module OpenSSL::Buffering

def readpartial(maxlen, buf=nil)
  if maxlen == 0
    if buf
      buf.clear
    else
      buf = ""
    end
    return @eof ? nil : buf
  end
  if @rbuffer.empty?
    begin
      return sysread(maxlen, buf)
    rescue Errno::EAGAIN
      retry
    end
  end
  ret = consume_rbuff(maxlen)
  if buf
    buf.replace(ret)
    ret = buf
  end
  raise EOFError if ret.empty?
  ret
end