crash when re-rendering a graph with layers (need to NULL out gvc pointers after...

diff --git a/lib/common/emit.c b/lib/common/emit.c
index 6b631fdbe4217a6e2acd6e9fe992cbeac9d19689..33522ebc0ffdaa94627453c5914a55fbaa7df5d5 100644 (file)
--- a/lib/common/emit.c
+++ b/lib/common/emit.c
@@ -612,11 +612,14 @@ static void init_layering(GVC_t * gvc, graph_t * g)
     char *str;
 
     /* free layer strings and pointers from previous graph */
-    if (gvc->layers)
-       free(gvc->layers);
-    if (gvc->layerIDs)
-       free(gvc->layerIDs);
-
+    if (gvc->layers) {
+               free(gvc->layers);
+               gvc->layers = NULL;
+       }
+    if (gvc->layerIDs) {
+               free(gvc->layerIDs);
+               gvc->layerIDs = NULL;
+       }
     if ((str = agget(g, "layers")) != 0) {
        gvc->numLayers = parse_layers(gvc, g, str);
     } else {