ps doesn't support "thcount" format specifier on Xenial

Bug #1410558 reported by Adrien Beau
14
This bug affects 2 people
Affects Status Importance Assigned to Milestone
procps (Ubuntu)
Fix Released
Undecided
Unassigned
Xenial
Fix Released
Undecided
Heitor Alves de Siqueira

Bug Description

[Impact]
ps -o thcount prints out an error (error: unknown user-defined format specifier "thcount")

[Description]
The Xenial version of procps has a bug in the thcount format specifier. ps doesn't recognize it, and complains about an unknown user-defined format.
This is due to the format specifier table in ps/output.c, which is queried with a binary search. Since the "thcount" entry appears out of order in Xenial, it can't be looked up and the program fails with the "unknown user-defined format specifier" error.

This has been fixed upstream by the commit below:
- Fix for Bug:1174313 (3a52dfa34027)

$ git describe --contains 3a52dfa34027
v3.3.12~58^2

$ rmadison procps
 procps | 2:3.3.10-4ubuntu2 | xenial | source, ...
 procps | 2:3.3.10-4ubuntu2.4 | xenial-security | source, ...
 procps | 2:3.3.10-4ubuntu2.4 | xenial-updates | source, ... <--------
 procps | 2:3.3.12-3ubuntu1 | bionic | source, ...
 procps | 2:3.3.12-3ubuntu1.1 | bionic-security | source, ...
 procps | 2:3.3.12-3ubuntu1.2 | bionic-updates | source, ...

Releases starting with Bionic already have this fix, so it's only needed for Xenial.

[Test case]
1. Boot up a Xenial environment with e.g. an lxd container:
# lxc launch images:ubuntu/xenial xenial

2. Execute ps with the '-o thcount' options:
# lxc exec xenial -- ps -o thcount
error: unknown user-defined format specifier "thcount"

Usage:
 ps [options]

 Try 'ps --help <simple|list|output|threads|misc|all>'
  or 'ps --help <s|l|o|t|m|a>'
 for additional help text.

For more details see ps(1).

[Regression Potential]
The fix just fixes the order of two entries in the format specifier array, so the regression potential is very low. Furthermore, the patch has been present and tested in up-to-date versions of procps since Bionic. Any new regressions introduced in Xenial will be checked with autopkgtest.

[Original Description]
In Ubuntu 12.04.5 LTS (procps 1:3.2.8-11ubuntu6.3), the following worked fine:

$ export PS_FORMAT=thcount
$ ps
THCNT
    1
    1

In Ubuntu 14.04.1 LTS (procps 1:3.3.9-1ubuntu2), it does not work anymore:

$ export PS_FORMAT=thcount
$ ps
warning: $PS_FORMAT ignored. (unknown user-defined format specifier "thcount")
  PID TTY TIME CMD
 6593 pts/1 00:00:00 ps
16633 pts/1 00:00:00 bash

Other PS_FORMAT specifiers still work fine (I have tried many, but not all).

In real-life usage, a more complex PS_FORMAT would of course be used, such as PS_FORMAT=pid,s,thcount,nice,euser,egroup,etime,cputime,%mem,rssize:6,size:7,vsize:7,command

Workaround: use nlwp instead of thcount (they are alias to the same data, and nlwp works fine in both versions).

Related branches

Revision history for this message
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in procps (Ubuntu):
status: New → Confirmed
tags: added: sts
description: updated
Changed in procps (Ubuntu):
status: Confirmed → Fix Released
Changed in procps (Ubuntu Xenial):
status: New → In Progress
assignee: nobody → Heitor Alves de Siqueira (halves)
summary: - PS_FORMAT=thcount does not work anymore
+ ps doesn't support "thcount" format specifier on Xenial
description: updated
Revision history for this message
Łukasz Zemczak (sil2100) wrote : Please test proposed package

Hello Adrien, or anyone else affected,

Accepted procps into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/procps/2:3.3.10-4ubuntu2.5 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Changed in procps (Ubuntu Xenial):
status: In Progress → Fix Committed
tags: added: verification-needed verification-needed-xenial
Revision history for this message
Heitor Alves de Siqueira (halves) wrote :

Verified according to test case from description:

ubuntu@xenial:~$ dpkg -l | grep procps
ii procps 2:3.3.10-4ubuntu2.5 amd64 /proc file system utilities

ubuntu@xenial:~$ ps -o thcount
THCNT
    1
    1

tags: added: verification-done verification-done-xenial
removed: verification-needed verification-needed-xenial
Revision history for this message
Ubuntu SRU Bot (ubuntu-sru-bot) wrote : Autopkgtest regression report (procps/2:3.3.10-4ubuntu2.5)

All autopkgtests for the newly accepted procps (2:3.3.10-4ubuntu2.5) for xenial have finished running.
The following regressions have been reported in tests triggered by the package:

apport/2.20.1-0ubuntu2.21 (amd64, i386)
openssh/1:7.2p2-4ubuntu2.8 (ppc64el, arm64, amd64, i386)
livecd-rootfs/2.408.57 (amd64, i386)
cmake/3.5.1-1ubuntu3 (armhf)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/xenial/update_excuses.html#procps

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

Revision history for this message
Heitor Alves de Siqueira (halves) wrote :

Given this is an extremely simple fix to the procps output flags, none of the autopkgtest regressions seem to be a result of this patch.
More details on each reported regression:

* apport/2.20.1-0ubuntu2.21 (amd64/i386)
- has failed since 2.20.1-0ubuntu2.18 according to [0]
- test_sandbox_cache_options: fails due to "ERROR: Package download error, try again later: Untrusted packages:"
- test_get_logind_session: fails due to a systemd-logind error
- test_core_dump_packaged, test_core_dump_unpackaged: fail with "leaves unexpected core file behind"
- test_crash_setuid_drop, test_crash_setuid_keep, test_crash_setuid_nonwritable_cwd, test_lock_symlink: fail to generate reports
- test_run_crash_kernel: fails due to an URL mismatch (http://linux-signed.bugs.example.com/5 vs http://linux.bugs.example.com/5)

* cmake/3.5.1-1ubuntu3 (armhf)
- retest could fix the proxy error
- CTestTestUpload: fails due to resolve error ("squid.internal" proxy)

* livecd-rootfs/2.408.57 (amd64/i386)
- tests timed out, a re-test should clear this regression

* openssh/1:7.2p2-4ubuntu2.8 (amd64/arm64/i386)
- failed due to host key certification, re-test should also clear this one

[0] http://autopkgtest.ubuntu.com/packages/a/apport/xenial/amd64

Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package procps - 2:3.3.10-4ubuntu2.5

---------------
procps (2:3.3.10-4ubuntu2.5) xenial; urgency=medium

  * d/p/lp1410558-fix-thcount.patch:
    - fix 'thcount' format specifier (LP: #1410558)

 -- Heitor Alves de Siqueira <email address hidden> Fri, 07 Feb 2020 14:06:26 +0000

Changed in procps (Ubuntu Xenial):
status: Fix Committed → Fix Released
Revision history for this message
Łukasz Zemczak (sil2100) wrote : Update Released

The verification of the Stable Release Update for procps has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

To post a comment you must log in.
This report contains Public information  
Everyone can see this information.

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.