ch14-timers.c

linux编程精髓 源代码

/* ch14-timers.c ---- demonstrate interval timers */

#include <stdio.h>
#include <assert.h>
#include <signal.h>
#include <sys/time.h>

/* handler --- handle SIGALRM */

void handler(int signo)
{
	static const char msg[] = "\n*** Timer expired, you lose ***\n";

	assert(signo == SIGALRM);

	write(2, msg, sizeof(msg) - 1);
	exit(1);
}

/* main --- set up timer, read data with timeout */

int main(void)
{
	struct itimerval tval;
	char string[BUFSIZ];

	timerclear(& tval.it_interval);	/* zero interval means no reset of timer */
	timerclear(& tval.it_value);

	tval.it_value.tv_sec = 10;	/* 10 second timeout */

	(void) signal(SIGALRM, handler);

	printf("You have ten seconds to enter\nyour name, rank, and serial number: ");

	(void) setitimer(ITIMER_REAL, & tval, NULL);
	if (fgets(string, sizeof string, stdin) != NULL) {
		(void) setitimer(ITIMER_REAL, NULL, NULL);	/* turn off timer */
		/* process rest of data, diagnostic print for illustration */
		printf("I'm glad you are being cooperative.\n");
	} else
		printf("\nEOF, eh?  We won't give up so easily!\n");

	exit(0);
}