[mutter] xwayland: Check the condition on displayfd ready

[Marge Bot <marge-bot src gnome org>]

commit b03ccfff4d958ed1e752d9937ed2f51ab03edc16
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Tue May 4 14:24:03 2021 +0200

    xwayland: Check the condition on displayfd ready
    
    The callback on_displayfd_ready() would unconditionally set the return
    value to TRUE, regardless of the condition.
    
    Use the GIO condition to determine if there was data written and adjust
    the return value accordingly.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1851>

 src/wayland/meta-xwayland.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/wayland/meta-xwayland.c b/src/wayland/meta-xwayland.c
index 0d3468d57e..c5a9303df9 100644
--- a/src/wayland/meta-xwayland.c
+++ b/src/wayland/meta-xwayland.c
@@ -898,7 +898,7 @@ on_displayfd_ready (int          fd,
    * socket when it's ready. We don't care about the data
    * in the socket, just that it wrote something, since
    * that means it's ready. */
-  g_task_return_boolean (task, TRUE);
+  g_task_return_boolean (task, !!(condition & G_IO_IN));
   g_object_unref (task);
 
   return G_SOURCE_REMOVE;