$OpenBSD: patch-src_regengine_cc,v 1.1 2016/01/15 19:42:40 sthen Exp $

Convert empty expressions into something that regex(3) will accept.

--- src/regengine.cc.orig	Fri Jan 15 19:37:30 2016
+++ src/regengine.cc	Fri Jan 15 19:38:06 2016
@@ -34,6 +34,9 @@ PosixRegex::PosixRegex(const char *pattern, bool case_
 {
 	int regex_flags = REG_EXTENDED | (case_insensitive ? REG_ICASE : 0);
 
+	if (strncmp(pattern, "", 2) == 0) {
+		pattern = "()";
+	}
 	int err = regcomp(&this->regex, pattern, regex_flags);
 	if(err) {
 		char err_msg[256];
