forked from Mirrorlandia_minetest/minetest
Try to fix safeWriteToFile producing empty files on Windows (#14085)
Use win32 APIs to write the temporary file before copying to the final destination. Because we've observed the final file being empty, we suspect that std::ostream::flush is not flushing. Also add a test for it.
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6eb9269741
@ -758,14 +758,32 @@ bool safeWriteToFile(const std::string &path, const std::string &content)
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std::string tmp_file = path + ".~mt";
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std::string tmp_file = path + ".~mt";
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// Write to a tmp file
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// Write to a tmp file
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std::ofstream os(tmp_file.c_str(), std::ios::binary);
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bool tmp_success = false;
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if (!os.good())
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#ifdef _WIN32
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// We've observed behavior suggesting that the MSVC implementation of std::ofstream::flush doesn't
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// actually flush, so we use win32 APIs.
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HANDLE tmp_handle = CreateFile(
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tmp_file.c_str(), GENERIC_WRITE, 0, nullptr, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, nullptr);
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if (tmp_handle == INVALID_HANDLE_VALUE) {
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return false;
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return false;
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}
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DWORD bytes_written;
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tmp_success = (WriteFile(tmp_handle, content.c_str(), content.size(), &bytes_written, nullptr) &&
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FlushFileBuffers(tmp_handle));
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CloseHandle(tmp_handle);
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#else
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std::ofstream os(tmp_file.c_str(), std::ios::binary);
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if (!os.good()) {
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return false;
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}
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os << content;
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os << content;
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os.flush();
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os.flush();
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os.close();
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os.close();
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if (os.fail()) {
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tmp_success = !os.fail();
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// Remove the temporary file because writing it failed and it's useless.
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#endif
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if (!tmp_success) {
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remove(tmp_file.c_str());
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remove(tmp_file.c_str());
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return false;
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return false;
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}
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}
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@ -777,14 +795,12 @@ bool safeWriteToFile(const std::string &path, const std::string &content)
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// When creating the file, it can cause Windows Search indexer, virus scanners and other apps
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// When creating the file, it can cause Windows Search indexer, virus scanners and other apps
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// to query the file. This can make the move file call below fail.
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// to query the file. This can make the move file call below fail.
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// We retry up to 5 times, with a 1ms sleep between, before we consider the whole operation failed
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// We retry up to 5 times, with a 1ms sleep between, before we consider the whole operation failed
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int number_attempts = 0;
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for (int attempt = 0; attempt < 5; attempt++) {
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while (number_attempts < 5) {
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rename_success = MoveFileEx(tmp_file.c_str(), path.c_str(),
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rename_success = MoveFileEx(tmp_file.c_str(), path.c_str(),
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MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH);
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MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH);
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if (rename_success)
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if (rename_success)
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break;
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break;
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sleep_ms(1);
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sleep_ms(1);
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++number_attempts;
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}
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}
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#else
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#else
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// On POSIX compliant systems rename() is specified to be able to swap the
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// On POSIX compliant systems rename() is specified to be able to swap the
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@ -9,7 +9,7 @@ set (UNITTEST_SRCS
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${CMAKE_CURRENT_SOURCE_DIR}/test_compression.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_compression.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_connection.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_connection.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_craft.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_craft.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_filepath.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_filesys.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_inventory.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_inventory.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_irrptr.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_irrptr.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_lua.cpp
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${CMAKE_CURRENT_SOURCE_DIR}/test_lua.cpp
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@ -26,10 +26,11 @@ with this program; if not, write to the Free Software Foundation, Inc.,
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#include "nodedef.h"
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#include "nodedef.h"
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#include "noise.h"
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#include "noise.h"
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class TestFilePath : public TestBase {
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class TestFileSys : public TestBase
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{
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public:
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public:
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TestFilePath() { TestManager::registerTestModule(this); }
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TestFileSys() { TestManager::registerTestModule(this); }
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const char *getName() { return "TestFilePath"; }
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const char *getName() { return "TestFileSys"; }
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void runTests(IGameDef *gamedef);
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void runTests(IGameDef *gamedef);
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@ -38,17 +39,19 @@ public:
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void testRemoveLastPathComponent();
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void testRemoveLastPathComponent();
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void testRemoveLastPathComponentWithTrailingDelimiter();
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void testRemoveLastPathComponentWithTrailingDelimiter();
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void testRemoveRelativePathComponent();
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void testRemoveRelativePathComponent();
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void testSafeWriteToFile();
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};
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};
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static TestFilePath g_test_instance;
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static TestFileSys g_test_instance;
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void TestFilePath::runTests(IGameDef *gamedef)
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void TestFileSys::runTests(IGameDef *gamedef)
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{
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{
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TEST(testIsDirDelimiter);
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TEST(testIsDirDelimiter);
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TEST(testPathStartsWith);
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TEST(testPathStartsWith);
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TEST(testRemoveLastPathComponent);
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TEST(testRemoveLastPathComponent);
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TEST(testRemoveLastPathComponentWithTrailingDelimiter);
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TEST(testRemoveLastPathComponentWithTrailingDelimiter);
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TEST(testRemoveRelativePathComponent);
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TEST(testRemoveRelativePathComponent);
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TEST(testSafeWriteToFile);
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}
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}
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////////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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@ -74,7 +77,7 @@ std::string p(std::string path)
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}
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}
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void TestFilePath::testIsDirDelimiter()
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void TestFileSys::testIsDirDelimiter()
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{
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{
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UASSERT(fs::IsDirDelimiter('/') == true);
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UASSERT(fs::IsDirDelimiter('/') == true);
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UASSERT(fs::IsDirDelimiter('A') == false);
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UASSERT(fs::IsDirDelimiter('A') == false);
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@ -87,7 +90,7 @@ void TestFilePath::testIsDirDelimiter()
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}
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}
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void TestFilePath::testPathStartsWith()
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void TestFileSys::testPathStartsWith()
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{
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{
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const int numpaths = 12;
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const int numpaths = 12;
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std::string paths[numpaths] = {
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std::string paths[numpaths] = {
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@ -163,7 +166,7 @@ void TestFilePath::testPathStartsWith()
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}
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}
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void TestFilePath::testRemoveLastPathComponent()
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void TestFileSys::testRemoveLastPathComponent()
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{
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{
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std::string path, result, removed;
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std::string path, result, removed;
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@ -200,7 +203,7 @@ void TestFilePath::testRemoveLastPathComponent()
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}
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}
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void TestFilePath::testRemoveLastPathComponentWithTrailingDelimiter()
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void TestFileSys::testRemoveLastPathComponentWithTrailingDelimiter()
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{
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{
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std::string path, result, removed;
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std::string path, result, removed;
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@ -236,7 +239,7 @@ void TestFilePath::testRemoveLastPathComponentWithTrailingDelimiter()
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}
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}
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void TestFilePath::testRemoveRelativePathComponent()
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void TestFileSys::testRemoveRelativePathComponent()
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{
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{
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std::string path, result;
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std::string path, result;
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@ -262,3 +265,15 @@ void TestFilePath::testRemoveRelativePathComponent()
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result = fs::RemoveRelativePathComponents(path);
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result = fs::RemoveRelativePathComponents(path);
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UASSERT(result == p("/a/e"));
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UASSERT(result == p("/a/e"));
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}
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}
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void TestFileSys::testSafeWriteToFile()
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{
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const std::string dest_path = fs::TempPath() + DIR_DELIM + "testSafeWriteToFile.txt";
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const std::string test_data("hello\0world", 11);
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fs::safeWriteToFile(dest_path, test_data);
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UASSERT(fs::PathExists(dest_path));
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std::string contents_actual;
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UASSERT(fs::ReadFile(dest_path, contents_actual));
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UASSERT(contents_actual == test_data);
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}
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