Make Diff.Compare able to cope with binary content

5 files changed, 63 insertions, 4 deletions

diff --git a/LibGit2Sharp.Tests/DiffBlobToBlobFixture.cs b/LibGit2Sharp.Tests/DiffBlobToBlobFixture.cs
index 15f36460..b62a57a2 100644
--- a/LibGit2Sharp.Tests/DiffBlobToBlobFixture.cs
+++ b/LibGit2Sharp.Tests/DiffBlobToBlobFixture.cs
@@ -1,4 +1,5 @@
-using System.Linq;
+using System.IO;
+using System.Linq;
 using System.Text;
 using LibGit2Sharp.Tests.TestHelpers;
 using Xunit;
@@ -32,6 +33,8 @@ namespace LibGit2Sharp.Tests
 
                 ContentChanges changes = repo.Diff.Compare(oldblob, newblob);
 
+                Assert.False(changes.IsBinaryComparison);
+
                 Assert.Equal(3, changes.LinesAdded);
                 Assert.Equal(1, changes.LinesDeleted);
 
@@ -57,5 +60,33 @@ namespace LibGit2Sharp.Tests
                 Assert.Equal(expected.ToString(), changes.Patch);
             }
         }
+
+        Blob CreateBinaryBlob(Repository repo)
+        {
+            var scd = BuildSelfCleaningDirectory();
+            Directory.CreateDirectory(scd.RootedDirectoryPath);
+            string fullpath = Path.Combine(scd.RootedDirectoryPath, "binary.bin");
+            File.WriteAllBytes(fullpath, new byte[] { 17, 16, 0, 4, 65 });
+
+            return repo.ObjectDatabase.CreateBlob(fullpath);
+        }
+
+        [Fact]
+        public void CanCompareATextualBlobAgainstABinaryBlob()
+        {
+            using (var repo = new Repository(StandardTestRepoPath))
+            {
+                Blob binBlob = CreateBinaryBlob(repo);
+
+                Blob blob = repo.Head.Tip.Tree.Blobs.First();
+
+                ContentChanges changes = repo.Diff.Compare(blob, binBlob);
+
+                Assert.True(changes.IsBinaryComparison);
+
+                Assert.Equal(0, changes.LinesAdded);
+                Assert.Equal(0, changes.LinesDeleted);
+            }
+        }
     }
 }
diff --git a/LibGit2Sharp.Tests/DiffTreeToTreeFixture.cs b/LibGit2Sharp.Tests/DiffTreeToTreeFixture.cs
index f877d61d..3a69d358 100644
--- a/LibGit2Sharp.Tests/DiffTreeToTreeFixture.cs
+++ b/LibGit2Sharp.Tests/DiffTreeToTreeFixture.cs
@@ -57,6 +57,7 @@ namespace LibGit2Sharp.Tests
                 Assert.Equal(1, changes.Added.Count());
 
                 TreeEntryChanges treeEntryChanges = changes["1.txt"];
+                Assert.False(treeEntryChanges.IsBinaryComparison);
 
                 Assert.Equal("1.txt", treeEntryChanges.Path);
                 Assert.Equal(ChangeKind.Added, treeEntryChanges.Status);
diff --git a/LibGit2Sharp/ContentChanges.cs b/LibGit2Sharp/ContentChanges.cs
index 23a90c56..c5c6cdac 100644
--- a/LibGit2Sharp/ContentChanges.cs
+++ b/LibGit2Sharp/ContentChanges.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.InteropServices;
 using System.Text;
 using LibGit2Sharp.Core;
 
@@ -20,10 +21,30 @@ namespace LibGit2Sharp
             using (var osw1 = new ObjectSafeWrapper(oldBlob.Id, repo))
             using (var osw2 = new ObjectSafeWrapper(newBlob.Id, repo))
             {
-                Ensure.Success(NativeMethods.git_diff_blobs(osw1.ObjectPtr, osw2.ObjectPtr, options, IntPtr.Zero, null, HunkCallback, LineCallback));
+                Ensure.Success(NativeMethods.git_diff_blobs(osw1.ObjectPtr, osw2.ObjectPtr, options, IntPtr.Zero, FileCallback, HunkCallback, LineCallback));
             }
         }
 
+        private int FileCallback(IntPtr data, GitDiffDelta delta, float progress)
+        {
+            IsBinaryComparison = IsBinaryDelta(delta);
+
+            if (!IsBinaryComparison)
+            {
+                return 0;
+            }
+
+            PatchBuilder.Append("Binary content differ\n");
+
+            return 0;
+        }
+
+        internal static bool IsBinaryDelta(GitDiffDelta delta)
+        {
+            //TODO Fix the interop issue on amd64 and use GitDiffDelta.Binary
+            return delta.OldFile.Flags.Has(GitDiffFileFlags.GIT_DIFF_FILE_BINARY) || delta.NewFile.Flags.Has(GitDiffFileFlags.GIT_DIFF_FILE_BINARY);
+        }
+
         private static string NativeToString(IntPtr content, IntPtr contentlen)
         {
             return ((Utf8Marshaler)(Utf8Marshaler.GetInstance(string.Empty))).NativeToString(content, contentlen.ToInt32());
@@ -69,6 +90,11 @@ namespace LibGit2Sharp
         }
 
         /// <summary>
+        ///   Determines if at least one of the compared <see cref="Blob"/>s holds some binary content.
+        /// </summary>
+        public bool IsBinaryComparison { get; protected set; }
+
+        /// <summary>
         ///   The number of lines added.
         /// </summary>
         public int LinesAdded { get; internal set; }
diff --git a/LibGit2Sharp/TreeChanges.cs b/LibGit2Sharp/TreeChanges.cs
index 0e81ad87..3bf3a7c0 100644
--- a/LibGit2Sharp/TreeChanges.cs
+++ b/LibGit2Sharp/TreeChanges.cs
@@ -89,7 +89,7 @@ namespace LibGit2Sharp
             var newMode = (Mode)delta.NewFile.Mode;
             var oldMode = (Mode)delta.OldFile.Mode;
 
-            var diffFile = new TreeEntryChanges(newFilePath, newMode, delta.Status, oldFilePath, oldMode);
+            var diffFile = new TreeEntryChanges(newFilePath, newMode, delta.Status, oldFilePath, oldMode, ContentChanges.IsBinaryDelta(delta));
 
             fileDispatcher[delta.Status](this, diffFile);
             changes.Add(diffFile.Path, diffFile);
diff --git a/LibGit2Sharp/TreeEntryChanges.cs b/LibGit2Sharp/TreeEntryChanges.cs
index ab78bd45..f19fbafa 100644
--- a/LibGit2Sharp/TreeEntryChanges.cs
+++ b/LibGit2Sharp/TreeEntryChanges.cs
@@ -7,13 +7,14 @@ namespace LibGit2Sharp
     /// </summary>
     public class TreeEntryChanges : ContentChanges
     {
-        internal TreeEntryChanges(string path, Mode mode, ChangeKind status, string oldPath, Mode oldMode)
+        internal TreeEntryChanges(string path, Mode mode, ChangeKind status, string oldPath, Mode oldMode, bool isBinaryComparison)
         {
             Path = path;
             Mode = mode;
             Status = status;
             OldPath = oldPath;
             OldMode = oldMode;
+            IsBinaryComparison = isBinaryComparison;
         }
 
         /// <summary>