State that the event is defined for a SYN_DROPPED

All clients that want to handle SYN_DROPPED correctly need to pass an EV_SYN
through their own handlers before starting with the syn events. Rather than
letting them synthesize that, guarantee that the event is defined the first
time LIBEVDEV_READ_STATUS_SYNC is returned.

This does not change existing behavior, it merely documents it so we can rely
on it.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
This commit is contained in:
Peter Hutterer 2013-12-06 12:44:33 +10:00
parent aac29742b0
commit f66bf57baa
2 changed files with 7 additions and 3 deletions

View file

@ -657,7 +657,8 @@ enum libevdev_read_status {
* time, it returns -EAGAIN and ev is undefined. * time, it returns -EAGAIN and ev is undefined.
* *
* If a SYN_DROPPED is read from the device, this function returns * If a SYN_DROPPED is read from the device, this function returns
* LIBEVDEV_READ_STATUS_SYNC. The caller should now call this function with the * LIBEVDEV_READ_STATUS_SYNC and ev is set to the EV_SYN event.
* The caller should now call this function with the
* LIBEVDEV_READ_FLAG_SYNC flag set, to get the set of events that make up the * LIBEVDEV_READ_FLAG_SYNC flag set, to get the set of events that make up the
* device state delta. This function returns LIBEVDEV_READ_STATUS_SYNC for * device state delta. This function returns LIBEVDEV_READ_STATUS_SYNC for
* each event part of that delta, until it returns -EAGAIN once all events * each event part of that delta, until it returns -EAGAIN once all events
@ -673,10 +674,11 @@ enum libevdev_read_status {
* set, the next event is read in sync mode. * set, the next event is read in sync mode.
* @param ev On success, set to the current event. * @param ev On success, set to the current event.
* @return On failure, a negative errno is returned. * @return On failure, a negative errno is returned.
* @retval LIBEVDEV_READ_STATUS_SUCCESS One or more events where read of the device * @retval LIBEVDEV_READ_STATUS_SUCCESS One or more events were read of the
* device and ev points to the next event in the queue
* @retval -EAGAIN No events are currently available on the device * @retval -EAGAIN No events are currently available on the device
* @retval LIBEVDEV_READ_STATUS_SYNC A SYN_DROPPED event was received, or a * @retval LIBEVDEV_READ_STATUS_SYNC A SYN_DROPPED event was received, or a
* synced event was returned. * synced event was returned and ev points to the SYN_DROPPED event
* *
* @note This function is signal-safe. * @note This function is signal-safe.
*/ */

View file

@ -108,6 +108,8 @@ START_TEST(test_syn_event)
ck_assert_int_eq(ev.code, SYN_REPORT); ck_assert_int_eq(ev.code, SYN_REPORT);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev); rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SYNC); ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SYNC);
ck_assert_int_eq(ev.type, EV_SYN);
ck_assert_int_eq(ev.code, SYN_DROPPED);
/* only check for the rc, nothing actually changed on the device */ /* only check for the rc, nothing actually changed on the device */