Function ExtractTar

src/fileio.cpp:590–654

* Extract the tar with the given filename in the directory * where the tar resides. * @param tar_filename the name of the tar to extract. * @param subdir The sub directory the tar is in. * @return false on failure. */

 * @return false on failure.
 */
bool ExtractTar(const std::string &tar_filename, Subdirectory subdir)
{
	TarList::iterator it = _tar_list[subdir].find(tar_filename);
	/* We don't know the file. */
	if (it == _tar_list[subdir].end()) return false;

	const auto &dirname = it->second;

	/* The file doesn't have a sub directory! */
	if (dirname.empty()) {
		Debug(misc, 3, "Extracting {} failed; archive rejected, the contents must be in a sub directory", tar_filename);
		return false;
	}

	std::string filename = tar_filename;
	auto p = filename.find_last_of(PATHSEPCHAR);
	/* The file's path does not have a separator? */
	if (p == std::string::npos) return false;

	filename.replace(p + 1, std::string::npos, dirname);
	Debug(misc, 8, "Extracting {} to directory {}", tar_filename, filename);
	FioCreateDirectory(filename);

	for (auto &it2 : _tar_filelist[subdir]) {
		if (tar_filename != it2.second.tar_filename) continue;

		/* it2.first is tarball + PATHSEPCHAR + name. */
		std::string_view name = it2.first;
		name.remove_prefix(name.find_first_of(PATHSEPCHAR) + 1);
		filename.replace(p + 1, std::string::npos, name);

		Debug(misc, 9, "  extracting {}", filename);

		/* First open the file in the .tar. */
		size_t to_copy = 0;
		auto in = FioFOpenFileTar(it2.second, &to_copy);
		if (!in.has_value()) {
			Debug(misc, 6, "Extracting {} failed; could not open {}", filename, tar_filename);
			return false;
		}

		/* Now open the 'output' file. */
		auto out = FileHandle::Open(filename, "wb");
		if (!out.has_value()) {
			Debug(misc, 6, "Extracting {} failed; could not open {}", filename, filename);
			return false;
		}

		/* Now read from the tar and write it into the file. */
		char buffer[4096];
		size_t read;
		for (; to_copy != 0; to_copy -= read) {
			read = fread(buffer, 1, std::min(to_copy, lengthof(buffer)), *in);
			if (read <= 0 || fwrite(buffer, 1, read, *out) != read) break;
		}

		if (to_copy != 0) {
			Debug(misc, 6, "Extracting {} failed; still {} bytes to copy", filename, to_copy);