Package: init-system-helpers
Version: 1.51
Severity: important
If two packages ship the same unit, `deb-systemd-helper purge` is
problematic. For example, the packages "ntp" and "ntpsec" both provide
a unit called "ntp.service". (I am the maintainer of ntpsec.)
dh_systemd_enable adds this to the postrm script of packages, where UNIT
is the relevant systemd unit:
if [ "$1" = "remove" ]; then
if [ -x "/usr/bin/deb-systemd-helper" ]; then
deb-systemd-helper mask UNIT >/dev/null
fi
fi
if [ "$1" = "purge" ]; then
if [ -x "/usr/bin/deb-systemd-helper" ]; then
deb-systemd-helper purge UNIT >/dev/null
deb-systemd-helper unmask UNIT >/dev/null
fi
fi
Consider this series of steps:
1) apt install ntp
2) apt install ntpsec
3) apt purge ntp
Step 1 installs /usr/lib/systemd/system/ntp.service, and the postinst
(by way of the dh_systemd_enable postinst snippet) enables the service.
Step 2 results in the ntp package being removed, which (by way of the
dh_systemd_enable postrm snippet quoted above) masks ntp.service. Then,
as ntpsec is installed, it installs /usr/lib/systemd/system/ntp.service,
which is unmasked and again enabled by its postinst.
Step 3 results in ntp's postrm script calling
`deb-systemd-helper purge ntp.service`. This creates a problem.
Desired results:
ntp.service is left enabled.
Actual results:
ntp.service is disabled
Internally, deb-systemd-helper implements purge as a disable plus some
extra steps conditionalized on is_purge(). It is this disable that is
problematic.
There are a number of ways to address this. My first thought is that
disable and/or purge should be skipped if the unit file still exists.
This would be similar to the documented behavior of update-rc.d.
(Unfortunately, update-rc.d isn't doing that, which creates the same
problem for me on sysvinit, which I just commented about in #680293.)
Purging ntp after installing ntpsec seems to be fairly common with
users. Accordingly, I'm setting the severity of this bug to important. I
would mark it serious, but I can't currently point to an explicit policy
item being violated nor am I the maintainer of this package (nor a
release manager).
The same thing happens, for the exact same reasons, if you start with
ntpsec, install ntp, then purge ntpsec.
Here are the deb-systemd-helper DEBUG logs from step 3 (apt purge ntp):
Purging configuration files for ntp (1:4.2.8p11+dfsg-1) ...
(deb-systemd-helper DEBUG) is purge = yes
(deb-systemd-helper DEBUG) action = disable, scriptname = ntp.service,
service_path = /lib/systemd/system/ntp.service
(deb-systemd-helper DEBUG) Reading state file
/var/lib/systemd/deb-systemd-helper-enabled/ntp.service.dsh-also
(deb-systemd-helper DEBUG) Contents: $VAR1 = [
'/etc/systemd/system/multi-user.target.wants/ntp.service'
];
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/graphical.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/graphical.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/multi-user.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/multi-user.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/network-online.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/network-online.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/paths.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/paths.target.wants) failed
(Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/remote-fs.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/remote-fs.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/sockets.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/sockets.target.wants) failed
(Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/sysinit.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/sysinit.target.wants) failed
(Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/time-sync.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/time-sync.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/var/lib/systemd/deb-systemd-helper-enabled/timers.target.wants
(deb-systemd-helper DEBUG)
rmdir(/var/lib/systemd/deb-systemd-helper-enabled/timers.target.wants) failed
(Directory not empty)
(deb-systemd-helper DEBUG) rmdir(/var/lib/systemd/deb-systemd-helper-enabled)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty /etc/systemd/system/getty.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/getty.target.wants) failed
(Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/graphical.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/graphical.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/multi-user.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/multi-user.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/network-online.target.wants
(deb-systemd-helper DEBUG)
rmdir(/etc/systemd/system/network-online.target.wants) failed (Directory not
empty)
(deb-systemd-helper DEBUG) rmdir_if_empty /etc/systemd/system/paths.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/paths.target.wants) failed
(Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/remote-fs.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/remote-fs.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/sockets.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/sockets.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/sysinit.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/sysinit.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/time-sync.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/time-sync.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) rmdir_if_empty
/etc/systemd/system/timers.target.wants
(deb-systemd-helper DEBUG) rmdir(/etc/systemd/system/timers.target.wants)
failed (Directory not empty)
(deb-systemd-helper DEBUG) is purge = no
(deb-systemd-helper DEBUG) action = unmask, scriptname = ntp.service,
service_path = /lib/systemd/system/ntp.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)
--
Richard
