From 6ec841b2df3bcf95180c7d8f6b73d80d7f44d4e6 Mon Sep 17 00:00:00 2001
From: ayumin <ayumin@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 19 Sep 2011 10:34:30 +0000
Subject: [PATCH] * lib/fileutils.rb (module FileUtils): improve performance of
   FileUtils.compare_stream. a patch by Masaki Matsushita.   [Feature #5337]
 [ruby-core:39622]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@33297 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog        |  6 ++++++
 lib/fileutils.rb | 17 +++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 7e50c99bc5..14adb17f51 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Sep 19 18:55:51 2011  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
+
+	* lib/fileutils.rb (module FileUtils): improve performance of
+	  FileUtils.compare_stream. a patch by Masaki Matsushita.
+	  [Feature #5337] [ruby-core:39622]
+
 Mon Sep 19 18:42:58 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* test/-ext-/old_thread_select/test_old_thread_select.rb:
diff --git a/lib/fileutils.rb b/lib/fileutils.rb
index d4213dd0be..168bef7405 100644
--- a/lib/fileutils.rb
+++ b/lib/fileutils.rb
@@ -823,16 +823,13 @@ module FileUtils
   #
   def compare_stream(a, b)
     bsize = fu_stream_blksize(a, b)
-    sa = sb = nil
-    while sa == sb
-      sa = a.read(bsize)
-      sb = b.read(bsize)
-      unless sa and sb
-        if sa.nil? and sb.nil?
-          return true
-        end
-      end
-    end
+    sa = ""
+    sb = ""
+    begin
+      a.read(bsize, sa)
+      b.read(bsize, sb)
+      return true if sa.empty? && sb.empty?
+    end while sa == sb
     false
   end
   module_function :compare_stream