Hi, I propose the inclussion of the following set of private members to the boost::filesystem::fstream class: private: void do_lock(); bool do_trylock(); bool do_timedlock(const xtime& xt); void do_unlock(); void do_lock(cv_state& state); void do_unlock(cv_state& state); this will enable additional classes: namespace boost { namespace filesystem { class scooped_lock; class scooped_try_lock; class scoped_timed_lock; } } with an interface like boost::thread::scooped_lock and sccoped_try_lock. What do you think about this? If you want to proceed and need help, please let me know, I can provide an implementation for Windows (NT and above) and posix (I'm currently working on this functionality). Cordially, Jordi Vilar