builtin/commit-graph.c: UNLEAK variables

`graph_verify()`, `graph_read()` and `graph_write()` do the hard work of
`cmd_commit_graph()`. As soon as these return, so does
`cmd_commit_graph()`.

`strbuf_getline()` may allocate memory in the strbuf, yet return EOF.
We need to release the strbuf or UNLEAK it. Go for the latter since we
are close to returning from `graph_write()`.

`graph_write()` also fails to free the strings in the string list. They
have been added to the list with `strdup_strings` set to 0. We could
flip `strdup_strings` before clearing the list, which is our usual hack
in situations like this. But since we are about to exit, let's just
UNLEAK the whole string list instead.

UNLEAK `graph` in `graph_verify`. While at it, and for consistency,
UNLEAK in `graph_read()` as well, and remove an unnecessary UNLEAK just
before dying.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit-graph.c

@@ -64,6 +64,7 @@ static int graph_verify(int argc, const char **argv)
 	if (!graph)
 		return 0;
 
+	UNLEAK(graph);
 	return verify_commit_graph(the_repository, graph);
 }
 
@@ -89,10 +90,8 @@ static int graph_read(int argc, const char **argv)
 	graph_name = get_commit_graph_filename(opts.obj_dir);
 	graph = load_commit_graph_one(graph_name);
 
-	if (!graph) {
-		UNLEAK(graph_name);
+	if (!graph)
 		die("graph file %s does not exist", graph_name);
-	}
 
 	FREE_AND_NULL(graph_name);
 
@@ -115,7 +114,7 @@ static int graph_read(int argc, const char **argv)
 		printf(" large_edges");
 	printf("\n");
 
-	free_commit_graph(graph);
+	UNLEAK(graph);
 
 	return 0;
 }
@@ -166,6 +165,8 @@ static int graph_write(int argc, const char **argv)
 			pack_indexes = &lines;
 		if (opts.stdin_commits)
 			commit_hex = &lines;
+
+		UNLEAK(buf);
 	}
 
 	write_commit_graph(opts.obj_dir,
@@ -174,7 +175,7 @@ static int graph_write(int argc, const char **argv)
 			   opts.append,
 			   1);
 
-	string_list_clear(&lines, 0);
+	UNLEAK(lines);
 	return 0;
 }