void PNGCBAPI
-png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
+png_default_write_data(png_structp png_ptr, png_bytep data, size_t length)
 {
-   png_size_t check;
+   size_t check;
   if (png_ptr == NULL)
      return;
--- a/source/Irrlicht/libpng/pngwrite.c
+++ b/source/Irrlicht/libpng/pngwrite.c
@ -1,10 +1,10 @@
 /* pngwrite.c - general routines to write a PNG file
 *
- * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 2018-2019 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -237,6 +237,11 @@ png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
      png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
 #endif
 #ifdef PNG_WRITE_eXIf_SUPPORTED
   if ((info_ptr->valid & PNG_INFO_eXIf) != 0)
      png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);
 #endif
 #ifdef PNG_WRITE_hIST_SUPPORTED
   if ((info_ptr->valid & PNG_INFO_hIST) != 0)
      png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
@ -432,6 +437,12 @@ png_write_end(png_structrp png_ptr, png_inforp info_ptr)
         }
      }
 #endif
 #ifdef PNG_WRITE_eXIf_SUPPORTED
   if ((info_ptr->valid & PNG_INFO_eXIf) != 0)
      png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);
 #endif
 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
      write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
 #endif
@ -458,7 +469,7 @@ png_write_end(png_structrp png_ptr, png_inforp info_ptr)
 #ifdef PNG_CONVERT_tIME_SUPPORTED
 void PNGAPI
-png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
+png_convert_from_struct_tm(png_timep ptime, const struct tm * ttime)
 {
   png_debug(1, "in png_convert_from_struct_tm");
@ -666,9 +677,9 @@ png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
         for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
         {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
+            png_uint_32 s0   = (png_uint_32)(*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
+            png_uint_32 s1   = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 s2   = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
            png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
            png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
            *(rp    ) = (png_byte)(red >> 8);
@ -901,7 +912,7 @@ png_set_flush(png_structrp png_ptr, int nrows)
   if (png_ptr == NULL)
      return;
-   png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
+   png_ptr->flush_dist = (nrows < 0 ? 0 : (png_uint_32)nrows);
 }
 /* Flush the current output buffers now */
@ -1007,8 +1018,8 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
         case 5:
         case 6:
         case 7: png_app_error(png_ptr, "Unknown row filter for method 0");
            /* FALL THROUGH */
 #endif /* WRITE_FILTER */
            /* FALLTHROUGH */
         case PNG_FILTER_VALUE_NONE:
            png_ptr->do_filter = PNG_FILTER_NONE; break;
@ -1525,7 +1536,8 @@ png_write_image_16bit(png_voidp argument)
       display->first_row);
   png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
   png_uint_16p row_end;
-   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+   unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
       3 : 1;
   int aindex = 0;
   png_uint_32 y = image->height;
@ -1539,9 +1551,9 @@ png_write_image_16bit(png_voidp argument)
         ++output_row;
      }
         else
-            aindex = channels;
+            aindex = (int)channels;
 #     else
-         aindex = channels;
+         aindex = (int)channels;
 #     endif
   }
@ -1554,14 +1566,14 @@ png_write_image_16bit(png_voidp argument)
    */
   row_end = output_row + image->width * (channels+1);
-   while (y-- > 0)
+   for (; y > 0; --y)
   {
      png_const_uint_16p in_ptr = input_row;
      png_uint_16p out_ptr = output_row;
      while (out_ptr < row_end)
      {
-         const png_uint_16 alpha = in_ptr[aindex];
+         png_uint_16 alpha = in_ptr[aindex];
         png_uint_32 reciprocal = 0;
         int c;
@ -1575,7 +1587,7 @@ png_write_image_16bit(png_voidp argument)
         if (alpha > 0 && alpha < 65535)
            reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
-         c = channels;
+         c = (int)channels;
         do /* always at least one channel */
         {
            png_uint_16 component = *in_ptr++;
@ -1610,7 +1622,7 @@ png_write_image_16bit(png_voidp argument)
      }
      png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
-      input_row += display->row_bytes/(sizeof (png_uint_16));
+      input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
   }
   return 1;
@ -1624,7 +1636,7 @@ png_write_image_16bit(png_voidp argument)
 * calculation can be done to 15 bits of accuracy; however, the output needs to
 * be scaled in the range 0..255*65535, so include that scaling here.
 */
-#   define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+(alpha>>1))/alpha)
+#   define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+((alpha)>>1))/(alpha))
 static png_byte
 png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
@ -1683,7 +1695,8 @@ png_write_image_8bit(png_voidp argument)
       display->first_row);
   png_bytep output_row = png_voidcast(png_bytep, display->local_row);
   png_uint_32 y = image->height;
-   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+   unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
       3 : 1;
   if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
   {
@ -1700,12 +1713,12 @@ png_write_image_8bit(png_voidp argument)
      else
 #   endif
-      aindex = channels;
+      aindex = (int)channels;
      /* Use row_end in place of a loop counter: */
      row_end = output_row + image->width * (channels+1);
-      while (y-- > 0)
+      for (; y > 0; --y)
      {
         png_const_uint_16p in_ptr = input_row;
         png_bytep out_ptr = output_row;
@ -1723,7 +1736,7 @@ png_write_image_8bit(png_voidp argument)
            if (alphabyte > 0 && alphabyte < 255)
               reciprocal = UNP_RECIPROCAL(alpha);
-            c = channels;
+            c = (int)channels;
            do /* always at least one channel */
               *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
            while (--c > 0);
@ -1735,7 +1748,7 @@ png_write_image_8bit(png_voidp argument)
         png_write_row(png_ptr, png_voidcast(png_const_bytep,
             display->local_row));
-         input_row += display->row_bytes/(sizeof (png_uint_16));
+         input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
      } /* while y */
   }
@ -1746,7 +1759,7 @@ png_write_image_8bit(png_voidp argument)
       */
      png_bytep row_end = output_row + image->width * channels;
-      while (y-- > 0)
+      for (; y > 0; --y)
      {
         png_const_uint_16p in_ptr = input_row;
         png_bytep out_ptr = output_row;
@ -1760,7 +1773,7 @@ png_write_image_8bit(png_voidp argument)
         }
         png_write_row(png_ptr, output_row);
-         input_row += display->row_bytes/(sizeof (png_uint_16));
+         input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
      }
   }
@ -1770,25 +1783,25 @@ png_write_image_8bit(png_voidp argument)
 static void
 png_image_set_PLTE(png_image_write_control *display)
 {
-   const png_imagep image = display->image;
+   png_imagep image = display->image;
   const void *cmap = display->colormap;
-   const int entries = image->colormap_entries > 256 ? 256 :
+   int entries = image->colormap_entries > 256 ? 256 :
       (int)image->colormap_entries;
   /* NOTE: the caller must check for cmap != NULL and entries != 0 */
-   const png_uint_32 format = image->format;
+   png_uint_32 format = image->format;
-   const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
+   unsigned int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
 #   if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
      defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
-      const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
+      int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
          (format & PNG_FORMAT_FLAG_ALPHA) != 0;
 #   else
 #     define afirst 0
 #   endif
 #   ifdef PNG_FORMAT_BGR_SUPPORTED
-      const int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
+      int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
 #   else
 #     define bgr 0
 #   endif
@ -1809,7 +1822,7 @@ png_image_set_PLTE(png_image_write_control *display)
      {
         png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
-         entry += i * channels;
+         entry += (unsigned int)i * channels;
         if ((channels & 1) != 0) /* no alpha */
         {
@ -1865,7 +1878,7 @@ png_image_set_PLTE(png_image_write_control *display)
      {
         png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
-         entry += i * channels;
+         entry += (unsigned int)i * channels;
         switch (channels)
         {
@ -1873,7 +1886,7 @@ png_image_set_PLTE(png_image_write_control *display)
               tRNS[i] = entry[afirst ? 0 : 3];
               if (tRNS[i] < 255)
                  num_trans = i+1;
-               /* FALL THROUGH */
+               /* FALLTHROUGH */
            case 3:
               palette[i].blue = entry[afirst + (2 ^ bgr)];
               palette[i].green = entry[afirst + 1];
@ -1884,7 +1897,7 @@ png_image_set_PLTE(png_image_write_control *display)
               tRNS[i] = entry[1 ^ afirst];
               if (tRNS[i] < 255)
                  num_trans = i+1;
-               /* FALL THROUGH */
+               /* FALLTHROUGH */
            case 1:
               palette[i].blue = palette[i].red = palette[i].green =
                  entry[afirst];
@ -1910,7 +1923,7 @@ png_image_set_PLTE(png_image_write_control *display)
      png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
          num_trans, NULL);
-   image->colormap_entries = entries;
+   image->colormap_entries = (png_uint_32)entries;
 }
 static int
@ -1927,7 +1940,7 @@ png_image_write_main(png_voidp argument)
   int colormap = (format & PNG_FORMAT_FLAG_COLORMAP);
   int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR); /* input */
   int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA);
-   int write_16bit = linear && !colormap && (display->convert_to_8bit == 0);
+   int write_16bit = linear && (display->convert_to_8bit == 0);
 #   ifdef PNG_BENIGN_ERRORS_SUPPORTED
      /* Make sure we error out on any bad situation */
@ -1938,21 +1951,21 @@ png_image_write_main(png_voidp argument)
    * and total image size to ensure that they are within the system limits.
    */
   {
-      const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
+      unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
+      if (image->width <= 0x7fffffffU/channels) /* no overflow */
      {
         png_uint_32 check;
-         const png_uint_32 png_row_stride = image->width * channels;
+         png_uint_32 png_row_stride = image->width * channels;
         if (display->row_stride == 0)
            display->row_stride = (png_int_32)/*SAFE*/png_row_stride;
         if (display->row_stride < 0)
-            check = -display->row_stride;
+            check = (png_uint_32)(-display->row_stride);
         else
-            check = display->row_stride;
+            check = (png_uint_32)display->row_stride;
         if (check >= png_row_stride)
         {
@ -1960,7 +1973,7 @@ png_image_write_main(png_voidp argument)
             * limits the whole image size to 32 bits for API compatibility with
             * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
             */
-            if (image->height > 0xFFFFFFFF/png_row_stride)
+            if (image->height > 0xffffffffU/png_row_stride)
               png_error(image->opaque->png_ptr, "memory image too large");
         }
@ -2039,7 +2052,7 @@ png_image_write_main(png_voidp argument)
    */
   if (write_16bit != 0)
   {
-      PNG_CONST png_uint_16 le = 0x0001;
+      png_uint_16 le = 0x0001;
      if ((*(png_const_bytep) & le) != 0)
         png_set_swap(png_ptr);
@ -2136,7 +2149,7 @@ png_image_write_main(png_voidp argument)
      ptrdiff_t row_bytes = display->row_bytes;
      png_uint_32 y = image->height;
-      while (y-- > 0)
+      for (; y > 0; --y)
      {
         png_write_row(png_ptr, row);
         row += row_bytes;
@ -2149,12 +2162,11 @@ png_image_write_main(png_voidp argument)
 static void (PNGCBAPI
-image_memory_write)(png_structp png_ptr, png_bytep/*const*/ data,
+image_memory_write)(png_structp png_ptr, png_bytep/*const*/ data, size_t size)
   png_size_t size)
 {
   png_image_write_control *display = png_voidcast(png_image_write_control*,
       png_ptr->io_ptr/*backdoor: png_get_io_ptr(png_ptr)*/);
-   const png_alloc_size_t ob = display->output_bytes;
+   png_alloc_size_t ob = display->output_bytes;
   /* Check for overflow; this should never happen: */
   if (size <= ((png_alloc_size_t)-1) - ob)
--- a/source/Irrlicht/libpng/pngwtran.c
+++ b/source/Irrlicht/libpng/pngwtran.c
@ -1,10 +1,10 @@
 /* pngwtran.c - transforms the data in a row for PNG writers
 *
- * Last changed in libpng 1.6.18 [July 23, 2015]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -177,7 +177,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
   if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
   {
      int shift_start[4], shift_dec[4];
-      int channels = 0;
+      unsigned int channels = 0;
      if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
      {
@ -212,9 +212,9 @@ png_do_shift(png_row_infop row_info, png_bytep row,
      if (row_info->bit_depth < 8)
      {
         png_bytep bp = row;
-         png_size_t i;
+         size_t i;
         unsigned int mask;
-         png_size_t row_bytes = row_info->rowbytes;
+         size_t row_bytes = row_info->rowbytes;
         if (bit_depth->gray == 1 && row_info->bit_depth == 2)
            mask = 0x55;
@ -254,8 +254,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
         for (i = 0; i < istop; i++, bp++)
         {
-
+            unsigned int c = i%channels;
            const unsigned int c = i%channels;
            int j;
            unsigned int v, out;
@ -283,7 +282,7 @@ png_do_shift(png_row_infop row_info, png_bytep row,
         for (bp = row, i = 0; i < istop; i++)
         {
-            const unsigned int c = i%channels;
+            unsigned int c = i%channels;
            int j;
            unsigned int value, v;
@ -514,7 +513,7 @@ png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
             (png_ptr,  /* png_ptr */
             row_info,  /* row_info: */
                /*  png_uint_32 width;       width of row */
-                /*  png_size_t rowbytes;     number of bytes in row */
+                /*  size_t rowbytes;         number of bytes in row */
                /*  png_byte color_type;     color type of pixels */
                /*  png_byte bit_depth;      bit depth of samples */
                /*  png_byte channels;       number of channels (1-4) */
--- a/source/Irrlicht/libpng/pngwutil.c
+++ b/source/Irrlicht/libpng/pngwutil.c
@ -1,10 +1,10 @@
 /* pngwutil.c - utilities to write a PNG file
 *
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Copyright (c) 2018 Cosmin Truta
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
- * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * Copyright (c) 1996-1997 Andreas Dilger
- * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
@ -59,7 +59,7 @@ png_write_sig(png_structrp png_ptr)
   /* Write the rest of the 8 byte signature */
   png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
-      (png_size_t)(8 - png_ptr->sig_bytes));
+       (size_t)(8 - png_ptr->sig_bytes));
   if (png_ptr->sig_bytes < 3)
      png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
@ -124,8 +124,7 @@ png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
 * given to png_write_chunk_header().
 */
 void PNGAPI
-png_write_chunk_data(png_structrp png_ptr, png_const_bytep data,
+png_write_chunk_data(png_structrp png_ptr, png_const_bytep data, size_t length)
    png_size_t length)
 {
   /* Write the data, and run the CRC over it */
   if (png_ptr == NULL)
@ -160,7 +159,7 @@ png_write_chunk_end(png_structrp png_ptr)
   /* Write the crc in a single operation */
   png_save_uint_32(buf, png_ptr->crc);
-   png_write_data(png_ptr, buf, (png_size_t)4);
+   png_write_data(png_ptr, buf, 4);
 }
 /* Write a PNG chunk all at once.  The type is an array of ASCII characters
@ -174,7 +173,7 @@ png_write_chunk_end(png_structrp png_ptr)
 */
 static void
 png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
-   png_const_bytep data, png_size_t length)
+    png_const_bytep data, size_t length)
 {
   if (png_ptr == NULL)
      return;
@ -191,7 +190,7 @@ png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
 /* This is the API that calls the internal function above. */
 void PNGAPI
 png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
-   png_const_bytep data, png_size_t length)
+    png_const_bytep data, size_t length)
 {
   png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data,
       length);
@ -408,7 +407,7 @@ png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
      png_ptr->zstream.avail_out = 0;
      /* Now initialize if required, setting the new parameters, otherwise just
-       * to a simple reset to the previous parameters.
+       * do a simple reset to the previous parameters.
       */
      if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
         ret = deflateReset(&png_ptr->zstream);
@ -675,6 +674,7 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
    int interlace_type)
 {
   png_byte buf[13]; /* Buffer to store the IHDR info */
   int is_invalid_depth;
   png_debug(1, "in png_write_IHDR");
@ -700,11 +700,11 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
         break;
      case PNG_COLOR_TYPE_RGB:
         is_invalid_depth = (bit_depth != 8);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
-         if (bit_depth != 8 && bit_depth != 16)
+         is_invalid_depth = (is_invalid_depth && bit_depth != 16);
 #else
         if (bit_depth != 8)
 #endif
         if (is_invalid_depth)
            png_error(png_ptr, "Invalid bit depth for RGB image");
         png_ptr->channels = 3;
@ -726,18 +726,22 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
         break;
      case PNG_COLOR_TYPE_GRAY_ALPHA:
-         if (bit_depth != 8 && bit_depth != 16)
+         is_invalid_depth = (bit_depth != 8);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
         is_invalid_depth = (is_invalid_depth && bit_depth != 16);
 #endif
         if (is_invalid_depth)
            png_error(png_ptr, "Invalid bit depth for grayscale+alpha image");
         png_ptr->channels = 2;
         break;
      case PNG_COLOR_TYPE_RGB_ALPHA:
         is_invalid_depth = (bit_depth != 8);
 #ifdef PNG_WRITE_16BIT_SUPPORTED
-         if (bit_depth != 8 && bit_depth != 16)
+         is_invalid_depth = (is_invalid_depth && bit_depth != 16);
 #else
         if (bit_depth != 8)
 #endif
         if (is_invalid_depth)
            png_error(png_ptr, "Invalid bit depth for RGBA image");
         png_ptr->channels = 4;
@ -815,7 +819,7 @@ png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
   buf[12] = (png_byte)interlace_type;
   /* Write the chunk */
-   png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13);
+   png_write_complete_chunk(png_ptr, png_IHDR, buf, 13);
   if ((png_ptr->do_filter) == PNG_NO_FILTERS)
   {
@ -884,7 +888,7 @@ png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
      buf[0] = pal_ptr->red;
      buf[1] = pal_ptr->green;
      buf[2] = pal_ptr->blue;
-      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
+      png_write_chunk_data(png_ptr, buf, 3);
   }
 #else
@ -898,7 +902,7 @@ png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
      buf[0] = pal_ptr[i].red;
      buf[1] = pal_ptr[i].green;
      buf[2] = pal_ptr[i].blue;
-      png_write_chunk_data(png_ptr, buf, (png_size_t)3);
+      png_write_chunk_data(png_ptr, buf, 3);
   }
 #endif
@ -998,6 +1002,7 @@ png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
               optimize_cmf(data, png_image_size(png_ptr));
 #endif
         if (size > 0)
            png_write_complete_chunk(png_ptr, png_IDAT, data, size);
         png_ptr->mode |= PNG_HAVE_IDAT;
@ -1044,6 +1049,7 @@ png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
            optimize_cmf(data, png_image_size(png_ptr));
 #endif
         if (size > 0)
            png_write_complete_chunk(png_ptr, png_IDAT, data, size);
         png_ptr->zstream.avail_out = 0;
         png_ptr->zstream.next_out = NULL;
@ -1068,7 +1074,7 @@ png_write_IEND(png_structrp png_ptr)
 {
   png_debug(1, "in png_write_IEND");
-   png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0);
+   png_write_complete_chunk(png_ptr, png_IEND, NULL, 0);
   png_ptr->mode |= PNG_HAVE_IEND;
 }
@ -1083,7 +1089,7 @@ png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
   /* file_gamma is saved in 1/100,000ths */
   png_save_uint_32(buf, (png_uint_32)file_gamma);
-   png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4);
+   png_write_complete_chunk(png_ptr, png_gAMA, buf, 4);
 }
 #endif
@ -1101,7 +1107,7 @@ png_write_sRGB(png_structrp png_ptr, int srgb_intent)
          "Invalid sRGB rendering intent specified");
   buf[0]=(png_byte)srgb_intent;
-   png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
+   png_write_complete_chunk(png_ptr, png_sRGB, buf, 1);
 }
 #endif
@ -1175,8 +1181,8 @@ png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
   png_uint_32 name_len;
   png_byte new_name[80];
   png_byte entrybuf[10];
-   png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
+   size_t entry_size = (spalette->depth == 8 ? 6 : 10);
-   png_size_t palette_size = entry_size * spalette->nentries;
+   size_t palette_size = entry_size * (size_t)spalette->nentries;
   png_sPLT_entryp ep;
 #ifndef PNG_POINTER_INDEXING_SUPPORTED
   int i;
@ -1193,10 +1199,9 @@ png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
   png_write_chunk_header(png_ptr, png_sPLT,
       (png_uint_32)(name_len + 2 + palette_size));
-   png_write_chunk_data(png_ptr, (png_bytep)new_name,
+   png_write_chunk_data(png_ptr, (png_bytep)new_name, (size_t)(name_len + 1));
       (png_size_t)(name_len + 1));
-   png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
+   png_write_chunk_data(png_ptr, &spalette->depth, 1);
   /* Loop through each palette entry, writing appropriately */
 #ifdef PNG_POINTER_INDEXING_SUPPORTED
@ -1258,7 +1263,7 @@ void /* PRIVATE */
 png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
 {
   png_byte buf[4];
-   png_size_t size;
+   size_t size;
   png_debug(1, "in png_write_sBIT");
@ -1358,7 +1363,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
      /* Write the chunk out as it is */
      png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha,
-         (png_size_t)num_trans);
+          (size_t)num_trans);
   }
   else if (color_type == PNG_COLOR_TYPE_GRAY)
@ -1373,7 +1378,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
      }
      png_save_uint_16(buf, tran->gray);
-      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2);
+      png_write_complete_chunk(png_ptr, png_tRNS, buf, 2);
   }
   else if (color_type == PNG_COLOR_TYPE_RGB)
@ -1393,7 +1398,7 @@ png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
         return;
      }
-      png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6);
+      png_write_complete_chunk(png_ptr, png_tRNS, buf, 6);
   }
   else
@ -1426,7 +1431,7 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
      }
      buf[0] = back->index;
-      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
+      png_write_complete_chunk(png_ptr, png_bKGD, buf, 1);
   }
   else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
@ -1441,12 +1446,13 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
 #endif
      {
         png_warning(png_ptr,
-             "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8");
+             "Ignoring attempt to write 16-bit bKGD chunk "
             "when bit_depth is 8");
         return;
      }
-      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6);
+      png_write_complete_chunk(png_ptr, png_bKGD, buf, 6);
   }
   else
@ -1460,11 +1466,33 @@ png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
      }
      png_save_uint_16(buf, back->gray);
-      png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2);
+      png_write_complete_chunk(png_ptr, png_bKGD, buf, 2);
   }
 }
 #endif
 #ifdef PNG_WRITE_eXIf_SUPPORTED
 /* Write the Exif data */
 void /* PRIVATE */
 png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif)
 {
   int i;
   png_byte buf[1];
   png_debug(1, "in png_write_eXIf");
   png_write_chunk_header(png_ptr, png_eXIf, (png_uint_32)(num_exif));
   for (i = 0; i < num_exif; i++)
   {
      buf[0] = exif[i];
      png_write_chunk_data(png_ptr, buf, 1);
   }
   png_write_chunk_end(png_ptr);
 }
 #endif
 #ifdef PNG_WRITE_hIST_SUPPORTED
 /* Write the histogram */
 void /* PRIVATE */
@ -1489,7 +1517,7 @@ png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
   for (i = 0; i < num_hist; i++)
   {
      png_save_uint_16(buf, hist[i]);
-      png_write_chunk_data(png_ptr, buf, (png_size_t)2);
+      png_write_chunk_data(png_ptr, buf, 2);
   }
   png_write_chunk_end(png_ptr);
@ -1500,7 +1528,7 @@ png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
 /* Write a tEXt chunk */
 void /* PRIVATE */
 png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
-    png_size_t text_len)
+    size_t text_len)
 {
   png_uint_32 key_len;
   png_byte new_key[80];
@ -1597,7 +1625,7 @@ png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key,
    png_const_charp lang, png_const_charp lang_key, png_const_charp text)
 {
   png_uint_32 key_len, prefix_len;
-   png_size_t lang_len, lang_key_len;
+   size_t lang_len, lang_key_len;
   png_byte new_key[82];
   compression_state comp;
@ -1707,7 +1735,7 @@ png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
   png_save_int_32(buf + 4, y_offset);
   buf[8] = (png_byte)unit_type;
-   png_write_complete_chunk(png_ptr, png_oFFs, buf, (png_size_t)9);
+   png_write_complete_chunk(png_ptr, png_oFFs, buf, 9);
 }
 #endif
 #ifdef PNG_WRITE_pCAL_SUPPORTED
@ -1718,7 +1746,7 @@ png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
    png_charpp params)
 {
   png_uint_32 purpose_len;
-   png_size_t units_len, total_len;
+   size_t units_len, total_len;
   png_size_tp params_len;
   png_byte buf[10];
   png_byte new_purpose[80];
@ -1742,7 +1770,7 @@ png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
   total_len = purpose_len + units_len + 10;
   params_len = (png_size_tp)png_malloc(png_ptr,
-       (png_alloc_size_t)(nparams * (sizeof (png_size_t))));
+       (png_alloc_size_t)((png_alloc_size_t)nparams * (sizeof (size_t))));
   /* Find the length of each parameter, making sure we don't count the
    * null terminator for the last parameter.
@ -1762,8 +1790,8 @@ png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
   png_save_int_32(buf + 4, X1);
   buf[8] = (png_byte)type;
   buf[9] = (png_byte)nparams;
-   png_write_chunk_data(png_ptr, buf, (png_size_t)10);
+   png_write_chunk_data(png_ptr, buf, 10);
-   png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
+   png_write_chunk_data(png_ptr, (png_const_bytep)units, (size_t)units_len);
   for (i = 0; i < nparams; i++)
   {
@ -1782,7 +1810,7 @@ png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
    png_const_charp height)
 {
   png_byte buf[64];
-   png_size_t wlen, hlen, total_len;
+   size_t wlen, hlen, total_len;
   png_debug(1, "in png_write_sCAL_s");
@ -1823,7 +1851,7 @@ png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
   png_save_uint_32(buf + 4, y_pixels_per_unit);
   buf[8] = (png_byte)unit_type;
-   png_write_complete_chunk(png_ptr, png_pHYs, buf, (png_size_t)9);
+   png_write_complete_chunk(png_ptr, png_pHYs, buf, 9);
 }
 #endif
@ -1853,7 +1881,7 @@ png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
   buf[5] = mod_time->minute;
   buf[6] = mod_time->second;
-   png_write_complete_chunk(png_ptr, png_tIME, buf, (png_size_t)7);
+   png_write_complete_chunk(png_ptr, png_tIME, buf, 7);
 }
 #endif
@ -1865,16 +1893,16 @@ png_write_start_row(png_structrp png_ptr)
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
   /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
   /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
   /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
   png_alloc_size_t buf_size;
@ -1980,16 +2008,16 @@ png_write_finish_row(png_structrp png_ptr)
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
   /* Offset to next interlace block */
-   static PNG_CONST png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
   /* Start of interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
+   static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
   /* Offset to next interlace block in the y direction */
-   static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
+   static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
   png_debug(1, "in png_write_finish_row");
@ -2043,8 +2071,8 @@ png_write_finish_row(png_structrp png_ptr)
      {
         if (png_ptr->prev_row != NULL)
            memset(png_ptr->prev_row, 0,
-                (png_size_t)(PNG_ROWBYTES(png_ptr->usr_channels*
+                PNG_ROWBYTES(png_ptr->usr_channels *
-                png_ptr->usr_bit_depth, png_ptr->width)) + 1);
+                png_ptr->usr_bit_depth, png_ptr->width) + 1);
         return;
      }
@ -2070,10 +2098,10 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
   /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
   /* Start of interlace block */
-   static PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
+   static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
   /* Offset to next interlace block */
-   static PNG_CONST png_byte  png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
   png_debug(1, "in png_do_write_interlace");
@ -2100,7 +2128,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
            for (i = png_pass_start[pass]; i < row_width;
               i += png_pass_inc[pass])
            {
-               sp = row + (png_size_t)(i >> 3);
+               sp = row + (size_t)(i >> 3);
               value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01;
               d |= (value << shift);
@ -2138,7 +2166,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
            for (i = png_pass_start[pass]; i < row_width;
               i += png_pass_inc[pass])
            {
-               sp = row + (png_size_t)(i >> 2);
+               sp = row + (size_t)(i >> 2);
               value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03;
               d |= (value << shift);
@ -2174,7 +2202,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
            for (i = png_pass_start[pass]; i < row_width;
                i += png_pass_inc[pass])
            {
-               sp = row + (png_size_t)(i >> 1);
+               sp = row + (size_t)(i >> 1);
               value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f;
               d |= (value << shift);
@ -2200,7 +2228,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
            png_bytep dp;
            png_uint_32 i;
            png_uint_32 row_width = row_info->width;
-            png_size_t pixel_bytes;
+            size_t pixel_bytes;
            /* Start at the beginning */
            dp = row;
@ -2213,7 +2241,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
               i += png_pass_inc[pass])
            {
               /* Find out where the original pixel is */
-               sp = row + (png_size_t)i * pixel_bytes;
+               sp = row + (size_t)i * pixel_bytes;
               /* Move the pixel */
               if (dp != sp)
@ -2244,17 +2272,17 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 */
 static void /* PRIVATE */
 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
-   png_size_t row_bytes);
+    size_t row_bytes);
 #ifdef PNG_WRITE_FILTER_SUPPORTED
-static png_size_t /* PRIVATE */
+static size_t /* PRIVATE */
-png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp,
+png_setup_sub_row(png_structrp png_ptr, png_uint_32 bpp,
-    const png_size_t row_bytes, const png_size_t lmins)
+    size_t row_bytes, size_t lmins)
 {
   png_bytep rp, dp, lp;
-   png_size_t i;
+   size_t i;
-   png_size_t sum = 0;
+   size_t sum = 0;
-   int v;
+   unsigned int v;
   png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
@ -2262,14 +2290,22 @@ png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp,
        i++, rp++, dp++)
   {
      v = *dp = *rp;
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
   }
   for (lp = png_ptr->row_buf + 1; i < row_bytes;
      i++, rp++, lp++, dp++)
   {
      v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@ -2278,14 +2314,35 @@ png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp,
   return (sum);
 }
-static png_size_t /* PRIVATE */
+static void /* PRIVATE */
-png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
+png_setup_sub_row_only(png_structrp png_ptr, png_uint_32 bpp,
-    const png_size_t lmins)
+    size_t row_bytes)
 {
   png_bytep rp, dp, lp;
   size_t i;
   png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
        i++, rp++, dp++)
   {
      *dp = *rp;
   }
   for (lp = png_ptr->row_buf + 1; i < row_bytes;
      i++, rp++, lp++, dp++)
   {
      *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
   }
 }
 static size_t /* PRIVATE */
 png_setup_up_row(png_structrp png_ptr, size_t row_bytes, size_t lmins)
 {
   png_bytep rp, dp, pp;
-   png_size_t i;
+   size_t i;
-   png_size_t sum = 0;
+   size_t sum = 0;
-   int v;
+   unsigned int v;
   png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
@ -2294,7 +2351,11 @@ png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
       i++, rp++, pp++, dp++)
   {
      v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@ -2302,15 +2363,30 @@ png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes,
   return (sum);
 }
 static void /* PRIVATE */
 png_setup_up_row_only(png_structrp png_ptr, size_t row_bytes)
 {
   png_bytep rp, dp, pp;
   size_t i;
-static png_size_t /* PRIVATE */
+   png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
-png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
+
-      const png_size_t row_bytes, const png_size_t lmins)
+   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
       pp = png_ptr->prev_row + 1; i < row_bytes;
       i++, rp++, pp++, dp++)
   {
      *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
   }
 }
 static size_t /* PRIVATE */
 png_setup_avg_row(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes, size_t lmins)
 {
   png_bytep rp, dp, pp, lp;
   png_uint_32 i;
-   png_size_t sum = 0;
+   size_t sum = 0;
-   int v;
+   unsigned int v;
   png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
@ -2319,7 +2395,11 @@ png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
   {
      v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
   }
   for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
@ -2327,7 +2407,11 @@ png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
      v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
          & 0xff);
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@ -2335,15 +2419,36 @@ png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp,
   return (sum);
 }
 static void /* PRIVATE */
 png_setup_avg_row_only(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes)
 {
   png_bytep rp, dp, pp, lp;
   png_uint_32 i;
-static png_size_t /* PRIVATE */
+   png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
-png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
+
-    const png_size_t row_bytes, const png_size_t lmins)
+   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
       pp = png_ptr->prev_row + 1; i < bpp; i++)
   {
      *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
   }
   for (lp = png_ptr->row_buf + 1; i < row_bytes; i++)
   {
      *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
          & 0xff);
   }
 }
 static size_t /* PRIVATE */
 png_setup_paeth_row(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes, size_t lmins)
 {
   png_bytep rp, dp, pp, cp, lp;
-   png_size_t i;
+   size_t i;
-   png_size_t sum = 0;
+   size_t sum = 0;
-   int v;
+   unsigned int v;
   png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
@ -2352,7 +2457,11 @@ png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
   {
      v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
   }
   for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
@ -2381,7 +2490,11 @@ png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
      v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
 #ifdef PNG_USE_ABS
      sum += 128 - abs((int)v - 128);
 #else
      sum += (v < 128) ? v : 256 - v;
 #endif
      if (sum > lmins)  /* We are already worse, don't continue. */
        break;
@ -2389,6 +2502,48 @@ png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp,
   return (sum);
 }
 static void /* PRIVATE */
 png_setup_paeth_row_only(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes)
 {
   png_bytep rp, dp, pp, cp, lp;
   size_t i;
   png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
   for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1,
       pp = png_ptr->prev_row + 1; i < bpp; i++)
   {
      *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
   }
   for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes;
        i++)
   {
      int a, b, c, pa, pb, pc, p;
      b = *pp++;
      c = *cp++;
      a = *lp++;
      p = b - c;
      pc = a - c;
 #ifdef PNG_USE_ABS
      pa = abs(p);
      pb = abs(pc);
      pc = abs(p + pc);
 #else
      pa = p < 0 ? -p : p;
      pb = pc < 0 ? -pc : pc;
      pc = (p + pc) < 0 ? -(p + pc) : p + pc;
 #endif
      p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
      *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
   }
 }
 #endif /* WRITE_FILTER */
 void /* PRIVATE */
@ -2397,12 +2552,12 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 #ifndef PNG_WRITE_FILTER_SUPPORTED
   png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
 #else
-   png_byte filter_to_do = png_ptr->do_filter;
+   unsigned int filter_to_do = png_ptr->do_filter;
   png_bytep row_buf;
   png_bytep best_row;
   png_uint_32 bpp;
-   png_size_t mins;
+   size_t mins;
-   png_size_t row_bytes = row_info->rowbytes;
+   size_t row_bytes = row_info->rowbytes;
   png_debug(1, "in png_write_find_filter");
@ -2443,32 +2598,33 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
    */
   best_row = png_ptr->row_buf;
   if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE)
   {
      png_bytep rp;
      png_size_t sum = 0;
      png_size_t i;
      int v;
   if (PNG_SIZE_MAX/128 <= row_bytes)
   {
-         for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
+      /* Overflow can occur in the calculation, just select the lowest set
       * filter.
       */
      filter_to_do &= 0U-filter_to_do;
   }
   else if ((filter_to_do & PNG_FILTER_NONE) != 0 &&
         filter_to_do != PNG_FILTER_NONE)
   {
-            /* Check for overflow */
+      /* Overflow not possible and multiple filters in the list, including the
-            if (sum > PNG_SIZE_MAX/128 - 256)
+       * 'none' filter.
-               break;
+       */
      png_bytep rp;
      size_t sum = 0;
      size_t i;
      unsigned int v;
            v = *rp;
            sum += (v < 128) ? v : 256 - v;
         }
      }
      else /* Overflow is not possible */
      {
         for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
         {
            v = *rp;
 #ifdef PNG_USE_ABS
            sum += 128 - abs((int)v - 128);
 #else
            sum += (v < 128) ? v : 256 - v;
 #endif
         }
      }
@ -2479,14 +2635,14 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   if (filter_to_do == PNG_FILTER_SUB)
   /* It's the only filter so no testing is needed */
   {
-      (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins);
+      png_setup_sub_row_only(png_ptr, bpp, row_bytes);
      best_row = png_ptr->try_row;
   }
   else if ((filter_to_do & PNG_FILTER_SUB) != 0)
   {
-      png_size_t sum;
+      size_t sum;
-      png_size_t lmins = mins;
+      size_t lmins = mins;
      sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins);
@ -2505,14 +2661,14 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   /* Up filter */
   if (filter_to_do == PNG_FILTER_UP)
   {
-      (void) png_setup_up_row(png_ptr, row_bytes, mins);
+      png_setup_up_row_only(png_ptr, row_bytes);
      best_row = png_ptr->try_row;
   }
   else if ((filter_to_do & PNG_FILTER_UP) != 0)
   {
-      png_size_t sum;
+      size_t sum;
-      png_size_t lmins = mins;
+      size_t lmins = mins;
      sum = png_setup_up_row(png_ptr, row_bytes, lmins);
@ -2531,14 +2687,14 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   /* Avg filter */
   if (filter_to_do == PNG_FILTER_AVG)
   {
-      (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins);
+      png_setup_avg_row_only(png_ptr, bpp, row_bytes);
      best_row = png_ptr->try_row;
   }
   else if ((filter_to_do & PNG_FILTER_AVG) != 0)
   {
-      png_size_t sum;
+      size_t sum;
-      png_size_t lmins = mins;
+      size_t lmins = mins;
      sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins);
@ -2555,16 +2711,16 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
   }
   /* Paeth filter */
-   if ((filter_to_do == PNG_FILTER_PAETH) != 0)
+   if (filter_to_do == PNG_FILTER_PAETH)
   {
-      (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins);
+      png_setup_paeth_row_only(png_ptr, bpp, row_bytes);
      best_row = png_ptr->try_row;
   }
   else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
   {
-      png_size_t sum;
+      size_t sum;
-      png_size_t lmins = mins;
+      size_t lmins = mins;
      sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins);
@ -2589,7 +2745,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
 /* Do the actual writing of a previously filtered row. */
 static void
 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
-   png_size_t full_row_length/*includes filter byte*/)
+    size_t full_row_length/*includes filter byte*/)
 {
   png_debug(1, "in png_write_filtered_row");