From 7c745da7ddac5d4c4086b40f592043b3c7744ea8 Mon Sep 17 00:00:00 2001
From: ellson <devnull@localhost>
Date: Tue, 18 Oct 2005 21:11:47 +0000
Subject: [PATCH] add some more safety checks for NULL parameters.

---
 tclpkg/gv/gv.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tclpkg/gv/gv.cpp b/tclpkg/gv/gv.cpp
index 3e6f3bb6a..029c9b09a 100644
--- a/tclpkg/gv/gv.cpp
+++ b/tclpkg/gv/gv.cpp
@@ -611,11 +611,15 @@ Agedge_t *nextout(Agraph_t *g, Agedge_t *e)
 
 Agedge_t *firstedge(Agraph_t *g)
 {
+    if (!g)
+	return NULL;
     return firstout(g);
 } 
 
 Agedge_t *nextedge(Agraph_t *g, Agedge_t *e)
 {
+    if (!g || !e)
+	return NULL;
     return nextout(g, e);
 } 
 
@@ -748,11 +752,15 @@ Agnode_t *nexttail(Agnode_t *n, Agnode_t *t)
 
 Agnode_t *firstnode(Agraph_t *g)
 {
+    if (!g)
+	return NULL;
     return agfstnode(g);
 }
 
 Agnode_t *nextnode(Agraph_t *g, Agnode_t *n)
 {
+    if (!g || !n)
+	return NULL;
     return agnxtnode(g, n);
 }
 
-- 
2.40.0