Package: dpkg
Version: 1.18.3
Severity: normal
Hi,
On a couple pam modules[1] we see the following pattern:
if [ "$1" = remove ] && [ "${DPKG_MAINTSCRIPT_PACKAGE_REFCOUNT:-1}" = 1];
then
: remove stuff
fi
However, this idiom is incorrect. Because REFCOUNT tracks the number of
packages that are above 'not-installed', it will include packages that
are removed but not purged. If the package in question has any conffiles
or a postrm, then the above block may never be executed. The semantics
of this variable make it impossible to answer when a dpkg-tracked (ie,
not a conffile) file is removed (eg, there is no copy of a multiarch
library installed).
I propose that a new variable is introduced, that tracks the number of
packages that are above 'config-files' (or maybe, at or above
'unpacked'). The idea is to more closely match the idea of "the number
of packages that are installed". A package that is removed, but not
purged, should not be considered in the refcount.
At the very least, this very weird semantics need to be better
explained in the manpage. It should explicitly mention removed but not
purged packages, and it should clarify what is the value when
`postrm purge` is invoked (this should also apply to my propsed
variable).
I note that of the 6 usages in the archive, only 2 are correct. I almost
introduced 3 more incorrect ones (but luckily those packages already had
postinst, so the error surfaced during testing). I used the following
pattern:
refcount=$(dpkg-query -f '${db:Status-Abbrev} ${binary:Package}\n' \
-W $package | grep '^i' | wc -l)
if [ $refcount -eq 0 ] ; then
: no binaries left, remove stuff
fi
[1]
https://codesearch.debian.net/perpackage-results/DPKG_MAINTSCRIPT_PACKAGE_REFCOUNT/2/page_0
-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 4.2.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages dpkg depends on:
ii libbz2-1.0 1.0.6-8
ii libc6 2.19-22
ii liblzma5 5.1.1alpha+20120614-2.1
ii libselinux1 2.3-2+b1
ii tar 1.28-2
ii zlib1g 1:1.2.8.dfsg-2+b1
dpkg recommends no packages.
Versions of packages dpkg suggests:
ii apt 1.1~exp14
-- no debconf information
