Fiddle binding for launch_activate_socket for launchd handing sockets to processes (http://www.manpagez.com/man/3/launch/)

launch.rb

module Launch
  extend Fiddle::Importer

  dlload '/usr/lib/system/liblaunch.dylib'

  @launch_activate_socket = import_function(*parse_signature("int launch_activate_socket(const char *name, int **fds, size_t *cnt)"))
  def self.launch_activate_socket(name)
    raise ArgumentError, "name must be a string" unless name.is_a? String

    fds_ptr = Fiddle::Pointer.new(0)
    count_ptr = Fiddle::Pointer.malloc(Fiddle::SIZEOF_SIZE_T)

    result = @launch_activate_socket.call(name, fds_ptr.ref, count_ptr)

    raise "launch_activate_socket returned #{result}" unless result.zero?

    count = count_ptr.to_s(Fiddle::SIZEOF_SIZE_T).unpack("I!").first
    fds = fds_ptr.to_s(Fiddle::SIZEOF_INT * count).unpack("i#{count}")
    
    Fiddle.free(fds_ptr.to_i)

    fds
  end
end