From: Emden Gansner <erg@research.att.com>
Date: Wed, 11 Jan 2012 22:35:49 +0000 (-0500)
Subject: Initialize static parsing data before parsing. On good graphs, this will be cleaned up
X-Git-Tag: LAST_LIBGRAPH~32^2~557^2~15^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=55542689f9bb1db9df1c8fc0ed860252264512ce;p=graphviz

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 5dfcc17d8..aa372a814 100644
--- 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;
 }