Thing that extracts files from Day of the Tentacle: Remastered (`tenta.cle`) and probably similar things

extract_tentacle.rb

require 'bindata'
require 'pathname'
require 'fileutils'
require 'optparse'

class Header < BinData::Record
  endian :little

  uint32 :magic
  float  :version
  uint32 :index_start
  uint32 :file_entries_start
  uint32 :file_names_start
  uint32 :data_start
  uint32 :index_size
  uint32 :file_entries_size
  uint32 :file_names_size
  uint32 :data_size
end

class FileEntry < BinData::Record
  endian :little

  uint32 :data_start
  uint32 :name_start # unreliable!
  uint32 :data_size
  uint32 :compressed_size
  uint32 :compression_type

  attr_accessor :filename
  def extract(header, file, dest)
    file.seek header.data_start + data_start
    IO.copy_stream file, dest, self.data_size
  end
end

options = {}
opt_parser = OptionParser.new do |opt|
  opt.banner = "Usage: parse_tentacle filename [OPTIONS]"
  opt.separator "OPTIONS"
  opt.on("-x" "--extract BASE", "extract files whose name start with BASE") do |file|
    options[:extract] = file
  end
end
opt_parser.parse!

file = ARGF
file.binmode
header = Header.read(file)
abort "unrecognized file type" unless header.magic == 0x4C50414B

num_files = header.file_entries_size / FileEntry.new.num_bytes
file.seek header.file_entries_start
file_entries = num_files.times.map { FileEntry.read(file) }

file.seek header.file_names_start
names = file.read(header.file_names_size).split("\0")

file_entries.each_with_index do |entry, index|
  entry.filename = names[index]
end
file_entries.sort_by! { |entry| entry.filename }

if options[:extract]
  file_entries.select { |entry| entry.filename.start_with?(options[:extract]) }.each do |entry|
    pn = Pathname.new(entry.filename)
    STDERR.puts entry.filename
    FileUtils.mkdir_p pn.dirname
    entry.extract header, file, File.open(entry.filename, 'wb')
  end
else
  # list
  file_entries.each do |entry|
    printf "%11d %s\n", entry.data_size, entry.filename
  end
end