size_t ngen = _hurd_id.gen.nuids < 1 ? 1 : _hurd_id.gen.nuids; uid_t newgen[ngen];  newgen[0] = uid; memcpy (&newgen[1], _hurd_id.gen.uids, (ngen - 1) * sizeof (uid_t));
if (_hurd_id.gen.nuids > 0) { _hurd_id.gen.uids[0] = uid; _hurd_id.valid = 0; }
DEFUN(seteuid, (uid), uid_t uid){  auth_t newauth;  error_t err;  HURD_CRITICAL_BEGIN;  __mutex_lock (&_hurd_id.lock);  err = _hurd_check_ids ();  if (!err)    {      /* Make a new auth handle which has EUID as the first element in the         list of effective uids.  */      size_t ngen = _hurd_id.gen.nuids < 1 ? 1 : _hurd_id.gen.nuids;      uid_t newgen[ngen];      newgen[0] = uid;      memcpy (&newgen[1], _hurd_id.gen.uids, (ngen - 1) * sizeof (uid_t));      err = __USEPORT (AUTH, __auth_makeauth		       (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,			newgen, ngen,			_hurd_id.aux.uids, _hurd_id.aux.nuids,			_hurd_id.gen.gids, _hurd_id.gen.ngids,			_hurd_id.aux.gids, _hurd_id.aux.ngids,			&newauth));    }  __mutex_unlock (&_hurd_id.lock);  HURD_CRITICAL_END;  if (err)    return __hurd_fail (err);  /* Install the new handle and reauthenticate everything.  */  err = __setauth (newauth);  __mach_port_deallocate (__mach_task_self (), newauth);  return err;}