Disconnect immediately even if Net::FTP#close is called without quit.

In that case, BufferedSSLSocket#read in FTP#close exceeded timeout because
BufferedSSLSocket#shutdown did nothing.  So BufferedIO#rbuf_fill is
overridden in BufferedSSLSocket to raise an EOFError if the connection is
shut down.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56880 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/net/ftp.rb

@@ -1443,16 +1443,32 @@ module Net
 
     if defined?(OpenSSL::SSL::SSLSocket)
       class BufferedSSLSocket <  BufferedSocket
+        def initialize(*args)
+          super
+          @is_shutdown = false
+        end
+
         def shutdown(*args)
           # SSL_shutdown() will be called from SSLSocket#close, and
           # SSL_shutdonw() will send the "close notify" alert to the peer,
           # so shutdown(2) should not be called.
+          @is_shutdown = true
         end
 
         def send(mesg, flags, dest = nil)
           # Ignore flags and dest.
           @io.write(mesg)
         end
+
+        private
+
+        def rbuf_fill
+          if @is_shutdown
+            raise EOFError, "shutdown has been called"
+          else
+            super
+          end
+        end
       end
     end
     # :startdoc: