Gem::Package::TarReader::Entry#readpartial

# File tmp/rubies/ruby-3.3.0/lib/rubygems/package/tar_reader/entry.rb, line 175
def readpartial(maxlen, outbuf = "".b)
  if eof? && maxlen > 0
    raise EOFError, "end of file reached"
  end

  max_read = [maxlen, @header.size - @read].min

  @io.readpartial(max_read, outbuf)
  @read += outbuf.size

  outbuf
end