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>
diff --git a/diff.c b/diff.c
index 97c62f4..7c730fe 100644
--- a/diff.c
+++ b/diff.c
@@ -4190,7 +4190,7 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,
die_errno("readlink(%s)", name);
prep_temp_blob(r->index, name, temp, sb.buf, sb.len,
(one->oid_valid ?
- &one->oid : &null_oid),
+ &one->oid : null_oid()),
(one->oid_valid ?
one->mode : S_IFLNK));
strbuf_release(&sb);
@@ -4199,7 +4199,7 @@ static struct diff_tempfile *prepare_temp_file(struct repository *r,
/* we can borrow from the file in the work tree */
temp->name = name;
if (!one->oid_valid)
- oid_to_hex_r(temp->hex, &null_oid);
+ oid_to_hex_r(temp->hex, null_oid());
else
oid_to_hex_r(temp->hex, &one->oid);
/* Even though we may sometimes borrow the
