fs.FileInfo
	// Uname should give a user name.
	Uname() (string, error)
	// Gname should give a group name.
	Gname() (string, error)
}

// isHeaderOnlyType checks if the given type flag is of the type that has no
// data section even if a size is specified.
func isHeaderOnlyType(flag byte) bool {
	switch flag {
	case TypeLink, TypeSymlink, TypeChar, TypeBlock, TypeDir, TypeFifo:
		return true
	default:
		return false
	}

func (tw *Writer) writeRawHeader(blk *block, size int64, flag byte) error {
	if err := tw.Flush(); err != nil {
		return err
	}
	if _, err := tw.w.Write(blk[:]); err != nil {
		return err
	}
	if isHeaderOnlyType(flag) {
		size = 0
	}
	tw.curr = &regFileWriter{tw.w, size}
	tw.pad = blockPadding(size)
	return nil
}

// AddFS adds the files from fs.FS to the archive.