lockfile API users: simplify and don't leak "path"

Fix a memory leak in code added in 6c622f9f0bb (commit-graph: write
commit-graph chains, 2019-06-18). We needed to free the "lock_name" if
we encounter errors, and the "graph_name" after we'd run unlink() on
it.

For the case of write_commit_graph_file() refactoring the code to free
the "lock_name" after we were done using the "struct lock_file lk"
would have made the control flow more complex. Luckily we can free the
"lock_file" right after the hold_lock_file_for_update() call, if it
makes use of "path" at all it'll have copied its contents to a "struct
strbuf" of its own.

While I'm at it let's fix code added in fb10ca5b543 (sparse-checkout:
write using lockfile, 2019-11-21) in write_patterns_and_update() to
avoid the same complexity that I thought I needed when I wrote the
initial fix for write_commit_graph_file(). We can free the
"sparse_filename" right after calling hold_lock_file_for_update(), we
don't need to wait until we're exiting the function to do so.

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

1 files changed, 1 insertions, 2 deletions

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 9c338d33ea..270ad49c2b 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -328,11 +328,11 @@ static int write_patterns_and_update(struct pattern_list *pl)
 
 	fd = hold_lock_file_for_update(&lk, sparse_filename,
 				      LOCK_DIE_ON_ERROR);
+	free(sparse_filename);
 
 	result = update_working_directory(pl);
 	if (result) {
 		rollback_lock_file(&lk);
-		free(sparse_filename);
 		clear_pattern_list(pl);
 		update_working_directory(NULL);
 		return result;
@@ -348,7 +348,6 @@ static int write_patterns_and_update(struct pattern_list *pl)
 	fflush(fp);
 	commit_lock_file(&lk);
 
-	free(sparse_filename);
 	clear_pattern_list(pl);
 
 	return 0;