An upcoming change to block/nbd-client.c will want to read the
tail of a structured reply chunk directly from the wire. Move
this function to make it easier.
Based on a patch from Vladimir Sementsov-Ogievskiy.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20171027104037.8319-12-eblake@redhat.com>