Function ReadCompressedBlock

TombEngine/Specific/level.cpp:1463–1509

#endif

bool ReadCompressedBlock(FILE* filePtr, bool skip)
{
	long long compressedSize = 0;
	long long uncompressedSize = 0;

	ReadFileEx(&uncompressedSize, 1, sizeof(long long), filePtr);
	ReadFileEx(&compressedSize, 1, sizeof(long long), filePtr);

#ifndef _WIN64
	// Safeguard against incompatible block size.
	if (uncompressedSize > INT_MAX || compressedSize > INT_MAX)
		throw std::exception{ "Level data block exceeds 2 GB and can't be loaded by a 32-bit version of the engine." };
#endif

	// Safeguard against changed file format.
	auto remainingSize = GetRemainingSize(filePtr);
	if (uncompressedSize <= 0 || compressedSize <= 0 || compressedSize > remainingSize)
		throw std::exception{ "Data block size is incorrect. Probably old level version?" };

	if (skip) 
	{
#ifdef _WIN64
		_fseeki64(filePtr, compressedSize, SEEK_CUR);
#else
		fseek(filePtr, compressedSize, SEEK_CUR);
#endif
		return false;
	}

	auto compressedBuffer = (char*)malloc(compressedSize);
	ReadFileEx(compressedBuffer, compressedSize, 1, filePtr);
	DataPtr = (char*)malloc(uncompressedSize);

	if (!Decompress(DataPtr, compressedBuffer, uncompressedSize))
	{
		free(compressedBuffer);
		free(DataPtr);
		DataPtr = nullptr;
		throw std::exception{ "LZ4 decompression failed." };
	}

	free(compressedBuffer);

	CurrentDataPtr = DataPtr;

	return true;
}

void FinalizeBlock()
{