((struct cmsghdr *)__CMSG_NEXT(cmsg))))
#define CMSG_FIRSTHDR(mhdr) ((size_t) (mhdr)->msg_controllen >= sizeof (struct cmsghdr) ? (struct cmsghdr *) (mhdr)->msg_control : (struct cmsghdr *) 0)
-/* Are these valid? */
#define CMSG_ALIGN(len) (((len) + sizeof (size_t) - 1) & (size_t) ~(sizeof (size_t) - 1))
#define CMSG_SPACE(len) (CMSG_ALIGN (len) + CMSG_ALIGN (sizeof (struct cmsghdr)))
#define CMSG_LEN(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + (len))