#include <stdio.h>
#include <signal.h>
#include <setjmp.h>
#include <unistd.h>
#include <sys/time.h>

sigjmp_buf jmp_env;

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

int main()
{
    // 當超時時間sec_timeout大于等于運行時間run_time時會跳過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)
    {
        // 超過用alarm函數設置的時間時產生此信號，調用connect_alarm函數
        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)
    {
        // 取消先前設置的鬧鐘
        alarm(0);
        printf("cancel timeout/n");
    }

    return 0;
}