Bug#824804: update-rc.d: may invoke insserv without -f flag when initscripts is installed but not configured

[Martin Pitt]

Control: tag -1 pending

Hello Felipe,

CC'ing Andreas for the util-linux part.

Felipe Sateler [2016-05-19 17:57 -0400]:
> update-rc.d currently has support for invoking insserv with the -f flag,
> to allow initscripts-less installations. This should allow packages to drop
> dependencies on the initscripts package. However, this does not work if the
> dependency is dropped, because now apt/dpkg can choose to configure the
> package before it configures initscripts. This leads to the situation that
> /etc/init.d/mountkernfs.sh exists (and thus invoke-rc.d does not pass -f flag),
> but the links in /etc/rc?.d/S??mountkernfs.sh are not created yet, and then
> insserv fails.

I have some trouble reproducing this. In a schroot without initscipts,
when I do

  dpkg --unpack initscripts_2.88dsf-59.7_amd64.deb

then there's only /etc/init.d/mountkernfs.sh.dpkg-new, as the
conffiles are only moved into place at configure time, not at unpack
time yet. And on upgrades the script and the previous rc?.d links
should already be in place.

So could it be that this is limited to debootstrap as that might just
directly unpack conffiles instead of installing them as *.dpkg-new on
unpack? This would make sense for debootstrap as that isn't concerned
about upgrades.

With this synthetic test I can reproduce it:

  apt-get download initscripts
  dpkg --unpack initscripts_*.deb
  mv /etc/init.d/mountkernfs.sh{.dpkg-new,}
  update-rc.d hwclock.sh defaults

> 2. Extend the check to the links (ie, check if
>    `glob /etc/rc?.d/S??mountkernfs.sh` is not empty.

I agree that this seems to be the best solution for now. Checkin for
/etc/init.d/mountkernfs.sh was supposed to be a test for "initscripts
is installed", but as you found it is only a sufficient test for
"initscripts is unpacked".

So I think this is mostly just limited to debootstrap and thus
util-linux. But I'd indeed prefer if we do this in update-rc.d and
drop the workaround from util-linux again.

> 3. Consult the dpkg database via dpkg-query to determine if initscripts has been
>    configured

Sounds fine as well, but more expensive than globbing, and actually
not quite trivial either. "dpkg-query --showformat='${Status}' --show"
needs parsing and has a trap as its package arguments are patterns,
not fixed names. And "dpkg-query --status" would also need a
non-trivial (but still simple, however) grep.

So I committed this now:

  http://anonscm.debian.org/cgit/collab-maint/init-system-helpers.git/commit/?id=14008bd4a

I tested this with three scenarios (no initscripts, unpacked
initscripts, configured initscripts) in a schroot and it now works
fine. Does that sound ok to you?

Thanks,

Martin

-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)