packed_object_info(): use object_id for returning delta base

If a caller sets the object_info.delta_base_sha1 to a non-NULL pointer,
we'll write the oid of the object's delta base to it. But we can
increase our type safety by switching this to a real object_id struct.
All of our callers are just pointing into the hash member of an
object_id anyway, so there's no inconvenience.

Note that we do still keep it as a pointer-to-struct, because the NULL
sentinel value tells us whether the caller is even interested in the
information.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/cat-file.c

@@ -262,7 +262,7 @@ static void expand_atom(struct strbuf *sb, const char *atom, int len,
 			strbuf_addstr(sb, data->rest);
 	} else if (is_atom("deltabase", atom, len)) {
 		if (data->mark_query)
-			data->info.delta_base_sha1 = data->delta_base_oid.hash;
+			data->info.delta_base_oid = &data->delta_base_oid;
 		else
 			strbuf_addstr(sb,
 				      oid_to_hex(&data->delta_base_oid));

object-store.h

@@ -300,7 +300,7 @@ struct object_info {
 	enum object_type *typep;
 	unsigned long *sizep;
 	off_t *disk_sizep;
-	unsigned char *delta_base_sha1;
+	struct object_id *delta_base_oid;
 	struct strbuf *type_name;
 	void **contentp;
 

packfile.c

@@ -1556,7 +1556,7 @@ int packed_object_info(struct repository *r, struct packed_git *p,
 		}
 	}
 
-	if (oi->delta_base_sha1) {
+	if (oi->delta_base_oid) {
 		if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
 			const unsigned char *base;
 
@@ -1567,9 +1567,9 @@ int packed_object_info(struct repository *r, struct packed_git *p,
 				goto out;
 			}
 
-			hashcpy(oi->delta_base_sha1, base);
+			hashcpy(oi->delta_base_oid->hash, base);
 		} else
-			hashclr(oi->delta_base_sha1);
+			oidclr(oi->delta_base_oid);
 	}
 
 	oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :

ref-filter.c

@@ -279,9 +279,9 @@ static int deltabase_atom_parser(const struct ref_format *format, struct used_at
 	if (arg)
 		return strbuf_addf_ret(err, -1, _("%%(deltabase) does not take arguments"));
 	if (*atom->name == '*')
-		oi_deref.info.delta_base_sha1 = oi_deref.delta_base_oid.hash;
+		oi_deref.info.delta_base_oid = &oi_deref.delta_base_oid;
 	else
-		oi.info.delta_base_sha1 = oi.delta_base_oid.hash;
+		oi.info.delta_base_oid = &oi.delta_base_oid;
 	return 0;
 }
 

sha1-file.c

@@ -1354,8 +1354,8 @@ static int loose_object_info(struct repository *r,
 	struct strbuf hdrbuf = STRBUF_INIT;
 	unsigned long size_scratch;
 
-	if (oi->delta_base_sha1)
-		hashclr(oi->delta_base_sha1);
+	if (oi->delta_base_oid)
+		oidclr(oi->delta_base_oid);
 
 	/*
 	 * If we don't care about type or size, then we don't
@@ -1474,8 +1474,8 @@ static int do_oid_object_info_extended(struct repository *r,
 			*(oi->sizep) = co->size;
 		if (oi->disk_sizep)
 			*(oi->disk_sizep) = 0;
-		if (oi->delta_base_sha1)
-			hashclr(oi->delta_base_sha1);
+		if (oi->delta_base_oid)
+			oidclr(oi->delta_base_oid);
 		if (oi->type_name)
 			strbuf_addstr(oi->type_name, type_name(co->type));
 		if (oi->contentp)