commit-graph: fix memory leak in misused string_list API

When this code was migrated to the string_list API in
d88b14b3fd6 (commit-graph: use string-list API for input, 2018-06-27)
it was made to use used both STRING_LIST_INIT_NODUP and a
strbuf_detach() pattern.

Those should not be used together if string_list_clear() is expected
to free the memory, instead we need to either use STRING_LIST_INIT_DUP
with a string_list_append_nodup(), or a STRING_LIST_INIT_NODUP and
manually fiddle with the "strdup_strings" member before calling
string_list_clear(). Let's do the former.

Since "strdup_strings = 1" is set now other code might be broken by
relying on "pack_indexes" not to duplicate it strings, but that
doesn't happen. When we pass this down to write_commit_graph() that
code uses the "struct string_list" without modifying it. Let's add a
"const" to the variable to have the compiler enforce that assumption.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/commit-graph.h b/commit-graph.h
index 04a94e1830..2e3ac35237 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -142,7 +142,7 @@ int write_commit_graph_reachable(struct object_directory *odb,
 				 enum commit_graph_write_flags flags,
 				 const struct commit_graph_opts *opts);
 int write_commit_graph(struct object_directory *odb,
-		       struct string_list *pack_indexes,
+		       const struct string_list *pack_indexes,
 		       struct oidset *commits,
 		       enum commit_graph_write_flags flags,
 		       const struct commit_graph_opts *opts);