/// <summary>
/// Applies a BSDIFF-format patch to an original and produces the updated version
/// </summary>
/// <param name="input">Readable, seekable stream of the original (older) data</param>
/// <param name="openPatchStream"><see cref="OpenPatchStream"/></param>
/// <param name="output">Writable stream where the updated data will be written</param>
public static void Apply(Stream input, OpenPatchStream openPatchStream, Stream output)
{
Stream controlStream, diffStream, extraStream;
var newSize = CreatePatchStreams(openPatchStream, out controlStream, out diffStream, out extraStream);
// prepare to read three parts of the patch in parallel
ApplyInternal(newSize, input, controlStream, diffStream, extraStream, output);
}
private static long CreatePatchStreams(OpenPatchStream openPatchStream, out Stream ctrl, out Stream diff, out Stream extra)
{
// read header
long controlLength, diffLength, newSize;
using (var patchStream = openPatchStream(0, BsDiff.HeaderSize))
{
// check patch stream capabilities
if (!patchStream.CanRead)
{
throw new ArgumentException("Patch stream must be readable", nameof(openPatchStream));
}
if (!patchStream.CanSeek)
{
throw new ArgumentException("Patch stream must be seekable", nameof(openPatchStream));
}
var header = new byte[BsDiff.HeaderSize];
patchStream.Read(header, 0, BsDiff.HeaderSize);
// check for appropriate magic
var signature = header.ReadLong();
if (signature != BsDiff.Signature)
{
throw new InvalidOperationException("Corrupt patch");
}
// read lengths from header
controlLength = header.ReadLongAt(8);
diffLength = header.ReadLongAt(16);
newSize = header.ReadLongAt(24);
if (controlLength < 0 || diffLength < 0 || newSize < 0)
{
throw new InvalidOperationException("Corrupt patch");
}
}
// prepare to read three parts of the patch in parallel
Stream
compressedControlStream = openPatchStream(BsDiff.HeaderSize, controlLength),
compressedDiffStream = openPatchStream(BsDiff.HeaderSize + controlLength, diffLength),
compressedExtraStream = openPatchStream(BsDiff.HeaderSize + controlLength + diffLength, 0);
// decompress each part (to read it)
ctrl = BsDiff.GetEncodingStream(compressedControlStream, false);
diff = BsDiff.GetEncodingStream(compressedDiffStream, false);
extra = BsDiff.GetEncodingStream(compressedExtraStream, false);
return(newSize);
}
public static void Apply(Stream input, byte[] diff, Stream output)
{
OpenPatchStream openPatchStream = (uOffset, uLength) => {
var offset = (int)uOffset;
var length = (int)uLength;
return(new MemoryStream(diff, offset,
uLength > 0
? length
: diff.Length - offset));
};
Stream controlStream, diffStream, extraStream;
var newSize = CreatePatchStreams(openPatchStream, out controlStream, out diffStream, out extraStream);
// prepare to read three parts of the patch in parallel
ApplyInternal(newSize, input, controlStream, diffStream, extraStream, output);
}
