[PATCH 31/44] connect: parse v2 refs with correct hash algorithm

["brian m. carlson" <sandals@xxxxxxxxxxxxxxxxxxxx>]

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.

Note that we use memcpy instead of oidcpy for copying values, since
oidcpy is intentionally limited to the current hash algorithm length,
and the copy will be too short if the server side uses SHA-256 but the
client side has not had a repository set up (and therefore defaults to
SHA-1).

Signed-off-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx>
---
 connect.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/connect.c b/connect.c
index bb4bc4ab7f..4e6462e52f 100644
--- a/connect.c
+++ b/connect.c
@@ -394,7 +394,7 @@ 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;
@@ -402,7 +402,7 @@ 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;
 
@@ -415,7 +415,8 @@ 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;
 			}
@@ -423,7 +424,8 @@ 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;
 
@@ -442,6 +444,7 @@ 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))
@@ -450,6 +453,14 @@ 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++)