Automatic cross-platform testing: part 7: 32 bit, again

I have written about this before, but I've had to do it again. I noted previously that Github's actions for things like checking out a repository and for retrieving build artifacts are now 64-bit only. You've been able to work around that by using older versions of the actions but I didn't want to do that so I'm taking a different approach.

My new method builds on work I've done previously to pull all my testing for different Unixy platforms together into one workflow. This tests on 64-bit versions of NetBSD, FreeBSD, OpenBSD, IllumOS (that is, the modern version of Open Solaris), and Linux. And as of earlier today it also runs the tests on 32-bit Linux. As in my previous blog entry it's still really 64-bit hardware, with modern x86 ISA extensions, but it's a 32-bit OS image with 32-bit addressing, userland, compiler toolchain and so on. If you absolutely must have a pure 32-bit x86 environment then you'll need to acquire some obsolete e-waste and run it yourself. Something like this based on the Vortex86 chipset looks like a good choice.

There are only two interesting bits of the workflow. The first implements enough of Github's actions/download-artifact for my purposes. In the YAML file it's all one line because YAML and everything that uses it is hateful, I've tidied it up here:

curl -L -H "X-GitHub-Api-Version: 2022-11-28"
        -H "Authorization: Bearer ${GH_TOKEN}"
        -o dist-for-install.zip
  $(curl -L -s
         -H "Accept: application/vnd.github+json"
         -H "Authorization: Bearer ${GH_TOKEN}"
         -H "X-GitHub-Api-Version: 2022-11-28"
         https://api.github.com/repos/${GH_REPOSITORY}/actions/artifacts
         -o -
    |jq -r '
         [.artifacts.[]|select(.expired == false)]
         |max_by(.created_at).archive_download_url
    '
  )

The inner curl uses the Github API to fetch a list of all the build artifacts that have ever been created for this repository, as JSON, which it filters using jq to find the most recent one which hasn't expired, and then extract its archive_download_url field. The outer curl then fetches that.

The second bit interesting bit is specific to testing my perl code. Perl can be built on 32-bit platforms to support either 32 or 64 bit integers. On 64-bit machines perl integers are always 64-bit - and there's been a note in the docs for 20 years about how a build-time parameter for 32-bit ints may be added later! I need to test with 32 bit ints, but most OS packages, even on 32-bit machines, will provide a perl with 64-bit ints. So I need to build my own. This is dead simple if a little wordy:

curl -o perl-5.42.0-src.tar.gz https://cpan.metacpan.org/authors/id/B/BO/BOOK/perl-5.42.0.tar.gz
tar xzf perl-5.42.0-src.tar.gz
cd perl-5.42.0
sh Configure -de -Dprefix=$HOME/perl-5.42.0-installed
make -j $(nproc)
make install
$HOME/perl-5.42.0-installed/bin/perl -MCPAN -e 'install qw(App::cpanminus)'

The call to the Configure script is where the OS packaging people make it have 64-bit ints by adding the -Duse64bitint flag. Normally you would make test too but I've satisfied myself that it does indeed pass its tests using this Docker image, so I skip that step to save a lot of time.

Finally, I can extract my software and test it. It is bloody irritating that Github automatically wrap my tarball in the obsolete zip format. I blame Microsoft:

unzip dist-for-install.zip
mkdir dist-for-test
tar -C dist-for-test -xzf *.tar.gz
cd dist-for-test/*
$HOME/perl-5.42.0-installed/bin/cpanm --installdeps .
$HOME/perl-5.42.0-installed/bin/perl Makefile.PL
make test TEST_VERBOSE=1

And there you have it - how to test your code automatically, using Github actions, on a 32-bit platform.