Re: [Qemu-block] [Qemu-devel] [RFC v1 2/4] util/oslib-win32: Remove invalid check

[Paolo Bonzini]

On 29/06/2017 18:37, Alistair Francis wrote:
>> Hmm, I think it's possible, poll_msgs is true here.
> poll_msgs?
> 
> If nhandles is 0 then we have already entered an earlier if statement
> and set ready to either WAIT_FAILED or WAIT_TIMEOUT in which case we
> can't enter this part of the if statement.

No, that's not correct.  The code is:

    if (poll_msgs) {
        /* Wait for either messages or handles
         * -> Use MsgWaitForMultipleObjectsEx
         */
        ready = MsgWaitForMultipleObjectsEx(nhandles, handles, timeout,
                                            QS_ALLINPUT, MWMO_ALERTABLE);

        if (ready == WAIT_FAILED) {
            gchar *emsg = g_win32_error_message(GetLastError());
            g_warning("MsgWaitForMultipleObjectsEx failed: %s", emsg);
            g_free(emsg);
        }
    } else if (nhandles == 0) {
        /* No handles to wait for, just the timeout */
        if (timeout == INFINITE) {
            ready = WAIT_FAILED;
        } else {
            SleepEx(timeout, TRUE);
            ready = WAIT_TIMEOUT;
        }

You can have poll_msgs == TRUE && nhandles == 0.  This happens for

   GPollFD fds[1] = { .fd = G_WIN32_MSG_HANDLE, .events = G_IO_IN };
   g_poll(fds, 1, timeout);

Thanks,

Paolo