merge: Expose git_merge_base_many()

include/git2/merge.h

@@ -30,6 +30,16 @@ GIT_BEGIN_DECL
  */
 GIT_EXTERN(int) git_merge_base(git_oid *out, git_repository *repo, git_oid *one, git_oid *two);
 
+/**
+ * Find a merge base given a list of commits
+ *
+ * @param out the OID of a merge base considering all the commits
+ * @param repo the repository where the commits exist
+ * @param input_array oids of the commits
+ * @param length The number of commits in the provided `input_array`
+ */
+GIT_EXTERN(int) git_merge_base_many(git_oid *out, git_repository *repo, const git_oid input_array[], size_t length);
+
 /** @} */
 GIT_END_DECL
 #endif

src/revwalk.c

@@ -104,6 +104,9 @@ static void commit_list_free(commit_list **list_p)
 {
 	commit_list *list = *list_p;
 
+	if (list == NULL)
+		return;
+
 	while (list) {
 		commit_list *temp = list;
 		list = temp->next;
@@ -345,6 +348,59 @@ static int merge_bases_many(commit_list **out, git_revwalk *walk, commit_object
 	return 0;
 }
 
+int git_merge_base_many(git_oid *out, git_repository *repo, const git_oid input_array[], size_t length)
+{
+	git_revwalk *walk;
+	git_vector list;
+	commit_list *result = NULL;
+	int error = -1;
+	unsigned int i;
+	commit_object *commit;
+
+	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 = commit_lookup(walk, &input_array[i]);
+		if (commit == NULL)
+			goto cleanup;
+
+		git_vector_insert(&list, commit);
+	}
+
+	commit = commit_lookup(walk, &input_array[0]);
+	if (commit == NULL)
+		goto cleanup;
+
+	if (merge_bases_many(&result, walk, commit, &list) < 0)
+		goto cleanup;
+
+	if (!result) {
+		error = GIT_ENOTFOUND;
+		goto cleanup;
+	}
+
+	git_oid_cpy(out, &result->item->oid);
+
+	error = 0;
+
+cleanup:
+	commit_list_free(&result);
+	git_revwalk_free(walk);
+	git_vector_free(&list);
+	return error;
+}
+
 int git_merge_base(git_oid *out, git_repository *repo, git_oid *one, git_oid *two)
 {
 	git_revwalk *walk;

tests-clar/revwalk/mergebase.c

@@ -1,4 +1,5 @@
 #include "clar_libgit2.h"
+#include "vector.h"
 
 static git_repository *_repo;
 
@@ -65,6 +66,71 @@ void test_revwalk_mergebase__no_common_ancestor_returns_ENOTFOUND(void)
 	cl_assert_equal_i(GIT_ENOTFOUND, error);
 }
 
+static void assert_mergebase_many(const char *expected_sha, int count, ...)
+{
+	va_list ap;
+	int i; 
+	git_oid *oids;
+	git_oid oid, expected;
+	char *partial_oid;
+	git_object *object;
+
+	oids = git__malloc(count * sizeof(git_oid));
+	cl_assert(oids != NULL);
+
+	memset(oids, 0x0, count * sizeof(git_oid));
+
+	va_start(ap, count);
+	
+	for (i = 0; i < count; ++i) {
+		partial_oid = va_arg(ap, char *);
+		cl_git_pass(git_oid_fromstrn(&oid, partial_oid, strlen(partial_oid)));
+
+		cl_git_pass(git_object_lookup_prefix(&object, _repo, &oid, strlen(partial_oid), GIT_OBJ_COMMIT));
+		git_oid_cpy(&oids[i], git_object_id(object));
+		git_object_free(object);
+	}
+
+	va_end(ap);
+
+	if (expected_sha == NULL)
+		cl_assert_equal_i(GIT_ENOTFOUND, git_merge_base_many(&oid, _repo, oids, count));
+	else {
+		cl_git_pass(git_merge_base_many(&oid, _repo, oids, count));
+		cl_git_pass(git_oid_fromstr(&expected, expected_sha));
+
+		cl_assert(git_oid_cmp(&expected, &oid) == 0);
+	}
+
+	git__free(oids);
+}
+
+void test_revwalk_mergebase__many_no_common_ancestor_returns_ENOTFOUND(void)
+{
+	assert_mergebase_many(NULL, 3, "41bc8c", "e90810", "a65fed");
+	assert_mergebase_many(NULL, 3, "e90810", "41bc8c", "a65fed");
+	assert_mergebase_many(NULL, 3, "e90810", "a65fed", "41bc8c");
+	assert_mergebase_many(NULL, 3, "a65fed", "e90810", "41bc8c");
+	assert_mergebase_many(NULL, 3, "a65fed", "e90810", "41bc8c");
+	assert_mergebase_many(NULL, 3, "a65fed", "41bc8c", "e90810");
+
+	assert_mergebase_many(NULL, 3, "e90810", "763d71", "a65fed");
+}
+
+void test_revwalk_mergebase__many_merge_branch(void)
+{
+	assert_mergebase_many("c47800c7266a2be04c571c04d5a6614691ea99bd", 3, "a65fed", "763d71", "849607");
+
+	assert_mergebase_many("c47800c7266a2be04c571c04d5a6614691ea99bd", 3, "763d71", "e90810", "a65fed");
+	assert_mergebase_many("c47800c7266a2be04c571c04d5a6614691ea99bd", 3, "763d71", "a65fed", "e90810");
+
+	assert_mergebase_many("c47800c7266a2be04c571c04d5a6614691ea99bd", 3, "a65fed", "763d71", "849607");
+	assert_mergebase_many("c47800c7266a2be04c571c04d5a6614691ea99bd", 3, "a65fed", "849607", "763d71");
+	assert_mergebase_many("8496071c1b46c854b31185ea97743be6a8774479", 3, "849607", "a65fed", "763d71");
+
+	assert_mergebase_many("5b5b025afb0b4c913b4c338a42934a3863bf3644", 5, "5b5b02", "763d71", "a4a7dc", "a65fed", "41bc8c");
+}
+
 /*
  * $ git log --graph --all
  * * commit 763d71aadf09a7951596c9746c024e7eece7c7af