Temporary workaround for event handling serialization issue

Ludovic Rousseau pointed out that libusb_unlock_events() is not called
when a thread gets terminated with a signal, meaning that event waiters
will not be woken up in this case.

Add a temporary hack to libusb_event_handler_active() so that at least
the other threads will realise on the next iteration of their event
handling loop.

The real fix will likely involve reworking most of this.

1 files changed, 15 insertions, 1 deletions

diff --git a/libusb/io.c b/libusb/io.c
index 6ed19c1..4e85bdf 100644
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -1145,7 +1145,21 @@ API_EXPORTED void libusb_unlock_events(void)
  */
 API_EXPORTED int libusb_event_handler_active(void)
 {
-	return event_handler_active;
+	int r;
+
+	if (!event_handler_active)
+		return 0;
+
+	/* FIXME: temporary hack to ensure thread didn't quit (e.g. due to signal)
+	 * without libusb_unlock_events being triggered */
+	r = pthread_mutex_trylock(&events_lock);
+	if (r == 0) {
+		event_handler_active = 0;
+		pthread_mutex_unlock(&events_lock);
+		return 0;
+	}
+
+	return 1;
 }
 
 /** \ingroup poll