private int ReadMultiUnitFile(byte[] buffer, BlockTableEntry blockEntry)
{
var sectorCount = blockEntry.FileSize / SectorSize + 1;
//if (blockEntry.FileSize%SectorSize > 0)
//sectorCount++;
var hasCRC = (blockEntry.Flags & BlockFlags.HasChecksums) != 0;
if (hasCRC)
{
sectorCount++;
}
var sectorTable = new int[sectorCount + 1];
for (var i = 0; i < sectorTable.Length; i++)
{
sectorTable[i] = _reader.ReadInt32();
}
var resultPosition = 0;
long left = blockEntry.FileSize;
for (var i = 0; i < sectorCount - (hasCRC ? 1 : 0); i++)
{
var position = sectorTable[i];
var length = sectorTable[i + 1] - position;
SeekToArchiveOffset(position + blockEntry.BlockOffset);
var tempBuffer = ArrayPool <byte> .Shared.Rent(length);
var decompressedBuffer = tempBuffer;
int decompressedLength = length;
var sectorData = _reader.Read(tempBuffer, 0, length);
Debug.Assert(sectorData == length);
if (blockEntry.IsCompressed && left > length)
{
var compressionFlags = (CompressionFlags)tempBuffer[0];
if (compressionFlags == CompressionFlags.Bzip2)
{
decompressedBuffer = Compression.BZip2Decompress(tempBuffer, 1, length - 1);
decompressedLength = decompressedBuffer.Length;
Array.Copy(decompressedBuffer, 0, buffer, resultPosition, decompressedLength);
}
else if (compressionFlags == CompressionFlags.Deflated)
{
decompressedLength = Compression.DeflateTo(tempBuffer, 1, length - 1, buffer.AsSpan(resultPosition));
}
else
{
throw new NotSupportedException(
"Currenlty only Bzip2 and Deflate compression is supported by Nmpq. Compression flags: " + compressionFlags);
}
}
else
{
Array.Copy(decompressedBuffer, 0, buffer, resultPosition, decompressedLength);
}
ArrayPool <byte> .Shared.Return(tempBuffer);
resultPosition += decompressedLength;
left -= decompressedLength;
}
return((int)blockEntry.FileSize);
}
// todos: support more decompression algorithms?
public int?ReadFile(byte[] buffer, string path)
{
if (path == null)
{
throw new ArgumentNullException("path");
}
var blockEntry = FindBlockTableEntry(path);
if (blockEntry == null)
{
return(null);
}
if (!blockEntry.Value.IsFile)
{
throw new NotSupportedException("Non-file blocks are not currently supported by Nmpq.");
}
if (blockEntry.Value.IsEncrypted)
{
throw new NotSupportedException("Encrypted files are not currently supported by Nmpq.");
}
if (blockEntry.Value.IsImploded)
{
throw new NotSupportedException("Imploded files are not currently supported by Nmpq.");
}
SeekToArchiveOffset(blockEntry.Value.BlockOffset);
if (!blockEntry.Value.IsFileSingleUnit)
{
return(ReadMultiUnitFile(buffer, blockEntry.Value));
}
// file is only compressed if the block size is smaller than the file size.
// per docs at (http://wiki.devklog.net/index.php?title=MPQ_format_specification)
var compressed = blockEntry.Value.IsCompressed && blockEntry.Value.BlockSize < blockEntry.Value.FileSize;
if (!compressed)
{
return(_reader.Read(buffer, 0, (int)blockEntry.Value.BlockSize));
}
// first byte of each compressed block is a set of flags indicating which
// compression algorithm(s) to use
var compressionFlags = (CompressionFlags)_reader.ReadByte();
// compression flags don't count toward the data size, but does toward the block size
var dataSize = (int)(blockEntry.Value.BlockSize - 1);
var compressedData = ArrayPool <byte> .Shared.Rent((int)dataSize);
_reader.Read(compressedData, 0, (int)dataSize);
int decompressedLength;
if (compressionFlags == CompressionFlags.Bzip2)
{
decompressedLength = Compression.BZip2Decompress(compressedData, 0, dataSize, buffer);
}
else if (compressionFlags == CompressionFlags.Deflated)
{
decompressedLength = Compression.Deflate(compressedData, 0, dataSize, buffer);
}
else
{
throw new NotSupportedException("Currenlty only Bzip2 and Deflate compression is supported by Nmpq. Compression flags: " + compressionFlags);
}
ArrayPool <byte> .Shared.Return(compressedData);
return(decompressedLength);
}