From 59383b1f9cffc2815d4a213710be253d9b6114d4 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sun, 16 Sep 2012 02:39:18 +0000
Subject: io.c: io_set_read_length

* io.c (io_set_read_length): if the read length equals to the buffer
  string size then nothing to do.  or ensure the string modifiable
  before setting the length only when the former is shorter.  based on
  the patch in [ruby-core:47541] by Hiroshi Shirosaki.
  [ruby-core:46586] [Bug #6764]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36980 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 io.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

(limited to 'io.c')

diff --git a/io.c b/io.c
index 24f141c825..e007512135 100644
--- a/io.c
+++ b/io.c
@@ -2158,6 +2158,15 @@ io_setstrbuf(VALUE *str, long len)
     rb_str_modify_expand(*str, len);
 }
 
+static void
+io_set_read_length(VALUE str, long n)
+{
+    if (RSTRING_LEN(str) != n) {
+	rb_str_modify(str);
+	rb_str_set_len(str, n);
+    }
+}
+
 static VALUE
 read_all(rb_io_t *fptr, long siz, VALUE str)
 {
@@ -2281,7 +2290,7 @@ io_getpartial(int argc, VALUE *argv, VALUE io, int nonblock)
             rb_sys_fail_path(fptr->pathv);
         }
     }
-    rb_str_set_len(str, n);
+    io_set_read_length(str, n);
 
     if (n == 0)
         return Qnil;
@@ -2602,7 +2611,7 @@ io_read(int argc, VALUE *argv, VALUE io)
     previous_mode = set_binary_mode_with_seek_cur(fptr);
 #endif
     n = io_fread(str, 0, len, fptr);
-    rb_str_set_len(str, n);
+    io_set_read_length(str, n);
 #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32)
     if (previous_mode == O_TEXT) {
 	setmode(fptr->fd, O_TEXT);
@@ -4390,7 +4399,7 @@ rb_io_sysread(int argc, VALUE *argv, VALUE io)
     if (n == -1) {
 	rb_sys_fail_path(fptr->pathv);
     }
-    rb_str_set_len(str, n);
+    io_set_read_length(str, n);
     if (n == 0 && ilen > 0) {
 	rb_eof_error();
     }
-- 
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