Bug #7366: Fix crashes when setting filters on source pictures.

Now, filters may only be set on source pictures when the filter is common to
all screens.  Also, like SetPictureTransform, ChangePictureFilter is now not
called on source pictures.

render/filter.c

@@ -271,11 +271,16 @@ PictureResetFilters (ScreenPtr pScreen)
 int
 SetPictureFilter (PicturePtr pPicture, char *name, int len, xFixed *params, int nparams)
 {
-    ScreenPtr		pScreen = pPicture->pDrawable->pScreen;
+    PictFilterPtr	pFilter;
-    PictureScreenPtr	ps = GetPictureScreen(pScreen);
-    PictFilterPtr	pFilter = PictureFindFilter (pScreen, name, len);
     xFixed		*new_params;
-    int			i, result;
+    int			i, s, result;
+
+    pFilter = PictureFindFilter (screenInfo.screens[0], name, len);
+
+    for (s = 0; s < screenInfo.numScreens; s++) {
+	if (PictureFindFilter (screenInfo.screens[s], name, len) != pFilter)
+	    return BadMatch;
+    }
 
     if (!pFilter)
 	return BadName;
@@ -300,8 +305,13 @@ SetPictureFilter (PicturePtr pPicture, char *name, int len, xFixed *params, int
 	pPicture->filter_params[i] = params[i];
     pPicture->filter = pFilter->id;
 
-    result = (*ps->ChangePictureFilter) (pPicture, pPicture->filter,
+    if (pPicture->pDrawable) {
-					 params, nparams);
+	ScreenPtr pScreen = pPicture->pDrawable->pScreen;
-    return result;
+	PictureScreenPtr ps = GetPictureScreen(pScreen);
+
+	result = (*ps->ChangePictureFilter) (pPicture, pPicture->filter,
+					     params, nparams);
+	return result;
+    }
     return Success;
 }

render/picturestr.h

@@ -355,7 +355,12 @@ typedef struct _PictureScreen {
      */
     ChangePictureTransformProcPtr   ChangePictureTransform;
 
+    /**
+     * Called immediately after a picture's transform is changed through the
+     * SetPictureFilter request.  Not called for source-only pictures.
+     */
     ChangePictureFilterProcPtr	ChangePictureFilter;
+
     DestroyPictureFilterProcPtr	DestroyPictureFilter;
 
     TrapezoidsProcPtr		Trapezoids;