Method NewFromBuffer

src/DartsDict.cpp:326–414

}

DartsDictPtr DartsDict::NewFromBuffer(const char* data, size_t size) {
  DartsDictPtr dict(new DartsDict());
  auto internal = dict->internal;

  size_t headerLen = strlen(OCDHEADER);
  if (size < headerLen || memcmp(data, OCDHEADER, headerLen) != 0) {
    throw InvalidFormat("Invalid OpenCC dictionary header");
  }
  size_t offset = headerLen;

  if (size - offset < 8) {
    throw InvalidFormat("Invalid OpenCC dictionary header (dartsSize)");
  }
  uint8_t probe[8];
  memcpy(probe, data + offset, 8);
  offset += 8;
  bool is64bit =
      (probe[4] == 0 && probe[5] == 0 && probe[6] == 0 && probe[7] == 0);

  if (is64bit) {
    uint64_t dartsSize64;
    memcpy(&dartsSize64, probe, 8);
    size_t dartsSize = static_cast<size_t>(dartsSize64);
    if (dartsSize > size - offset) {
      throw InvalidFormat(
          "Invalid OpenCC dictionary (dartsSize exceeds file size)");
    }
    if (dartsSize % sizeof(LegacyUnit64) != 0) {
      throw InvalidFormat("Invalid legacy OCD dictionary unit alignment");
    }
    std::unique_ptr<void, decltype(&free)> buffer(malloc(dartsSize), free);
    if (!buffer) {
      throw std::bad_alloc();
    }
    memcpy(buffer.get(), data + offset, dartsSize);
    offset += dartsSize;

    BinaryDictPtr binary = BinaryDict::NewFromBuffer(data + offset, size - offset);

    internal->buffer = buffer.release();
    internal->binary = std::move(binary);
    internal->legacyArray64 = static_cast<const LegacyUnit64*>(internal->buffer);

    dict->lexicon = internal->binary->GetLexicon();
    dict->maxLength = internal->binary->KeyMaxLength();
    size_t numUnits = dartsSize / sizeof(LegacyUnit64);
    if (!ValidateLegacy64(internal->legacyArray64, numUnits,
                          static_cast<int>(dict->lexicon->Length()))) {
      throw InvalidFormat("Invalid legacy OCD dictionary darts data");
    }
    return dict;
  }

  // 32-bit: dartsSize is the first 4 bytes of probe; probe[4..7] belong to the
  // darts array, so rewind 4 bytes before reading the array.
  uint32_t dartsSize32;
  memcpy(&dartsSize32, probe, 4);
  size_t dartsSize = dartsSize32;