#define CMSG_FOREACH(cmsg, mh) \
for ((cmsg) = CMSG_FIRSTHDR(mh); (cmsg); (cmsg) = CMSG_NXTHDR((mh), (cmsg)))
+struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length);
+
/* Covers only file system and abstract AF_UNIX socket addresses, but not unnamed socket addresses. */
#define SOCKADDR_UN_LEN(sa) \
({ \