From: Emden R. Gansner <erg@research.att.com>
Date: Tue, 13 Aug 2013 00:41:02 +0000 (-0400)
Subject: Catch case where pattern match reports success but with an empty string. This probably
X-Git-Tag: LAST_LIBGRAPH~32^2~88
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=09a2ac6a34fdb8b2ae10756629b3dd7ce8a9b1b7;p=graphviz

Catch case where pattern match reports success but with an empty string. This probably
corresponds to ill-specified pattern such as '&'
---

diff --git a/lib/expr/exeval.c b/lib/expr/exeval.c
index 29dfaeba0..5301e58d5 100644
--- a/lib/expr/exeval.c
+++ b/lib/expr/exeval.c
@@ -828,6 +828,11 @@ exsub(Expr_t * ex, register Exnode_t * expr, void *env, int global)
 		v.string = vmstrdup(ex->ve, str);
 		return v;
 	}
+    if (sub[0] == sub[1]) {
+		exwarn("pattern match of empty string - ill-specified pattern \"%s\"?", pat);
+		v.string = vmstrdup(ex->ve, str);
+		return v;
+    } 
 	sfwrite(ex->tmp, str, sub[0]);
 	if (repl)
 		replace(ex->tmp, str, repl, ng, sub);