decodeKVKey.go

const (
	ENC_GROUP_SIZE = 8
	ENC_MARKER     = byte(0xFF)
)

func DecodeKVStorageKeyToKey(data []byte) []byte {
	key := make([]byte, 0, len(data)/(ENC_GROUP_SIZE+1)*ENC_GROUP_SIZE)
	offset := 0
	chunkLen := ENC_GROUP_SIZE + 1
	for {
		nextOffset := offset + chunkLen
		if nextOffset > len(data) {
			return nil
		}
		chunk := data[offset:nextOffset]
		offset = nextOffset
		marker, bytes := chunk[len(chunk)-1], chunk[:len(chunk)-1]
		padSize := int(ENC_MARKER - marker)
		if padSize == 0 {
			key = append(key, bytes...)
			continue
		}
		if padSize > ENC_GROUP_SIZE {
			return nil
		}
		bytes, padding := bytes[:ENC_GROUP_SIZE-padSize], bytes[ENC_GROUP_SIZE-padSize:]
		key = append(key, bytes...)
		for _, x := range padding {
			if x != 0 {
				return nil
			}
		}
		data = data[offset:]
		return key
	}
}