USBGuard daemon can't start if there is no (empty) IPCAccessControl.d folder #670
Description
not sure if this is considered a bug resp. is worth fixing... but at least i wanted to mention it as it took me quite some time to work it out as i found not even the slightest clue about that anywhere.
on an older machine - on which USBGuard was already installed but not activated - i just wanted to quickly try something... so i generated an initial rule set (to be on the safe side), checked the config and tried to start the daemon, which refused. the error message and the logs were not really helpful.
so i checked everything again but no luck. then i started to play around with the rules.d folder and the file names... as IIRC some daemons have/had issues with some characters in the file names; split the rules, combined them; went back to just one rules.conf and no folder at all etc.; but still nothing changed.
i was about to give up, until i noticed on an completely new system after installing USBGurad there is not just an empty rules.conf file and a rules.d folder, but also an empty IPCAccessControl.d folder... so i created this empty folder - although the legacy system was perfectly set up all the time in the usbguard-daemon.conf - and voila, the USBGuard daemon started without complaining.
i'm not sure if this might be considered as a safety measure as it was sufficient to just have an empty folder; but if you intend to use the legacy system, it makes no sense at all.
if this won't be fixed/changed, at least mentioning somewhere in the docs that at least an empty IPCAccessControl.d folder is mandatory, would be appreciated.