boost interprocess file_lock can't lock file it does not own

Question

When I use boost file_lock to try to lock files it doesn't own with lock() or lock_sharable(), it throws an exception. Is there any way for it to lock a file owned by a different user so it can modify it safely (the modifying user has correct write permissions).

Answer 1

The fact that you're throwing an exception means that it's not waiting for any existing exclusive or shareable locks to be released (this should be a blocking call). Make sure that you actually have the file-name correct, or check the error code in the boost::interprocess_exception that is being thrown using either the what() , get_native_error() , or get_error_code() methods. For instance, you could be having a file-permissions problem, or the file may not exist, etc. An exception is not thrown because of lock contention, so that's not your problem ...