bug#36508: GDM files have incorrect owner after temporarily removing service

[Brendan Tildesley via Bug reports for GNU Guix <bug-guix@gnu.org>]

> On 04/14/2021 12:32 PM Ludovic Courtès <ludo@gnu.org> wrote:
> 
>  
> Hi Mark,
> 
> Mark H Weaver <mhw@netris.org> skribis:
> 
> > Brendan Tildesley via Bug reports for GNU Guix <bug-guix@gnu.org>
> > writes:
> >
> >> I recently encountered what is likely the same bug. The directory /var/lib/gdm
> >> had the correct permissions gdm:gdm, but all the files inside had something like
> >> 973:gdm
> >
> > The underlying problem here, which I've also experienced, is that if you
> > reconfigure your system with fewer users/groups, and then later add
> > those users/groups back, there is no guarantee that they will be
> > assigned the same UIDs and GIDs.
> 
> Yes.
> 
> The patch Brendan posted LGTM (though I’m surprised the directory itself
> can have the right UID/GID while files inside it don’t; perhaps this was
> made possible by 2161820ebbbab62a5ce76c9101ebaec54dc61586, which chowns
> the home directory unconditionally.)
> 
> Note that there are other places, in addition to GDM, where we
> forcefully reset the UID/GID of the home directory (e.g., for the
> ‘knot-resolver’ service.)
> 
> My preferred solution to this would be to unconditionally chown -R home
> directories upon activation (for efficiency, it would be best if we
> could do that if and only if the home directory itself has wrong
> ownership).  Thoughts?
> 
I'm confused. It sounds like you're suggesting to add the very IF condition that my
patch removes from %gdm-activation in order to fix the problem.