range-diff: plug memory leak in common invocation

Create a public release_patch() version of the private free_patch()
function added in 13b5af22f39 (apply: move libified code from
builtin/apply.c to apply.{c,h}, 2016-04-22). Unlike the existing
function this one doesn't free() the "struct patch" itself, so we can
use it for variables on the stack.

Use it in range-diff.c to fix a memory leak in common range-diff
invocations, e.g.:

    git -P range-diff origin/master origin/next origin/seen

Would emit several errors when compiled with SANITIZE=leak, but now
runs cleanly.

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

1 files changed, 6 insertions, 1 deletions

diff --git a/apply.c b/apply.c
index 0912307bd9..01f9181642 100644
--- a/apply.c
+++ b/apply.c
@@ -219,13 +219,18 @@ static void free_fragment_list(struct fragment *list)
 	}
 }
 
-static void free_patch(struct patch *patch)
+void release_patch(struct patch *patch)
 {
 	free_fragment_list(patch->fragments);
 	free(patch->def_name);
 	free(patch->old_name);
 	free(patch->new_name);
 	free(patch->result);
+}
+
+static void free_patch(struct patch *patch)
+{
+	release_patch(patch);
 	free(patch);
 }