48 files changed, 344 insertions, 12 deletions

diff --git a/include/git2.h b/include/git2.h
index fe8b02103..e138e279a 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -23,6 +23,7 @@
 #include "git2/repository.h"
 #include "git2/revwalk.h"
 #include "git2/merge.h"
+#include "git2/graph.h"
 #include "git2/refs.h"
 #include "git2/reflog.h"
 #include "git2/revparse.h"
diff --git a/include/git2/graph.h b/include/git2/graph.h
new file mode 100644
index 000000000..c89efa6dd
--- /dev/null
+++ b/include/git2/graph.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_graph_h__
+#define INCLUDE_git_graph_h__
+
+#include "common.h"
+#include "types.h"
+#include "oid.h"
+
+/**
+ * @file git2/graph.h
+ * @brief Git graph traversal routines
+ * @defgroup git_revwalk Git graph traversal routines
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Count the number of unique commits between two commit objects
+ *
+ * @param ahead number of commits, starting at `one`, unique from commits in `two`
+ * @param behind number of commits, starting at `two`, unique from commits in `one`
+ * @param repo the repository where the commits exist
+ * @param one one of the commits
+ * @param two the other commit
+ */
+GIT_EXTERN(int) git_graph_ahead_behind(size_t *ahead, size_t *behind, git_repository *repo, const git_oid *one, const git_oid *two);
+
+/** @} */
+GIT_END_DECL
+#endif
diff --git a/src/commit_list.c b/src/commit_list.c
index c1a7b223f..d79934a2f 100644
--- a/src/commit_list.c
+++ b/src/commit_list.c
@@ -127,7 +127,7 @@ static int commit_quick_parse(git_revwalk *walk, git_commit_list_node *commit, g
 		if (git_oid_fromstr(&oid, (char *)buffer + strlen("parent ")) < 0)
 			return -1;
 
-		commit->parents[i] = commit_lookup(walk, &oid);
+		commit->parents[i] = git_revwalk__commit_lookup(walk, &oid);
 		if (commit->parents[i] == NULL)
 			return -1;
 
@@ -181,9 +181,13 @@ int git_commit_list_parse(git_revwalk *walk, git_commit_list_node *commit)
 
 	if ((error = git_odb_read(&obj, walk->odb, &commit->oid)) < 0)
 		return error;
-	assert(obj->raw.type == GIT_OBJ_COMMIT);
 
-	error = commit_quick_parse(walk, commit, &obj->raw);
+	if (obj->raw.type != GIT_OBJ_COMMIT) {
+		giterr_set(GITERR_INVALID, "Object is no commit object");
+		error = -1;
+	} else
+		error = commit_quick_parse(walk, commit, &obj->raw);
+
 	git_odb_object_free(obj);
 	return error;
 }
diff --git a/src/graph.c b/src/graph.c
new file mode 100644
index 000000000..28026d4b4
--- /dev/null
+++ b/src/graph.c
@@ -0,0 +1,93 @@
+
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "revwalk.h"
+#include "merge.h"
+#include "git2/graph.h"
+
+static int ahead_behind(git_commit_list_node *one, git_commit_list_node *two,
+	size_t *ahead, size_t *behind)
+{
+	git_commit_list_node *commit;
+	git_pqueue pq;
+	int i;
+	*ahead = 0;
+	*behind = 0;
+
+	if (git_pqueue_init(&pq, 2, git_commit_list_time_cmp) < 0)
+		return -1;
+	if (git_pqueue_insert(&pq, one) < 0)
+		return -1;
+	if (git_pqueue_insert(&pq, two) < 0)
+		return -1;
+
+	while ((commit = git_pqueue_pop(&pq)) != NULL) {
+		if (commit->flags & RESULT ||
+			(commit->flags & (PARENT1 | PARENT2)) == (PARENT1 | PARENT2))
+			continue;
+		else if (commit->flags & PARENT1)
+			(*behind)++;
+		else if (commit->flags & PARENT2)
+			(*ahead)++;
+
+		for (i = 0; i < commit->out_degree; i++) {
+			git_commit_list_node *p = commit->parents[i];
+			if (git_pqueue_insert(&pq, p) < 0)
+				return -1;
+		}
+		commit->flags |= RESULT;
+	}
+
+	return 0;
+}
+
+int git_graph_ahead_behind(size_t *ahead, size_t *behind, git_repository *repo,
+	const git_oid *one, const git_oid *two)
+{
+	git_revwalk *walk;
+	git_vector list;
+	struct git_commit_list *result = NULL;
+	git_commit_list_node *commit1, *commit2;
+	void *contents[1];
+
+	if (git_revwalk_new(&walk, repo) < 0)
+		return -1;
+
+	commit2 = git_revwalk__commit_lookup(walk, two);
+	if (commit2 == NULL)
+		goto on_error;
+
+	/* This is just one value, so we can do it on the stack */
+	memset(&list, 0x0, sizeof(git_vector));
+	contents[0] = commit2;
+	list.length = 1;
+	list.contents = contents;
+
+	commit1 = git_revwalk__commit_lookup(walk, one);
+	if (commit1 == NULL)
+		goto on_error;
+
+	if (git_merge__bases_many(&result, walk, commit1, &list) < 0)
+		goto on_error;
+	if (ahead_behind(commit1, commit2, ahead, behind) < 0)
+		goto on_error;
+
+	if (!result) {
+		git_revwalk_free(walk);
+		return GIT_ENOTFOUND;
+	}
+
+	git_commit_list_free(&result);
+	git_revwalk_free(walk);
+
+	return 0;
+
+on_error:
+	git_revwalk_free(walk);
+	return -1;
+}
diff --git a/src/merge.c b/src/merge.c
index c795b808b..1386d0908 100644
--- a/src/merge.c
+++ b/src/merge.c
@@ -71,14 +71,14 @@ int git_merge_base_many(git_oid *out, git_repository *repo, const git_oid input_
 		goto cleanup;
 
 	for (i = 1; i < length; i++) {
-		commit = commit_lookup(walk, &input_array[i]);
+		commit = git_revwalk__commit_lookup(walk, &input_array[i]);
 		if (commit == NULL)
 			goto cleanup;
 
 		git_vector_insert(&list, commit);
 	}
 
-	commit = commit_lookup(walk, &input_array[0]);
+	commit = git_revwalk__commit_lookup(walk, &input_array[0]);
 	if (commit == NULL)
 		goto cleanup;
 
@@ -112,7 +112,7 @@ int git_merge_base(git_oid *out, git_repository *repo, const git_oid *one, const
 	if (git_revwalk_new(&walk, repo) < 0)
 		return -1;
 
-	commit = commit_lookup(walk, two);
+	commit = git_revwalk__commit_lookup(walk, two);
 	if (commit == NULL)
 		goto on_error;
 
@@ -122,7 +122,7 @@ int git_merge_base(git_oid *out, git_repository *repo, const git_oid *one, const
 	list.length = 1;
 	list.contents = contents;
 
-	commit = commit_lookup(walk, one);
+	commit = git_revwalk__commit_lookup(walk, one);
 	if (commit == NULL)
 		goto on_error;
 
@@ -241,4 +241,3 @@ int git_merge__bases_many(git_commit_list **out, git_revwalk *walk, git_commit_l
 	*out = result;
 	return 0;
 }
-
diff --git a/src/revwalk.c b/src/revwalk.c
index bdbbdbd17..cad2f09bd 100644
--- a/src/revwalk.c
+++ b/src/revwalk.c
@@ -15,7 +15,8 @@
 
 #include <regex.h>
 
-git_commit_list_node *commit_lookup(git_revwalk *walk, const git_oid *oid)
+git_commit_list_node *git_revwalk__commit_lookup(
+	git_revwalk *walk, const git_oid *oid)
 {
 	git_commit_list_node *commit;
 	khiter_t pos;
@@ -101,7 +102,7 @@ static int push_commit(git_revwalk *walk, const git_oid *oid, int uninteresting)
 		return -1;
 	}
 
-	commit = commit_lookup(walk, oid);
+	commit = git_revwalk__commit_lookup(walk, oid);
 	if (commit == NULL)
 		return -1; /* error already reported by failed lookup */
 
diff --git a/src/revwalk.h b/src/revwalk.h
index 2d482cfcc..6146eaf25 100644
--- a/src/revwalk.h
+++ b/src/revwalk.h
@@ -39,6 +39,6 @@ struct git_revwalk {
 	git_vector twos;
 };
 
-git_commit_list_node *commit_lookup(git_revwalk *walk, const git_oid *oid);
+git_commit_list_node *git_revwalk__commit_lookup(git_revwalk *walk, const git_oid *oid);
 
 #endif
diff --git a/tests-clar/resources/twowaymerge.git/HEAD b/tests-clar/resources/twowaymerge.git/HEAD
new file mode 100644
index 000000000..cb089cd89
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/HEAD
@@ -0,0 +1 @@
+ref: refs/heads/master
diff --git a/tests-clar/resources/twowaymerge.git/config b/tests-clar/resources/twowaymerge.git/config
new file mode 100644
index 000000000..c53d818dd
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/config
@@ -0,0 +1,5 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true
+	ignorecase = true
diff --git a/tests-clar/resources/twowaymerge.git/description b/tests-clar/resources/twowaymerge.git/description
new file mode 100644
index 000000000..498b267a8
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/description
@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.
diff --git a/tests-clar/resources/twowaymerge.git/info/exclude b/tests-clar/resources/twowaymerge.git/info/exclude
new file mode 100644
index 000000000..a5196d1be
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/info/exclude
@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~
diff --git a/tests-clar/resources/twowaymerge.git/objects/0c/8a3f1f3d5f421cf83048c7c73ee3b55a5e0f29 b/tests-clar/resources/twowaymerge.git/objects/0c/8a3f1f3d5f421cf83048c7c73ee3b55a5e0f29
new file mode 100644
index 000000000..12698affa
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/0c/8a3f1f3d5f421cf83048c7c73ee3b55a5e0f29
diff --git a/tests-clar/resources/twowaymerge.git/objects/10/2dce8e3081f398e4bdd9fd894dc85ac3ca6a67 b/tests-clar/resources/twowaymerge.git/objects/10/2dce8e3081f398e4bdd9fd894dc85ac3ca6a67
new file mode 100644
index 000000000..3806ee74c
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/10/2dce8e3081f398e4bdd9fd894dc85ac3ca6a67
diff --git a/tests-clar/resources/twowaymerge.git/objects/17/7d8634a28e26ec7819284752757ebe01a479d5 b/tests-clar/resources/twowaymerge.git/objects/17/7d8634a28e26ec7819284752757ebe01a479d5
new file mode 100644
index 000000000..e91e06db2
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/17/7d8634a28e26ec7819284752757ebe01a479d5
diff --git a/tests-clar/resources/twowaymerge.git/objects/1c/30b88f5f3ee66d78df6520a7de9e89b890818b b/tests-clar/resources/twowaymerge.git/objects/1c/30b88f5f3ee66d78df6520a7de9e89b890818b
new file mode 100644
index 000000000..57d1a0f1e
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/1c/30b88f5f3ee66d78df6520a7de9e89b890818b
@@ -0,0 +1,3 @@
+x
��M
+�0F]�s
���	���z�I���i����^��{<>�TKy4`6����,y��9j�GJ�8����b��\�f��5/
�^�8v�'����˜�`SƝ�%[��
+�T[�[���,p���s�L�6o�K����5�;���n��-�=����D�
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diff --git a/tests-clar/resources/twowaymerge.git/objects/1f/4c0311a24b63f6fc209a59a1e404942d4a5006 b/tests-clar/resources/twowaymerge.git/objects/1f/4c0311a24b63f6fc209a59a1e404942d4a5006
new file mode 100644
index 000000000..99288fdd7
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/1f/4c0311a24b63f6fc209a59a1e404942d4a5006
@@ -0,0 +1,2 @@
+x
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r�5g�N�X��ű)Eg]�DY2c	R8x�7��
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diff --git a/tests-clar/resources/twowaymerge.git/objects/22/24e191514cb4bd8c566d80dac22dfcb1e9bb83 b/tests-clar/resources/twowaymerge.git/objects/22/24e191514cb4bd8c566d80dac22dfcb1e9bb83
new file mode 100644
index 000000000..48466ea51
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/22/24e191514cb4bd8c566d80dac22dfcb1e9bb83
@@ -0,0 +1,3 @@
+x
��K
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K&��	���z��4��HM�o������bY���1t�[J�b�lɈ���4vɡ�L�
�'�՛��V`B��� .
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diff --git a/tests-clar/resources/twowaymerge.git/objects/29/6e56023cdc034d2735fee8c0d85a659d1b07f4 b/tests-clar/resources/twowaymerge.git/objects/29/6e56023cdc034d2735fee8c0d85a659d1b07f4
new file mode 100644
index 000000000..aa3fccdf0
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/29/6e56023cdc034d2735fee8c0d85a659d1b07f4
diff --git a/tests-clar/resources/twowaymerge.git/objects/31/51880ae2b363f1c262cf98b750c1f169a0d432 b/tests-clar/resources/twowaymerge.git/objects/31/51880ae2b363f1c262cf98b750c1f169a0d432
new file mode 100644
index 000000000..235d42bff
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/31/51880ae2b363f1c262cf98b750c1f169a0d432
diff --git a/tests-clar/resources/twowaymerge.git/objects/3b/287f8730c81d0b763c2d294618a5e32b67b4f8 b/tests-clar/resources/twowaymerge.git/objects/3b/287f8730c81d0b763c2d294618a5e32b67b4f8
new file mode 100644
index 000000000..56ddac5ee
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/3b/287f8730c81d0b763c2d294618a5e32b67b4f8
diff --git a/tests-clar/resources/twowaymerge.git/objects/42/b7311aa626e712891940c1ec5d5cba201946a4 b/tests-clar/resources/twowaymerge.git/objects/42/b7311aa626e712891940c1ec5d5cba201946a4
new file mode 100644
index 000000000..a8e6581f8
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/42/b7311aa626e712891940c1ec5d5cba201946a4
@@ -0,0 +1,3 @@
+x
�ν
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diff --git a/tests-clar/resources/twowaymerge.git/objects/49/6d6428b9cf92981dc9495211e6e1120fb6f2ba b/tests-clar/resources/twowaymerge.git/objects/49/6d6428b9cf92981dc9495211e6e1120fb6f2ba
new file mode 100644
index 000000000..978bc3448
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/49/6d6428b9cf92981dc9495211e6e1120fb6f2ba
diff --git a/tests-clar/resources/twowaymerge.git/objects/59/b0cf7d74659e1cdb13305319d6d4ce2733c118 b/tests-clar/resources/twowaymerge.git/objects/59/b0cf7d74659e1cdb13305319d6d4ce2733c118
new file mode 100644
index 000000000..30b507c06
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/59/b0cf7d74659e1cdb13305319d6d4ce2733c118
diff --git a/tests-clar/resources/twowaymerge.git/objects/6a/b5d28acbf3c3bdff276f7ccfdf29c1520e542f b/tests-clar/resources/twowaymerge.git/objects/6a/b5d28acbf3c3bdff276f7ccfdf29c1520e542f
new file mode 100644
index 000000000..ff6a386ac
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/6a/b5d28acbf3c3bdff276f7ccfdf29c1520e542f
@@ -0,0 +1 @@
+x
��M�0@a�=�\@2�cܙ��e��R����ܾŗǵ���R�Զ�@���(i$�uO�1�9Ro"�
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diff --git a/tests-clar/resources/twowaymerge.git/objects/6c/fca542b55b8b37017e6125a4b8f59a6eae6f11 b/tests-clar/resources/twowaymerge.git/objects/6c/fca542b55b8b37017e6125a4b8f59a6eae6f11
new file mode 100644
index 000000000..9a969a279
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/6c/fca542b55b8b37017e6125a4b8f59a6eae6f11
diff --git a/tests-clar/resources/twowaymerge.git/objects/76/5b32c65d38f04c4f287abda055818ec0f26912 b/tests-clar/resources/twowaymerge.git/objects/76/5b32c65d38f04c4f287abda055818ec0f26912
new file mode 100644
index 000000000..493bbc076
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/76/5b32c65d38f04c4f287abda055818ec0f26912
diff --git a/tests-clar/resources/twowaymerge.git/objects/7b/8c336c45fc6895c1c60827260fe5d798e5d247 b/tests-clar/resources/twowaymerge.git/objects/7b/8c336c45fc6895c1c60827260fe5d798e5d247
new file mode 100644
index 000000000..19e7ef463
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/7b/8c336c45fc6895c1c60827260fe5d798e5d247
@@ -0,0 +1,3 @@
+x
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diff --git a/tests-clar/resources/twowaymerge.git/objects/82/bf9a1a10a4b25c1f14c9607b60970705e92545 b/tests-clar/resources/twowaymerge.git/objects/82/bf9a1a10a4b25c1f14c9607b60970705e92545
new file mode 100644
index 000000000..89b0b9f9b
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/82/bf9a1a10a4b25c1f14c9607b60970705e92545
@@ -0,0 +1 @@
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\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/8b/82fb1794cb1c8c7f172ec730a4c2db0ae3e650 b/tests-clar/resources/twowaymerge.git/objects/8b/82fb1794cb1c8c7f172ec730a4c2db0ae3e650
new file mode 100644
index 000000000..8e9b758ea
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/8b/82fb1794cb1c8c7f172ec730a4c2db0ae3e650
@@ -0,0 +1,3 @@
+x
�ν
�0@ajOq�7BtH�Lp��%A8F�ٟ��W<=���
�����x"ʎ�$�%1�d�c�DNL�:Yv=�7�yi�c
+l�$�\b{�D�bOd��9x+
+�6�T[�{����??y��qnӖ:����c���QZ�]�͖����7�H�
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diff --git a/tests-clar/resources/twowaymerge.git/objects/9a/40a2f11c191f180c47e54b11567cb3c1e89b30 b/tests-clar/resources/twowaymerge.git/objects/9a/40a2f11c191f180c47e54b11567cb3c1e89b30
new file mode 100644
index 000000000..1de1224f7
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/9a/40a2f11c191f180c47e54b11567cb3c1e89b30
diff --git a/tests-clar/resources/twowaymerge.git/objects/9b/219343610c88a1187c996d0dc58330b55cee28 b/tests-clar/resources/twowaymerge.git/objects/9b/219343610c88a1187c996d0dc58330b55cee28
new file mode 100644
index 000000000..8b64b4381
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/9b/219343610c88a1187c996d0dc58330b55cee28
@@ -0,0 +1,2 @@
+x
��Kj1Ь����Fj}Z��3��	�V��dFA#�?�\ �z�u]�F�So"��J��&�^���,9$G�E�d)7|�&[6�(FU"&�h<��F�c4Aƿ>"Z�Q;m9�\;�KP%1b9k�93�G�k�w����n���i���[��uZ�����h�"R��Y��C�[]�=0�I�rK�p����O:���
+�p�ʯ
_�(c�
\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/9f/e06a50f4d1634d6c6879854d01d80857388706 b/tests-clar/resources/twowaymerge.git/objects/9f/e06a50f4d1634d6c6879854d01d80857388706
new file mode 100644
index 000000000..055de0158
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/9f/e06a50f4d1634d6c6879854d01d80857388706
diff --git a/tests-clar/resources/twowaymerge.git/objects/a4/1a49f8f5cd9b6cb14a076bf8394881ed0b4d19 b/tests-clar/resources/twowaymerge.git/objects/a4/1a49f8f5cd9b6cb14a076bf8394881ed0b4d19
new file mode 100644
index 000000000..cb4d34e77
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/a4/1a49f8f5cd9b6cb14a076bf8394881ed0b4d19
@@ -0,0 +1,3 @@
+x
�ν
�0@ajOq��7'!D�D���	A$F�ٟ��W<=��<5���Z
+8N(C��zDž$'2�!�>[):#D�zǵ,
z��	�M�	
d�=��t���Nŭ=�
+w�����k}�9.p���9^Ʃ=��I��@�Y���=��u�l����D�
\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/a9/53a018c5b10b20c86e69fef55ebc8ad4c5a417 b/tests-clar/resources/twowaymerge.git/objects/a9/53a018c5b10b20c86e69fef55ebc8ad4c5a417
new file mode 100644
index 000000000..8235f1839
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/a9/53a018c5b10b20c86e69fef55ebc8ad4c5a417
@@ -0,0 +1 @@
+x
���J�0�]�)�nV3$�is"���O���NŶ�ɼ��\��|8����!dz����dXG/ޫϹp*��C�X���@Z�8|�f[V�0HD�H�E]6��g�I#g�*���9UE�H�H!MḦ��h��R����uo�.{��z���Sײ���|���үw�Ⱦ>��1�4�C8;rn8�q�ۿ�7k�
���Nui�~�M���^�
\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/a9/cce3cd1b3efbda5b1f4a6dcc3f1570b2d3d74c b/tests-clar/resources/twowaymerge.git/objects/a9/cce3cd1b3efbda5b1f4a6dcc3f1570b2d3d74c
new file mode 100644
index 000000000..4da7e826a
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/a9/cce3cd1b3efbda5b1f4a6dcc3f1570b2d3d74c
@@ -0,0 +1 @@
+x
+)JMU044c040031QHdx6���M�9{wk�+��q�IO�D�d6>�|��X%
>�9j
\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/bd/1732c43c68d712ad09e1d872b9be6d4b9efdc4 b/tests-clar/resources/twowaymerge.git/objects/bd/1732c43c68d712ad09e1d872b9be6d4b9efdc4
new file mode 100644
index 000000000..b9b60122d
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/bd/1732c43c68d712ad09e1d872b9be6d4b9efdc4
diff --git a/tests-clar/resources/twowaymerge.git/objects/c3/7a783c20d92ac92362a78a32860f7eebf938ef b/tests-clar/resources/twowaymerge.git/objects/c3/7a783c20d92ac92362a78a32860f7eebf938ef
new file mode 100644
index 000000000..041e890ab
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/c3/7a783c20d92ac92362a78a32860f7eebf938ef
diff --git a/tests-clar/resources/twowaymerge.git/objects/cb/dd40facab1682754eb67f7a43f29e672903cf6 b/tests-clar/resources/twowaymerge.git/objects/cb/dd40facab1682754eb67f7a43f29e672903cf6
new file mode 100644
index 000000000..ccb156d88
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/cb/dd40facab1682754eb67f7a43f29e672903cf6
diff --git a/tests-clar/resources/twowaymerge.git/objects/cd/f97fd3bb48eb3827638bb33d208f5fd32d0aa6 b/tests-clar/resources/twowaymerge.git/objects/cd/f97fd3bb48eb3827638bb33d208f5fd32d0aa6
new file mode 100644
index 000000000..0e028dc01
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/cd/f97fd3bb48eb3827638bb33d208f5fd32d0aa6
diff --git a/tests-clar/resources/twowaymerge.git/objects/d6/f10d549cb335b9e6d38afc1f0088be69b50494 b/tests-clar/resources/twowaymerge.git/objects/d6/f10d549cb335b9e6d38afc1f0088be69b50494
new file mode 100644
index 000000000..b298c520e
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/d6/f10d549cb335b9e6d38afc1f0088be69b50494
diff --git a/tests-clar/resources/twowaymerge.git/objects/d9/acdc7ae7632adfeec67fa73c1e343cf4d1f47e b/tests-clar/resources/twowaymerge.git/objects/d9/acdc7ae7632adfeec67fa73c1e343cf4d1f47e
new file mode 100644
index 000000000..de94528a4
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/d9/acdc7ae7632adfeec67fa73c1e343cf4d1f47e
@@ -0,0 +1 @@
+x
+)JMU044c040031QHdx6���M�9{wk�+��q�IO�D�d>�4|��X%
:79U
\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391 b/tests-clar/resources/twowaymerge.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
new file mode 100644
index 000000000..711223894
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/tests-clar/resources/twowaymerge.git/objects/ef/0488f0b722f0be8bcb90a7730ac7efafd1d694 b/tests-clar/resources/twowaymerge.git/objects/ef/0488f0b722f0be8bcb90a7730ac7efafd1d694
new file mode 100644
index 000000000..00f7d3615
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/ef/0488f0b722f0be8bcb90a7730ac7efafd1d694
@@ -0,0 +1 @@
+x
��M� F]s����0�_cܙ��@��H1��_��ۗ�}y���h@�mK	8���Y�����4Ѩ�t^'�`lPى���ڠ�<g�y�Y���1*m������F����
�
��5����#��2?ڲ�!�r�Z�5ƎpD�(:�-�} ��#E�
\ No newline at end of file
diff --git a/tests-clar/resources/twowaymerge.git/objects/fc/f7e3f51c11d199ab7a78403ee4f9ccd028da25 b/tests-clar/resources/twowaymerge.git/objects/fc/f7e3f51c11d199ab7a78403ee4f9ccd028da25
new file mode 100644
index 000000000..54989ea87
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/objects/fc/f7e3f51c11d199ab7a78403ee4f9ccd028da25
diff --git a/tests-clar/resources/twowaymerge.git/refs/heads/first-branch b/tests-clar/resources/twowaymerge.git/refs/heads/first-branch
new file mode 100644
index 000000000..ef0dead7f
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/refs/heads/first-branch
@@ -0,0 +1 @@
+2224e191514cb4bd8c566d80dac22dfcb1e9bb83
diff --git a/tests-clar/resources/twowaymerge.git/refs/heads/master b/tests-clar/resources/twowaymerge.git/refs/heads/master
new file mode 100644
index 000000000..ebf18f58e
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/refs/heads/master
@@ -0,0 +1 @@
+1c30b88f5f3ee66d78df6520a7de9e89b890818b
diff --git a/tests-clar/resources/twowaymerge.git/refs/heads/second-branch b/tests-clar/resources/twowaymerge.git/refs/heads/second-branch
new file mode 100644
index 000000000..586a14a84
--- /dev/null
+++ b/tests-clar/resources/twowaymerge.git/refs/heads/second-branch
@@ -0,0 +1 @@
+9b219343610c88a1187c996d0dc58330b55cee28
diff --git a/tests-clar/revwalk/mergebase.c b/tests-clar/revwalk/mergebase.c
index 268574eb6..9707d42ca 100644
--- a/tests-clar/revwalk/mergebase.c
+++ b/tests-clar/revwalk/mergebase.c
@@ -3,10 +3,12 @@
 #include <stdarg.h>
 
 static git_repository *_repo;
+static git_repository *_repo2;
 
 void test_revwalk_mergebase__initialize(void)
 {
 	cl_git_pass(git_repository_open(&_repo, cl_fixture("testrepo.git")));
+	cl_git_pass(git_repository_open(&_repo2, cl_fixture("twowaymerge.git")));
 }
 
 void test_revwalk_mergebase__cleanup(void)
@@ -18,6 +20,7 @@ void test_revwalk_mergebase__cleanup(void)
 void test_revwalk_mergebase__single1(void)
 {
 	git_oid result, one, two, expected;
+	size_t ahead, behind;
 
 	cl_git_pass(git_oid_fromstr(&one, "c47800c7266a2be04c571c04d5a6614691ea99bd "));
 	cl_git_pass(git_oid_fromstr(&two, "9fd738e8f7967c078dceed8190330fc8648ee56a"));
@@ -25,11 +28,20 @@ void test_revwalk_mergebase__single1(void)
 
 	cl_git_pass(git_merge_base(&result, _repo, &one, &two));
 	cl_assert(git_oid_cmp(&result, &expected) == 0);
+
+	cl_git_pass(git_graph_ahead_behind(&ahead, &behind, _repo, &one, &two));
+	cl_assert_equal_i(ahead, 2);
+	cl_assert_equal_i(behind, 1);
+
+	cl_git_pass(git_graph_ahead_behind(&ahead, &behind, _repo, &two, &one));
+	cl_assert_equal_i(ahead,  1);
+	cl_assert_equal_i(behind,  2);
 }
 
 void test_revwalk_mergebase__single2(void)
 {
 	git_oid result, one, two, expected;
+	size_t ahead, behind;
 
 	cl_git_pass(git_oid_fromstr(&one, "763d71aadf09a7951596c9746c024e7eece7c7af"));
 	cl_git_pass(git_oid_fromstr(&two, "a65fedf39aefe402d3bb6e24df4d4f5fe4547750"));
@@ -37,11 +49,20 @@ void test_revwalk_mergebase__single2(void)
 
 	cl_git_pass(git_merge_base(&result, _repo, &one, &two));
 	cl_assert(git_oid_cmp(&result, &expected) == 0);
+
+	cl_git_pass(git_graph_ahead_behind( &ahead, &behind, _repo, &one, &two));
+	cl_assert_equal_i(ahead,  4);
+	cl_assert_equal_i(behind,  1);
+
+	cl_git_pass(git_graph_ahead_behind( &ahead, &behind, _repo, &two, &one));
+	cl_assert_equal_i(ahead,  1);
+	cl_assert_equal_i(behind,  4);
 }
 
 void test_revwalk_mergebase__merged_branch(void)
 {
 	git_oid result, one, two, expected;
+	size_t ahead, behind;
 
 	cl_git_pass(git_oid_fromstr(&one, "a65fedf39aefe402d3bb6e24df4d4f5fe4547750"));
 	cl_git_pass(git_oid_fromstr(&two, "9fd738e8f7967c078dceed8190330fc8648ee56a"));
@@ -52,11 +73,38 @@ void test_revwalk_mergebase__merged_branch(void)
 
 	cl_git_pass(git_merge_base(&result, _repo, &two, &one));
 	cl_assert(git_oid_cmp(&result, &expected) == 0);
+
+	cl_git_pass(git_graph_ahead_behind(&ahead, &behind, _repo, &one, &two));
+	cl_assert_equal_i(ahead,  0);
+	cl_assert_equal_i(behind,  3);
+
+	cl_git_pass(git_graph_ahead_behind(&ahead, &behind, _repo, &two, &one));
+	cl_assert_equal_i(ahead,  3);
+	cl_assert_equal_i(behind,  0);
+}
+
+void test_revwalk_mergebase__two_way_merge(void)
+{
+	git_oid one, two;
+	size_t ahead, behind;
+
+	cl_git_pass(git_oid_fromstr(&one, "9b219343610c88a1187c996d0dc58330b55cee28"));
+	cl_git_pass(git_oid_fromstr(&two, "a953a018c5b10b20c86e69fef55ebc8ad4c5a417"));
+	cl_git_pass(git_graph_ahead_behind(&ahead, &behind, _repo2, &one, &two));
+
+	cl_assert_equal_i(ahead,  2);
+	cl_assert_equal_i(behind,  8);
+
+	cl_git_pass(git_graph_ahead_behind(&ahead, &behind, _repo2, &two, &one));
+
+	cl_assert_equal_i(ahead,  8);
+	cl_assert_equal_i(behind,  2);
 }
 
 void test_revwalk_mergebase__no_common_ancestor_returns_ENOTFOUND(void)
 {
 	git_oid result, one, two;
+	size_t ahead, behind;
 	int error;
 
 	cl_git_pass(git_oid_fromstr(&one, "763d71aadf09a7951596c9746c024e7eece7c7af"));
@@ -66,6 +114,11 @@ void test_revwalk_mergebase__no_common_ancestor_returns_ENOTFOUND(void)
 	cl_git_fail(error);
 
 	cl_assert_equal_i(GIT_ENOTFOUND, error);
+
+	cl_git_fail(git_graph_ahead_behind(&ahead, &behind, _repo, &one, &two));
+	cl_git_fail(error);
+
+	cl_assert_equal_i(GIT_ENOTFOUND, error);
 }
 
 void test_revwalk_mergebase__no_off_by_one_missing(void)
@@ -143,7 +196,7 @@ void test_revwalk_mergebase__many_merge_branch(void)
 }
 
 /*
- * $ git log --graph --all
+ * testrepo.git $ git log --graph --all
  * * commit 763d71aadf09a7951596c9746c024e7eece7c7af
  * | Author: nulltoken <emeric.fermas@gmail.com>
  * | Date:   Sun Oct 9 12:54:47 2011 +0200
@@ -222,3 +275,104 @@ void test_revwalk_mergebase__many_merge_branch(void)
  * 
  *       packed commit one
  */
+
+/*
+ * twowaymerge.git $ git log --graph --all
+ * *   commit 9b219343610c88a1187c996d0dc58330b55cee28
+ * |\  Merge: c37a783 2224e19
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:31:04 2012 -0800
+ * | | 
+ * | |     Merge branch 'first-branch' into second-branch
+ * | |   
+ * | * commit 2224e191514cb4bd8c566d80dac22dfcb1e9bb83
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:28:51 2012 -0800
+ * | | 
+ * | |     j
+ * | |   
+ * | * commit a41a49f8f5cd9b6cb14a076bf8394881ed0b4d19
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:28:39 2012 -0800
+ * | | 
+ * | |     i
+ * | |   
+ * | * commit 82bf9a1a10a4b25c1f14c9607b60970705e92545
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:28:28 2012 -0800
+ * | | 
+ * | |     h
+ * | |   
+ * * | commit c37a783c20d92ac92362a78a32860f7eebf938ef
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:30:57 2012 -0800
+ * | | 
+ * | |     n
+ * | |   
+ * * | commit 8b82fb1794cb1c8c7f172ec730a4c2db0ae3e650
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:30:43 2012 -0800
+ * | | 
+ * | |     m
+ * | |   
+ * * | commit 6ab5d28acbf3c3bdff276f7ccfdf29c1520e542f
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:30:38 2012 -0800
+ * | | 
+ * | |     l
+ * | |   
+ * * | commit 7b8c336c45fc6895c1c60827260fe5d798e5d247
+ * | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | Date:   Tue Nov 27 20:30:24 2012 -0800
+ * | | 
+ * | |     k
+ * | |     
+ * | | * commit 1c30b88f5f3ee66d78df6520a7de9e89b890818b
+ * | | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | | Date:   Tue Nov 27 20:28:10 2012 -0800
+ * | | | 
+ * | | |     e
+ * | | |    
+ * | | * commit 42b7311aa626e712891940c1ec5d5cba201946a4
+ * | | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | | Date:   Tue Nov 27 20:28:06 2012 -0800
+ * | | | 
+ * | | |     d
+ * | | |      
+ * | | *   commit a953a018c5b10b20c86e69fef55ebc8ad4c5a417
+ * | | |\  Merge: bd1732c cdf97fd
+ * | | |/  Author: Scott J. Goldman <scottjg@github.com>
+ * | |/|   Date:   Tue Nov 27 20:26:43 2012 -0800
+ * | | |   
+ * | | |       Merge branch 'first-branch'
+ * | | |    
+ * | * | commit cdf97fd3bb48eb3827638bb33d208f5fd32d0aa6
+ * | | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | | Date:   Tue Nov 27 20:24:46 2012 -0800
+ * | | | 
+ * | | |     g
+ * | | |    
+ * | * | commit ef0488f0b722f0be8bcb90a7730ac7efafd1d694
+ * | | | Author: Scott J. Goldman <scottjg@github.com>
+ * | | | Date:   Tue Nov 27 20:24:39 2012 -0800
+ * | | | 
+ * | | |     f
+ * | | |    
+ * | | * commit bd1732c43c68d712ad09e1d872b9be6d4b9efdc4
+ * | |/  Author: Scott J. Goldman <scottjg@github.com>
+ * | |   Date:   Tue Nov 27 17:43:58 2012 -0800
+ * | |   
+ * | |       c
+ * | |   
+ * | * commit 0c8a3f1f3d5f421cf83048c7c73ee3b55a5e0f29
+ * |/  Author: Scott J. Goldman <scottjg@github.com>
+ * |   Date:   Tue Nov 27 17:43:48 2012 -0800
+ * |   
+ * |       b
+ * |  
+ * * commit 1f4c0311a24b63f6fc209a59a1e404942d4a5006
+ *   Author: Scott J. Goldman <scottjg@github.com>
+ *   Date:   Tue Nov 27 17:43:41 2012 -0800
+ *
+ *       a
+ */