f     *File
	desr  io.Reader // if non-nil, where to read the data descriptor
	err   error     // sticky error
}

func (r *checksumReader) Stat() (fs.FileInfo, error) {
	return headerFileInfo{&r.f.FileHeader}, nil
}

func (r *checksumReader) Read(b []byte) (n int, err error) {
	if r.err != nil {
		return 0, r.err
	}
	n, err = r.rc.Read(b)
	r.hash.Write(b[:n])

	blk  block      // Buffer to use as temporary local storage

	// err is a persistent error.
	// It is only the responsibility of every exported method of Reader to
	// ensure that this error is sticky.
	err error
}

type fileReader interface {
	io.Reader
	fileState

	WriteTo(io.Writer) (int64, error)
}

// NewReader creates a new [Reader] reading from r.
func NewReader(r io.Reader) *Reader {