if err != nil {
			return err
		}
		defer f.Close()
		_, err = io.Copy(tw, f)
		return err
	})
}

// splitUSTARPath splits a path according to USTAR prefix and suffix rules.
// If the path is not splittable, then it will return ("", "", false).
func splitUSTARPath(name string) (prefix, suffix string, ok bool) {
	length := len(name)
	if length <= nameSize || !isASCII(name) {
		return "", "", false

			whyNoGNU = fmt.Sprintf("GNU cannot encode %s=%q", name, s)
			format.mustNotBe(FormatGNU)
		}
		if !isASCII(s) || tooLong {
			canSplitUSTAR := paxKey == paxPath
			if _, _, ok := splitUSTARPath(s); !canSplitUSTAR || !ok {
				whyNoUSTAR = fmt.Sprintf("USTAR cannot encode %s=%q", name, s)
				format.mustNotBe(FormatUSTAR)
			}
			if paxKey == paxNone {