cliptest: Avoid use of uninitialized memory when regions don't intersect

Prevent attempting to draw the intersection polygon when it contains no
vertices.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

diff --git a/clients/cliptest.c b/clients/cliptest.c
index 612b3d1..907c5d4 100644 (file)
--- a/clients/cliptest.c
+++ b/clients/cliptest.c
@@ -570,12 +570,14 @@ draw_geometry(cairo_t *cr, struct weston_surface *surface,
        cairo_set_source_rgba(cr, 0.0, 0.0, 1.0, 0.4);
        cairo_fill(cr);
 
-       draw_polygon_closed(cr, ex, ey, n);
-       cairo_set_source_rgb(cr, 0.0, 1.0, 0.0);
-       cairo_stroke(cr);
+       if (n) {
+               draw_polygon_closed(cr, ex, ey, n);
+               cairo_set_source_rgb(cr, 0.0, 1.0, 0.0);
+               cairo_stroke(cr);
 
-       cairo_set_source_rgba(cr, 0.0, 1.0, 0.0, 0.5);
-       draw_polygon_labels(cr, ex, ey, n);
+               cairo_set_source_rgba(cr, 0.0, 1.0, 0.0, 0.5);
+               draw_polygon_labels(cr, ex, ey, n);
+       }
 }
 
 static void