read2.c

#include "apue.h"
#include <setjmp.h>

static void		sig_alrm(int);
static jmp_buf	env_alrm;

int
main(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 void
sig_alrm(int signo)
{
	longjmp(env_alrm, 1);
}