hash: provide per-algorithm null OIDs

Up until recently, object IDs did not have an algorithm member, only a
hash.  Consequently, it was possible to share one null (all-zeros)
object ID among all hash algorithms.  Now that we're going to be
handling objects from multiple hash algorithms, it's important to make
sure that all object IDs have a correct algorithm field.

Introduce a per-algorithm null OID, and add it to struct hash_algo.
Introduce a wrapper function as well, and use it everywhere we used to
use the null_oid constant.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson
2021-04-26 01:02:56 +00:00
committed by Junio C Hamano
parent 5a6dce70d7
commit 14228447c9
42 changed files with 119 additions and 95 deletions

View File

@ -600,7 +600,7 @@ int notes_merge(struct notes_merge_options *o,
/* Find merge bases */
bases = get_merge_bases(local, remote);
if (!bases) {
base_oid = &null_oid;
base_oid = null_oid();
base_tree_oid = the_hash_algo->empty_tree;
if (o->verbosity >= 4)
printf("No merge base found; doing history-less merge\n");