* 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

@@ -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:

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