Why do you suppose xscreensaver wouldn't register a startup entry?

annoying_daniel · 2017-04-19 20:58:03

I'm really baffled by this after I kept rebooting but the daemon kept needing to be restarted manually in order to lock the screen via xflock4 in xfce.

Apparently, there was supposed to be a startup entry automatically made in my "application autostart" section with the command:

xscreensaver -no-splash

-- after multiple reboots while the daemon never started on its own, I just decided to make a manual one with a different title than "Screensaver" (which I believe is the default entry) and so far on this boot the daemon appears to be started normally (automatically.)

There is one other entry "Screensaver" entry that appears to have been made automatically. The command under that one is:

xset s 0 dpms 0 0 0

Am I fine in this situation and why would you speculate the startup entry wasn't made automatically? A naming conflict perhaps since there already was an existing "Screensaver" entry?

Last edited by annoying_daniel (2017-04-19 20:59:08)

Lone_Wolf · 2017-04-20 14:46:05

The documentation of xscreensaver doesn't mention anything about some DEs autostarting it, so it's probably something those DEs do themselves.

Seems like a change in xfce may have caused this, is this a systemwide or user-specific entry ?
(incase you're not sure, create a new user and check if they have this in their xfce settings.)

EDIT As for being fine : have you tried to figure out what that command does ?

Last edited by Lone_Wolf (2017-04-20 14:47:00)

annoying_daniel · 2017-04-20 16:17:06

You're probably right about xfce configuring the startup entry. I suspect "xfce4-session" managing these autostart entries. I tried adding another user and experienced the same behaviour but I now know that Light Locker is responsible for the other "Screensaver" entry that will be made once its settings have been modified and changes applied. (And I just now forgot to add the new user to the sudoers file, but I don't think anything applies in this situation since we already saw that Light Locker was able to invoke its own script.)

Another possible explanation is that I'm using igpu (intel 630 graphics)+hdmi video that might not support DPMS and, through a convoluted process, never sends a signal to my current session that a xscreensaver daemon needs to be registered.

As for the command "xscreensaver -no-splash" -- that simply starts the daemon. I have no idea if parallel daemons can exist. I would think that would be really bad though.

Lone_Wolf · 2017-04-22 13:58:32

Checking https://www.jwz.org/xscreensaver/faq.ht … creensaver , i'm convinced that Light Locker is the ubuntu rewrite mentioned.

If you didn't have LDM installed, xfce may have been able to use the screensaver for xscreensaver .

P.S. If you're interested in security details, check the "On Toolkits" link in that faq section.

Last edited by Lone_Wolf (2017-04-22 13:58:40)

annoying_daniel · 2017-04-24 01:14:36

I also found a bug in xscreensaver (perhaps more of a window manager issue with X) that doesn't limit information disclosure when it comes to Thunderbird email notifications and notifications in general (via notifyd.) A quick search came up with a couple unanswered bug reports:
https://bugzilla.redhat.com/show_bug.cgi?id=1411115
https://bugzilla.mozilla.org/show_bug.cgi?id=565670

Bug is simple to reproduce:

1. confirm xscreensaver daemon is running.
2: (if not using xfce, use your appropriate screen-locker cmd in place of the following xflock4):

$ xflock4 && sleep 7 && notify-send "[this message is classified and should not be readable over the lock screen]"

3. information disclosure is easily obtainable by simply observing the notification overlay on top of the screen saver.

Last edited by annoying_daniel (2017-04-24 03:57:22)

seth · 2017-04-24 06:38:42

What does this have to do with the original topic and did you bother reading the xscreensaver faq?
https://www.jwz.org/xscreensaver/faq.html#popup-windows

Done? Those are override_redirect windows.
What xscreensaver probably *could* do was to XGrabServer grab the entire server connection, but I'm not sure what kind of bugs/annoyances this would cause...

Arch Linux

#1 2017-04-19 20:58:03

Why do you suppose xscreensaver wouldn't register a startup entry?

#2 2017-04-20 14:46:05

Re: Why do you suppose xscreensaver wouldn't register a startup entry?

#3 2017-04-20 16:17:06

Re: Why do you suppose xscreensaver wouldn't register a startup entry?

#4 2017-04-22 13:58:32

Re: Why do you suppose xscreensaver wouldn't register a startup entry?

#5 2017-04-24 01:14:36

Re: Why do you suppose xscreensaver wouldn't register a startup entry?

#6 2017-04-24 06:38:42

Re: Why do you suppose xscreensaver wouldn't register a startup entry?

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