pack-write.c: plug a leak in stage_tmp_packfiles()

The function `stage_tmp_packfiles()` generates a filename to use for
staging the contents of what will become the pack's ".mtimes" file.

The name is generated in `write_mtimes_file()` and the result is
returned back to `stage_tmp_packfiles()` which uses it to rename the
temporary file into place via `rename_tmp_packfiles()`.

`write_mtimes_file()` returns a `const char *`, indicating that callers
are not expected to free its result (similar to, e.g., `oid_to_hex()`).
But callers are expected to free its result, so this return type is
incorrect.

Change the function's signature to return a non-const `char *`, and free
it at the end of `stage_tmp_packfiles()`.

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

pack-write.c

@@ -312,13 +312,13 @@ static void write_mtimes_trailer(struct hashfile *f, const unsigned char *hash)
 	hashwrite(f, hash, the_hash_algo->rawsz);
 }
 
-static const char *write_mtimes_file(struct packing_data *to_pack,
-				     struct pack_idx_entry **objects,
-				     uint32_t nr_objects,
-				     const unsigned char *hash)
+static char *write_mtimes_file(struct packing_data *to_pack,
+			       struct pack_idx_entry **objects,
+			       uint32_t nr_objects,
+			       const unsigned char *hash)
 {
 	struct strbuf tmp_file = STRBUF_INIT;
-	const char *mtimes_name;
+	char *mtimes_name;
 	struct hashfile *f;
 	int fd;
 
@@ -544,7 +544,7 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
 			 char **idx_tmp_name)
 {
 	const char *rev_tmp_name = NULL;
-	const char *mtimes_tmp_name = NULL;
+	char *mtimes_tmp_name = NULL;
 
 	if (adjust_shared_perm(pack_tmp_name))
 		die_errno("unable to make temporary pack file readable");
@@ -568,6 +568,8 @@ void stage_tmp_packfiles(struct strbuf *name_buffer,
 		rename_tmp_packfile(name_buffer, rev_tmp_name, "rev");
 	if (mtimes_tmp_name)
 		rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
+
+	free(mtimes_tmp_name);
 }
 
 void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought)