On Wed, 13 May 2020 at 02:58, brian m. carlson
<sandals@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> 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).
> - oidcpy(&ref->old_oid, &old_oid);
> + memcpy(ref->old_oid.hash, old_oid.hash, reader->hash_algo->rawsz);
Might an `oidcpy_algop()` prove useful over time?
oidcpy_algop(&ref->old_oid, &old_oid, reader->hash_algo);
> @@ -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);
> + }
> +
(Similar to an earlier comment I made, if we don't see any
"object-format", we rely on `reader->hash_algo` to have been properly
set up (which it has) and to not have been modified since (which we
could probably rely on, hmm?).)
Martin
