Re: [PATCH v2 0/3] Improving apt cache

["Roberto A. Foglietta" <roberto.foglietta@gmail.com>]

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On Thu, 19 Jan 2023 at 08:36, Uladzimir Bely <ubely@ilbers.de> wrote:

>
> I got time to get back to this patches and checked this moment. And it
> really
> does not work as I expected.
>
> Original patch includes the following:
>
> -        --chroot-setup-commands="cp -n --no-preserve=owner ${ext_deb_dir}/
> *.deb -t ${deb_dir}/ || :" \
> +        --chroot-setup-commands="ln -Pf ${ext_deb_dir}/*.deb -t
> ${deb_dir}/
> 2>/dev/null || :" \
>
> This results to to failing "ReproTest" in CI with the following error (for
> libhello, for example):
>
> sbuild-build-depends-dose3-dummy:armhf : Depends: dose-distcheck:amd64 but
> it
> is not installable
> E: Unable to correct problems, you have held broken packages.
>
> To debug it, I removed `2>/dev/null` and found, that hardlinks simply
> don't
> work and the following errors are now seen earlier:
>
> ln: failed to create hard link
> '/var/cache/apt/archives/adduser_3.118_all.deb'
> => '/home/builder/libhello/rootfs/var/cache/apt/archives/
> adduser_3.118_all.deb': Invalid cross-device link
> ... #tons of similar errors...
> ln: failed to create hard link '/var/cache/apt/archives/
> zlib1g_1%3a1.2.11.dfsg-2+deb11u2_mipsel.deb' => '/home/builder/libhello/
> rootfs/var/cache/apt/archives/zlib1g_1%3a1.2.11.dfsg-2+deb11u2_mipsel.deb':
>
> Invalid cross-device link
>
> I: Finished running 'ln -Pf /home/builder/libhello/rootfs/var/cache/apt/
> archives/*.deb -t /var/cache/apt/archives/ || :'.
>
> So, it works for network builds (when missing packages always can be
> downloaded by apt), but it fails for local builds from apt-cache (when, at
> first network build, sbuild dependencies are simply not exported to
> download
> directory due to non-working hardlinks, plus with hidden stderr)
>

Hi, first of all I do not fully understand why we use ln -P instead of ln
-Pf in the exporting debs.

        --finished-build-commands="ln -P ${deb_dir}/*.deb -t
${ext_deb_dir}/ 2>/dev/null || :" \

This code's goal is to build a deb that should be exported otherwise we are
continuing using the old package. It seems that breaks things but - again -
I did fully not understand what and why but simply accepted the suggestion.
Now, I have reverted back to ln -Pf.

Second, those lines are supposed to fail - and obviously fail in both
directions: import and export - but the following

(a) if export fail we will not have the custom packages but we have them
(b) removing that lines and the code will always fail

These mean that ln -Pf complains to fail but make a difference and make the
difference that we want. However, I might not have understood the case in
which it fails completely so:

mv build/downloads .
rm -rf build
./build.sh basic-os (DONE)
./clean.sh isar
./build.sh (DONE)
./clean.sh all
./build.sh (DONE)

remove that two lines about ln -Pf that are supposed to do nothing than fail

./clean.sh all
./build.sh (DONE with the same building time)

rm -rf build/downloads
mv downloads build

./clean.sh isar
./build.sh complete (FAIL)

put back those two command lines with ln -Pf and

./clean.sh all
./build.sh (DONE)

I do not say you are wrong and I see ln -Pf complains on stderr but nothing
that tin my private fork cannot be solved using a stderr redirection to
/dev/null

However there are some other ways to do this thing:

1. sbuild uses schroot by default, using chroot instead
2. keep the default in schroot, elsewhere it uses upper folder that can be
populated in advance

I did not make any changes because I did not identified the issue.

Best regards, R-

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