From 7eed0ca619fc7602737bb81d42a63dc60751367b Mon Sep 17 00:00:00 2001
From: naruse <naruse@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 15 Feb 2012 08:45:15 +0000
Subject: [PATCH] * io.c (io_strsetbuf): call rb_str_modify to make str
 independent   before calling rb_str_set_len for r34580.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34624 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog | 5 +++++
 io.c      | 5 ++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 64071007c5..c649166b95 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Feb 15 17:41:31 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* io.c (io_strsetbuf): call rb_str_modify to make str independent
+	  before calling rb_str_set_len for r34580.
+
 Wed Feb 15 12:30:10 2012  Eric Hodel  <drbrain@segment7.net>
 
 	* ext/zlib/zlib.c (Init_zlib):  Added Zlib::TEXT and note that
diff --git a/io.c b/io.c
index 074d2c50f7..f404b539a4 100644
--- a/io.c
+++ b/io.c
@@ -2084,7 +2084,10 @@ io_setstrbuf(VALUE *str, long len)
 	VALUE s = StringValue(*str);
 	long clen = RSTRING_LEN(s);
 	if (clen >= len) {
-	    if (clen != len) rb_str_set_len(s, len);
+	    if (clen != len) {
+		rb_str_modify(s);
+		rb_str_set_len(s, len);
+	    }
 	    return;
 	}
 	len -= clen;