treewide: prefer lockfiles on the stack

There is no longer any need to allocate and leak a `struct lock_file`.
The previous patch addressed an instance where we needed a minor tweak
alongside the trivial changes.

Deal with the remaining instances where we allocate and leak a struct
within a single function. Change them to have the `struct lock_file` on
the stack instead.

These instances were identified by running `git grep "^\s*struct
lock_file\s*\*"`.

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

4 files changed, 23 insertions, 29 deletions

diff --git a/builtin/am.c b/builtin/am.c
index d7513f5375..4e16fd428f 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1134,11 +1134,11 @@ static const char *msgnum(const struct am_state *state)
  */
 static void refresh_and_write_cache(void)
 {
-	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+	struct lock_file lock_file = LOCK_INIT;
 
-	hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 	refresh_cache(REFRESH_QUIET);
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write index file"));
 }
 
@@ -1946,15 +1946,14 @@ next:
  */
 static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
 {
-	struct lock_file *lock_file;
+	struct lock_file lock_file = LOCK_INIT;
 	struct unpack_trees_options opts;
 	struct tree_desc t[2];
 
 	if (parse_tree(head) || parse_tree(remote))
 		return -1;
 
-	lock_file = xcalloc(1, sizeof(struct lock_file));
-	hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 
 	refresh_cache(REFRESH_QUIET);
 
@@ -1970,11 +1969,11 @@ static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
 	init_tree_desc(&t[1], remote->buffer, remote->size);
 
 	if (unpack_trees(2, t, &opts)) {
-		rollback_lock_file(lock_file);
+		rollback_lock_file(&lock_file);
 		return -1;
 	}
 
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
 	return 0;
@@ -1986,15 +1985,14 @@ static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
  */
 static int merge_tree(struct tree *tree)
 {
-	struct lock_file *lock_file;
+	struct lock_file lock_file = LOCK_INIT;
 	struct unpack_trees_options opts;
 	struct tree_desc t[1];
 
 	if (parse_tree(tree))
 		return -1;
 
-	lock_file = xcalloc(1, sizeof(struct lock_file));
-	hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 
 	memset(&opts, 0, sizeof(opts));
 	opts.head_idx = 1;
@@ -2005,11 +2003,11 @@ static int merge_tree(struct tree *tree)
 	init_tree_desc(&t[0], tree->buffer, tree->size);
 
 	if (unpack_trees(1, t, &opts)) {
-		rollback_lock_file(lock_file);
+		rollback_lock_file(&lock_file);
 		return -1;
 	}
 
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
 	return 0;
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 3345a0d16f..34c3c5b615 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -247,7 +247,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 	struct object_id rev;
 	struct commit *head;
 	int errs = 0;
-	struct lock_file *lock_file;
+	struct lock_file lock_file = LOCK_INIT;
 
 	if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 		die(_("'%s' cannot be used with updating paths"), "--track");
@@ -275,9 +275,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 		return run_add_interactive(revision, "--patch=checkout",
 					   &opts->pathspec);
 
-	lock_file = xcalloc(1, sizeof(struct lock_file));
-
-	hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 	if (read_cache_preload(&opts->pathspec) < 0)
 		return error(_("index file corrupt"));
 
@@ -376,7 +374,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 	}
 	errs |= finish_delayed_checkout(&state);
 
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
 	read_ref_full("HEAD", 0, rev.hash, NULL);
@@ -472,9 +470,9 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			      int *writeout_error)
 {
 	int ret;
-	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+	struct lock_file lock_file = LOCK_INIT;
 
-	hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 	if (read_cache_preload(NULL) < 0)
 		return error(_("index file corrupt"));
 
@@ -591,7 +589,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 	if (!cache_tree_fully_valid(active_cache_tree))
 		cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
 	if (!opts->force && !opts->quiet)
diff --git a/builtin/clone.c b/builtin/clone.c
index dbddd98f80..96a3aaaa1f 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -706,7 +706,7 @@ static int checkout(int submodule_progress)
 {
 	struct object_id oid;
 	char *head;
-	struct lock_file *lock_file;
+	struct lock_file lock_file = LOCK_INIT;
 	struct unpack_trees_options opts;
 	struct tree *tree;
 	struct tree_desc t;
@@ -733,8 +733,7 @@ static int checkout(int submodule_progress)
 	/* We need to be in the new work tree for the checkout */
 	setup_work_tree();
 
-	lock_file = xcalloc(1, sizeof(struct lock_file));
-	hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
+	hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 
 	memset(&opts, 0, sizeof opts);
 	opts.update = 1;
@@ -750,7 +749,7 @@ static int checkout(int submodule_progress)
 	if (unpack_trees(1, &t, &opts) < 0)
 		die(_("unable to checkout working tree"));
 
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+	if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
 
 	err |= run_hook_le(NULL, "post-checkout", sha1_to_hex(null_sha1),
diff --git a/builtin/diff.c b/builtin/diff.c
index 7e3ebcea38..91995965d7 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -203,17 +203,16 @@ static int builtin_diff_combined(struct rev_info *revs,
 
 static void refresh_index_quietly(void)
 {
-	struct lock_file *lock_file;
+	struct lock_file lock_file = LOCK_INIT;
 	int fd;
 
-	lock_file = xcalloc(1, sizeof(struct lock_file));
-	fd = hold_locked_index(lock_file, 0);
+	fd = hold_locked_index(&lock_file, 0);
 	if (fd < 0)
 		return;
 	discard_cache();
 	read_cache();
 	refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
-	update_index_if_able(&the_index, lock_file);
+	update_index_if_able(&the_index, &lock_file);
 }
 
 static int builtin_diff_files(struct rev_info *revs, int argc, const char **argv)