Exposed git_merge_base as CommitCollection.GetCommonAncestor(...)

LibGit2Sharp.Tests/CommitFixture.cs

@@ -37,6 +37,63 @@ public void CanCorrectlyCountCommitsWhenSwitchingToAnotherBranch()
             }
         }
 
+        /* BareTestRepoPath structure
+
+            * commit 4c062a6361ae6959e06292c1fa5e2822d9c96345
+            |
+            *   commit be3563ae3f795b2b4353bcce3a527ad0a4f7f644
+            |\ 
+            | |
+            | * commit c47800c7266a2be04c571c04d5a6614691ea99bd
+            | |
+            * | commit 9fd738e8f7967c078dceed8190330fc8648ee56a
+            | |
+            * | commit 4a202b346bb0fb0db7eff3cffeb3c70babbd2045
+            |/  
+            |
+            * commit 5b5b025afb0b4c913b4c338a42934a3863bf3644
+            |
+            * commit 8496071c1b46c854b31185ea97743be6a877447
+
+        */
+        [Fact]
+        public void CanCorrectlyGetCommonAncestorForTwoCommits()
+        {
+            using (var repo = new Repository(BareTestRepoPath))
+            {
+                Commit first = repo.Lookup<Commit>("c47800c7266a2be04c571c04d5a6614691ea99bd");
+
+                Commit second = repo.Lookup<Commit>("9fd738e8f7967c078dceed8190330fc8648ee56a");
+
+                Commit ancestor = repo.Commits.GetCommonAncestor(first, second);
+
+                Assert.NotNull(ancestor);
+
+                ancestor.Id.Sha.ShouldEqual("5b5b025afb0b4c913b4c338a42934a3863bf3644");
+            }
+        }
+
+        [Fact]
+        public void CanCorrectlyGetCommonAncestorForSeveralCommits()
+        {
+            using (var repo = new Repository(BareTestRepoPath))
+            {
+                Commit first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
+
+                Commit second = repo.Lookup<Commit>("be3563ae3f795b2b4353bcce3a527ad0a4f7f644");
+
+                Commit third = repo.Lookup<Commit>("c47800c7266a2be04c571c04d5a6614691ea99bd");
+
+                Commit fourth = repo.Lookup<Commit>("5b5b025afb0b4c913b4c338a42934a3863bf3644");
+
+                Commit ancestor = repo.Commits.GetCommonAncestor(first, second, third, fourth);
+
+                Assert.NotNull(ancestor);
+
+                ancestor.Id.Sha.ShouldEqual("5b5b025afb0b4c913b4c338a42934a3863bf3644");
+            }
+        }
+
         [Fact]
         public void CanEnumerateCommits()
         {

LibGit2Sharp/CommitCollection.cs

@@ -74,6 +74,7 @@ IEnumerator IEnumerable.GetEnumerator()
 
         #endregion
 
+
         /// <summary>
         ///   Returns the list of commits of the repository matching the specified <paramref name = "filter" />.
         /// </summary>
@@ -124,6 +125,48 @@ private static bool PointsAtTheHead(string shaOrRefName)
             return ("HEAD".Equals(shaOrRefName, StringComparison.Ordinal) || "refs/heads/master".Equals(shaOrRefName, StringComparison.Ordinal));
         }
 
+        /// <summary>
+        /// Find as good common ancestors as possible for a merge given second <see cref="Commit"/>.
+        /// </summary>
+        /// <param name="first">The first <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <param name="second">The second <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <returns>The common ancestor or null if none found.</returns>
+        public Commit GetCommonAncestor(Commit first, Commit second)
+        {
+            Ensure.ArgumentNotNull(first, "first");
+            Ensure.ArgumentNotNull(second, "second");
+            GitOid ret;
+            using (var osw1 = new ObjectSafeWrapper(first.Id, this.repo))
+            using (var osw2 = new ObjectSafeWrapper(second.Id, this.repo))
+            {
+                Ensure.Success(NativeMethods.git_merge_base(out ret, this.repo.Handle, osw1.ObjectPtr, osw2.ObjectPtr));
+                return this.repo.Lookup<Commit>(new ObjectId(ret));
+            }
+        }
+
+        /// <summary>
+        /// Find as good common ancestors as possible for a merge given second or more <see cref="Commit"/>.
+        /// </summary>
+        /// <param name="commits">The <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <returns>The common ancestor or null if none found.</returns>
+        public Commit GetCommonAncestor(IEnumerable<Commit> commits)
+        {
+            Ensure.ArgumentNotNull(commits, "commits");
+
+            return commits.Aggregate(this.GetCommonAncestor);
+        }
+
+        /// <summary>
+        /// Find as good common ancestors as possible for a merge given second or more <see cref="Commit"/>.
+        /// </summary>
+        /// <param name="commits">The <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <returns>The common ancestor or null if none found.</returns>
+        public Commit GetCommonAncestor(params Commit[] commits)
+        {
+            return this.GetCommonAncestor((IEnumerable<Commit>)commits);
+        }
+
+
         /// <summary>
         ///   Stores the content of the <see cref = "Repository.Index" /> as a new <see cref = "Commit" /> into the repository.
         ///   The tip of the <see cref = "Repository.Head"/> will be used as the parent of this new Commit.

LibGit2Sharp/Core/Ensure.cs

@@ -7,9 +7,10 @@ namespace LibGit2Sharp.Core
     /// <summary>
     ///   Ensure input parameters
     /// </summary>
-    [DebuggerStepThrough]
+    //[DebuggerStepThrough]
     internal static class Ensure
     {
+        private static readonly Utf8Marshaler marshaler = (Utf8Marshaler)Utf8Marshaler.GetInstance(string.Empty);
         /// <summary>
         ///   Checks an argument to ensure it isn't null.
         /// </summary>
@@ -62,10 +63,12 @@ public static void Success(int result, bool allowPositiveResult = false)
                 return;
             }
 
-            string errorMessage = NativeMethods.git_lasterror();
+            GitError error = NativeMethods.giterr_last();
+
+            string errorMsg= "";//  = (string)marshaler.MarshalNativeToManaged(error.Message);
 
             throw new LibGit2Exception(
-                String.Format(CultureInfo.InvariantCulture, "An error was raised by libgit2. Error code = {0} ({1}).{2}{3}", Enum.GetName(typeof(GitErrorCode), result), result, Environment.NewLine, errorMessage));
+                String.Format(CultureInfo.InvariantCulture, "An error was raised by libgit2. Error code = {0} ({1}).{2}{3}", Enum.GetName(typeof(GitErrorCode), result), result, Environment.NewLine, errorMsg));
         }
 
         /// <summary>

LibGit2Sharp/Core/GitError.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace LibGit2Sharp.Core
+{
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct GitError
+    {
+        public IntPtr Message;
+        public int Klass;
+    }
+}

LibGit2Sharp/Core/GitErrorCode.cs

@@ -1,5 +1,7 @@
 namespace LibGit2Sharp.Core
 {
+
+
     internal enum GitErrorCode
     {
         /// <summary>
@@ -15,111 +17,11 @@ internal enum GitErrorCode
         /// </summary>
         GIT_ERROR = -1,
 
-        /// <summary>
-        ///   Input was not a properly formatted Git object id.
-        /// </summary>
-        GIT_ENOTOID = -2,
-
         /// <summary>
         ///   Input does not exist in the scope searched.
         /// </summary>
         GIT_ENOTFOUND = -3,
 
-        /// <summary>
-        ///   Not enough space available.
-        /// </summary>
-        GIT_ENOMEM = -4,
-
-        /// <summary>
-        ///   Consult the OS error information.
-        /// </summary>
-        GIT_EOSERR = -5,
-
-        /// <summary>
-        ///   The specified object is of invalid type
-        /// </summary>
-        GIT_EOBJTYPE = -6,
-
-        /// <summary>
-        ///   The specified repository is invalid
-        /// </summary>
-        GIT_ENOTAREPO = -7,
-
-        /// <summary>
-        ///   The object type is invalid or doesn't match
-        /// </summary>
-        GIT_EINVALIDTYPE = -8,
-
-        /// <summary>
-        ///   The object cannot be written that because it's missing internal data
-        /// </summary>
-        GIT_EMISSINGOBJDATA = -9,
-
-        /// <summary>
-        ///   The packfile for the ODB is corrupted
-        /// </summary>
-        GIT_EPACKCORRUPTED = -10,
-
-        /// <summary>
-        ///   Failed to adquire or release a file lock
-        /// </summary>
-        GIT_EFLOCKFAIL = -11,
-
-        /// <summary>
-        ///   The Z library failed to inflate/deflate an object's data
-        /// </summary>
-        GIT_EZLIB = -12,
-
-        /// <summary>
-        ///   The queried object is currently busy
-        /// </summary>
-        GIT_EBUSY = -13,
-
-        /// <summary>
-        ///   The index file is not backed up by an existing repository
-        /// </summary>
-        GIT_EBAREINDEX = -14,
-
-        /// <summary>
-        ///   The name of the reference is not valid
-        /// </summary>
-        GIT_EINVALIDREFNAME = -15,
-
-        /// <summary>
-        ///   The specified reference has its data corrupted
-        /// </summary>
-        GIT_EREFCORRUPTED = -16,
-
-        /// <summary>
-        ///   The specified symbolic reference is too deeply nested
-        /// </summary>
-        GIT_ETOONESTEDSYMREF = -17,
-
-        /// <summary>
-        ///   The pack-refs file is either corrupted of its format is not currently supported
-        /// </summary>
-        GIT_EPACKEDREFSCORRUPTED = -18,
-
-        /// <summary>
-        ///   The path is invalid
-        /// </summary>
-        GIT_EINVALIDPATH = -19,
-
-        /// <summary>
-        ///   The revision walker is empty; there are no more commits left to iterate
-        /// </summary>
-        GIT_EREVWALKOVER = -20,
-
-        /// <summary>
-        ///   The state of the reference is not valid
-        /// </summary>
-        GIT_EINVALIDREFSTATE = -21,
-
-        /// <summary>
-        ///   This feature has not been implemented yet
-        /// </summary>
-        GIT_ENOTIMPLEMENTED = -22,
-
         /// <summary>
         ///   A reference with this name already exists
         /// </summary>
@@ -131,33 +33,23 @@ internal enum GitErrorCode
         GIT_EOVERFLOW = -24,
 
         /// <summary>
-        ///   The given literal is not a valid number
-        /// </summary>
-        GIT_ENOTNUM = -25,
-
-        /// <summary>
-        ///   Streaming error
-        /// </summary>
-        GIT_ESTREAM = -26,
-
-        /// <summary>
-        ///   invalid arguments to function
+        ///   The given short oid is ambiguous
         /// </summary>
-        GIT_EINVALIDARGS = -27,
+        GIT_EAMBIGUOUS = -29,
 
         /// <summary>
-        ///   The specified object has its data corrupted
+        ///   Skip and passthrough the given ODB backend
         /// </summary>
-        GIT_EOBJCORRUPTED = -28,
-
+        GIT_EPASSTHROUGH = -30,
+        
         /// <summary>
-        ///   The given short oid is ambiguous
+        ///   The buffer is too short to satisfy the request
         /// </summary>
-        GIT_EAMBIGUOUSOIDPREFIX = -29,
+        GIT_ESHORTBUFFER = -32,
 
         /// <summary>
-        ///   Skip and passthrough the given ODB backend
+        ///   The revision walker is empty; there are no more commits left to iterate
         /// </summary>
-        GIT_EPASSTHROUGH = -30,
+        GIT_EREVWALKOVER = -33,
     }
 }

LibGit2Sharp/Core/NativeMethods.cs

@@ -65,6 +65,9 @@ public static bool RepositoryStateChecker(RepositorySafeHandle repositoryPtr, Fu
             return (res == 1);
         }
 
+        [DllImport(libgit2)]
+        public static extern GitError giterr_last();
+
         [DllImport(libgit2)]
         public static extern int git_blob_create_fromfile(
             ref GitOid oid,
@@ -302,8 +305,11 @@ public static extern int git_index_find(
         public static extern int git_index_write(IndexSafeHandle index);
 
         [DllImport(libgit2)]
-        [return : MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(Utf8Marshaler))]
-        public static extern string git_lasterror();
+        public static extern int git_merge_base(
+            out GitOid mergeBase,
+            RepositorySafeHandle repo,
+            GitObjectSafeHandle one,
+            GitObjectSafeHandle two);
 
         [DllImport(libgit2)]
         public static extern int git_odb_exists(ObjectDatabaseSafeHandle odb, ref GitOid id);

LibGit2Sharp/IQueryableCommitCollection.cs

@@ -1,4 +1,6 @@
-namespace LibGit2Sharp
+using System.Collections.Generic;
+
+namespace LibGit2Sharp
 {
     public interface IQueryableCommitCollection : ICommitCollection //TODO: Find a name that's more explicit than IQueryableCommitCollection
     {
@@ -20,5 +22,28 @@ public interface IQueryableCommitCollection : ICommitCollection //TODO: Find a n
         /// <param name = "amendPreviousCommit">True to amend the current <see cref = "Commit"/> pointed at by <see cref = "Repository.Head"/>, false otherwise.</param>
         /// <returns>The generated <see cref = "Commit" />.</returns>
         Commit Create(string message, Signature author, Signature committer, bool amendPreviousCommit);
+
+
+        /// <summary>
+        /// Find as good common ancestors as possible for a merge given second <see cref="Commit"/>.
+        /// </summary>
+        /// <param name="first">The first <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <param name="second">The second <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <returns>The common ancestor or null if none found.</returns>
+        Commit GetCommonAncestor(Commit first, Commit second);
+
+        /// <summary>
+        /// Find as good common ancestors as possible for a merge given second or more <see cref="Commit"/>.
+        /// </summary>
+        /// <param name="commits">The <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <returns>The common ancestor or null if none found.</returns>
+        Commit GetCommonAncestor(IEnumerable<Commit> commits);
+
+        /// <summary>
+        /// Find as good common ancestors as possible for a merge given second or more <see cref="Commit"/>.
+        /// </summary>
+        /// <param name="commits">The <see cref="Commit"/> for which to find the common ancestor.</param>
+        /// <returns>The common ancestor or null if none found.</returns>
+        Commit GetCommonAncestor(params Commit[] commits);
     }
 }

LibGit2Sharp/LibGit2Sharp.csproj

@@ -61,6 +61,7 @@
     <Compile Include="Core\EnumExtensions.cs" />
     <Compile Include="ChangeKind.cs" />
     <Compile Include="Core\GitDiff.cs" />
+    <Compile Include="Core\GitError.cs" />
     <Compile Include="Core\GitObjectExtensions.cs" />
     <Compile Include="Core\Handles\ObjectDatabaseSafeHandle.cs" />
     <Compile Include="Core\Handles\DiffListSafeHandle.cs" />