[PATCH v2 2/3] sequencer: add a "goto cleanup" to do_reset()

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

Restructure code that's mostly added in 9055e401dd6 (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 that I'm not
bothering to covert, those don't need to rollback anything, or free
any resources, so let's leave, even though they could safely "goto
cleanup" as well.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 sequencer.c | 32 +++++++++++++-------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 6872b7b00a4..457eba4ab10 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3650,7 +3650,7 @@ 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;
@@ -3684,10 +3684,8 @@ 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;
 		}
 	}
 
@@ -3703,24 +3701,18 @@ 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);
@@ -3728,13 +3720,15 @@ static int do_reset(struct repository *r,
 
 	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;
 }
-- 
2.33.0.1446.g6af949f83bd