def populate_and_check_magic
      magic = @raw_data[0..3].unpack("N").first

      raise MagicError, magic unless Utils.magic?(magic)
      raise FatBinaryError if Utils.fat_magic?(magic)

      @endianness = Utils.little_magic?(magic) ? :little : :big

      magic
    end
def populate_and_check_magic
      magic = @raw_data[0..3].unpack("N").first

      raise MagicError, magic unless Utils.magic?(magic)
      raise FatBinaryError if Utils.fat_magic?(magic)

      @endianness = Utils.little_magic?(magic) ? :little : :big

      magic
    end
Read just the file's magic number and check its validity.
 @return [Integer] the magic
 @raise [MagicError] if the magic is not valid Mach-O magic
 @raise [FatBinaryError] if the magic is for a Fat file
 @api private