Don't segfault on purge.hash() with NULL string. Fixes #307.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3163 d4fa192b-c00b-0410-8231-f00ffab90ce4

lib/libvcl/vcc_action.c

@@ -336,22 +336,26 @@ parse_unset(struct tokenlist *tl)
 static void
 parse_purge_url(struct tokenlist *tl)
 {
+	struct var *vp;
 
 	vcc_NextToken(tl);
 	
-	Fb(tl, 1, "VRT_purge(");
-	
 	Expect(tl, '(');
 	vcc_NextToken(tl);
 	
-	if (!vcc_StringVal(tl)) {
+	vp = vcc_FindVar(tl, tl->t, vcc_vars);
+	ERRCHK(tl);
+	assert(vp != NULL);
+	if (vp->fmt != STRING) {
 		vcc_ExpectedStringval(tl);
 		return;
 	}
 	
+	Fb(tl, 1, "if (%s) VRT_purge(%s, 0);\n", vp->rname, vp->rname);
+	vcc_NextToken(tl);
+
 	Expect(tl, ')');
 	vcc_NextToken(tl);
-	Fb(tl, 0, ", 0);\n");
 }