Gem::Package#extract_files

# File tmp/rubies/ruby-3.4.1/lib/rubygems/package.rb, line 385
def extract_files(destination_dir, pattern = "*")
  verify unless @spec

  FileUtils.mkdir_p destination_dir, mode: dir_mode && 0o755

  @gem.with_read_io do |io|
    reader = Gem::Package::TarReader.new io

    reader.each do |entry|
      next unless entry.full_name == "data.tar.gz"

      extract_tar_gz entry, destination_dir, pattern

      break # ignore further entries
    end
  end
rescue Zlib::GzipFile::Error, EOFError, Gem::Package::TarInvalidError => e
  raise Gem::Package::FormatError.new e.message, @gem
end