ROUNDUP_cmsglen
(ROUNDUP_cmsglen(len + (int)sizeof (struct cmsghdr)) -
(((uint8_t *)control) + ROUNDUP_cmsglen(controllen));
startoff -= ROUNDUP_cmsglen(cmsg->cmsg_len);
len += ROUNDUP_cmsglen(cmsg->cmsg_len);
optlen += ROUNDUP_cmsglen(ocmsg->cmsg_len);
ROUNDUP_cmsglen(ocmsg->cmsg_len));
ROUNDUP_cmsglen((cmsg)->cmsg_len))