// but we choose pseudo-random numbers instead of just zeros.
		rng := rand.New(rand.NewSource(time.Now().UnixNano()))
		opts = append([]s2.WriterOption{s2.WriterPadding(compPadEncrypted), s2.WriterPaddingSrc(rng)}, compressOpts...)
	}
	comp := s2.NewWriter(pw, opts...)
	indexCh := make(chan []byte, 1)
	go func() {
		defer xioutil.SafeClose(indexCh)
		cn, err := io.Copy(comp, r)
		if err != nil {