Function GRFGetSizeOfDataSection

src/newgrf_config.cpp:227–249

* Get the data section size of a GRF. * @param f GRF. * @return Size of the data section or SIZE_MAX if the file has no separate data section. */

 * @return Size of the data section or SIZE_MAX if the file has no separate data section.
 */
size_t GRFGetSizeOfDataSection(FileHandle &f)
{
	extern const std::array<uint8_t, 8> _grf_cont_v2_sig;
	static const uint header_len = 14;

	uint8_t data[header_len];
	if (fread(data, 1, header_len, f) == header_len) {
		if (data[0] == 0 && data[1] == 0 && std::ranges::equal(std::span(data + 2, _grf_cont_v2_sig.size()), _grf_cont_v2_sig)) {
			/* Valid container version 2, get data section size. */
			size_t offset = (static_cast<size_t>(data[13]) << 24) | (static_cast<size_t>(data[12]) << 16) | (static_cast<size_t>(data[11]) << 8) | static_cast<size_t>(data[10]);
			if (offset >= 1 * 1024 * 1024 * 1024) {
				Debug(grf, 0, "Unexpectedly large offset for NewGRF");
				/* Having more than 1 GiB of data is very implausible. Mostly because then
				 * all pools in OpenTTD are flooded already. Or it's just Action C all over.
				 * In any case, the offsets to graphics will likely not work either. */
				return SIZE_MAX;
			}
			return header_len + offset;
		}
	}

	return SIZE_MAX;
}

/**
 * Calculate the MD5 sum for a GRF, and store it in the config.