b.uint32(h.CRC32)
		if h.isZip64() || h.offset >= uint32max {
			// the file needs a zip64 header. store maxint in both
			// 32 bit size fields (and offset later) to signal that the
			// zip64 extra header should be used.
			b.uint32(uint32max) // compressed size
			b.uint32(uint32max) // uncompressed size

			// append a zip64 extra block to Extra
			var buf [28]byte // 2x uint16 + 3x uint64
			eb := writeBuf(buf[:])

		return -1, nil // the file is not a valid zip64-file
	}
	p := b.uint64()      // relative offset of the zip64 end of central directory record
	if b.uint32() != 1 { // total number of disks
		return -1, nil // the file is not a valid zip64-file
	}
	return int64(p), nil
}

// readDirectory64End reads the zip64 directory end and updates the

See the [ZIP specification] for details.

This package does not support disk spanning.

A note about ZIP64:

To be backwards compatible the FileHeader has both 32 and 64 bit Size
fields. The 64 bit fields will always contain the correct value and
for normal archives both fields will be the same. For files requiring
the ZIP64 format the 32 bit fields will be 0xffffffff and the 64 bit
fields must be used instead.

			},
		},
	},
	{
		Name: "zip64.zip",
		File: []ZipTestFile{
			{
				Name:     "README",
				Content:  []byte("This small file is in ZIP64 format.\n"),
				Modified: time.Date(2012, 8, 10, 14, 33, 32, 0, time.UTC),
				Mode:     0644,
			},
		},
	},
	// Another zip64 file with different Extras fields. (golang.org/issue/7069)
	{
		Name: "zip64-2.zip",
		File: []ZipTestFile{
			{