Method SaveToDisk

src/ini.cpp:42–102

* Save the Ini file's data to the disk. * @param filename the file to save to. * @return true if saving succeeded. */

 * @return true if saving succeeded.
 */
bool IniFile::SaveToDisk(const std::string &filename)
{
	/*
	 * First write the configuration to a (temporary) file and then rename
	 * that file. This to prevent that when OpenTTD crashes during the save
	 * you end up with a truncated configuration file.
	 */
	std::string file_new{ filename };
	file_new.append(".new");

	std::ofstream os(OTTD2FS(file_new).c_str());
	if (os.fail()) return false;

	for (const IniGroup &group : this->groups) {
		os << group.comment << "[" << group.name << "]\n";
		for (const IniItem &item : group.items) {
			os << item.comment;

			/* protect item->name with quotes if needed */
			if (item.name.find(' ') != std::string::npos ||
				item.name[0] == '[') {
				os << "\"" << item.name << "\"";
			} else {
				os << item.name;
			}

			os << " = " << item.value.value_or("") << "\n";
		}
	}
	os << this->comment;

	os.flush();
	os.close();
	if (os.fail()) return false;

/*
 * POSIX (and friends) do not guarantee that when a file is closed it is
 * flushed to the disk. So we manually flush it do disk if we have the
 * APIs to do so. We only need to flush the data as the metadata itself
 * (modification date etc.) is not important to us; only the real data is.
 */
#if defined(_POSIX_SYNCHRONIZED_IO) && _POSIX_SYNCHRONIZED_IO > 0
	int f = open(file_new.c_str(), O_RDWR);
	if (f < 0) return false;
	int ret = fdatasync(f);
	close(f);
	if (ret != 0) return false;
#endif

	std::error_code ec;
	std::filesystem::rename(OTTD2FS(file_new), OTTD2FS(filename), ec);
	if (ec) {
		Debug(misc, 0, "Renaming {} to {} failed; configuration not saved: {}", file_new, filename, ec.message());
	}

#ifdef __EMSCRIPTEN__
	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
#endif