# File lib/http/form_data/composite_io.rb, line 31
      def read(length = nil, outbuf = nil)
        outbuf = outbuf.to_s.clear
        # buffer in JRuby is sometimes US-ASCII, force to ASCII-8BIT
        outbuf.force_encoding(Encoding::BINARY)

        while current_io
          current_io.read(length, @buffer)
          outbuf << @buffer.force_encoding(Encoding::BINARY)

          if length
            length -= @buffer.bytesize
            break if length.zero?
          end

          advance_io
        end

        outbuf unless length && outbuf.empty?
      end