Teach Branch to cope with unborn tracked branches

6 files changed, 67 insertions, 23 deletions

diff --git a/LibGit2Sharp.Tests/BranchFixture.cs b/LibGit2Sharp.Tests/BranchFixture.cs
index 5e6fbea8..34155144 100644
--- a/LibGit2Sharp.Tests/BranchFixture.cs
+++ b/LibGit2Sharp.Tests/BranchFixture.cs
@@ -603,5 +603,24 @@ namespace LibGit2Sharp.Tests
                 Assert.Null(repo.Head.TrackedBranch);
             }
         }
+
+        [Fact]
+        public void RemoteBranchesDoNotTrackAnything()
+        {
+            using (var repo = new Repository(StandardTestRepoPath))
+            {
+                var branches = repo.Branches.Where(b => b.IsRemote);
+
+                foreach (var branch in branches)
+                {
+                    Assert.True(branch.IsRemote);
+                    Assert.Null(branch.Remote);
+                    Assert.False(branch.IsTracking);
+                    Assert.Null(branch.TrackedBranch);
+                    Assert.Null(branch.AheadBy);
+                    Assert.Null(branch.BehindBy);
+                }
+            }
+        }
     }
 }
diff --git a/LibGit2Sharp/Branch.cs b/LibGit2Sharp/Branch.cs
index da7e8dd7..97a2c270 100644
--- a/LibGit2Sharp/Branch.cs
+++ b/LibGit2Sharp/Branch.cs
@@ -214,24 +214,26 @@ namespace LibGit2Sharp
 
         private Branch ResolveTrackedBranch()
         {
-            using (ReferenceSafeHandle branchPtr = repo.Refs.RetrieveReferencePtr(CanonicalName, false))
+            if (IsRemote)
             {
-                if (branchPtr == null)
-                {
-                    return null;
-                }
+                return null;
+            }
 
-                using (ReferenceSafeHandle referencePtr = Proxy.git_branch_tracking(branchPtr))
-                {
-                    if (referencePtr == null)
-                    {
-                        return null;
-                    }
+            string trackedReferenceName = Proxy.git_branch_tracking_name(repo.Handle, CanonicalName);
 
-                    var reference = Reference.BuildFromPtr<Reference>(referencePtr, repo);
-                    return repo.Branches[reference.CanonicalName];
-                }
+            if (trackedReferenceName == null)
+            {
+                return null;
+            }
+
+            Branch branch = repo.Branches[trackedReferenceName];
+
+            if (branch != null)
+            {
+                return branch;
             }
+
+            return new Branch(repo, new VoidReference(trackedReferenceName), trackedReferenceName);
         }
 
         private static bool IsRemoteBranch(string canonicalName)
diff --git a/LibGit2Sharp/Core/NativeMethods.cs b/LibGit2Sharp/Core/NativeMethods.cs
index 7554ea0d..22a08581 100644
--- a/LibGit2Sharp/Core/NativeMethods.cs
+++ b/LibGit2Sharp/Core/NativeMethods.cs
@@ -142,9 +142,11 @@ namespace LibGit2Sharp.Core
             [MarshalAs(UnmanagedType.Bool)] bool force);
 
         [DllImport(libgit2)]
-        internal static extern int git_branch_tracking(
-            out ReferenceSafeHandle reference,
-            ReferenceSafeHandle branch);
+        internal static extern int git_branch_tracking_name(
+            byte[] tracking_branch_name_out, // NB: This is more properly a StringBuilder, but it's UTF8
+            UIntPtr buffer_size,
+            RepositorySafeHandle repo,
+            [MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(Utf8Marshaler))] string referenceName);
 
         [DllImport(libgit2)]
         internal static extern int git_checkout_tree(
diff --git a/LibGit2Sharp/Core/Proxy.cs b/LibGit2Sharp/Core/Proxy.cs
index c26dcdae..cb45a1b1 100644
--- a/LibGit2Sharp/Core/Proxy.cs
+++ b/LibGit2Sharp/Core/Proxy.cs
@@ -148,21 +148,27 @@ namespace LibGit2Sharp.Core
             }
         }
 
-        public static ReferenceSafeHandle git_branch_tracking(ReferenceSafeHandle branch)
+        public static string git_branch_tracking_name(RepositorySafeHandle handle, string canonicalReferenceName)
         {
             using (ThreadAffinity())
             {
-                ReferenceSafeHandle reference;
-                int res = NativeMethods.git_branch_tracking(out reference, branch);
+                int bufSize = NativeMethods.git_branch_tracking_name(
+                    null, UIntPtr.Zero, handle, canonicalReferenceName);
 
-                if (res == (int)GitErrorCode.NotFound)
+                if (bufSize == (int)GitErrorCode.NotFound)
                 {
                     return null;
                 }
 
-                Ensure.Success(res);
+                Ensure.Success(bufSize, true);
 
-                return reference;
+                var buffer = new byte[bufSize];
+
+                int res = NativeMethods.git_branch_tracking_name(
+                    buffer, (UIntPtr)buffer.Length, handle, canonicalReferenceName);
+                Ensure.Success(res, true);
+
+                return Utf8Marshaler.Utf8FromBuffer(buffer);
             }
         }
 
diff --git a/LibGit2Sharp/LibGit2Sharp.csproj b/LibGit2Sharp/LibGit2Sharp.csproj
index 38be381e..b659dbcb 100644
--- a/LibGit2Sharp/LibGit2Sharp.csproj
+++ b/LibGit2Sharp/LibGit2Sharp.csproj
@@ -209,6 +209,7 @@
     <Compile Include="TreeDefinition.cs" />
     <Compile Include="TreeEntry.cs" />
     <Compile Include="TreeEntryDefinition.cs" />
+    <Compile Include="VoidReference.cs" />
   </ItemGroup>
   <ItemGroup>
     <CodeAnalysisDictionary Include="CustomDictionary.xml" />
diff --git a/LibGit2Sharp/VoidReference.cs b/LibGit2Sharp/VoidReference.cs
new file mode 100644
index 00000000..b8defc8c
--- /dev/null
+++ b/LibGit2Sharp/VoidReference.cs
@@ -0,0 +1,14 @@
+namespace LibGit2Sharp
+{
+    internal class VoidReference : Reference
+    {
+        internal VoidReference(string canonicalName)
+            : base(canonicalName, null)
+        { }
+
+        public override DirectReference ResolveToDirectReference()
+        {
+            return null;
+        }
+    }
+}