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Package: init-system-helpers
Version: 1.67
Severity: normal
Tags: patch

When installing libvirt-daemon on a testing/unstable system, the
following error message is reported:

/usr/bin/deb-systemd-helper: error: unable to read virtlockd.socket

Full debug output, with useless information redacted:

$ sudo _DEB_SYSTEMD_HELPER_DEBUG=1 apt-get install --no-install-recommends libvirt-daemon
The following NEW packages will be installed:
libvirt-daemon
Selecting previously unselected package libvirt-daemon.
Unpacking libvirt-daemon (10.10.0-3) ...
Setting up libvirt-daemon (10.10.0-3) ...
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = unmask, scriptname = libvirtd.service, service_path = /lib/systemd/system/libvirtd.service
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-user-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-user-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = was-enabled, scriptname = libvirtd.service, service_path = /lib/systemd/system/libvirtd.service
(deb-systemd-helper DEBUG) Reading state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.service.dsh-also
(deb-systemd-helper DEBUG) Contents: $VAR1 = [];

(deb-systemd-helper DEBUG) All links present, considering libvirtd.service was-enabled.
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = enable, scriptname = libvirtd.service, service_path = /lib/systemd/system/libvirtd.service
(deb-systemd-helper DEBUG) Using systemctl preset to enable libvirtd.service
Failed to enable auxiliary unit virtlockd.socket, ignoring.
Created symlink '/etc/systemd/system/sockets.target.wants/libvirtd.socket' → '/usr/lib/systemd/system/libvirtd.socket'.
Created symlink '/etc/systemd/system/sockets.target.wants/libvirtd-ro.socket' → '/usr/lib/systemd/system/libvirtd-ro.socket'.
Created symlink '/etc/systemd/system/sockets.target.wants/libvirtd-admin.socket' → '/usr/lib/systemd/system/libvirtd-admin.socket'.
/usr/bin/deb-systemd-helper: error: unable to read virtlockd.socket
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = unmask, scriptname = libvirtd-admin.socket, service_path = /lib/systemd/system/libvirtd-admin.socket
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-user-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-user-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = was-enabled, scriptname = libvirtd-admin.socket, service_path = /lib/systemd/system/libvirtd-admin.socket
(deb-systemd-helper DEBUG) Reading state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Contents: $VAR1 = [];

(deb-systemd-helper DEBUG) All links present, considering libvirtd-admin.socket was-enabled.
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = enable, scriptname = libvirtd-admin.socket, service_path = /lib/systemd/system/libvirtd-admin.socket
(deb-systemd-helper DEBUG) Using systemctl preset to enable libvirtd-admin.socket
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statefOsJc.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statenPIoH.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateLCkXc.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statep2PDL.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateM29Ok.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateF7a2H.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateDAd0c.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-admin.socket.dsh-also
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = unmask, scriptname = libvirtd-ro.socket, service_path = /lib/systemd/system/libvirtd-ro.socket
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-user-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-user-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = was-enabled, scriptname = libvirtd-ro.socket, service_path = /lib/systemd/system/libvirtd-ro.socket
(deb-systemd-helper DEBUG) Reading state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Contents: $VAR1 = [];

(deb-systemd-helper DEBUG) All links present, considering libvirtd-ro.socket was-enabled.
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = enable, scriptname = libvirtd-ro.socket, service_path = /lib/systemd/system/libvirtd-ro.socket
(deb-systemd-helper DEBUG) Using systemctl preset to enable libvirtd-ro.socket
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statetIBlZ.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateBihfm.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateH5caR.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateQDBhi.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.state1lH4W.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateXiC5q.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statepS8xr.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd-ro.socket.dsh-also
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = unmask, scriptname = libvirtd.socket, service_path = /lib/systemd/system/libvirtd.socket
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) rmdir_if_empty /var/lib/systemd/deb-systemd-user-helper-masked
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-user-helper-masked) failed (No such file or directory)
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = was-enabled, scriptname = libvirtd.socket, service_path = /lib/systemd/system/libvirtd.socket
(deb-systemd-helper DEBUG) Reading state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Contents: $VAR1 = [];

(deb-systemd-helper DEBUG) All links present, considering libvirtd.socket was-enabled.
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = enable, scriptname = libvirtd.socket, service_path = /lib/systemd/system/libvirtd.socket
(deb-systemd-helper DEBUG) Using systemctl preset to enable libvirtd.socket
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.state0LqFQ.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statePtygq.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateyivti.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statelrMK_.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.statesTPSG.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.state2YGDX.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also
(deb-systemd-helper DEBUG) Renaming temp file /var/lib/systemd/deb-systemd-helper-enabled/.stateQmQOZ.tmp to state file /var/lib/systemd/deb-systemd-helper-enabled/libvirtd.socket.dsh-also

Note that I had installed all dependencies (libvirt-daemon-common, libvirt-daemon-log) ahead of time to ensure that only the relevant
package would be included in this transaction.

This issue has been reported several months ago as

https://bugs.debian.org/1082939

and unfortunately I hadn't been able to turn that into a proper
report against init-system-helpers until now. Apologies for the
delay.

The root cause is that libvirtd.service contains

[Install]
Also=virtlockd.socket

but virtlockd (as well as its sockets) is shipped in the
libvirt-daemon-lock package, and the libvirt-daemon package (which
contains libvirtd and its sockets) *intentionally* does not Depend on
it.

The explanation is that virtlockd is a soft dependency for libvirtd: specifically, libvirtd.service contains

[Unit]
Wants=virtlockd.socket
After=virtlockd.socket

but it can work perfectly well without it, and in fact in most cases
the virtlockd integration will be disabled, as per default
configuration. This is why Wants= is used instead of Requires=.

systemd itself handles this nicely by simply ignoring the soft
dependency when the corresponing unit doesn't exist.
deb-systemd-helper, on the other hand, reports an error and refuses
to create the libvirtd.service.dsh-also state file, which in turns
results in partial cleanup on purge as well as potentially other
side-effects that I haven't noticed.

I believe that deb-systemd-helper should follow systemd's example and
treat this situation more gracefully, but to be completely honest I
don't fully understand what its state files are used for in the first
place, so it's quite possible that this take is unhelpfully naive :)

I've attached a tentative patch that turns the hard failure into a
soft one. Consider it a mere conversation starter.

Cheers.

--
Andrea Bolognani <eof@kiyuko.org>
Resistance is futile, you will be garbage collected.

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diff -Naru a/script/deb-systemd-helper b/script/deb-systemd-helper
--- a/script/deb-systemd-helper 2024-12-27 22:59:19.475279724 +0100
+++ b/script/deb-systemd-helper 2024-12-27 23:00:28.003801265 +0100
@@ -233,7 +233,10 @@
# as values. Since unit names can't have whitespace in systemd,
# simply use split and strip any leading/trailing quotes. See
# systemd-escape(1) for examples of valid unit names.
- open my $fh, '<', "$dpkg_root$service_path" or error("unable to read $dpkg_root$service_path");
+ open my $fh, '<', "$dpkg_root$service_path" or do {
+ debug("unable to read $dpkg_root$service_path");
+ return @links;
+ };
while (my $line = <$fh>) {
chomp($line);
my $service_link;

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