/// <summary>
/// Generates a signature stream for the given file and compares it with an existing signature stream, if one exists.
/// </summary>
/// <param name="fs">The file to examine, the filestream should be at position 0</param>
/// <param name="s">The full name of the file</param>
/// <param name="signaturefile">The signature archive file</param>
/// <returns>The signature stream if the file is new or modified, null if the file has not been modified</returns>
private System.IO.Stream ProccessDiff(System.IO.Stream fs, string s, Library.Interface.ICompression signaturefile)
{
string relpath = GetRelativeName(s);
m_examinedfilesize += fs.Length;
m_examinedfiles++;
System.IO.MemoryStream ms = new MemoryStream();
SharpRSync.ChecksumFileWriter ws = new Duplicati.Library.SharpRSync.ChecksumFileWriter(ms);
//Expand the memorystream to contain all bytes, which avoids re-allocation
ms.Capacity = Math.Max(ws.BytesGeneratedForSignature((long)(fs.Length * FILESIZE_GROW_MARGIN_MULTIPLIER)), ms.Capacity);
ws.AddStream(fs);
ms.Position = 0;
if (!m_oldSignatures.ContainsKey(relpath))
{
m_newfiles.Add(s, null);
return ms;
}
else
{
bool equals;
//File exists in archive, check if signature has changed
using (System.IO.Stream s2 = m_oldSignatures[relpath].OpenRead(relpath))
equals = Utility.Utility.CompareStreams(s2, ms, false);
ms.Position = 0;
if (!equals)
{
//Yes, changed, return the signature stream
m_modifiedFiles.Add(s, null);
return ms;
}
else
{
//No changes, discard the signature stream
ms.Close();
ms.Dispose();
m_oldSignatures.Remove(relpath);
return null;
}
}
}
/// <summary>
/// Generates a signature, and writes it to the stream
/// </summary>
/// <param name="input">The stream to create the signature for</param>
/// <param name="output">The stream to write the signature into</param>
public static void GenerateSignature(Stream input, Stream output)
{
SharpRSync.ChecksumFileWriter cs = new Duplicati.Library.SharpRSync.ChecksumFileWriter(output);
cs.AddStream(input);
}