Add for_each_commit_graft() to iterate all grafts

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit.c

@@ -214,6 +214,14 @@ struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 	return commit_graft[pos];
 }
 
+int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
+{
+	int i, ret;
+	for (i = ret = 0; i < commit_graft_nr && !ret; i++)
+		ret = fn(commit_graft[i], cb_data);
+	return ret;
+}
+
 int write_shallow_commits(struct strbuf *out, int use_pack_protocol)
 {
 	int i, count = 0;

commit.h

@@ -142,6 +142,7 @@ struct commit_graft {
 	int nr_parent; /* < 0 if shallow commit */
 	unsigned char parent[FLEX_ARRAY][20]; /* more */
 };
+typedef int (*each_commit_graft_fn)(const struct commit_graft *, void *);
 
 struct commit_graft *read_graft_line(char *buf, int len);
 int register_commit_graft(struct commit_graft *, int);
@@ -154,6 +155,7 @@ extern struct commit_list *get_octopus_merge_bases(struct commit_list *in);
 extern int register_shallow(const unsigned char *sha1);
 extern int unregister_shallow(const unsigned char *sha1);
 extern int write_shallow_commits(struct strbuf *out, int use_pack_protocol);
+extern int for_each_commit_graft(each_commit_graft_fn, void *);
 extern int is_repository_shallow(void);
 extern struct commit_list *get_shallow_commits(struct object_array *heads,
 		int depth, int shallow_flag, int not_shallow_flag);