#include	"unpxti.h"int		listenfd, connfd;voidsig_poll(int signo){	int		n, flags;	char	buff[MAXLINE];	printf("SIGPOLL, event = %d\n", t_look(connfd));	n = T_rcv(connfd, buff, sizeof(buff), &flags);	printf("received %d bytes, flags = %d\n", n, flags);}intmain(int argc, char **argv){	if (argc == 2)		listenfd = Tcp_listen(NULL, argv[1], NULL);	else if (argc == 3)		listenfd = Tcp_listen(argv[1], argv[2], NULL);	else		err_quit("usage: test05 [ <host> ] <service or port>");		connfd = Xti_accept(listenfd, NULL, 0);	Signal(SIGPOLL, sig_poll);	Ioctl(connfd, I_SETSIG, S_RDNORM);	for ( ; ; ) {		pause();	}}