t.Fatalf("entry %d, Next(): got %v, want %v", i, err, nil)
				}
				buf := make([]byte, tc.cnt)
				if _, err := io.ReadFull(tr, buf); err != nil {
					t.Fatalf("entry %d, ReadFull(): got %v, want %v", i, err, nil)
				}
				if string(buf) != tc.output {
					t.Fatalf("entry %d, ReadFull(): got %q, want %q", i, string(buf), tc.output)
				}
			}

			if _, err := tr.Next(); err != io.EOF {

// also returned.
func cmpReaders(r1, r2 io.Reader) (bool, string) {
	bufLen := 32 * 1024
	b1, b2 := make([]byte, bufLen), make([]byte, bufLen)
	for i := 0; true; i++ {
		n1, e1 := io.ReadFull(r1, b1)
		n2, e2 := io.ReadFull(r2, b2)
		if n1 != n2 {
			return false, fmt.Sprintf("Read %d != %d bytes from the readers", n1, n2)
		}
		if !bytes.Equal(b1[:n1], b2[:n2]) {

	//
	// The signature is 64 bytes long (hex-encoded SHA256 hash) and
	// starts with a 16 byte header: len("chunk-signature=") + 64 == 80.
	var signature [80]byte
	_, err = io.ReadFull(cr.reader, signature[:])
	if err == io.EOF {
		err = io.ErrUnexpectedEOF
	}
	if err != nil {
		cr.err = err
		return n, cr.err
	}
	if !bytes.HasPrefix(signature[:], []byte("chunk-signature=")) {

	}
	if length <= 0 {
		length = accessKeyMaxLen
	}
	if length < accessKeyMinLen {
		return "", errors.New("auth: access key length is too short")
	}

	key := make([]byte, length)
	if _, err := io.ReadFull(random, key); err != nil {
		return "", err
	}
	for i := range key {
		key[i] = alphaNumericTable[key[i]%alphaNumericTableLen]
	}
	return string(key), nil
}

func (tr *Reader) readHeader() (*Header, *block, error) {
	// Two blocks of zero bytes marks the end of the archive.
	if _, err := io.ReadFull(tr.r, tr.blk[:]); err != nil {
		return nil, nil, err // EOF is okay here; exactly 0 bytes read
	}
	if bytes.Equal(tr.blk[:], zeroBlock[:]) {
		if _, err := io.ReadFull(tr.r, tr.blk[:]); err != nil {
			return nil, nil, err // EOF is okay here; exactly 1 block of zeros read
		}

		return errFileCorrupt
	}

	bufp := xioutil.ODirectPoolSmall.Get()
	defer xioutil.ODirectPoolSmall.Put(bufp)

	for left > 0 {
		// Read expected hash...
		h.Reset()
		n, err := io.ReadFull(r, hashBuf)
		if err != nil {
			// Read's failed for object with right size, file is corrupt.
			return err
		}
		// Subtract hash length..
		left -= int64(n)
		if left < shardSize {
			shardSize = left

	// first read just those 4 bytes to see if it exists.
	if _, err := io.ReadFull(r, buf[:4]); err != nil {
		return err
	}
	off := 0
	maybeSig := readBuf(buf[:4])
	if maybeSig.uint32() != dataDescriptorSignature {
		// No data descriptor signature. Keep these four
		// bytes.
		off += 4
	}
	if _, err := io.ReadFull(r, buf[off:12]); err != nil {
		return err
	}
	b := readBuf(buf[:12])

		if err != nil {
			t.Fatalf("Test %d: failed to create ErasureStorage: %v", i, err)
		}
		data := make([]byte, test.size)
		if _, err = io.ReadFull(rand.Reader, data); err != nil {
			t.Fatalf("Test %d: failed to create random test data: %v", i, err)
		}
		buffer := make([]byte, test.blocksize, 2*test.blocksize)
		writers := make([]io.Writer, len(disks))

		if err != nil {
			t.Fatalf("Test %d: failed to create ErasureStorage: %v", i, err)
		}
		buffer := make([]byte, test.blocksize, 2*test.blocksize)

		data := make([]byte, test.data)
		if _, err = io.ReadFull(rand.Reader, data); err != nil {
			t.Fatalf("Test %d: failed to generate random test data: %v", i, err)
		}
		writers := make([]io.Writer, len(disks))
		for i, disk := range disks {
			if disk == OfflineDisk {

		if err != nil {
			t.Fatalf("Test %d: failed to create ErasureStorage: %v", i, err)
		}
		disks := setup.disks
		data := make([]byte, test.data)
		if _, err = io.ReadFull(crand.Reader, data); err != nil {
			t.Fatalf("Test %d: failed to generate random test data: %v", i, err)
		}

		writeAlgorithm := test.algorithm
		if !test.algorithm.Available() {