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Fix compatibility of MapBlock decoding

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also properly drop support for version < 22, which hasn't worked in years
This commit is contained in:
sfan5 2020-05-06 22:31:50 +02:00
parent 92f6b051a5
commit 2979dc5b6b
2 changed files with 27 additions and 16 deletions
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41
BlockDecoder.cpp
View File

@ -11,20 +11,18 @@ static inline uint16_t readU16(const unsigned char *data)
return data[0] << 8 | data[1];
}
static int readBlockContent(const unsigned char *mapData, u8 version, unsigned int datapos)
static int readBlockContent(const unsigned char *mapData, u8 contentWidth, unsigned int datapos)
{
if (version >= 24) {
if (contentWidth == 2) {
size_t index = datapos << 1;
return (mapData[index] << 8) | mapData[index + 1];
} else if (version >= 20) {
if (mapData[datapos] <= 0x80)
return mapData[datapos];
} else {
u8 param = mapData[datapos];
if (param <= 0x7f)
return param;
else
return (int(mapData[datapos]) << 4) | (int(mapData[datapos + 0x2000]) >> 4);
return (int(param) << 4) | (int(mapData[datapos + 0x2000]) >> 4);
}
std::ostringstream oss;
oss << "Unsupported map version " << version;
throw std::runtime_error(oss.str());
}
BlockDecoder::BlockDecoder()
@ -39,6 +37,7 @@ void BlockDecoder::reset()
m_nameMap.clear();
m_version = 0;
m_contentWidth = 0;
m_mapData = ustring();
}
@ -50,16 +49,30 @@ void BlockDecoder::decode(const ustring &datastr)
uint8_t version = data[0];
//uint8_t flags = data[1];
if (version < 22) {
std::ostringstream oss;
oss << "Unsupported map version " << (int)version;
throw std::runtime_error(oss.str());
}
m_version = version;
size_t dataOffset = 0;
if (version >= 27)
dataOffset = 6;
else if (version >= 22)
dataOffset = 4;
else
dataOffset = 2;
uint8_t contentWidth = data[dataOffset];
dataOffset++;
uint8_t paramsWidth = data[dataOffset];
dataOffset++;
if (contentWidth != 1 && contentWidth != 2)
throw std::runtime_error("unsupported map version (contentWidth)");
if (paramsWidth != 2)
throw std::runtime_error("unsupported map version (paramsWidth)");
m_contentWidth = contentWidth;
ZlibDecompressor decompressor(data, length);
decompressor.setSeekPos(dataOffset);
m_mapData = decompressor.decompress();
@ -67,8 +80,6 @@ void BlockDecoder::decode(const ustring &datastr)
dataOffset = decompressor.seekPos();
// Skip unused data
if (version <= 21)
dataOffset += 2;
if (version == 23)
dataOffset += 1;
if (version == 24) {
@ -92,7 +103,7 @@ void BlockDecoder::decode(const ustring &datastr)
dataOffset += 4; // Skip timestamp
// Read mapping
if (version >= 22) {
{
dataOffset++; // mapping version
uint16_t numMappings = readU16(data + dataOffset);
dataOffset += 2;
@ -130,7 +141,7 @@ bool BlockDecoder::isEmpty() const
std::string BlockDecoder::getNode(u8 x, u8 y, u8 z) const
{
unsigned int position = x + (y << 4) + (z << 8);
int content = readBlockContent(m_mapData.c_str(), m_version, position);
int content = readBlockContent(m_mapData.c_str(), m_contentWidth, position);
if (content == m_blockAirId || content == m_blockIgnoreId)
return "";
NameMap::const_iterator it = m_nameMap.find(content);

2
include/BlockDecoder.h
View File

@ -20,7 +20,7 @@ private:
int m_blockAirId;
int m_blockIgnoreId;
u8 m_version;
u8 m_version, m_contentWidth;
ustring m_mapData;
};