[PATCH 08/10] unpack-trees: don't leak memory in verify_clean_subdirectory()

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Fix two different but related memory leaks in
verify_clean_subdirectory(). We leaked both the "pathbuf" if
read_directory() returned non-zero, and we never cleaned up our own
"struct dir_struct" either.

 * "pathbuf": When the read_directory() call followed by the
   free(pathbuf) was added in c81935348be (Fix switching to a branch
   with D/F when current branch has file D., 2007-03-15) we didn't
   bother to free() before we called die().

   But when this code was later libified in 203a2fe1170 (Allow callers
   of unpack_trees() to handle failure, 2008-02-07) we started to leak
   as we returned data to the caller. This fixes that memory leak,
   which can be observed under SANITIZE=leak with e.g. the
   "t1001-read-tree-m-2way.sh" test.

 * "struct dir_struct": We've leaked the dir_struct ever since this
   code was added back in c81935348be.

   When that commit was written there wasn't an equivalent of
   dir_clear(). Since it was added in 270be816049 (dir.c: provide
   clear_directory() for reclaiming dir_struct memory, 2013-01-06)
   we've omitted freeing the memory allocated here.

   This memory leak could also be observed under SANITIZE=leak and the
   "t1001-read-tree-m-2way.sh" test.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 unpack-trees.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/unpack-trees.c b/unpack-trees.c
index bea598c9ece..260e7ec5bb4 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -2138,9 +2138,10 @@ static int verify_clean_subdirectory(const struct cache_entry *ce,
 
 	d.exclude_per_dir = o->dir.exclude_per_dir;
 	i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
+	dir_clear(&d);
+	free(pathbuf);
 	if (i)
 		return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
-	free(pathbuf);
 	return cnt;
 }
 
-- 
2.33.0.1404.g83021034c5d