OKFREE
OKFREE(mode = fcntl(fd, F_GETFL, NULL), new); /*%< side effect: validate fd. */
OKFREE(ioctl(fd, FIONBIO, (char *)&on), new);
OKFREE(fcntl(fd, F_SETFL, mode | PORT_NONBLOCK), new);
OKFREE(listen(fd, maxconn), new);