Bug#1014115: uninstall does not properly remove enablement symlinks

[Luca Boccassi]

On Thu, 30 Jun 2022 at 20:20, Michael Biebl <biebl at debian.org> wrote:
>
>
> Am 30.06.22 um 18:18 schrieb Michael Biebl:
> > Am 30.06.22 um 17:31 schrieb Luca Boccassi:
> >> On Thu, 30 Jun 2022 at 15:44, Michael Biebl <biebl at debian.org> wrote:
> >>>
> >>> Am 30.06.22 um 16:32 schrieb Luca Boccassi:
> >>>> On Thu, 30 Jun 2022 at 15:24, Michael Biebl <biebl at debian.org> wrote:
> >>>>>
> >>>>> Am 30.06.22 um 16:13 schrieb Luca Boccassi:
> >>>>>> On Thu, 30 Jun 2022 at 15:08, Michael Biebl <biebl at debian.org> wrote:
> >>>>>>>
> >>>>>>> Am 30.06.22 um 14:26 schrieb Michael Biebl:
> >>>>>>>> This might be a bug in i-s-h, but filing against systemd-homed for
> >>>>>>>> now.
> >>>>>>>>
> >>>>>>>> systemd-homed.service:
> >>>>>>>> [Install]
> >>>>>>>> WantedBy=multi-user.target
> >>>>>>>> Alias=dbus-org.freedesktop.home1.service
> >>>>>>>> Also=systemd-homed-activate.service systemd-userdbd.service
> >>>>>>>>
> >>>>>>>> systemd-homed-activate.service:
> >>>>>>>> [Install]
> >>>>>>>> WantedBy=systemd-homed.service
> >>>>>>>> Also=systemd-homed.service
> >>>>>>>>
> >>>>>>>> → we have a circular dependency here, maybe deb-systemd-helper
> >>>>>>>> get's
> >>>>>>>> confused by that
> >>>>>>>
> >>>>>>>
> >>>>>>> I just checked that we can mitigate this issue by removing this
> >>>>>>> circular
> >>>>>>> Also= dependency. It is indeed deb-systemd-helper getting
> >>>>>>> confused by
> >>>>>>> that and as a result not writing proper state files to
> >>>>>>> /var/lib/systemd/deb-systemd-helper.
> >>>>>>> So the damage is already done during installation in postinst.
> >>>>>>> Thus raising to RC to warn users from installing systemd-homed atm.
> >>>>>>>
> >>>>>>> I propose a patch like the attached one, i.e. dropping the Also=
> >>>>>>> from
> >>>>>>> systemd-homed-active.service. WDYT?
> >>>>>
> >>>>> Are you against shipping this patch for the time being until we have a
> >>>>> proper fix?
> >>>>
> >>>> Given the problem is that i-s-h doesn't generate the correct postinst,
> >>>> can we instead add a workaround to the postinst itself?
> >>>
> >>> No, it's not an incorrect postinst. The generated postinst code looks
> >>> fine afaics.
> >>>
> >>> It's deb-systemd-helper failing in postinst [1] (due to the circular
> >>> Also=) and subsequently not writing any state files to
> >>> /var/lib/systemd/deb-systemd-helper (which means it can't clean up the
> >>> state on purge).
> >>>
> >>>
> >>> I'm pasting the error message again, for reference
> >>>
> >>>> Setting up systemd-homed (251.2-7) ...
> >>>> Created symlink
> >>>> /etc/systemd/system/systemd-homed.service.wants/systemd-homed-activate.service
> >>>> -> /lib/systemd/system/systemd-homed-activate.service.
> >>>> Created symlink
> >>>> /etc/systemd/system/dbus-org.freedesktop.home1.service ->
> >>>> /lib/systemd/system/systemd-homed.service.
> >>>> Created symlink
> >>>> /etc/systemd/system/multi-user.target.wants/systemd-homed.service ->
> >>>> /lib/systemd/system/systemd-
> >>>> homed.service.
> >>>> Deep recursion on subroutine "main::get_link_closure" at
> >>>> /usr/bin/deb-systemd-helper line 253, <$fh> line 23.
> >>>> /usr/bin/deb-systemd-helper: error: unable to read
> >>>> /lib/systemd/system/systemd-homed.service
> >>>> Deep recursion on subroutine "main::get_link_closure" at
> >>>> /usr/bin/deb-systemd-helper line 253, <$fh> line 41.
> >>>> /usr/bin/deb-systemd-helper: error: unable to read
> >>>> /lib/systemd/system/systemd-homed-activate.service
> >>
> >> I see, then could it be fixed in the postinst manually after the calls
> >> added by the helper?
> >
> > I don't see how.
>
> Let me put this differently: this would mean manually implementing in
> shell what deb-systemd-helper is doing in perl and creating the state
> files ourselves.
> Feasible, yes. Doable, I'd say no.
> I'd rather prefer a one-line patch.

The problem is some files leftover, no? Just delete them in the
postinst or postrm?