pkgCacheFile unlocks in destructor even if it did not acquire lock

This bug was fixed in the package apt - 1.7.0~rc2ubuntu1

---------------
apt (1.7.0~rc2ubuntu1) cosmic; urgency=medium

  * Fix calculation of elapsed usec in downloads
  * pkgCacheFile: Only unlock in destructor if locked before (LP: #1794053)

 -- Julian Andres Klode <email address hidden> Mon, 24 Sep 2018 12:18:26 +0200

Hello Julian, or anyone else affected,

Accepted apt into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/apt/1.6.5 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-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. 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.

Hello Julian, or anyone else affected,

Accepted apt into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/apt/1.2.28 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.

Hello Julian, or anyone else affected,

Accepted apt into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/apt/1.2.29 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.

Hello Julian, or anyone else affected,

Accepted apt into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/apt/1.6.6 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-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. 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.

bionic (1.6.3ubuntu0.1 -> 1.6.6):

root@dashing-panda:~# python3 a.py
total 0
[...]
lrwx------ 1 root root 64 Oct 18 12:07 3 -> /var/lib/dpkg/lock
l-wx------ 1 root root 64 Oct 18 12:07 6 -> 'pipe:[27578280]'
Reading package lists... Done
Building dependency tree
Reading state information... Done
total 0
[...]
l-wx------ 1 root root 64 Oct 18 12:07 6 -> 'pipe:[27578280]'
Traceback (most recent call last):
  File "a.py", line 13, in <module>
    apt_pkg.pkgsystem_unlock()
apt_pkg.Error: E:Not locked
[...]

=> We can see that the cache was already unlocked when it should not have been

root@dashing-panda:~# apt install libapt-pkg5.0
[...]
Unpacking libapt-pkg5.0:amd64 (1.6.6) over (1.6.3ubuntu0.1) ...
[...]
root@dashing-panda:~# python3 a.py
total 0
[...]
lrwx------ 1 root root 64 Oct 18 12:08 3 -> /var/lib/dpkg/lock-frontend
lrwx------ 1 root root 64 Oct 18 12:08 4 -> /var/lib/dpkg/lock
l-wx------ 1 root root 64 Oct 18 12:08 6 -> 'pipe:[27578280]'
Reading package lists... Done
Building dependency tree
Reading state information... Done
total 0
[...]
lrwx------ 1 root root 64 Oct 18 12:08 3 -> /var/lib/dpkg/lock-frontend
lrwx------ 1 root root 64 Oct 18 12:08 4 -> /var/lib/dpkg/lock
l-wx------ 1 root root 64 Oct 18 12:08 6 -> 'pipe:[27578280]'
root@dashing-panda:~#

=> script worked fine, we see that the lock is still open in the second ls, and there are no error messages

xenial
======

With 1.2.27
-----------

root@glowing-mastodon:~# python3 a.py
total 0
[...]
lrwx------ 1 root root 64 Oct 18 12:15 3 -> /var/lib/dpkg/lock
l-wx------ 1 root root 64 Oct 18 12:15 6 -> pipe:[27632799]
Reading package lists... Done
Building dependency tree
Reading state information... Done
total 0
[...]
l-wx------ 1 root root 64 Oct 18 12:15 6 -> pipe:[27632799]
Traceback (most recent call last):
  File "a.py", line 13, in <module>
    apt_pkg.pkgsystem_unlock()
SystemError: E:Not locked

=> broken as expected

With 1.2.29
-----------

root@glowing-mastodon:~# python3 a.py
total 0
[...]
lrwx------ 1 root root 64 Oct 18 12:17 3 -> /var/lib/dpkg/lock-frontend
lrwx------ 1 root root 64 Oct 18 12:17 4 -> /var/lib/dpkg/lock
l-wx------ 1 root root 64 Oct 18 12:17 6 -> pipe:[27632799]
Reading package lists... Done
Building dependency tree
Reading state information... Done
total 0
[...]
lrwx------ 1 root root 64 Oct 18 12:17 3 -> /var/lib/dpkg/lock-frontend
lrwx------ 1 root root 64 Oct 18 12:17 4 -> /var/lib/dpkg/lock
l-wx------ 1 root root 64 Oct 18 12:17 6 -> pipe:[27632799]
root@glowing-mastodon:~#

=> lock is still held at second ls, and releasing it worked fine.

This bug was fixed in the package apt - 1.6.6

---------------
apt (1.6.6) bionic; urgency=medium

  * Set DPKG_FRONTEND_LOCKED when running {pre,post}-invoke scripts.
    Some post-invoke scripts install packages, which fails because
    the environment variable is not set. This sets the variable for
    all three kinds of scripts {pre,post-}invoke and pre-install-pkgs,
    but we will only allow post-invoke at a later time.
    (LP: #1796808)

apt (1.6.5) bionic; urgency=medium

  [ David Kalnischkies ]
  * Support records larger than 32kb in 'apt show' (Closes: #905527)
    (LP: #1787120)

  [ Julian Andres Klode ]
  * Add support for dpkg frontend lock (Closes: #869546) (LP: #1781169)
  * Set DPKG_FRONTEND_LOCKED as needed when doing selection changes
  * http: Stop pipeline after close only if it was not filled before
    (LP: #1794957)
  * pkgCacheFile: Only unlock in destructor if locked before (LP: #1794053)
  * Update libapt-pkg5.0 symbols for frontend locking

 -- Julian Andres Klode <email address hidden> Tue, 09 Oct 2018 12:16:51 +0200

The verification of the Stable Release Update for apt has completed successfully and the package has now been 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.

This bug was fixed in the package apt - 1.2.29

---------------
apt (1.2.29) xenial; urgency=medium

  * Set DPKG_FRONTEND_LOCKED when running {pre,post}-invoke scripts.
    Some post-invoke scripts install packages, which fails because
    the environment variable is not set. This sets the variable for
    all three kinds of scripts {pre,post-}invoke and pre-install-pkgs,
    but we will only allow post-invoke at a later time.
    (LP: #1796808)

apt (1.2.28) xenial; urgency=medium

  [ Julian Andres Klode ]
  * apt.conf.autoremove: Add linux-cloud-tools to list (LP: #1698159)
  * Add support for dpkg frontend lock (Closes: #869546) (LP: #1781169)
  * Set DPKG_FRONTEND_LOCKED as needed when doing selection changes
  * http: Stop pipeline after close only if it was not filled before
    (LP: #1794957)
  * pkgCacheFile: Only unlock in destructor if locked before (LP: #1794053)
  * Update libapt-pkg5.0 symbols for frontend locking

  [ David Kalnischkies ]
  * Support records larger than 32kb in 'apt show' (Closes: #905527)
    (LP: #1787120)

 -- Julian Andres Klode <email address hidden> Tue, 09 Oct 2018 12:35:03 +0200