#include "apue.h"#include <setjmp.h>static void		sig_alrm(int);static jmp_buf	env_alrm;intmain(void){	int		n;	char	line[MAXLINE];	if (signal(SIGALRM, sig_alrm) == SIG_ERR)		err_sys("signal(SIGALRM) error");	if (setjmp(env_alrm) != 0)		err_quit("read timeout");	alarm(10);	if ((n = read(STDIN_FILENO, line, MAXLINE)) < 0)		err_sys("read error");	alarm(0);	write(STDOUT_FILENO, line, n);	exit(0);}static voidsig_alrm(int signo){	longjmp(env_alrm, 1);}