[PATCH libinput] evdev: Pass along device overflow information

[Derek Foreman]

Currently libinput users just see choppy input if the kernel event queue
overflows.  This patch passes along an event so the caller can at least
log it.
---
 src/evdev.c            |  1 +
 src/libinput-private.h |  3 +++
 src/libinput.c         | 18 ++++++++++++++++++
 src/libinput.h         |  5 +++++
 4 files changed, 27 insertions(+)

diff --git a/src/evdev.c b/src/evdev.c
index d8e3e5a..157bed7 100644
--- a/src/evdev.c
+++ b/src/evdev.c
@@ -929,6 +929,7 @@ evdev_device_dispatch(void *data)
 			   to the current state */
 			ev.code = SYN_REPORT;
 			evdev_device_dispatch_one(device, &ev);
+			notify_overflowed_device(&device->base);
 
 			rc = evdev_sync_device(device);
 			if (rc == 0)
diff --git a/src/libinput-private.h b/src/libinput-private.h
index 5a975d9..4606565 100644
--- a/src/libinput-private.h
+++ b/src/libinput-private.h
@@ -212,6 +212,9 @@ void
 notify_removed_device(struct libinput_device *device);
 
 void
+notify_overflowed_device(struct libinput_device *device);
+
+void
 keyboard_notify_key(struct libinput_device *device,
 		    uint32_t time,
 		    uint32_t key,
diff --git a/src/libinput.c b/src/libinput.c
index 5780a92..81528b7 100644
--- a/src/libinput.c
+++ b/src/libinput.c
@@ -171,6 +171,7 @@ libinput_event_get_pointer_event(struct libinput_event *event)
 		abort(); /* not used as actual event type */
 	case LIBINPUT_EVENT_DEVICE_ADDED:
 	case LIBINPUT_EVENT_DEVICE_REMOVED:
+	case LIBINPUT_EVENT_DEVICE_OVERFLOW:
 	case LIBINPUT_EVENT_KEYBOARD_KEY:
 		break;
 	case LIBINPUT_EVENT_POINTER_MOTION:
@@ -197,6 +198,7 @@ libinput_event_get_keyboard_event(struct libinput_event *event)
 		abort(); /* not used as actual event type */
 	case LIBINPUT_EVENT_DEVICE_ADDED:
 	case LIBINPUT_EVENT_DEVICE_REMOVED:
+	case LIBINPUT_EVENT_DEVICE_OVERFLOW:
 		break;
 	case LIBINPUT_EVENT_KEYBOARD_KEY:
 		return (struct libinput_event_keyboard *) event;
@@ -223,6 +225,7 @@ libinput_event_get_touch_event(struct libinput_event *event)
 		abort(); /* not used as actual event type */
 	case LIBINPUT_EVENT_DEVICE_ADDED:
 	case LIBINPUT_EVENT_DEVICE_REMOVED:
+	case LIBINPUT_EVENT_DEVICE_OVERFLOW:
 	case LIBINPUT_EVENT_KEYBOARD_KEY:
 	case LIBINPUT_EVENT_POINTER_MOTION:
 	case LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE:
@@ -248,6 +251,7 @@ libinput_event_get_device_notify_event(struct libinput_event *event)
 		abort(); /* not used as actual event type */
 	case LIBINPUT_EVENT_DEVICE_ADDED:
 	case LIBINPUT_EVENT_DEVICE_REMOVED:
+	case LIBINPUT_EVENT_DEVICE_OVERFLOW:
 		return (struct libinput_event_device_notify *) event;
 	case LIBINPUT_EVENT_KEYBOARD_KEY:
 	case LIBINPUT_EVENT_POINTER_MOTION:
@@ -831,6 +835,20 @@ notify_removed_device(struct libinput_device *device)
 }
 
 void
+notify_overflowed_device(struct libinput_device *device)
+{
+	struct libinput_event_device_notify *overflowed_device_event;
+
+	overflowed_device_event = zalloc(sizeof *overflowed_device_event);
+	if (!overflowed_device_event)
+		return;
+
+	post_base_event(device,
+			LIBINPUT_EVENT_DEVICE_OVERFLOW,
+			&overflowed_device_event->base);
+}
+
+void
 keyboard_notify_key(struct libinput_device *device,
 		    uint32_t time,
 		    uint32_t key,
diff --git a/src/libinput.h b/src/libinput.h
index 9cc6f52..39c9f92 100644
--- a/src/libinput.h
+++ b/src/libinput.h
@@ -230,6 +230,11 @@ enum libinput_event_type {
 	 */
 	LIBINPUT_EVENT_DEVICE_REMOVED,
 
+	/**
+	 * Signals that the kernel event queue for the device has overflowed.
+	 */
+	LIBINPUT_EVENT_DEVICE_OVERFLOW,
+
 	LIBINPUT_EVENT_KEYBOARD_KEY = 300,
 
 	LIBINPUT_EVENT_POINTER_MOTION = 400,
-- 
2.1.1