MAXFDS
cmsg = malloc(CMSG_SPACE((MAXFDS + 1) * sizeof(int)));
.msg_controllen = CMSG_LEN((MAXFDS + 1) * sizeof(int)),
putfds(cmsg, fd[0], MAXFDS + 1);
putfds(cmsg, fd[0], MAXFDS);
msghdr.msg_controllen = CMSG_LEN(MAXFDS * sizeof(int));
ATF_REQUIRE(getnfds() == (int)(nfds + MAXFDS));