// Because unused fields are filled with NULs, we need
	// to skip leading NULs. Fields may also be padded with
	// spaces or NULs.
	// So we remove leading and trailing NULs and spaces to
	// be sure.
	b = bytes.Trim(b, " \x00")

	if len(b) == 0 {
		return 0
	}
	x, perr := strconv.ParseUint(p.parseString(b), 8, 64)
	if perr != nil {
		p.err = ErrHeader
	}
	return int64(x)
}