[PATCH libinput] evdev: drop relative x/y motion from a device not marked as pointer

[Bill Spitzak]

On Mon, Aug 17, 2015 at 10:08 PM, Peter Hutterer <peter.hutterer at who-t.net>
wrote:

> A device with REL_X/Y and keys gets marked only as ID_INPUT_KEY,
> initializes
> as keyboard and then segfaults when we send x/y coordinates - pointer
> acceleration never initializes.
>
> Ignore the events and log a bug instead. This intentionally only papers
> over
> the underlying issue, let's wait for a real device to trigger this and then
> look at the correct solution.
>
> +static inline bool
> +evdev_reject_relative(struct evdev_device *device,
> +                     const struct input_event *e,
> +                     uint64_t time)
> +{
> +       struct libinput *libinput = device->base.seat->libinput;
> +
> +       if ((e->code == REL_X || e->code == REL_Y) &&
> +           (device->seat_caps & EVDEV_DEVICE_POINTER) == 0) {
> +               switch (ratelimit_test(&device->nonpointer_rel_limit)) {
> +               case RATELIMIT_PASS:
> +                       log_bug_libinput(libinput,
> +                                        "REL_X/Y from device '%s', but
> this device is not a pointer\n",
> +                                        device->devname);
> +                       break;
> +               case RATELIMIT_THRESHOLD:
> +                       log_bug_libinput(libinput,
> +                                        "REL_X/Y event flood from '%s'\n",
> +                                        device->devname);
> +                       break;
> +               case RATELIMIT_EXCEEDED:
> +                       break;
> +               }
> +
> +               return true;
> +       }
> +
> +       return false;
> +}
>

It seems like some kind of ratelimit_log(&limit, "format", ...) function
might be useful so this is not copied everywhere.

Also wondering if there is a direct test for "pointer acceleration never
initializes" and perhaps you should do that test instead.


> +
>  static inline void
>  evdev_process_relative(struct evdev_device *device,
>                        struct input_event *e, uint64_t time)
> @@ -645,6 +675,9 @@ evdev_process_relative(struct evdev_device *device,
>         struct normalized_coords wheel_degrees = { 0.0, 0.0 };
>         struct discrete_coords discrete = { 0.0, 0.0 };
>
> +       if (evdev_reject_relative(device, e, time))
> +               return;
> +
>         switch (e->code) {
>         case REL_X:
>                 if (device->pending_event != EVDEV_RELATIVE_MOTION)
>

I think it would look better and be clearer if you put the
evdev_reject_relative call in the REL_X and REL_Y cases of the switch (you
could also remove the test for REL_X/Y from the function itself).
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