Interrupted system call

Question

I have more then three timer running from main as given below, and I have defined one message queue in main section. My timer's expiration time in 10(max). Why, when timer expires "msgrcv" gives error like "Interrupted system call"?

    timer_t timer1 = create_timer(TT_SIGUSR1);
    install_sighandler(TT_SIGUSR1, signal_handler);
    set_timer(timer1, TIME_INTERVAL_1);
     -
      -
       -

    flag = IPC_CREAT | 0666;
    key = 1234;

    msgqid = msgget(key,flag);
    printf("msgqid = %d\n",msgqid);

    while (1)
    {
            msgsz = msgrcv(msgqid, &sendMsg, sizeof(sendMsg), 0,0);
            perror("prashant");

            sleep(1);
    }
    return 0;

score 2 · Answer 1 · answered Mar 09 '12 at 10:08

Because you probably setup your timer to send you a signal when it expires. Receiving a signal while blocked on certain system calls will make said system calls fail with errno = EINTR.

The msgrcv() function shall fail if:

    [EINTR]
    The msgrcv() function was interrupted by a signal.

Interrupted system call

1 Answers1