/// <summary>
/// Creates the patch based on the difference between two streams.
/// </summary>
/// <param name="baseStream">The untouched stream.</param>
/// <param name="modStream">The modified stream.</param>
public override sealed void Create(Stream baseStream, Stream modStream)
{
using (HashStream <TPatchAlgorithm> patchHashStream = new HashStream <TPatchAlgorithm>(BaseStream, HashAlgorithm))
using (HashStream <TBaseAlgorithm> baseHashStream = new HashStream <TBaseAlgorithm>(baseStream))
using (HashStream <TModAlgorithm> modHashStream = new HashStream <TModAlgorithm>(modStream))
{
BaseStream = patchHashStream;
patchHashStream.Initialize();
Create(patchHashStream, baseHashStream, modHashStream);
if (!baseHashStream.HasFlushedFinalBlock)
{
baseHashStream.Position = baseHashStream.Length;
baseHashStream.FlushFinalBlock();
}
if (!modHashStream.HasFlushedFinalBlock)
{
modHashStream.Position = modHashStream.Length;
modHashStream.FlushFinalBlock();
}
WriteVerificationFooter(patchHashStream, baseHashStream, modHashStream);
BaseStream = patchHashStream.BaseStream;
}
}
/// <summary>
/// Applies the patch.
/// </summary>
/// <param name="baseStream">The stream to read the data to patch from.</param>
/// <param name="outputStream">The stream to write the patched data to.</param>
public override sealed void Apply(Stream baseStream, Stream outputStream)
{
if (!ValidHash.SequenceEqual(Hash))
{
throw new ChecksumException(Hash, ValidHash);
}
using (HashStream <TPatchAlgorithm> patchHashStream = new HashStream <TPatchAlgorithm>(BaseStream, HashAlgorithm))
using (HashStream <TBaseAlgorithm> baseHashStream = new HashStream <TBaseAlgorithm>(baseStream))
using (HashStream <TModAlgorithm> outputHashStream = new HashStream <TModAlgorithm>(outputStream))
{
Apply(baseHashStream, outputHashStream);
if (!baseHashStream.HasFlushedFinalBlock)
{
baseHashStream.Position = baseHashStream.Length;
baseHashStream.FlushFinalBlock();
}
if (!outputHashStream.HasFlushedFinalBlock)
{
outputHashStream.Position = outputHashStream.Length;
outputHashStream.FlushFinalBlock();
}
Verify(baseHashStream, outputHashStream);
}
}
/// <summary>
/// Analyzes the verification-footer.
/// </summary>
/// <param name="patchStream">The stream of the patch.</param>
protected override void AnalyzeVerificationFooter(HashStream <Crc32> patchStream)
{
base.AnalyzeVerificationFooter(patchStream);
patchStream.FlushFinalBlock();
using (BinaryReader reader = Reader)
{
ValidHash = reader.ReadBytes(4).Reverse().ToArray();
}
}
/// <summary>
/// Writes a header that can be used for verifying the integrity of the streams.
/// </summary>
/// <param name="patchStream">The stream of the patch.</param>
/// <param name="baseStream">The untouched stream.</param>
/// <param name="modStream">The modified stream.</param>
protected override void WriteVerificationFooter(HashStream <Crc32> patchStream, HashStream <Crc32> baseStream, HashStream <Crc32> modStream)
{
base.WriteVerificationFooter(patchStream, baseStream, modStream);
using (BinaryWriter writer = Writer)
{
writer.Write(baseStream.Hash.Reverse().ToArray());
writer.Write(modStream.Hash.Reverse().ToArray());
patchStream.FlushFinalBlock();
writer.Write(patchStream.Hash.Reverse().ToArray());
}
}
/// <summary>
/// Analyzes the entire patch.
/// </summary>
protected override void Analyze()
{
using (HashStream <TPatchAlgorithm> patchHashStream = new HashStream <TPatchAlgorithm>(BaseStream, HashAlgorithm))
{
BaseStream = patchHashStream;
patchHashStream.Initialize();
base.Analyze();
AnalyzeVerificationFooter(patchHashStream);
if (!patchHashStream.HasFlushedFinalBlock)
{
patchHashStream.FlushFinalBlock();
}
BaseStream = patchHashStream.BaseStream;
}
}
