if err != ErrFormat {
		t.Errorf("zeroes: error=%v, want %v", err, ErrFormat)
	}

	// repeated directoryEndSignatures
	sig := make([]byte, 4)
	binary.LittleEndian.PutUint32(sig, directoryEndSignature)
	for i := 0; i < size-4; i += 4 {
		copy(b[i:i+4], sig)
	}
	_, err = NewReader(bytes.NewReader(b), size)
	if err != ErrFormat {
		t.Errorf("sigs: error=%v, want %v", err, ErrFormat)
	}

		UncompressedSize64: 5678,
	}); err != nil {
		t.Fatal(err)
	}
	if err := w.Close(); err != nil {
		t.Fatal(err)
	}
	b := buf.Bytes()

	var sig [4]byte
	binary.LittleEndian.PutUint32(sig[:], uint32(fileHeaderSignature))

	idx := bytes.Index(b, sig[:])
	if idx == -1 {
		t.Fatal("file header not found")
	}
	b = b[idx:]

func (f *File) findBodyOffset() (int64, error) {
	var buf [fileHeaderLen]byte
	if _, err := f.zipr.ReadAt(buf[:], f.headerOffset); err != nil {
		return 0, err
	}
	b := readBuf(buf[:])
	if sig := b.uint32(); sig != fileHeaderSignature {
		return 0, ErrFormat
	}
	b = b[22:] // skip over most of the header
	filenameLen := int(b.uint16())
	extraLen := int(b.uint16())

		return false
	}

	d = make([]byte, directory64EndLen)
	if _, err := zip.ReadAt(d, dirOff); err != nil {
		t.Fatalf("ReadAt(off=%d): %v", dirOff, err)
	}

	b := readBuf(d)
	if sig := b.uint32(); sig != directory64EndSignature {
		return false
	}

	size := b.uint64()
	if size != directory64EndLen-12 {
		t.Errorf("expected length of %d, got %d", directory64EndLen-12, size)
	}
	return true
}

	default:
		panic(fmt.Sprintf("unknown type %T", typ))
	}
}

func (w *Walker) writeSignature(buf *bytes.Buffer, sig *types.Signature) {
	if tparams := sig.TypeParams(); tparams != nil {
		w.writeTypeParams(buf, tparams, true)
	}
	w.writeParams(buf, sig.Params(), sig.Variadic())
	switch res := sig.Results(); res.Len() {
	case 0:
		// nothing to do
	case 1:
		buf.WriteByte(' ')
		w.writeType(buf, res.At(0).Type())