From 389abf1b3b9e65b5944fa3616bea93259b137a92 Mon Sep 17 00:00:00 2001
From: akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 8 Jan 2008 06:04:26 +0000
Subject: [PATCH] * string.c (str_gsub): avoid appending empty pre-match
 substr.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14944 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog | 4 ++++
 string.c  | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 67c3213b9a..bdffe38aee 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jan  8 15:03:10 2008  Tanaka Akira  <akr@fsij.org>
+
+	* string.c (str_gsub): avoid appending empty pre-match substr.
+
 Tue Jan  8 13:05:57 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* compile.c (iseq_build_from_ary), iseq.c (iseq_load): fix for format change.
diff --git a/string.c b/string.c
index 189cc1b751..d72d0352c7 100644
--- a/string.c
+++ b/string.c
@@ -2720,7 +2720,9 @@ str_gsub(int argc, VALUE *argv, VALUE str, int bang)
 	if (OBJ_TAINTED(val)) tainted = 1;
 
 	len = beg - offset;	/* copy pre-match substr */
-        rb_enc_str_buf_cat(dest, cp, len, str_enc);
+        if (len) {
+            rb_enc_str_buf_cat(dest, cp, len, str_enc);
+        }
 
         rb_str_buf_append(dest, val);