Check for errors when reading and decompressing datafile data

Check if datafile data cannot be read entirely (according to the data size specified in the header) and check for decompression errors. In case of errors, let `GetData` return `nullptr` and `GetDataSize` return `0` for the respective index.

Internally the decompressed size is set to `-1` for data which failed to load, so loading of those data will not be attempted again because it would only fail again and can cause additional log messages.

src/engine/shared/datafile.cpp

@@ -309,7 +309,10 @@ int CDataFileReader::GetDataSize(int Index) const
  return GetFileDataSize(Index);
  }
  }
- return m_pDataFile->m_pDataSizes[Index];
+ const int Size = m_pDataFile->m_pDataSizes[Index];
+ if(Size < 0)
+ return 0; // summarize all errors as zero size
+ return Size;
 }
 
 void *CDataFileReader::GetDataImpl(int Index, bool Swap)
@@ -323,45 +326,71 @@ void *CDataFileReader::GetDataImpl(int Index, bool Swap)
  // load it if needed
  if(!m_pDataFile->m_ppDataPtrs[Index])
  {
+ // don't try to load again if it previously failed
+ if(m_pDataFile->m_pDataSizes[Index] < 0)
+ return nullptr;
+
  // fetch the data size
- int DataSize = GetFileDataSize(Index);
+ unsigned DataSize = GetFileDataSize(Index);
 #if defined(CONF_ARCH_ENDIAN_BIG)
- int SwapSize = DataSize;
+ unsigned SwapSize = DataSize;
 #endif
 
  if(m_pDataFile->m_Header.m_Version == 4)
  {
  // v4 has compressed data
- void *pTemp = malloc(DataSize);
- unsigned long UncompressedSize = m_pDataFile->m_Info.m_pDataSizes[Index];
- unsigned long s;
+ const unsigned OriginalUncompressedSize = m_pDataFile->m_Info.m_pDataSizes[Index];
+ unsigned long UncompressedSize = OriginalUncompressedSize;
 
- log_trace("datafile", "loading data index=%d size=%d uncompressed=%lu", Index, DataSize, UncompressedSize);
- m_pDataFile->m_ppDataPtrs[Index] = (char *)malloc(UncompressedSize);
- m_pDataFile->m_pDataSizes[Index] = UncompressedSize;
+ log_trace("datafile", "loading data. index=%d size=%u uncompressed=%u", Index, DataSize, OriginalUncompressedSize);
 
  // read the compressed data
+ void *pCompressedData = malloc(DataSize);
  m_pMemoryReader->SetPosition(m_pDataFile->m_DataStartOffset + m_pDataFile->m_Info.m_pDataOffsets[Index]);
- m_pMemoryReader->Read(pTemp, DataSize);
+ const unsigned ActualDataSize = m_pMemoryReader->Read(pCompressedData, DataSize);
+ if(DataSize != ActualDataSize)
+ {
+ dbg_msg("datafile", "truncation error, could not read all data. index=%d wanted=%u got=%u", Index, DataSize, ActualDataSize);
+ free(pCompressedData);
+ m_pDataFile->m_ppDataPtrs[Index] = nullptr;
+ m_pDataFile->m_pDataSizes[Index] = -1;
+ return nullptr;
+ }
+
+ // decompress the data
+ m_pDataFile->m_ppDataPtrs[Index] = (char *)malloc(UncompressedSize);
+ m_pDataFile->m_pDataSizes[Index] = UncompressedSize;
+ const int Result = uncompress((Bytef *)m_pDataFile->m_ppDataPtrs[Index], &UncompressedSize, (Bytef *)pCompressedData, DataSize);
+ free(pCompressedData);
+ if(Result != Z_OK || UncompressedSize != OriginalUncompressedSize)
+ {
+ dbg_msg("datafile", "uncompress error %d, size %lu", Result, UncompressedSize);
+ free(m_pDataFile->m_ppDataPtrs[Index]);
+ m_pDataFile->m_ppDataPtrs[Index] = nullptr;
+ m_pDataFile->m_pDataSizes[Index] = -1;
+ return nullptr;
+ }
 
- // decompress the data, TODO: check for errors
- s = UncompressedSize;
- uncompress((Bytef *)m_pDataFile->m_ppDataPtrs[Index], &s, (Bytef *)pTemp, DataSize);
 #if defined(CONF_ARCH_ENDIAN_BIG)
- SwapSize = s;
+ SwapSize = UncompressedSize;
 #endif
-
- // clean up the temporary buffers
- free(pTemp);
  }
  else
  {
  // load the data
- log_trace("datafile", "loading data index=%d size=%d", Index, DataSize);
- m_pDataFile->m_ppDataPtrs[Index] = (char *)malloc(DataSize);
+ log_trace("datafile", "loading data. index=%d size=%d", Index, DataSize);
+ m_pDataFile->m_ppDataPtrs[Index] = static_cast<char *>(malloc(DataSize));
  m_pDataFile->m_pDataSizes[Index] = DataSize;
  m_pMemoryReader->SetPosition(m_pDataFile->m_DataStartOffset + m_pDataFile->m_Info.m_pDataOffsets[Index]);
- m_pMemoryReader->Read(m_pDataFile->m_ppDataPtrs[Index], DataSize);
+ const unsigned ActualDataSize = m_pMemoryReader->Read(m_pDataFile->m_ppDataPtrs[Index], DataSize);
+ if(DataSize != ActualDataSize)
+ {
+ dbg_msg("datafile", "truncation error, could not read all data. index=%d wanted=%u got=%u", Index, DataSize, ActualDataSize);
+ free(m_pDataFile->m_ppDataPtrs[Index]);
+ m_pDataFile->m_ppDataPtrs[Index] = nullptr;
+ m_pDataFile->m_pDataSizes[Index] = -1;
+ return nullptr;
+ }
  }
 
 #if defined(CONF_ARCH_ENDIAN_BIG)
@@ -385,10 +414,7 @@ void *CDataFileReader::GetDataSwapped(int Index)
 
 void CDataFileReader::ReplaceData(int Index, char *pData, size_t Size)
 {
- // make sure the data has been loaded
- GetDataImpl(Index, 0);
-
- UnloadData(Index);
+ free(m_pDataFile->m_ppDataPtrs[Index]);
  m_pDataFile->m_ppDataPtrs[Index] = pData;
  m_pDataFile->m_pDataSizes[Index] = Size;
 }