Re: Strange failure of python-apt to when trying to update apt cache (Was: Accepted blends 0.6.101 (source) into experimental)

[Andreas Tille <andreas@an3as.eu>]

Hi,

I've found a broken symlink in

    /var/lib/apt/lists/_tmp_autopkgtest*

After removal the issue vanished.

Kind regards

       Andreas.

On Mon, Mar 26, 2018 at 11:21:51AM +0200, Andreas Tille wrote:
> Hi Julian,
> 
> after a rewrite of blends-dev which is working on apt cache to find out
> what packages are available in a specified release I'm facing a problem
> on a specific computer[1].  I tried to cut down the code to a minimum
> that shows the problem:
> 
> 
> #!/usr/bin/python3
> 
> import tempfile
> import os
> import shutil
> import apt
> 
> d = tempfile.mkdtemp()
> print(d)
> os.makedirs(os.path.join(d, 'etc', 'apt'))
> shutil.copytree('/etc/apt/trusted.gpg.d',
>                 os.path.join(d, 'etc', 'apt', 'trusted.gpg.d'))
> # for simple reproduction copy system sources.list
> shutil.copy('/etc/apt/sources.list',
>                 os.path.join(d, 'etc', 'apt', 'sources.list'))
> c = apt.Cache(rootdir=d, memonly=True)
> c.update()
> 
> 
> On the computer in question this fails with:
> 
> 
> /tmp/tmpdzr_ldvz
> Can't open file /var/lib/apt/lists/_tmp_autopkgtest.qDlH8X_binaries_Packages: No such file or directory
> I do not have permission to write to /var/lib/debtags/
> Traceback (most recent call last):
>   File "/usr/lib/python3/dist-packages/apt/cache.py", line 503, in update
>     pulse_interval)
> apt_pkg.Error: E:Problem executing scripts APT::Update::Post-Invoke-Success 'test -x /usr/bin/apt-show-versions || exit 0 ; apt-show-versions -i', E:Sub-process returned an error code
> 
> During handling of the above exception, another exception occurred:
> 
> Traceback (most recent call last):
>   File "./test_apt_cache.py", line 17, in <module>
>     c.update()
>   File "/usr/lib/python3/dist-packages/apt/cache.py", line 505, in update
>     raise FetchFailedException(e)
> apt.cache.FetchFailedException: E:Problem executing scripts APT::Update::Post-Invoke-Success 'test -x /usr/bin/apt-show-versions || exit 0 ; apt-show-versions -i', E:Sub-process returned an error code
> 
> 
> This happens for python3-apt version 1.4.0~beta3+b1 and 1.6.0~rc2.  The
> system is running testing with some selected packages from unstable.  I
> do not remember that I did some specific apt configuration.  When I'm
> running the code above on a different system running stable everything
> works as expected.
> 
> Can you imagine any setting that might lead to the attempt to write to
> /var/lib/apt/lists/ which is not writable for a normal user (the script
> is not run with root permissions).
> 
> What other information do you possibly need to answer this question?
> 
> Kind regards
> 
>       Andreas.
> 
> [1] https://lists.debian.org/debian-blends/2018/03/msg00035.html
> 
> -- 
> http://fam-tille.de
> 
> 

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