$NetBSD: patch-ba,v 1.1 2011/10/27 16:52:51 drochner Exp $

--- pixman/pixman-image.c.orig	2011-06-09 19:19:44.000000000 +0000
+++ pixman/pixman-image.c
@@ -160,27 +160,54 @@ _pixman_image_reset_clip_region (pixman_
     image->common.have_clip_region = FALSE;
 }
 
-/* Executive Summary: This function is a no-op that only exists
- * for historical reasons.
- *
- * There used to be a bug in the X server where it would rely on
- * out-of-bounds accesses when it was asked to composite with a
- * window as the source. It would create a pixman image pointing
- * to some bogus position in memory, but then set a clip region
- * to the position where the actual bits were.
+static pixman_bool_t out_of_bounds_workaround = TRUE;
+
+/* Old X servers rely on out-of-bounds accesses when they are asked
+ * to composite with a window as the source. They create a pixman image
+ * pointing to some bogus position in memory, but then they set a clip
+ * region to the position where the actual bits are.
  *
  * Due to a bug in old versions of pixman, where it would not clip
  * against the image bounds when a clip region was set, this would
- * actually work. So when the pixman bug was fixed, a workaround was
- * added to allow certain out-of-bound accesses. This function disabled
- * those workarounds.
+ * actually work. So by default we allow certain out-of-bound access
+ * to happen unless explicitly disabled.
  *
- * Since 0.21.2, pixman doesn't do these workarounds anymore, so now
- * this function is a no-op.
+ * Fixed X servers should call this function to disable the workaround.
  */
 PIXMAN_EXPORT void
 pixman_disable_out_of_bounds_workaround (void)
 {
+    out_of_bounds_workaround = FALSE;
+}
+
+static pixman_bool_t
+source_image_needs_out_of_bounds_workaround (bits_image_t *image)
+{
+    if (image->common.clip_sources                      &&
+        image->common.repeat == PIXMAN_REPEAT_NONE      &&
+	image->common.have_clip_region			&&
+        out_of_bounds_workaround)
+    {
+	if (!image->common.client_clip)
+	{
+	    /* There is no client clip, so if the clip region extends beyond the
+	     * drawable geometry, it must be because the X server generated the
+	     * bogus clip region.
+	     */
+	    const pixman_box32_t *extents =
+		pixman_region32_extents (&image->common.clip_region);
+
+	    if (extents->x1 >= 0 && extents->x2 <= image->width &&
+		extents->y1 >= 0 && extents->y2 <= image->height)
+	    {
+		return FALSE;
+	    }
+	}
+
+	return TRUE;
+    }
+
+    return FALSE;
 }
 
 static void
@@ -332,6 +359,9 @@ compute_image_info (pixman_image_t *imag
 		flags |= FAST_PATH_IS_OPAQUE;
 	}
 
+	if (source_image_needs_out_of_bounds_workaround (&image->bits))
+	    flags |= FAST_PATH_NEEDS_WORKAROUND;
+
 	if (image->bits.read_func || image->bits.write_func)
 	    flags &= ~FAST_PATH_NO_ACCESSORS;