builtin/verify-commit: convert to struct object_id

This is a prerequisite to convert to lookup_commit, which we will
convert later.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/verify-commit.c

@@ -18,14 +18,14 @@ static const char * const verify_commit_usage[] = {
 		NULL
 };
 
-static int run_gpg_verify(const unsigned char *sha1, const char *buf, unsigned long size, unsigned flags)
+static int run_gpg_verify(const struct object_id *oid, const char *buf, unsigned long size, unsigned flags)
 {
 	struct signature_check signature_check;
 	int ret;
 
 	memset(&signature_check, 0, sizeof(signature_check));
 
-	ret = check_commit_signature(lookup_commit(sha1), &signature_check);
+	ret = check_commit_signature(lookup_commit(oid->hash), &signature_check);
 	print_signature_buffer(&signature_check, flags);
 
 	signature_check_clear(&signature_check);
@@ -35,22 +35,22 @@ static int run_gpg_verify(const unsigned char *sha1, const char *buf, unsigned l
 static int verify_commit(const char *name, unsigned flags)
 {
 	enum object_type type;
-	unsigned char sha1[20];
+	struct object_id oid;
 	char *buf;
 	unsigned long size;
 	int ret;
 
-	if (get_sha1(name, sha1))
+	if (get_oid(name, &oid))
 		return error("commit '%s' not found.", name);
 
-	buf = read_sha1_file(sha1, &type, &size);
+	buf = read_sha1_file(oid.hash, &type, &size);
 	if (!buf)
 		return error("%s: unable to read file.", name);
 	if (type != OBJ_COMMIT)
 		return error("%s: cannot verify a non-commit object of type %s.",
 				name, typename(type));
 
-	ret = run_gpg_verify(sha1, buf, size, flags);
+	ret = run_gpg_verify(&oid, buf, size, flags);
 
 	free(buf);
 	return ret;