Function LoadNewGRFFileFromFile

src/newgrf.cpp:1295–1381

* Load a particular NewGRF from a SpriteFile. * @param config The configuration of the to be loaded NewGRF. * @param stage The loading stage of the NewGRF. * @param file The file to load the GRF data from. */

 * @param file   The file to load the GRF data from.
 */
static void LoadNewGRFFileFromFile(GRFConfig &config, GrfLoadingStage stage, SpriteFile &file)
{
	AutoRestoreBackup cur_file(_cur_gps.file, &file);
	AutoRestoreBackup cur_config(_cur_gps.grfconfig, &config);

	Debug(grf, 2, "LoadNewGRFFile: Reading NewGRF-file '{}'", config.filename);

	uint8_t grf_container_version = file.GetContainerVersion();
	if (grf_container_version == 0) {
		Debug(grf, 7, "LoadNewGRFFile: Custom .grf has invalid format");
		return;
	}

	if (stage == GLS_INIT || stage == GLS_ACTIVATION) {
		/* We need the sprite offsets in the init stage for NewGRF sounds
		 * and in the activation stage for real sprites. */
		ReadGRFSpriteOffsets(file);
	} else {
		/* Skip sprite section offset if present. */
		if (grf_container_version >= 2) file.ReadDword();
	}

	if (grf_container_version >= 2) {
		/* Read compression value. */
		uint8_t compression = file.ReadByte();
		if (compression != 0) {
			Debug(grf, 7, "LoadNewGRFFile: Unsupported compression format");
			return;
		}
	}

	/* Skip the first sprite; we don't care about how many sprites this
	 * does contain; newest TTDPatches and George's longvehicles don't
	 * neither, apparently. */
	uint32_t num = grf_container_version >= 2 ? file.ReadDword() : file.ReadWord();
	if (num == 4 && file.ReadByte() == 0xFF) {
		file.ReadDword();
	} else {
		Debug(grf, 7, "LoadNewGRFFile: Custom .grf has invalid format");
		return;
	}

	_cur_gps.ClearDataForNextFile();

	ReusableBuffer<uint8_t> allocator;

	while ((num = (grf_container_version >= 2 ? file.ReadDword() : file.ReadWord())) != 0) {
		uint8_t type = file.ReadByte();
		_cur_gps.nfo_line++;

		if (type == 0xFF) {
			if (_cur_gps.skip_sprites == 0) {
				/* Limit the special sprites to 1 MiB. */
				if (num > 1024 * 1024) {
					GrfMsg(0, "LoadNewGRFFile: Unexpectedly large sprite, disabling");
					DisableGrf(STR_NEWGRF_ERROR_UNEXPECTED_SPRITE);
					break;
				}