VersionedFileDiffEngine.cs :  » Installers-Generators » WiX » Microsoft » Deployment » Samples » DDiff » C# / CSharp Open Source

using System;
using System.IO;
using Microsoft.Deployment.WindowsInstaller;

namespace Microsoft.Deployment.Samples.DDiff{
  public class VersionedFileDiffEngine : IDiffEngine
  {
    public VersionedFileDiffEngine()
    {
    }

    private bool IsVersionedFile(string file)
    {
      return Installer.GetFileVersion(file) != "";
    }

    public float GetDiffQuality(string diffInput1, string diffInput2, string[] options, IDiffEngineFactory diffFactory)
    {
      if(diffInput1 != null && File.Exists(diffInput1) &&
         diffInput2 != null && File.Exists(diffInput2) &&
         (IsVersionedFile(diffInput1) || IsVersionedFile(diffInput2)))
      {
        return .20f;
      }
      else
      {
        return 0;
      }
    }

    public bool GetDiff(string diffInput1, string diffInput2, string[] options, TextWriter diffOutput, string linePrefix, IDiffEngineFactory diffFactory)
    {
      bool difference = false;

      string ver1 = Installer.GetFileVersion(diffInput1);
      string ver2 = Installer.GetFileVersion(diffInput2);

      if(ver1 != ver2)
      {
        diffOutput.WriteLine("{0}File version: {1} -> {2}", linePrefix, ver1, ver2);
        difference = true;
      }
      else
      {
        FileStream stream1 = new FileStream(diffInput1, FileMode.Open, FileAccess.Read, FileShare.Read);
        FileStream stream2 = new FileStream(diffInput2, FileMode.Open, FileAccess.Read, FileShare.Read);

        byte[] buf1 = new byte[512];
        byte[] buf2 = new byte[512];

        while(!difference)
        {
          int count1 = stream1.Read(buf1, 0, buf1.Length);
          int count2 = stream2.Read(buf2, 0, buf2.Length);

          for(int i = 0; i < count1; i++)
          {
            if(i == count2 || buf1[i] != buf2[i])
            {
              difference = true;
              break;
            }
          }
          if(count1 < buf1.Length) // EOF
          {
            break;
          }
        }

        stream1.Close();
        stream2.Close();

        if(difference)
        {
          diffOutput.WriteLine("{0}File versions match but bits differ.", linePrefix);
        }
      }

      return difference;
    }

    public IDiffEngine Clone()
    {
      return new VersionedFileDiffEngine();
    }
  }
}