Quick and dirty utility to extract a unitypackage's contents

unitypackage_extractor.rb

require 'rubygems'
require 'rubygems/package'
require 'zlib'
require 'fileutils'
require 'pathname'

def unpack filename, output
  output_path = Pathname.new output

  Zlib::GzipReader.open filename do |gz|
    Gem::Package::TarReader.new gz do |tar|
      directories = tar.filter(&:directory?)

      puts "found #{directories.length} dirs"

      directories.each do |dir|
        puts "attempting to open #{dir.full_name}"

        pathname = ""
        asset = ""

        tar.seek(dir.full_name + "pathname") do |pathname_file|
          pathname = pathname_file.read
          puts "found pathname file #{pathname}"
        end

        tar.seek(dir.full_name + "asset") do |asset_file|
          asset = asset_file.read
          puts "found asset file"
        end

        next if asset.empty? || pathname.empty?

        path = output_path.join pathname

        puts "writing to #{path.to_s}"

        path.dirname.mkpath

        path.open "w+" do |asset_file|
          asset_file.write asset
        end
      end
    end
  end
end

puts "Unpacking unitypackage #{ARGV[0]} to #{ARGV[1]}"

unpack ARGV[0], ARGV[1]