Am 10.01.21 um 12:20 schrieb Tormod Volden:
On Fri, Jan 8, 2021 at 10:00 PM Jamie Zawinski wrote:In xscreensaver (or maybe lightdm). Why is xscreensaver started in the lightdm session anyway? Is xscreensaver really usable as a per user service or should it be per session? Why is the lightdm xscreensaver instance interfering with the xscreensaver instance of the logged in user? Questions that only the xscreensaver maintainer can answer. If he thinks there is a genuine systemd issue, then I'd appreciate if it was reassigned back with more details.XScreenSaver author here. I know nothing about lightdm, and didn't write the code attempting to integrate the two. However: 1) XScreenSaver should be running as the logged-in user, and terminate when they log out. Typically this happens when the X server dies and the $DISPLAY socket is closed, but SIGTERM works just as well. 2) It is also reasonable to configure things so that XScreenSaver is running when no one is logged in (so that there is a screensaver atop the login screen). If it is launched as root, it will setuid to "nobody" at startup, etc. But in this case, when a user logs in, it must be killed and re-started as that user.It was not intentional from my side to have it run in the login window by default. We used to just ship a systemd unit file that a user could install if he wanted. Recently, in 5.44+dfsg1-2, we added the debian/*.user.service file, it was part of a debhlper clean-up from my package upload sponsor and I didn't foresee the implications. "lightdm" is a system user (UID < 1000), is possible to have systemd have it start only for "normal" users?
See man systemd.unit:
ConditionUser=
ConditionUser= takes a numeric "UID", a UNIX user name, or the
special value "@system". This condition may be used to check
whether the service manager is running as the given user. The
special value "@system" can be used to check if the user id is
within the system user range. This option is not useful for system
services, as the system manager exclusively runs as the root user,
and thus the test result is constant.
Negating @system might work. Something like ConditionUser=!@system, but untested.
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