使用Linux中的信号, 每隔三秒发送一次定时启动handler函数

timer_test.c

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

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

/* handler --- handle SIGALRM */

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

    assert(signo == SIGALRM);

    printf("%s\n", msg);

    (void) setitimer(ITIMER_REAL, &tval, NULL);
    // exit(1);
}

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

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

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

    tval.it_value.tv_sec = 3;  /* 3 second timeout */

    (void) signal(SIGALRM, handler);

    (void) setitimer(ITIMER_REAL, & tval, NULL);

    while(1);
    exit(0);
}