Switchuser Issue

[Rainer Dorsch]

Hi,

small addition:

There is at least one user on #debian-kde who claims that sddm and switchuser 
works for him.

For sddm this line should apply in kdisplaymanager.cpp:

return exec("caps\n", re) && re.indexOf("\tlocal") >= 0;

What does that do? I do not find a file caps which can be executed :-/

Thanks
Rainer

On Dienstag, 15. Mai 2018 17:12:25 CEST you wrote:
> Hi,
> 
> I digged a little further:
> 
> On Dienstag, 15. Mai 2018 09:02:52 CEST Rainer Dorsch wrote:
> > Hi,
> > 
> > I have an issue with switch user in ksmserver on my newly installed Debian
> > buster system (plama-workspaces 5.12.5):
> > 
> > When I try to swich user, I get the switchuser dialog displayed, but when
> > I
> > click on switch, I get to my own session's lockscreen. This doesn't seem
> > to
> > be a general issue, there is at least one person on #debian-kde who
> > reports
> > that switching users works for him.
> > 
> > I traced the code and ended up in
> > 
> > /usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/userswitch
> > er / UserSwitcher.qml
> 
> That gets executed, modifying the text of a button took effect, nice that it
> is a scripting language... :-)
> 
> > Since I am not an qml writer (or reader ;-) I was so far not able to find
> > out what
> > 
> > sessionsModel.switchUser(block.userListCurrentModelData.vtNumber,
> > sessionsModel.shouldLock)
> > 
> > does. As a first test, can I add a log statement to test, if that line in
> > the code is really reached (maybe just log to /tmp/switchuserdebug.log)?
> > 
> > Any idea is welcome.
> 
> ...and I am back in sessionsmodel.cpp
> 
> it seems there are a few return statements which effectively (as I
> understand it) simply skip the switch user. That is what I actually see.
> 
> void SessionsModel::switchUser(int vt, bool shouldLock)
> {
>     if (vt < 0) {
>         startNewSession(shouldLock);
>         return;
>     }
> 
>     if (!canSwitchUser()) {
>         return;
>     }
> 
>     if (!shouldLock) {
>         m_displayManager.switchVT(vt);
>         emit switchedUser(vt);
>         return;
>     }
> 
>     checkScreenLocked([this, vt](bool locked) {
>         if (locked) {
>             // already locked, switch right away
>             m_displayManager.switchVT(vt);
>             emit switchedUser(vt);
>         } else {
>             m_pendingReserve = false;
>             m_pendingVt = vt;
> 
>             emit aboutToLockScreen();
>             m_screensaverInterface->Lock();
>         }
>     });
> }
> 
> In particular I suspect that the
> 
>     if (!canSwitchUser()) {
>         return;
>     }
> 
> is executed:
> 
> bool SessionsModel::canSwitchUser() const
> {
>     return const_cast<SessionsModel
> *>(this)->m_displayManager.isSwitchable() &&
> KAuthorized::authorizeAction(QLatin1String("switch_user"));
> }
> 
> Unfortunately, for me it is not clear, what could
> KAuthorized::authorizeAction(QLatin1String("switch_user") make false or how
> I can validate if SessionsModel *>(this)->m_displayManager.isSwitchable()
> is true.
> 
> Looking at isSwitchable:
> 
> bool
> KDisplayManager::isSwitchable()
> {
>     if (DMType == NewGDM || DMType == LightDM) {
>         QDBusObjectPath currentSeat;
>         if (getCurrentSeat(0, &currentSeat)) {
>             SystemdSeat SDseat(currentSeat);
>             if (SDseat.isValid()) {
>                 QVariant prop = SDseat.property("CanMultiSession");
>                 if (prop.isValid())
>                     return prop.toBool();
>             }
>             CKSeat CKseat(currentSeat);
>             if (CKseat.isValid()) {
>                 QDBusReply<bool> r =
> CKseat.call(QStringLiteral("CanActivateSessions"));
>                 if (r.isValid())
>                     return r.value();
>             }
>         }
>         return false;
>     }
> 
>     if (DMType == OldKDM)
>         return dpy[0] == ':';
> 
>     if (DMType == OldGDM)
>         return exec("QUERY_VT\n");
> 
>     QByteArray re;
> 
>     return exec("caps\n", re) && re.indexOf("\tlocal") >= 0;
> }
> 
> Is sddm covered here?
> 
> Trying with lightDM as default display manager....and the problem goes away
> 
> :-)
> 
> Is it true that sddm is not supported? I am surprised since switchuser
> worked with sddm for me in Debian Stretch (plasma-5.8.6)?
> 
> Also it would helped me tremendously, if a log entry (or even a pop-up
> message...) would have been produced instead of a silent failure.... It
> seems that would not add a lot of code...
> 
> Thanks
> Rainer


-- 
Rainer Dorsch
http://bokomoko.de/