/// <summary>
/// Reads data from a file at the specified offset, of specified size into a stream and returns the stream. If no stream is specified, a new memory stream is created.
/// </summary>
/// <param name="filePath"></param>
/// <param name="offset"></param>
/// <param name="size"></param>
/// <returns></returns>
public static Stream ReadExternalData(string filePath, long offset, int size, Stream outStream = null)
{
if (!File.Exists(filePath))
{
return(null);
}
using Stream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
if (offset + size > fs.Length)
{
return(null); //invalid pointer, outside bounds
}
outStream ??= new MemoryStream();
fs.Seek(offset, SeekOrigin.Begin);
var startPos = outStream.Position;
fs.CopyToEx(outStream, size);
outStream.Position = startPos;
return(outStream);
}
public MemoryStream DecompressEntry(int index)
{
MemoryStream result = MixinHandler.MixinMemoryStreamManager.GetStream();
FileEntryStruct e = Files[index];
uint count = 0;
byte[] inputBlock;
byte[] outputBlock = new byte[Header.MaxBlockSize];
long left = e.RealUncompressedSize;
FileStream fs = new FileStream(FileName, FileMode.Open, FileAccess.Read);
fs.Seek(e.BlockOffsets[0], SeekOrigin.Begin);
//byte[] buff;
if (e.BlockSizeIndex == 0xFFFFFFFF)
{
fs.CopyToEx(result, (int)e.RealUncompressedSize);
//buff = new byte[e.RealUncompressedSize];
//fs.Read(buff, 0, buff.Length);
//result.Write(buff, 0, buff.Length);
}
else
{
while (left > 0)
{
uint compressedBlockSize = e.BlockSizes[count];
if (compressedBlockSize == 0)
{
compressedBlockSize = Header.MaxBlockSize;
}
if (compressedBlockSize == Header.MaxBlockSize || compressedBlockSize == left)
{
fs.CopyToEx(result, (int)compressedBlockSize);
//buff = new byte[compressedBlockSize];
//fs.Read(buff, 0, buff.Length);
//result.Write(buff, 0, buff.Length);
left -= compressedBlockSize;
}
else
{
var uncompressedBlockSize = (uint)Math.Min(left, Header.MaxBlockSize);
if (compressedBlockSize < 5)
{
throw new Exception("SFAR compressed block size smaller than 5 bytes");
}
inputBlock = new byte[compressedBlockSize];
fs.Read(inputBlock, 0, (int)compressedBlockSize);
uint actualUncompressedBlockSize = uncompressedBlockSize;
uint actualCompressedBlockSize = compressedBlockSize;
outputBlock = SevenZipHelper.LZMA.Decompress(inputBlock, actualUncompressedBlockSize);
if (outputBlock.Length != actualUncompressedBlockSize)
{
throw new Exception("SFAR decompression error");
}
result.Write(outputBlock, 0, (int)actualUncompressedBlockSize);
left -= uncompressedBlockSize;
}
count++;
}
}
fs.Close();
result.Position = 0;
return(result);
}
