From 7c8c86f6308c7e0816b9638465a5917b12159e8f Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Fri, 20 Mar 2015 18:25:01 -0400
Subject: [PATCH] suppress backref processing in ERE regcomp

one of the features of ERE is that it's actually a regular language
and does not admit expressions which cannot be matched in linear time.
introduction of \n backref support into regcomp's ERE parsing was
unintentional.
---
 src/regex/regcomp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/regex/regcomp.c b/src/regex/regcomp.c
index bce6bc15..4d80cb1c 100644
--- a/src/regex/regcomp.c
+++ b/src/regex/regcomp.c
@@ -839,7 +839,7 @@ static reg_errcode_t parse_atom(tre_parse_ctx_t *ctx, const char *s)
 			s--;
 			break;
 		default:
-			if (isdigit(*s)) {
+			if (!ere && isdigit(*s)) {
 				/* back reference */
 				int val = *s - '0';
 				node = tre_ast_new_literal(ctx->mem, BACKREF, val, ctx->position);
-- 
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