func findDirectory64End()

in reader.go [554:575]

• 22 lines of code
• 6 McCabe index (conditional complexity)

func findDirectory64End(r io.ReaderAt, directoryEndOffset int64) (int64, error) {
	locOffset := directoryEndOffset - directory64LocLen
	if locOffset < 0 {
		return -1, nil // no need to look for a header outside the file
	}
	buf := make([]byte, directory64LocLen)
	if _, err := r.ReadAt(buf, locOffset); err != nil {
		return -1, err
	}
	b := readBuf(buf)
	if sig := b.uint32(); sig != directory64LocSignature {
		return -1, nil
	}
	if b.uint32() != 0 { // number of the disk with the start of the zip64 end of central directory
		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
}