func HalfReader(r io.Reader) io.Reader { return &halfReader{r} }

type halfReader struct {
	r io.Reader
}

func (r *halfReader) Read(p []byte) (int, error) {
	return r.r.Read(p[0 : (len(p)+1)/2])
}

// DataErrReader changes the way errors are handled by a Reader. Normally, a
// Reader returns an error (typically EOF) from the first Read call after the
// last piece of data is read. DataErrReader wraps a Reader and changes its

		t.Fatal("ReadAt:", err)
	}
	if n != len(want) {
		t.Fatalf("ReadAt: got %d bytes, want %d bytes", n, len(want))
	}
	if string(got) != want {
		t.Fatalf("ReadAt: got %q, want %q", got, want)
	}

	// Use ReadAt with non-zero offset.
	off = int64(7)
	want = want[off:]
	got = make([]byte, len(want))
	n, err = at.ReadAt(got, off)
	if err != nil {
		t.Fatal("ReadAt:", err)
	}
	if n != len(want) {

	}
}

func TestReaderZero(t *testing.T) {
	if l := (&strings.Reader{}).Len(); l != 0 {
		t.Errorf("Len: got %d, want 0", l)
	}

	if n, err := (&strings.Reader{}).Read(nil); n != 0 || err != io.EOF {
		t.Errorf("Read: got %d, %v; want 0, io.EOF", n, err)
	}

	if n, err := (&strings.Reader{}).ReadAt(nil, 11); n != 0 || err != io.EOF {
		t.Errorf("ReadAt: got %d, %v; want 0, io.EOF", n, err)
	}

func elfBuildID(file string) (string, error) {
	buf := make([]byte, 256)
	f, err := os.Open(file)
	if err != nil {
		return "", err
	}
	defer f.Close()

	if _, err := f.ReadAt(buf[:64], 0); err != nil {
		return "", err
	}

	// ELF file begins with \x7F E L F.
	if buf[0] != 0x7F || buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F' {
		return "", errBadELF
	}

					br.Close()
				}
				p.readers[i] = nil

				// Since ReadAt returned error, trigger another read.
				readTriggerCh <- true
				return
			}
			newBufLK.Lock()
			newBuf[bufIdx] = p.buf[bufIdx][:n]
			newBufLK.Unlock()
			// Since ReadAt returned success, there is no need to trigger another read.
			readTriggerCh <- false
		}(readerIndex)
		readerIndex++
	}
	wg.Wait()

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
}

// ReadAt implements the [io.ReaderAt] interface.
func (r *Reader) ReadAt(b []byte, off int64) (n int, err error) {
	// cannot modify state - see io.ReaderAt
	if off < 0 {

		bw.Close()
	}

	reader := newBitrotReader(disk, nil, volume, filePath, 35, bitrotAlgo, bitrotWriterSum(writer), 10)
	b := make([]byte, 10)
	if _, err = reader.ReadAt(b, 0); err != nil {
		t.Fatal(err)
	}
	if _, err = reader.ReadAt(b, 10); err != nil {
		t.Fatal(err)
	}
	if _, err = reader.ReadAt(b, 20); err != nil {
		t.Fatal(err)
	}
	if _, err = reader.ReadAt(b[:5], 30); err != nil {
		t.Fatal(err)
	}

		// drain the body for connection reuse at network layer.
		xhttp.DrainBody(struct {
			io.Reader
			io.Closer
		}{
			Reader: b.rc,
			Closer: closeWrapper(func() error { return nil }),
		})
		return closer.Close()
	}
	return nil
}

func (b *streamingBitrotReader) ReadAt(buf []byte, offset int64) (int, error) {
	var err error
	if offset%b.shardSize != 0 {

// ReadAt blocks until either all the data is available or an error occurs.
// In this respect ReadAt is different from Read.
//
// If the n = len(p) bytes returned by ReadAt are at the end of the
// input source, ReadAt may return either err == EOF or err == nil.
//
// If ReadAt is reading from an input source with a seek offset,
// ReadAt should not affect nor be affected by the underlying

			err = machoUpdateLoadCommand(reader, linkseg, linkoffset, &linkEditDataCmd{}, "DataOff")
		case LC_ENCRYPTION_INFO, LC_ENCRYPTION_INFO_64:
			err = machoUpdateLoadCommand(reader, linkseg, linkoffset, &encryptionInfoCmd{}, "CryptOff")
		case LC_UUID:
			var u uuidCmd
			err = reader.ReadAt(0, &u)
			if err == nil {
				copy(u.Uuid[:], uuidFromGoBuildId(*flagBuildid))
				err = reader.WriteAt(0, &u)
			}