[PATCH 3/3] xwayland: unredirect sub-windows when root destroyed

[Robert Bragg]

From: Robert Bragg <robert at linux.intel.com>

This ensures that we unredirect root sub-windows when the root window is
being destroyed. We need to do this explicitly rather than rely on the
the CompositeClientSubwindows resource being freed automatically because
that may not happen until after the root window has already been freed
resulting in uninitialized memory access.
---
 composite/compalloc.c                  |    5 +++++
 composite/compositeext.h               |    2 ++
 hw/xfree86/xwayland/xwayland-private.h |    1 +
 hw/xfree86/xwayland/xwayland-window.c  |   23 +++++++++++++++++++++++
 4 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/composite/compalloc.c b/composite/compalloc.c
index 9fd460a..40bbcc3 100644
--- a/composite/compalloc.c
+++ b/composite/compalloc.c
@@ -470,6 +470,11 @@ compUnredirectSubwindows (ClientPtr pClient, WindowPtr pWin, int update)
     return BadValue;
 }
 
+int CompositeUnRedirectSubwindows (WindowPtr pWin, int update)
+{
+    return compUnredirectSubwindows (serverClient, pWin, update);
+}
+
 /*
  * Add redirection information for one subwindow (during reparent)
  */
diff --git a/composite/compositeext.h b/composite/compositeext.h
index c1e915a..9c5330a 100644
--- a/composite/compositeext.h
+++ b/composite/compositeext.h
@@ -36,5 +36,7 @@ extern _X_EXPORT Bool CompositeRegisterAlternateVisuals(ScreenPtr pScreen,
                                                         int nVisuals);
 extern _X_EXPORT int CompositeRedirectSubwindows(WindowPtr pWin,
 						 int update);
+extern _X_EXPORT int CompositeUnRedirectSubwindows (WindowPtr pWin,
+						    int update);
 
 #endif /* _COMPOSITEEXT_H_ */
diff --git a/hw/xfree86/xwayland/xwayland-private.h b/hw/xfree86/xwayland/xwayland-private.h
index e337b7a..47cdd63 100644
--- a/hw/xfree86/xwayland/xwayland-private.h
+++ b/hw/xfree86/xwayland/xwayland-private.h
@@ -66,6 +66,7 @@ struct xwl_screen {
     int32_t			 root_x, root_y;
 
     CreateWindowProcPtr		 CreateWindow;
+    DestroyWindowProcPtr	 DestroyWindow;
     RealizeWindowProcPtr	 RealizeWindow;
     UnrealizeWindowProcPtr	 UnrealizeWindow;
     SetWindowPixmapProcPtr	 SetWindowPixmap;
diff --git a/hw/xfree86/xwayland/xwayland-window.c b/hw/xfree86/xwayland/xwayland-window.c
index c2d31cb..fcda2f2 100644
--- a/hw/xfree86/xwayland/xwayland-window.c
+++ b/hw/xfree86/xwayland/xwayland-window.c
@@ -125,6 +125,26 @@ xwl_create_window(WindowPtr window)
     return ret;
 }
 
+static int
+xwl_destroy_window (WindowPtr window)
+{
+    ScreenPtr screen = window->drawable.pScreen;
+    struct xwl_screen *xwl_screen;
+    Bool ret;
+
+    if (window->parent == NULL)
+	CompositeUnRedirectSubwindows (window, CompositeRedirectManual);
+
+    xwl_screen = xwl_screen_get(screen);
+
+    screen->DestroyWindow = xwl_screen->DestroyWindow;
+    ret = (*screen->DestroyWindow)(window);
+    xwl_screen->DestroyWindow = screen->DestroyWindow;
+    screen->DestroyWindow = xwl_destroy_window;
+
+    return ret;
+}
+
 static void
 damage_report(DamagePtr pDamage, RegionPtr pRegion, void *data)
 {
@@ -287,6 +307,9 @@ xwl_screen_init_window(struct xwl_screen *xwl_screen, ScreenPtr screen)
     xwl_screen->CreateWindow = screen->CreateWindow;
     screen->CreateWindow = xwl_create_window;
 
+    xwl_screen->DestroyWindow = screen->DestroyWindow;
+    screen->DestroyWindow = xwl_destroy_window;
+
     xwl_screen->RealizeWindow = screen->RealizeWindow;
     screen->RealizeWindow = xwl_realize_window;
 
-- 
1.7.7.5