2015-08-26 03:13:59 +0100, Pádraig Brady: [...] > I notice both with and without inotify > there is a similar issue (for different reasons) > when multiple devices are specified: > > tail ---dis -f /dev/tty /dev/tty > > I.E. we generally can't deal with this case in either case, > though it probably makes sense in any case to avoid inotify > for device nodes? > > BTW, in the inotify case, theoretically the kernel should be returning > an error if the watch events are not supported? > > The same argument applies that the kernel should return > and error when adding a watch on pseudo file systems like /proc? > To work around that, we'd have to get real kludgy and see > were the files on a "dummy" file system or something. > Though tail -f /proc files in either mode is not that useful, > so probably not worrying about that case. [...]
All very good points. Many files in /proc, /sys... can only be read reliably in one read() operation anyway, and doing tail -f on them would give you garbage even if it worked. I guess the best approach would be to only use inotify for regular files, address blocking files (pipe, devices...) when several files are being watched with poll() and/or non-blocking IO, or alarm()/timers or threads, and document the other issues. Or not do anything and just document those limitations as they are mostly edge cases. -- Stephane
