[PATCH wayland] client: read_events should return -1 after an error

[Marek Chalupa]

When a thread is sleeping, waiting until another thread read
from the display, it always returns 0. Even when an error
occured. In documentation stands:

  "return 0 on success or -1 on error.  In case of error errno will
   be set accordingly"

So this is a fix for this.

Along with the read_events, fix a test so that it now complies
with this behaviour (and we have this tested)

Signed-off-by: Marek Chalupa <mchqwerty at gmail.com>
---
 src/wayland-client.c | 5 +++++
 tests/display-test.c | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/wayland-client.c b/src/wayland-client.c
index b0f77b9..1a70dc7 100644
--- a/src/wayland-client.c
+++ b/src/wayland-client.c
@@ -1187,6 +1187,11 @@ read_events(struct wl_display *display)
 		while (display->read_serial == serial)
 			pthread_cond_wait(&display->reader_cond,
 					  &display->mutex);
+
+		if (display->last_error) {
+			errno = display->last_error;
+			return -1;
+		}
 	}
 
 	return 0;
diff --git a/tests/display-test.c b/tests/display-test.c
index eb4ba1c..6ce9fe5 100644
--- a/tests/display-test.c
+++ b/tests/display-test.c
@@ -384,9 +384,9 @@ thread_read_error(void *data)
 	 * thread should be woken up or it will block indefinitely.
 	 */
 	c->display_stopped = 1;
-	assert(wl_display_read_events(c->wl_display) == 0);
+	assert(wl_display_read_events(c->wl_display) == -1);
 
-	wl_display_dispatch_pending(c->wl_display);
+	assert(wl_display_dispatch_pending(c->wl_display) == -1);
 	assert(wl_display_get_error(c->wl_display));
 
 	pthread_exit(NULL);
-- 
1.9.3