Function load_cimage

Source/astcenccli_image_load_store.cpp:2599–2688

See header for documentation. */

/* See header for documentation. */
int load_cimage(
	const char* filename,
	astc_compressed_image& img
) {
	std::ifstream file(filename, std::ios::in | std::ios::binary);
	if (!file)
	{
		print_error("ERROR: File open failed '%s'\n", filename);
		return 1;
	}

	astc_header hdr;
	file.read(reinterpret_cast<char*>(&hdr), sizeof(astc_header));
	if (file.fail())
	{
		print_error("ERROR: File read failed '%s'\n", filename);
		return 1;
	}

	unsigned int magicval = unpack_bytes(hdr.magic[0], hdr.magic[1], hdr.magic[2], hdr.magic[3]);
	if (magicval != ASTC_MAGIC_ID)
	{
		print_error("ERROR: Image header corrupt '%s'\n", filename);
		return 1;
	}

	// Ensure these are not zero to avoid div by zero
	size_t block_x = astc::max(static_cast<unsigned int>(hdr.block_x), 1u);
	size_t block_y = astc::max(static_cast<unsigned int>(hdr.block_y), 1u);
	size_t block_z = astc::max(static_cast<unsigned int>(hdr.block_z), 1u);

	size_t dim_x = unpack_bytes(hdr.dim_x[0], hdr.dim_x[1], hdr.dim_x[2], 0);
	size_t dim_y = unpack_bytes(hdr.dim_y[0], hdr.dim_y[1], hdr.dim_y[2], 0);
	size_t dim_z = unpack_bytes(hdr.dim_z[0], hdr.dim_z[1], hdr.dim_z[2], 0);

	if (dim_x == 0 || dim_y == 0 || dim_z == 0)
	{
		print_error("ERROR: Image header corrupt '%s'\n", filename);
		return 1;
	}

	// These cannot overflow as dim_* values are limited to 2^24 - 1
	size_t blocks_x = (dim_x + block_x - 1) / block_x;
	size_t blocks_y = (dim_y + block_y - 1) / block_y;
	size_t blocks_z = (dim_z + block_z - 1) / block_z;

	// This can overflow if dim_* sizes are large
	bool overflow { false };

	size_t data_size = astc::mul_safe(blocks_x, blocks_y, overflow);
	data_size = astc::mul_safe(data_size, blocks_z, overflow);
	data_size = astc::mul_safe(data_size, 16, overflow);

	if (overflow)
	{
		print_error("ERROR: Image header corrupt '%s'\n", filename);
		return 1;
	}