connect: parse v2 refs with correct hash algorithm

When using protocol v2, we need to know what hash algorithm is used by
the remote end.  See if the server has sent us an object-format
capability, and if so, use it to determine the hash algorithm in use and
set that value in the packet reader.  Parse the refs using this
algorithm.

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

connect.c

@@ -283,7 +283,7 @@ static int process_ref(const struct packet_reader *reader, int len,
 		die(_("protocol error: unexpected capabilities^{}"));
 	} else if (check_ref(name, flags)) {
 		struct ref *ref = alloc_ref(name);
-		memcpy(ref->old_oid.hash, old_oid.hash, reader->hash_algo->rawsz);
+		oidcpy(&ref->old_oid, &old_oid);
 		**list = ref;
 		*list = &ref->next;
 	}
@@ -395,7 +395,7 @@ static int process_ref_v2(struct packet_reader *reader, struct ref ***list)
 		goto out;
 	}
 
-	if (parse_oid_hex(line_sections.items[i++].string, &old_oid, &end) ||
+	if (parse_oid_hex_algop(line_sections.items[i++].string, &old_oid, &end, reader->hash_algo) ||
 	    *end) {
 		ret = 0;
 		goto out;
@@ -403,7 +403,7 @@ static int process_ref_v2(struct packet_reader *reader, struct ref ***list)
 
 	ref = alloc_ref(line_sections.items[i++].string);
 
-	oidcpy(&ref->old_oid, &old_oid);
+	memcpy(ref->old_oid.hash, old_oid.hash, reader->hash_algo->rawsz);
 	**list = ref;
 	*list = &ref->next;
 
@@ -416,7 +416,8 @@ static int process_ref_v2(struct packet_reader *reader, struct ref ***list)
 			struct object_id peeled_oid;
 			char *peeled_name;
 			struct ref *peeled;
-			if (parse_oid_hex(arg, &peeled_oid, &end) || *end) {
+			if (parse_oid_hex_algop(arg, &peeled_oid, &end,
+						reader->hash_algo) || *end) {
 				ret = 0;
 				goto out;
 			}
@@ -424,7 +425,8 @@ static int process_ref_v2(struct packet_reader *reader, struct ref ***list)
 			peeled_name = xstrfmt("%s^{}", ref->name);
 			peeled = alloc_ref(peeled_name);
 
-			oidcpy(&peeled->old_oid, &peeled_oid);
+			memcpy(peeled->old_oid.hash, peeled_oid.hash,
+			       reader->hash_algo->rawsz);
 			**list = peeled;
 			*list = &peeled->next;
 
@@ -443,6 +445,7 @@ struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
 			     const struct string_list *server_options)
 {
 	int i;
+	const char *hash_name;
 	*list = NULL;
 
 	if (server_supports_v2("ls-refs", 1))
@@ -451,6 +454,14 @@ struct ref **get_remote_refs(int fd_out, struct packet_reader *reader,
 	if (server_supports_v2("agent", 0))
 		packet_write_fmt(fd_out, "agent=%s", git_user_agent_sanitized());
 
+	if (server_feature_v2("object-format", &hash_name)) {
+		int hash_algo = hash_algo_by_name(hash_name);
+		if (hash_algo == GIT_HASH_UNKNOWN)
+			die(_("unknown object format '%s' specified by server"), hash_name);
+		reader->hash_algo = &hash_algos[hash_algo];
+		packet_write_fmt(fd_out, "object-format=%s", reader->hash_algo->name);
+	}
+
 	if (server_options && server_options->nr &&
 	    server_supports_v2("server-option", 1))
 		for (i = 0; i < server_options->nr; i++)