commit: fix leaking parents when calling `commit_tree_extended()`

When creating commits via `commit_tree_extended()`, the caller passes in
a string list of parents. This call implicitly transfers ownership of
that list to the function, which is quite surprising to begin with. But
to make matters worse, `commit_tree_extended()` doesn't even bother to
free the list of parents in error cases. The result is a memory leak,
and one that the caller cannot fix by themselves because they do not
know whether parts of the string list have already been released.

Refactor the code such that callers can keep ownership of the list of
parents, which is getting indicated by parameter being a constant
pointer now. Free the lists at the calling site and add a common exit
path to those sites as required.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/commit.h b/commit.h
index 62fe0d77a7..442e50ff24 100644
--- a/commit.h
+++ b/commit.h
@@ -260,19 +260,19 @@ struct commit_extra_header {
 	size_t len;
 };
 
-void append_merge_tag_headers(struct commit_list *parents,
+void append_merge_tag_headers(const struct commit_list *parents,
 			      struct commit_extra_header ***tail);
 
 int commit_tree(const char *msg, size_t msg_len,
 		const struct object_id *tree,
-		struct commit_list *parents, struct object_id *ret,
+		const struct commit_list *parents, struct object_id *ret,
 		const char *author, const char *sign_commit);
 
 int commit_tree_extended(const char *msg, size_t msg_len,
 			 const struct object_id *tree,
-			 struct commit_list *parents, struct object_id *ret,
+			 const struct commit_list *parents, struct object_id *ret,
 			 const char *author, const char *committer,
-			 const char *sign_commit, struct commit_extra_header *);
+			 const char *sign_commit, const struct commit_extra_header *);
 
 struct commit_extra_header *read_commit_extra_headers(struct commit *, const char **);
 
@@ -306,7 +306,7 @@ struct merge_remote_desc {
 	struct object *obj; /* the named object, could be a tag */
 	char name[FLEX_ARRAY];
 };
-struct merge_remote_desc *merge_remote_util(struct commit *);
+struct merge_remote_desc *merge_remote_util(const struct commit *);
 void set_merge_remote_desc(struct commit *commit,
 			   const char *name, struct object *obj);