Bug#875356: Wrong timeout computation in xf86WaitForInput breaks xserver-xorg-input-wacom

["Thomas Richter" <thorfdbg@t-online.de>]

Package: xserver-xorg-core
Version: 2:1.19.2-1+deb9u1
Severity: important

The current debian version of xserver-xorg-core breaks due to a protocol
change xserver-xorg-input-wacom. In particular, the function affected is
xf86WaitForInput(), which used to expect a timeout in microseconds due
to its implementation on top of select(), though now runs into
xserver_poll(), which expects a delay in milliseconds.
xserver-xorg-input-wacom uses this function to initiate a delay of
250msecs to reset the wacom serial protocol, but now receives a delay of
250seconds instead. IOWS, the xserver startup hangs for all practical
purposes.

The current source of xf86WaitForInput is as follows:

int
xf86WaitForInput(int fd, int timeout)
{
    int r;
    struct pollfd poll_fd;

    poll_fd.fd = fd;
    poll_fd.events = POLLIN;

    if (fd >= 0) {
        SYSCALL(r = xserver_poll(&poll_fd, 1, timeout));
    }
    else {
        SYSCALL(r = xserver_poll(&poll_fd, 0, timeout));
    }
    xf86ErrorFVerb(9, "poll returned %d\n", r);
    return r;
}

Note that this bug has been fixed upstream which includes the necessary
scaling:


int
xf86WaitForInput(int fd, int timeout)
{
    int r;
    struct pollfd poll_fd;

    poll_fd.fd = fd;
    poll_fd.events = POLLIN;

    /* convert microseconds to milliseconds */
    timeout = (timeout + 999) / 1000;

    if (fd >= 0) {
        SYSCALL(r = xserver_poll(&poll_fd, 1, timeout));
    }
    else {
        SYSCALL(r = xserver_poll(&poll_fd, 0, timeout));
    }
    xf86ErrorFVerb(9, "poll returned %d\n", r);
    return r;
}

Please consider adding this fix to the debian version as otherwise at
least the wacom input module will break.