xar unarchiver (.xar, .pkg, .xip)
Initial commit
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czar.cr
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czar.cr
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#!/usr/bin/env crystal
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require "binary_parser"
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require "zlib"
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require "xml"
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def perror(msg : String)
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STDERR.write Slice.new (msg + "\n").to_unsafe, (msg + "\n").size
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exit 1
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end
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CHECKSUM_ALGO = {
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0 => :NONE,
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1 => :SHA1,
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2 => :MD5,
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}
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class XARHeader < BinaryParser
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endian :big
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string :magic, {count: 4}
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uint16 :header_size
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uint16 :version
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uint64 :length_compressed
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uint64 :length_uncompressed
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uint32 :checksum_algo
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end
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class SliceIO < IO
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def initialize(@slice : Bytes)
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end
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def read(slice : Bytes)
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slice.size.times { |i| slice[i] = @slice[i] }
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@slice += slice.size
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slice.size
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end
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def write(slice : Bytes)
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slice.size.times { |i| @slice[i] = slice[i] }
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@slice += slice.size
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nil
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end
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def to_slice
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@slice
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end
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end
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def xml_select(xml : XML::Node, node : String)
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perror "error in xml_select" if xml.nil?
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xml.children.select { |e| e.name == node }
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end
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def xml_value(xml : XML::Node, name : String)
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perror "error in xml_value" if xml.nil?
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xml.children.select { |e| e.name == name }.map { |e| e.content }
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end
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def xar_decode(entity : XML::Node, path : String = "./")
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entity_name = xml_value(entity, "name")
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if entity_name.size < 1
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puts "entity without name: #{entity.to_s}"
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return
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end
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entity_name = entity_name.first
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entity_type = xml_value(entity, "type")
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if entity_type.size < 1
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puts "entity without type: #{entity.to_s}"
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return
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end
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entity_type = entity_type.first
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puts "#{path}#{entity_name} (#{entity_type})"
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children = xml_select(entity, "file")
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if children.size > 0
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if entity_type != "directory"
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puts "warn: found a #{entity_type} with #{children.size} children"
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end
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children.each do |child|
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xar_decode child, "#{path}#{entity_name}/"
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end
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end
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end
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File.open "test.xar", "r" do |file|
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header = XARHeader.new
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header.load file
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perror "not a xar file" if header.magic != "xar!"
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puts "#{header.magic}"
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puts "header size #{header.header_size}"
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puts "format version #{header.version}"
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puts "TOC length (compressed) #{header.length_compressed}"
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puts "TOC length (uncompressed) #{header.length_uncompressed}"
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puts "checksum algo #{CHECKSUM_ALGO[header.checksum_algo]}"
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toc_data = Bytes.new header.length_uncompressed
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file.seek header.header_size
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Zlib::Reader.open file do |zfile|
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zfile.read toc_data
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end
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xar = XML.parse SliceIO.new toc_data
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toc = xml_select(xar, "xar").first
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toc = xml_select(toc, "toc").first
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data_offset = header.header_size + header.length_compressed
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data_checksum = xml_select(toc, "checksum").first
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data_checksum_offset = xml_value(data_checksum, "offset").first.to_i
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data_checksum_size = xml_value(data_checksum, "size").first.to_i
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data_checksum_type = data_checksum["style"]
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puts "TOC is checksummed as #{data_checksum_type}, #{data_checksum_size} bytes stored at offset #{data_checksum_offset}"
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file.seek data_offset
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file.seek data_checksum_offset, IO::Seek::Current
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data_files = xml_select(toc, "file")
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puts "found #{data_files.size} files at the root"
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data_files.each do |entity|
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xar_decode entity
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end
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end