add_gem_contents

# File lib/rubygems/package/tar_output.rb, line 61
  def add_gem_contents
    @tar_writer.add_file "data.tar.gz", 0644 do |inner|
      sio = @signer ? StringIO.new : nil
      Zlib::GzipWriter.wrap(sio || inner) do |os|

        Gem::Package::TarWriter.new os do |data_tar_writer|
          # :stopdoc:
          def data_tar_writer.metadata() @metadata end
          def data_tar_writer.metadata=(metadata) @metadata = metadata end
          # :startdoc:

          yield data_tar_writer

          @metadata = data_tar_writer.metadata
        end
      end

      # if we have a signing key, then sign the data
      # digest and return the signature
      if @signer then
        require 'rubygems/security'
        digest = Gem::Security::OPT[:dgst_algo].digest sio.string
        @data_signature = @signer.sign digest
        inner.write sio.string
      end
    end

    self
  end