brew/Library/Homebrew/cask/lib/hbc/container/xip.rb

require "tmpdir"

module Hbc
  class Container
    class Xip < Base
      def self.me?(criteria)
        criteria.magic_number(%r{^xar!}n) &&
          IO.popen(["/usr/bin/xar", "-t", "-f", criteria.path.to_s], err: "/dev/null") { |io| io.read =~ %r{\AContent\nMetadata\n\Z} }
      end

      def extract
        Dir.mktmpdir do |unpack_dir|
          begin
            ohai "Verifying signature for #{@path.basename}"
            @command.run!("/usr/sbin/pkgutil", args: ["--check-signature", @path])
          rescue
            raise "Signature check failed."
          end

          @command.run!("/usr/bin/xar", args: ["-x", "-f", @path, "Content", "-C", unpack_dir])

          Dir.chdir(@cask.staged_path) do
            @command.run!("/usr/bin/cpio", args: ["--quiet", "-i", "-I", Pathname(unpack_dir).join("Content")])
          end
        end
      end
    end
  end
end