type dirReader struct {
	err error
}

func (r *dirReader) Read([]byte) (int, error) {
	return 0, r.err
}

func (r *dirReader) Close() error {
	return nil
}

type checksumReader struct {
	rc    io.ReadCloser
	hash  hash.Hash32
	nread uint64 // number of bytes read so far
	f     *File
	desr  io.Reader // if non-nil, where to read the data descriptor
	err   error     // sticky error
}

			s.buf = newBuf
			s.end -= s.start
			s.start = 0
		}
		// Finally we can read some input. Make sure we don't get stuck with
		// a misbehaving Reader. Officially we don't need to do this, but let's
		// be extra careful: Scanner is for safe, simple jobs.
		for loop := 0; ; {
			n, err := s.r.Read(s.buf[s.end:len(s.buf)])
			if n < 0 || len(s.buf)-s.end < n {
				s.setErr(ErrBadReadCount)
				break

		t.Errorf("r.Len(): got %d, want %d", got, want)
	}
	if n, err := r.Read(make([]byte, 10)); err != nil || n != 10 {
		t.Errorf("Read failed: read %d %v", n, err)
	}
	if got, want := r.Len(), 1; got != want {
		t.Errorf("r.Len(): got %d, want %d", got, want)
	}
	if n, err := r.Read(make([]byte, 1)); err != nil || n != 1 {
		t.Errorf("Read failed: read %d %v; want 1, nil", n, err)
	}
	if got, want := r.Len(), 0; got != want {

		b := w.AvailableBuffer()
		b = strconv.AppendInt(b, i, 10)
		b = append(b, ' ')
		w.Write(b)
	}
	w.Flush()
	// Output: 1 2 3 4
}

// The simplest use of a Scanner, to read standard input as a set of lines.
func ExampleScanner_lines() {
	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		fmt.Println(scanner.Text()) // Println will add back the final '\n'
	}

	fmt.Printf("%s\n", b.Next(2))
	fmt.Printf("%s\n", b.Next(2))
	fmt.Printf("%s", b.Next(2))
	// Output:
	// ab
	// cd
	// e
}

func ExampleBuffer_Read() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	rdbuf := make([]byte, 1)
	n, err := b.Read(rdbuf)
	if err != nil {
		panic(err)
	}
	fmt.Println(n)
	fmt.Println(b.String())
	fmt.Println(string(rdbuf))
	// Output:
	// 1
	// bcde

// The result is unaffected by any method calls except [Reader.Reset].
func (r *Reader) Size() int64 { return int64(len(r.s)) }

// Read implements the [io.Reader] interface.
func (r *Reader) Read(b []byte) (n int, err error) {
	if r.i >= int64(len(r.s)) {
		return 0, io.EOF
	}
	r.prevRune = -1
	n = copy(b, r.s[r.i:])
	r.i += int64(n)
	return
}

	for i := 0; i < chunks; i++ {
		_, err := io.ReadFull(rc, chunk)
		if err != nil {
			t.Fatal("read:", err)
		}
	}
	if frag := int(size % chunkSize); frag > 0 {
		_, err := io.ReadFull(rc, chunk[:frag])
		if err != nil {
			t.Fatal("read:", err)
		}
	}
	gotEnd, err := io.ReadAll(rc)
	if err != nil {
		t.Fatal("read end:", err)
	}
	if !bytes.Equal(gotEnd, end) {

	buf := make([]byte, 1)
	if _, err := b.Read(nil); err != nil {
		t.Fatalf("1st nil Read = %v; want nil", err)
	}
	if _, err := b.Read(buf); err != errFake {
		t.Fatalf("1st Read = %v; want errFake", err)
	}
	if _, err := b.Read(nil); err != nil {
		t.Fatalf("2nd nil Read = %v; want nil", err)
	}
	if _, err := b.Read(buf); err != nil {
		t.Fatalf("3rd Read with buffer = %v; want nil", err)
	}

	// check not at EOF
	b.WriteString("abcdefghijklmnopqrstuvwxyz")

	// after unsuccessful read
	if n, err := b.Read(nil); n != 0 || err != nil {
		t.Fatalf("Read(nil) = %d,%v; want 0,nil", n, err)
	}
	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after Read(nil): got no error")
	}

	// after successful read
	if _, err := b.ReadBytes('m'); err != nil {
		t.Fatalf("ReadBytes: %v", err)
	}

func FuzzReader(f *testing.F) {
	testdata, err := os.ReadDir("testdata")
	if err != nil {
		f.Fatalf("failed to read testdata directory: %s", err)
	}
	for _, de := range testdata {
		if de.IsDir() {
			continue
		}
		b, err := os.ReadFile(filepath.Join("testdata", de.Name()))
		if err != nil {
			f.Fatalf("failed to read testdata: %s", err)
		}
		f.Add(b)
	}

	f.Fuzz(func(t *testing.T, b []byte) {