public static bool Patch(Stream input, Stream delta, Stream output)
{
if (input == null)
{
throw new ArgumentNullException("input");
}
if (delta == null)
{
throw new ArgumentNullException("delta");
}
if (output == null)
{
throw new ArgumentNullException("output");
}
const Endian endian = Endian.Big;
var work = new byte[0x10000];
var inputBytes = new byte[0x10000];
var deltaBytes = new byte[0x10000];
while (delta.Position < delta.Length)
{
var rawFlags = delta.ReadValueU32(endian);
var count = (int)(rawFlags & 0xFFFFFFF);
var type = (PatchType)(rawFlags >> 28);
switch (type)
{
case PatchType.Copy:
{
for (int i = 0; i < count; i++)
{
var inputRead = CompressionHelper.DecompressBlock(input, inputBytes, work);
output.Write(inputBytes, 0, inputRead);
}
break;
}
case PatchType.CompressedChange:
{
var inputRead = CompressionHelper.DecompressBlock(input, inputBytes, work);
int o = 0;
for (int i = 0; i < count; i++)
{
var inputOffset = delta.ReadValueU16(endian);
var inputSkipLength = delta.ReadValueU16(endian);
var inputCopyLength = inputOffset - o;
if (o + inputCopyLength > inputRead)
{
throw new EndOfStreamException();
}
output.Write(inputBytes, o, inputCopyLength);
var deltaRead = CompressionHelper.DecompressBlock(delta, deltaBytes, work);
output.Write(deltaBytes, 0, deltaRead);
o = inputOffset + inputSkipLength;
}
output.Write(inputBytes, o, inputRead - o);
break;
}
case PatchType.UncompressedChange:
{
var inputRead = CompressionHelper.DecompressBlock(input, inputBytes, work);
var totalSize = 1 + delta.ReadValueU16(endian);
var basePosition = output.Position;
using (var temp = delta.ReadToMemoryStream(count))
{
temp.Position = 0;
int o = 0;
while (temp.Position < temp.Length)
{
var inputOffset = temp.ReadValueU16(endian);
var inputSkipLength = temp.ReadValueU8();
var deltaCopyLength = temp.ReadValueU8();
var inputCopyLength = inputOffset - o;
if (o + inputCopyLength > inputRead)
{
throw new EndOfStreamException();
}
output.Write(inputBytes, o, inputCopyLength);
if (deltaCopyLength > 0)
{
var deltaRead = temp.Read(deltaBytes, 0, deltaCopyLength);
if (deltaRead != deltaCopyLength)
{
throw new EndOfStreamException();
}
output.Write(deltaBytes, 0, deltaCopyLength);
}
o = inputOffset + inputSkipLength;
}
output.Write(inputBytes, o, inputRead - o);
}
if ((output.Position - basePosition) != totalSize)
{
throw new InvalidOperationException();
}
break;
}
case PatchType.Add:
{
for (int i = 0; i < count; i++)
{
var deltaRead = CompressionHelper.DecompressBlock(delta, deltaBytes, work);
output.Write(deltaBytes, 0, deltaRead);
}
break;
}
case PatchType.Remove:
{
for (int i = 0; i < count; i++)
{
CompressionHelper.SkipBlock(input);
}
break;
}
default:
{
throw new NotImplementedException();
}
}
}
if (delta.Position != delta.Length)
{
throw new InvalidOperationException();
}
return(true);
}