Initialize static parsing data before parsing. On good graphs, this will be cleaned up

at the end, but on error, the data is left pointing to graph data that has been freed,
causing a subsequent parse to crash.

diff --git a/lib/cgraph/grammar.y b/lib/cgraph/grammar.y
index 5dfcc17d8e702e6a5faeb5557e3b65d7450145b2..aa372a81438ba3a99e1a88c2a36e0b87c6d2da61 100644 (file)
--- a/lib/cgraph/grammar.y
+++ b/lib/cgraph/grammar.y
@@ -227,6 +227,11 @@ static void delete_items(item *ilist)
        }
 }
 
+static void initlist(list_t *list)
+{
+       list->first = list->last = NILitem;
+}
+
 static void deletelist(list_t *list)
 {
        delete_items(list->first);
@@ -537,6 +542,9 @@ Agraph_t *agconcat(Agraph_t *g, void *chan, Agdisc_t *disc)
        Ag_G_global = NILgraph;
        Disc = (disc? disc :  &AgDefaultDisc);
        aglexinit(Disc, chan);
+       initlist(&Attrlist);
+       initlist(&Nodelist);
+       initlist(&Edgelist);
        yyparse();
        return Ag_G_global;
 }