Bug#1110696: libglib2.0-0t64: Purging libglib2.0-0:i386 removed gschemas.compiled

[Tianyu Chen]

Simon McVittie <smcv at debian.org> 于2025年8月12日周二 07:06写道：
> This is actually not quite enough! To reproduce the bug, you have to
> purge libglib2.0-0:amd64 *before* libglib2.0-0:i386, so that the
> refcount transition for libglib2.0-0 goes from 1 to 0 while purging
> libglib2.0-0:i386. If you had purged those two packages the other way
> round, it would have been OK.

Actually I don't think I've purged libglib2.0-0:amd64 when testing
bookworm->trixie upgrading. But the steps you provided on
debian:bookworm-slim are correct.
Let me reproduce it again to see the difference later..

Thank you!
Tianyu Chen


> Reproducer for the bug, which hacks the postrm of libglib2.0-0 to add a
> `set -x` so that it's obvious what it is doing:
>
> $ podman run --rm -it debian:bookworm-slim    # or use an expendable chroot
> # dpkg --add-architecture i386
> # apt update
> # apt install --no-install-recommends \
>    libglib2.0-0:i386 libglib2.0-0:amd64 \
>    gsettings-desktop-schemas \
>    dconf-gsettings-backend dconf-gsettings-backend:i386 \
>    dbus-x11 dbus-user-session-
> # apt remove --allow-remove-essential $(dpkg-query -W -f '${binary:Package}\n' | grep :i386)
> # dpkg --remove-architecture i386
> # sed -i -e 's/^set -e$/&x/' /var/lib/dpkg/info/libglib2.0-0\:*.postrm
> # sed -i -e 's/bookworm/trixie/g' /etc/apt/sources.list.d/debian.sources
> # apt update
> # apt dist-upgrade
> …
> Preparing to unpack .../libglib2.0-0t64_2.84.3-1_amd64.deb ...
> libglib2.0-0t64.preinst: Removing /var/lib/dpkg/info/libglib2.0-0:amd64.postrm to avoid loss of /usr/share/glib-2.0/sc
> hemas/gschemas.compiled...
> removed '/var/lib/dpkg/info/libglib2.0-0:amd64.postrm'
> …
> # test -e /usr/share/glib-2.0/schemas/gschemas.compiled && echo ok
> ok
> # dpkg --purge libglib2.0-0:amd64
> (Reading database ... 6472 files and directories currently installed.)
> # dpkg --purge libglib2.0-0:i386
> (Reading database ... 6472 files and directories currently installed.)
> Purging configuration files for libglib2.0-0:i386 (2.74.6-2+deb12u6) ...
> + [ -d /usr/lib/i386-linux-gnu/gio/modules ]
> + [ purge = purge ]
> + [ -d /usr/share/glib-2.0/schemas ]
> + [ 1 = 1 ]
> + rm -f /usr/share/glib-2.0/schemas/gschemas.compiled
> + rmdir -p --ignore-fail-on-non-empty /usr/share/glib-2.0/schemas
> # test -e /usr/share/glib-2.0/schemas/gschemas.compiled && echo still ok
> (no output!)
>
> Here, gsettings-desktop-schemas is a convenient example of a package that
> contains a GSettings schema (which GLib summarizes into
> an architecture-independent gschemas.compiled via a dpkg trigger).
> Similarly dconf-gsettings-backend is a convenient example of a package
> that contains GIO modules (which GLib summarizes into a module list per
> architecture). dbus-x11 and dbus-user-session- just avoid wasting time
> installing and upgrading systemd in a container with no init system.
>
> With an updated libglib2.0-0t64.preinst that disarms libglib2.0-0.postrm
> on a more complete set of architectures, the bug no longer appears.
>
> On Sun, 10 Aug 2025 at 10:50:40 +0100, Simon McVittie wrote:
> >dpkg team: is there a good way to ask dpkg for a full list of
> >architectures that might conceivably have a package installed?
> >
> >I suppose there's
> >
> >    dpkg-query -W -f '${Architecture}\n' | sort -u | grep -v '^all$'
> >
> >but, ugh.
>
> Of course the command I wasn't thinking of at the time is:
>
>      $(dpkg-query -W -f '${Architecture}\n' libglib2.0-0
>
> which lists the architectures of any versions of libglib2.0-0 that might
> still be present and in particular might still have a postrm, including
> removed-but-not-purged status.
>
>      smcv