1 files changed, 83 insertions, 0 deletions

diff --git a/src/samples/Dtf/DDiff/TextFileDiffEngine.cs b/src/samples/Dtf/DDiff/TextFileDiffEngine.cs
new file mode 100644
index 00000000..22567023
--- /dev/null
+++ b/src/samples/Dtf/DDiff/TextFileDiffEngine.cs
@@ -0,0 +1,83 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+using System;
+using System.IO;
+using System.Diagnostics;
+
+namespace WixToolset.Dtf.Samples.DDiff
+{
+        public class TextFileDiffEngine : IDiffEngine
+        {
+                public TextFileDiffEngine()
+                {
+                }
+
+                private bool IsTextFile(string file)
+                {
+                        // Guess whether this is a text file by reading the first few bytes and checking for non-ascii chars.
+
+                        bool isText = true;
+                        FileStream stream = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.Read);
+                        byte[] buf = new byte[256];
+                        int count = stream.Read(buf, 0, buf.Length);
+                        for(int i = 0; i < count; i++)
+                        {
+                                if((buf[i] & 0x80) != 0)
+                                {
+                                        isText = false;
+                                        break;
+                                }
+                        }
+                        stream.Close();
+                        return isText;
+                }
+
+                public float GetDiffQuality(string diffInput1, string diffInput2, string[] options, IDiffEngineFactory diffFactory)
+                {
+                        if(diffInput1 != null && File.Exists(diffInput1) &&
+                                diffInput2 != null && File.Exists(diffInput2) &&
+                                (IsTextFile(diffInput1) && IsTextFile(diffInput2)))
+                        {
+                                return .70f;
+                        }
+                        else
+                        {
+                                return 0;
+                        }
+                }
+
+                public bool GetDiff(string diffInput1, string diffInput2, string[] options, TextWriter diffOutput, string linePrefix, IDiffEngineFactory diffFactory)
+                {
+                        try
+                        {
+                                bool difference = false;
+                                ProcessStartInfo psi = new ProcessStartInfo("diff.exe");
+                                psi.Arguments = String.Format("\"{0}\" \"{1}\"", diffInput1, diffInput2);
+                                psi.WorkingDirectory = null;
+                                psi.UseShellExecute = false;
+                                psi.WindowStyle = ProcessWindowStyle.Hidden;
+                                psi.RedirectStandardOutput = true;
+                                Process proc = Process.Start(psi);
+
+                                string line;
+                                while((line = proc.StandardOutput.ReadLine()) != null)
+                                {
+                                        diffOutput.WriteLine("{0}{1}", linePrefix, line);
+                                        difference = true;
+                                }
+
+                                proc.WaitForExit();
+                                return difference;
+                        }
+                        catch(System.ComponentModel.Win32Exception)  // If diff.exe is not found, just compare the bytes
+                        {
+                                return new FileDiffEngine().GetDiff(diffInput1, diffInput2, options, diffOutput, linePrefix, diffFactory);
+                        }
+                }
+
+                public IDiffEngine Clone()
+                {
+                        return new TextFileDiffEngine();
+                }
+        }
+}