On Mon, 04 Mar 2019 16:38:44 +0100, Yann Droneaud said: > O_EXCL is intended to be used to prevent opening an existing file. Said > differently, it's used to ensure a new file is created, useful to > prevent race condition, where multiple processes compete to create a > file. For example think of temporary file created with random name. Which means that if you're trying to regulate exclusive use of a character device or similar, you use O_EXCL|O_CREAT to create a lock file, and make sure that all the programs competing for the character device use the same pathname to create the lock file - which has been a tried-and-true way of handling exclusive locking for serial ports for 4 decades now. The fact that 'strings /usr/sbin/ModemManager | grep /' proves pretty clearly that ModemManager is trusting DBus to keep track of things rather than using lock files on the modems is almost certainly part of the reason it's a steaming pile of dingo's kidneys rather than a helpful piece of software. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
