[PATCH weston] compositor: fix crash when destroying incompletely created output

[Dawid Gajownik]

When output can't be created in foo_backend_create_output(),
weston_output_destroy() is called without executing
weston_compositor_add_output(). In such a case output->link is not initialized
and causes application crash on wl_list_remove(&output->link).

This problem happens when drm, fbdev, rdp, rpi or wayland backend is used.

Signed-off-by: Dawid Gajownik <gajownik at gmail.com>
---
 src/compositor.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/compositor.c b/src/compositor.c
index 66c3eee..30924f6 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -3893,7 +3893,11 @@ weston_output_destroy(struct weston_output *output)
 	weston_presentation_feedback_discard_list(&output->feedback_list);
 
 	weston_compositor_remove_output(output->compositor, output);
-	wl_list_remove(&output->link);
+
+	/* output->link might be not initialized if foo_backend_create_output()
+	 * ends before weston_compositor_add_output() */
+	if (output->link.prev && output->link.next)
+		wl_list_remove(&output->link);
 
 	wl_signal_emit(&output->compositor->output_destroyed_signal, output);
 	wl_signal_emit(&output->destroy_signal, output);
-- 
2.4.3