directoryHeaderSignature = 0x02014b50
	directoryEndSignature    = 0x06054b50
	directory64LocSignature  = 0x07064b50
	directory64EndSignature  = 0x06064b50
	dataDescriptorSignature  = 0x08074b50 // de-facto standard; required by OS X Finder
	fileHeaderLen            = 30         // + filename + extra
	directoryHeaderLen       = 46         // + filename + extra + comment
	directoryEndLen          = 22         // + comment

	dirents, err := os.ReadDir(goroot)
	if err != nil {
		return err
	}
	for _, de := range dirents {
		switch de.Name() {
		case "bin", "pkg":
			// We already created GOROOT/bin and GOROOT/pkg above; skip those.
			continue
		}
		if err := adb("push", filepath.Join(goroot, de.Name()), path.Join(deviceGoroot, de.Name())); err != nil {
			return err
		}
	}

		},
	}, {
		maker: makeSparse{makeReg{"abcde", 5}, sparseDatas{{1, 3}, {6, 0}, {6, 0}, {6, 2}}, 8},
		tests: []testFnc{
			testRemaining{8, 5},
			testWriteTo{fileOps{int64(1), "abc", int64(2), "de"}, 8, nil},
			testRemaining{0, 0},
		},
	}, {
		maker: makeSparse{makeReg{"abcde", 5}, sparseDatas{{1, 3}, {6, 2}}, 10},
		tests: []testFnc{
			testRead{100, "\x00abc\x00\x00de\x00\x00", io.EOF},
		},

	var buf []byte
	if w.isZip64() {
		buf = make([]byte, dataDescriptor64Len)
	} else {
		buf = make([]byte, dataDescriptorLen)
	}
	b := writeBuf(buf)
	b.uint32(dataDescriptorSignature) // de-facto standard, required by OS X
	b.uint32(w.CRC32)
	if w.isZip64() {
		b.uint64(w.CompressedSize64)
		b.uint64(w.UncompressedSize64)
	} else {
		b.uint32(w.CompressedSize)
		b.uint32(w.UncompressedSize)
	}