hier mal meine funktion um einen filesystem tree zu erzeugen:

void createFATTree(const string &path_current, int depth = 0, int maxdepth = 2, int subdircount = 2) {
	if(depth > maxdepth)
		return;
	for(unsigned int i = 0; i < subdircount; i++) {
		stringstream s, ast;
		s << depth;
       		ast << i;
		createDirectory(path_current + "/FOO_" + s.str() + "_" + ast.str());
		createFile(path_current + "/FOO_" + s.str() + "_" + ast.str());
       		createFATTree(path_current + "/FOO_" + s.str() + "_" + ast.str(), depth+1, maxdepth, subdircount);
	}
}

void createDirectory(const string &dir_name) {
	fs::path dir_path(dir_name, fs::native);
	if(!fs::create_directory( dir_path ))
		throw fs::filesystem_error("mkdir failed", dir_path, errno);
        string tmp(dir_path.string());
	tmp.erase(0, root_str.length()); 
	config << "type=Directory " << "name=" << tmp << endl;
}

void createFile(const string &file_name, const string &content = "") {
	string filename = file_name + ".txt";
	ofstream file(filename.c_str());

        // if content == "" fill file with random data
	if(content.length() == 0) {
		unsigned int random_integer = (rand()%file_size_max)+file_size_min;

		char buffer[random_integer*SIZE];
		memset(&buffer, 0, sizeof(buffer));

		ifstream random_data("/dev/urandom", ios::in | ios::binary);
		random_data.read(buffer, random_integer*SIZE);
		random_data.close();

		file.write(buffer, random_integer*SIZE);
	}
	else {
		file.write(content.c_str(), content.length());
	}
	file.close();
}

BTW: ob du das mit boost filesystem machst oder mit native Funktionen ist vollkommen egal.