.pak file format of Quake game engine: Ruby parsing library

Application

Quake game engine

File extension

pak

KS implementation details

License: CC0-1.0

This page hosts a formal specification of .pak file format of Quake game engine using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.

The Ruby runtime library can be installed from RubyGems:

gem install kaitai-struct

Code

Parse a local file and get structure in memory:

data = QuakePak.from_file("path/to/local/file.pak")

Or parse structure from a string of bytes:

bytes = "\x00\x01\x02..."
data = QuakePak.new(Kaitai::Struct::Stream.new(bytes))

After that, one can get various attributes from the structure by invoking getter methods like:

data.magic # => get magic

Ruby source code to parse .pak file format of Quake game engine

quake_pak.rb

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

require 'kaitai/struct/struct'

unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
  raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end


##
# @see https://quakewiki.org/wiki/.pak#Format_specification Source
class QuakePak < Kaitai::Struct::Struct
  def initialize(_io, _parent = nil, _root = self)
    super(_io, _parent, _root)
    _read
  end

  def _read
    @magic = @_io.read_bytes(4)
    raise Kaitai::Struct::ValidationNotEqualError.new([80, 65, 67, 75].pack('C*'), magic, _io, "/seq/0") if not magic == [80, 65, 67, 75].pack('C*')
    @ofs_index = @_io.read_u4le
    @len_index = @_io.read_u4le
    self
  end
  class IndexStruct < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @entries = []
      i = 0
      while not @_io.eof?
        @entries << IndexEntry.new(@_io, self, @_root)
        i += 1
      end
      self
    end
    attr_reader :entries
  end
  class IndexEntry < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @name = (Kaitai::Struct::Stream::bytes_terminate(Kaitai::Struct::Stream::bytes_strip_right(@_io.read_bytes(56), 0), 0, false)).force_encoding("UTF-8")
      @ofs = @_io.read_u4le
      @size = @_io.read_u4le
      self
    end
    def body
      return @body unless @body.nil?
      io = _root._io
      _pos = io.pos
      io.seek(ofs)
      @body = io.read_bytes(size)
      io.seek(_pos)
      @body
    end
    attr_reader :name
    attr_reader :ofs
    attr_reader :size
  end
  def index
    return @index unless @index.nil?
    _pos = @_io.pos
    @_io.seek(ofs_index)
    @_raw_index = @_io.read_bytes(len_index)
    _io__raw_index = Kaitai::Struct::Stream.new(@_raw_index)
    @index = IndexStruct.new(_io__raw_index, self, @_root)
    @_io.seek(_pos)
    @index
  end
  attr_reader :magic
  attr_reader :ofs_index
  attr_reader :len_index
  attr_reader :_raw_index
end