[ tvtime-Bugs-3484607 ] Declared with attribute warn_unused_result [-Wunused-result]

Bugs item #3484607, was opened at 2012-02-05 02:48
Message generated for change (Tracker Item Submitted) made by zradu
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Pojar George (zradu)
Assigned to: Nobody/Anonymous (nobody)
Summary: Declared with attribute warn_unused_result [-Wunused-result]

Initial Comment:
-------------------------------------------------------------------------------------
int rtctimer_next_tick( rtctimer_t *rtctimer )
{
    unsigned long rtc_data;
    struct pollfd pfd;
    pfd.fd = rtctimer->rtc_fd;
    pfd.events = POLLIN | POLLERR;

again:
    if( poll( &pfd, 1, 100000 ) < 0 ) {
        if( errno == EINTR ) {
            goto again;
        }

        if( rtctimer->verbose ) {
            fprintf( stderr, "rtctimer: poll call failed: %s\n",
                 strerror( errno ) );
        }
        return 0;
    }

    read( rtctimer->rtc_fd, &rtc_data, sizeof( rtc_data ) );
    return 1;
}

-------------------------------------------------------------------------------------

I compiled tvtime and the following warning popped up. One of them is:
-------------------------------------------------------------------------------------
rtctimer.c: In function 'rtctimer_next_tick':
rtctimer.c: warning: ignoring return value of 'read', declared with attribute warn_unused_result [-Wunused-result]
-------------------------------------------------------------------------------------

If you don't check what read returns, chances are very high that your program will fail unexpectedly if a read error does occur, and it will be impossible to debug.
Always check the return value of library calls, especially I/O ones since they do fail in normal circumstances.
Thancks.


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