sigjmp_buf jmp_env;

static void connect_alarm(int)
{
    siglongjmp(jmp_env, 1);
}

int main()
{
    // 當(dāng)超時(shí)時(shí)間sec_timeout大于等于運(yùn)行時(shí)間run_time時(shí)會(huì)跳過(guò)printf("running...\n");
    int sec_timeout = 3;
    int run_time = 2;

    printf("timeout = %d, run time = %d\n", sec_timeout, run_time);
    if (sec_timeout)
    {
        // 超過(guò)用alarm函數(shù)設(shè)置的時(shí)間時(shí)產(chǎn)生此信號(hào)，調(diào)用connect_alarm函數(shù)
        signal(SIGALRM, connect_alarm);
        alarm(sec_timeout);
        printf("set timeout\n");
        if (sigsetjmp(jmp_env, 1))
        {
            printf("timeout\n");
            goto out;
        }
    }

    sleep(run_time);
    printf("running...\n");

out:
    if (sec_timeout)
    {
        // 取消先前設(shè)置的鬧鐘
        alarm(0);
        printf("cancel timeout\n");
    }

    return 0;
}