[mutter] wayland/window: Update toplevel main monitor before non-toplevel

[Jonas Ådahl <jadahl src gnome org>]

commit 4afa66fe41f0d82c1d9e025cb87ab0a2a4ca6cb4
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Jul 13 12:38:02 2017 +0800

    wayland/window: Update toplevel main monitor before non-toplevel
    
    When updating the main monitor, make sure to update the toplevel main
    monitor before trying to use that as the main monitor for non-toplevel
    windows (such as popups). Without this, when the main monitor is
    updated as a side effect to monitors being changed (for example due to
    a hot plug event, or coming back from being suspended) the
    main monitor pointer may, after 'monitors-changed' has completed, point to
    freed memory resulting in undefined behaviour.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784867

 src/core/window-private.h         |    3 ++-
 src/core/window.c                 |    2 +-
 src/wayland/meta-window-wayland.c |    4 +++-
 src/x11/window-x11.c              |    3 ++-
 4 files changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/src/core/window-private.h b/src/core/window-private.h
index 5c8ed98..0b667fb 100644
--- a/src/core/window-private.h
+++ b/src/core/window-private.h
@@ -531,7 +531,8 @@ struct _MetaWindowClass
                                   cairo_surface_t **icon,
                                   cairo_surface_t **mini_icon);
   uint32_t (*get_client_pid)     (MetaWindow *window);
-  void (*update_main_monitor)    (MetaWindow *window);
+  void (*update_main_monitor)    (MetaWindow *window,
+                                  gboolean    user_op);
   void (*main_monitor_changed)   (MetaWindow *window,
                                   const MetaLogicalMonitor *old);
 };
diff --git a/src/core/window.c b/src/core/window.c
index 68d5bcb..fa01e57 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -3603,7 +3603,7 @@ meta_window_update_monitor (MetaWindow *window,
   const MetaLogicalMonitor *old;
 
   old = window->monitor;
-  META_WINDOW_GET_CLASS (window)->update_main_monitor (window);
+  META_WINDOW_GET_CLASS (window)->update_main_monitor (window, user_op);
   if (old != window->monitor)
     {
       meta_window_on_all_workspaces_changed (window);
diff --git a/src/wayland/meta-window-wayland.c b/src/wayland/meta-window-wayland.c
index 6ae57d1..efe299f 100644
--- a/src/wayland/meta-window-wayland.c
+++ b/src/wayland/meta-window-wayland.c
@@ -350,7 +350,8 @@ scale_rect_size (MetaRectangle *rect,
 }
 
 static void
-meta_window_wayland_update_main_monitor (MetaWindow *window)
+meta_window_wayland_update_main_monitor (MetaWindow *window,
+                                         gboolean    user_op)
 {
   MetaBackend *backend = meta_get_backend ();
   MetaMonitorManager *monitor_manager =
@@ -370,6 +371,7 @@ meta_window_wayland_update_main_monitor (MetaWindow *window)
   toplevel_window = meta_wayland_surface_get_toplevel_window (window->surface);
   if (toplevel_window != window)
     {
+      meta_window_update_monitor (toplevel_window, user_op);
       window->monitor = toplevel_window->monitor;
       return;
     }
diff --git a/src/x11/window-x11.c b/src/x11/window-x11.c
index fafa929..07f0922 100644
--- a/src/x11/window-x11.c
+++ b/src/x11/window-x11.c
@@ -1456,7 +1456,8 @@ meta_window_x11_update_icon (MetaWindow       *window,
 }
 
 static void
-meta_window_x11_update_main_monitor (MetaWindow *window)
+meta_window_x11_update_main_monitor (MetaWindow *window,
+                                     gboolean    user_op)
 {
   window->monitor = meta_window_calculate_main_logical_monitor (window);
 }