sequencer: add a "goto cleanup" to do_reset()

avar · gitster · commit 0c52cf8e00f6 · 2021-10-13T10:37:11.000-07:00
Restructure code that's mostly added in 9055e40 (sequencer: introduce new commands to reset the revision, 2018-04-25) to avoid code duplication, and to make freeing other resources easier in a subsequent commit. It's safe to initialize "tree_desc" to be zero'd out in order to unconditionally free desc.buffer, it won't be initialized on the first couple of "goto"'s. There are three earlier "return"'s in this function which should probably be made to use this new "cleanup" too, per [1] it looks like they're leaving behind stale locks. But let's not try to fix every potential bug here now, I'm just trying to narrowly plug a memory leak. 1. https://lore.kernel.org/git/CABPp-BH=3DP-dXRCphY53-3eZd1TU8h5GY_M12nnbEGm-UYB9Q@mail.gmail.com/ Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/sequencer.c b/sequencer.c
@@ -3644,7 +3644,7 @@ static int do_reset(struct repository *r,
 	struct strbuf ref_name = STRBUF_INIT;
 	struct object_id oid;
 	struct lock_file lock = LOCK_INIT;
-	struct tree_desc desc;
+	struct tree_desc desc = { 0 };
 	struct tree *tree;
 	struct unpack_trees_options unpack_tree_opts;
 	int ret = 0;
@@ -3678,10 +3678,8 @@ static int do_reset(struct repository *r,
 		strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
 		if (get_oid(ref_name.buf, &oid) &&
 		    get_oid(ref_name.buf + strlen("refs/rewritten/"), &oid)) {
-			error(_("could not read '%s'"), ref_name.buf);
-			rollback_lock_file(&lock);
-			strbuf_release(&ref_name);
-			return -1;
+			ret = error(_("could not read '%s'"), ref_name.buf);
+			goto cleanup;
 		}
 	}
 
@@ -3696,38 +3694,34 @@ static int do_reset(struct repository *r,
 	init_checkout_metadata(&unpack_tree_opts.meta, name, &oid, NULL);
 
 	if (repo_read_index_unmerged(r)) {
-		rollback_lock_file(&lock);
-		strbuf_release(&ref_name);
-		return error_resolve_conflict(_(action_name(opts)));
+		ret = error_resolve_conflict(_(action_name(opts)));
+		goto cleanup;
 	}
 
 	if (!fill_tree_descriptor(r, &desc, &oid)) {
-		error(_("failed to find tree of %s"), oid_to_hex(&oid));
-		rollback_lock_file(&lock);
-		free((void *)desc.buffer);
-		strbuf_release(&ref_name);
-		return -1;
+		ret = error(_("failed to find tree of %s"), oid_to_hex(&oid));
+		goto cleanup;
 	}
 
 	if (unpack_trees(1, &desc, &unpack_tree_opts)) {
-		rollback_lock_file(&lock);
-		free((void *)desc.buffer);
-		strbuf_release(&ref_name);
-		return -1;
+		ret = -1;
+		goto cleanup;
 	}
 
 	tree = parse_tree_indirect(&oid);
 	prime_cache_tree(r, r->index, tree);
 
 	if (write_locked_index(r->index, &lock, COMMIT_LOCK) < 0)
 		ret = error(_("could not write index"));
-	free((void *)desc.buffer);
 
 	if (!ret)
 		ret = update_ref(reflog_message(opts, "reset", "'%.*s'",
 						len, name), "HEAD", &oid,
 				 NULL, 0, UPDATE_REFS_MSG_ON_ERR);
-
+cleanup:
+	free((void *)desc.buffer);
+	if (ret < 0)
+		rollback_lock_file(&lock);
 	strbuf_release(&ref_name);
 	return ret;
 }
