webrick: use IO.copy_stream for single range response

This is also compatible with range responses generated
by Rack::File (tested with rack 2.0.3).

* lib/webrick/httpresponse.rb (send_body_io): use Content-Range
* lib/webrick/httpservlet/filehandler.rb (make_partial_content):
  use File object for the single range case
* test/webrick/test_filehandler.rb (get_res_body): use send_body
  to test result

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62955 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/webrick/httpresponse.rb

@@ -410,9 +410,15 @@ module WEBrick
           buf.clear
           socket.write("0#{CRLF}#{CRLF}")
         else
-          size = @header['content-length']
-          size = size.to_i if size
-          @sent_size = IO.copy_stream(@body, socket, size)
+          if %r{\Abytes (\d+)-(\d+)/\d+\z} =~ @header['content-range']
+            offset = $1.to_i
+            size = $2.to_i - offset + 1
+          else
+            offset = nil
+            size = @header['content-length']
+            size = size.to_i if size
+          end
+          @sent_size = IO.copy_stream(@body, socket, size, offset)
         end
       ensure
         @body.close

lib/webrick/httpservlet/filehandler.rb

@@ -116,17 +116,10 @@ module WEBrick
           elsif range = ranges[0]
             first, last = prepare_range(range, filesize)
             raise HTTPStatus::RequestRangeNotSatisfiable if first < 0
-            if last == filesize - 1
-              content = io.dup
-              content.pos = first
-            else
-              io.pos = first
-              content = io.read(last-first+1)
-            end
             res['content-type'] = mtype
             res['content-range'] = "bytes #{first}-#{last}/#{filesize}"
             res['content-length'] = last - first + 1
-            res.body = content
+            res.body = io.dup
           else
             raise HTTPStatus::BadRequest
           end

test/webrick/test_filehandler.rb

@@ -20,16 +20,10 @@ class WEBrick::TestFileHandler < Test::Unit::TestCase
   end
 
   def get_res_body(res)
-    body = res.body
-    if defined? body.read
-      begin
-        body.read
-      ensure
-        body.close
-      end
-    else
-      body
-    end
+    sio = StringIO.new
+    sio.binmode
+    res.send_body(sio)
+    sio.string
   end
 
   def make_range_request(range_spec)