# File lib/net/telnet.rb, line 528
    def waitfor(options) # :yield: recvdata
      time_out = @options["Timeout"]
      waittime = @options["Waittime"]
      fail_eof = @options["FailEOF"]

      if options.kind_of?(Hash)
        prompt   = if options.has_key?("Match")
                     options["Match"]
                   elsif options.has_key?("Prompt")
                     options["Prompt"]
                   elsif options.has_key?("String")
                     Regexp.new( Regexp.quote(options["String"]) )
                   end
        time_out = options["Timeout"]  if options.has_key?("Timeout")
        waittime = options["Waittime"] if options.has_key?("Waittime")
        fail_eof = options["FailEOF"]  if options.has_key?("FailEOF")
      else
        prompt = options
      end

      if time_out == false
        time_out = nil
      end

      line = ''
      buf = ''
      rest = ''
      until(prompt === line and not IO::select([@sock], nil, nil, waittime))
        unless IO::select([@sock], nil, nil, time_out)
          raise Net::ReadTimeout, "timed out while waiting for more data"
        end
        begin
          c = @sock.readpartial(1024 * 1024)
          @dumplog.log_dump('<', c) if @options.has_key?("Dump_log")
          if @options["Telnetmode"]
            c = rest + c
            if Integer(c.rindex(/#{IAC}#{SE}/no) || 0) <
               Integer(c.rindex(/#{IAC}#{SB}/no) || 0)
              buf = preprocess(c[0 ... c.rindex(/#{IAC}#{SB}/no)])
              rest = c[c.rindex(/#{IAC}#{SB}/no) .. -1]
            elsif pt = c.rindex(/#{IAC}[^#{IAC}#{AO}#{AYT}#{DM}#{IP}#{NOP}]?\z/no) ||
                       c.rindex(/\r\z/no)
              buf = preprocess(c[0 ... pt])
              rest = c[pt .. -1]
            else
              buf = preprocess(c)
              rest = ''
            end
         else
           # Not Telnetmode.
           #
           # We cannot use preprocess() on this data, because that
           # method makes some Telnetmode-specific assumptions.
           buf = rest + c
           rest = ''
           unless @options["Binmode"]
             if pt = buf.rindex(/\r\z/no)
               buf = buf[0 ... pt]
               rest = buf[pt .. -1]
             end
             buf.gsub!(/#{EOL}/no, "\n")
           end
          end
          @log.print(buf) if @options.has_key?("Output_log")
          line += buf
          yield buf if block_given?
        rescue EOFError # End of file reached
          raise if fail_eof
          if line == ''
            line = nil
            yield nil if block_given?
          end
          break
        end
      end
      line
    end