Add git_merge_bases_many.

CHANGELOG.md

@@ -58,3 +58,6 @@ v0.21 + 1
 
 * Introduce git_merge_bases() and the git_oidarray type to expose all
   merge bases between two commits.
+
+* Introduce git_merge_bases_many() to expose all merge bases between
+  multiple commits.

include/git2/merge.h

@@ -351,6 +351,21 @@ GIT_EXTERN(int) git_merge_base_many(
 	size_t length,
 	const git_oid input_array[]);
 
+/**
+ * Find all merge bases given a list of commits
+ *
+ * @param out array in which to store the resulting ids
+ * @param repo the repository where the commits exist
+ * @param length The number of commits in the provided `input_array`
+ * @param input_array oids of the commits
+ * @return Zero on success; GIT_ENOTFOUND or -1 on failure.
+ */
+GIT_EXTERN(int) git_merge_bases_many(
+	git_oidarray *out,
+	git_repository *repo,
+	size_t length,
+	const git_oid input_array[]);
+
 /**
  * Find a merge base in preparation for an octopus merge
  *

src/merge.c

@@ -116,6 +116,73 @@ cleanup:
 	return error;
 }
 
+int git_merge_bases_many(git_oidarray *out, git_repository *repo, size_t length, const git_oid input_array[])
+{
+	git_revwalk *walk;
+	git_vector list;
+	git_commit_list *current, *result = NULL;
+	int error = -1;
+	unsigned int i;
+	git_commit_list_node *commit;
+	git_array_oid_t array;
+
+	assert(out && repo && input_array);
+
+	if (length < 2) {
+		giterr_set(GITERR_INVALID, "At least two commits are required to find an ancestor. Provided 'length' was %u.", length);
+		return -1;
+	}
+
+	if (git_vector_init(&list, length - 1, NULL) < 0)
+		return -1;
+
+	if (git_revwalk_new(&walk, repo) < 0)
+		goto cleanup;
+
+	for (i = 1; i < length; i++) {
+		commit = git_revwalk__commit_lookup(walk, &input_array[i]);
+		if (commit == NULL)
+			goto cleanup;
+
+		git_vector_insert(&list, commit);
+	}
+
+	commit = git_revwalk__commit_lookup(walk, &input_array[0]);
+	if (commit == NULL)
+		goto cleanup;
+
+	if (git_merge__bases_many(&result, walk, commit, &list) < 0)
+		goto cleanup;
+
+	if (!result) {
+		giterr_set(GITERR_MERGE, "No merge base found");
+		error = GIT_ENOTFOUND;
+		goto cleanup;
+	}
+
+	git_array_init(array);
+
+	current = result;
+	while (current) {
+		git_oid *id = git_array_alloc(array);
+		if (id == NULL)
+			goto cleanup;
+
+		git_oid_cpy(id, &current->item->oid);
+		current = current->next;
+	}
+
+	git_oidarray__from_array(out, &array);
+
+	error = 0;
+
+cleanup:
+	git_commit_list_free(&result);
+	git_revwalk_free(walk);
+	git_vector_free(&list);
+	return error;
+}
+
 int git_merge_base_octopus(git_oid *out, git_repository *repo, size_t length, const git_oid input_array[])
 {
 	git_oid result;

tests/revwalk/mergebase.c

@@ -127,7 +127,7 @@ void test_revwalk_mergebase__prefer_youngest_merge_base(void)
 {
 	git_oid result, one, two, expected;
 
-	cl_git_pass(git_oid_fromstr(&one, "a4a7dce85cf63874e984719f4fdd239f5145052f "));
+	cl_git_pass(git_oid_fromstr(&one, "a4a7dce85cf63874e984719f4fdd239f5145052f"));
 	cl_git_pass(git_oid_fromstr(&two, "be3563ae3f795b2b4353bcce3a527ad0a4f7f644"));
 	cl_git_pass(git_oid_fromstr(&expected, "c47800c7266a2be04c571c04d5a6614691ea99bd"));
 
@@ -140,7 +140,7 @@ void test_revwalk_mergebase__multiple_merge_bases(void)
 	git_oid one, two, expected1, expected2;
 	git_oidarray result = {NULL, 0};
 
-	cl_git_pass(git_oid_fromstr(&one, "a4a7dce85cf63874e984719f4fdd239f5145052f "));
+	cl_git_pass(git_oid_fromstr(&one, "a4a7dce85cf63874e984719f4fdd239f5145052f"));
 	cl_git_pass(git_oid_fromstr(&two, "be3563ae3f795b2b4353bcce3a527ad0a4f7f644"));
 	cl_git_pass(git_oid_fromstr(&expected1, "c47800c7266a2be04c571c04d5a6614691ea99bd"));
 	cl_git_pass(git_oid_fromstr(&expected2, "9fd738e8f7967c078dceed8190330fc8648ee56a"));
@@ -153,6 +153,26 @@ void test_revwalk_mergebase__multiple_merge_bases(void)
 	git_oidarray_free(&result);
 }
 
+void test_revwalk_mergebase__multiple_merge_bases_many_commits(void)
+{
+	git_oid expected1, expected2;
+	git_oidarray result = {NULL, 0};
+
+	git_oid *input = git__malloc(sizeof(git_oid) * 2);
+
+	cl_git_pass(git_oid_fromstr(&input[0], "a4a7dce85cf63874e984719f4fdd239f5145052f"));
+	cl_git_pass(git_oid_fromstr(&input[1], "be3563ae3f795b2b4353bcce3a527ad0a4f7f644"));
+	cl_git_pass(git_oid_fromstr(&expected1, "c47800c7266a2be04c571c04d5a6614691ea99bd"));
+	cl_git_pass(git_oid_fromstr(&expected2, "9fd738e8f7967c078dceed8190330fc8648ee56a"));
+
+	cl_git_pass(git_merge_bases_many(&result, _repo, 2, input));
+	cl_assert_equal_i(2, result.count);
+	cl_assert_equal_oid(&expected1, &result.ids[0]);
+	cl_assert_equal_oid(&expected2, &result.ids[1]);
+
+	git_oidarray_free(&result);
+}
+
 void test_revwalk_mergebase__no_off_by_one_missing(void)
 {
 	git_oid result, one, two;