# File lib/sup/mbox/ssh-file.rb, line 34
  def add data, offset=endd
    #MBox::debug "+ adding #{data.length} bytes; size will be #{size + data.length}; limit #{SSHFile::MAX_BUF_SIZE}"

    if start.nil?
      @buf = data
      @start = offset
      return
    end

    raise "non-continguous data added to buffer (data #{offset}:#{offset + data.length}, buf range #{start}:#{endd})" if offset + data.length < start || offset > endd

    if offset < start
      @buf = data[0 ... (start - offset)] + @buf
      @start = offset
    else
      return if offset + data.length < endd
      @buf += data[(endd - offset) .. -1]
    end
  end