[RFE] support xz compressed comps.xml

[mattiaverga]

It seems createrepo_c version 1.x defaults to XZ compress comps.xml also.
I tried to use something like:

                    if repo_info['group'].endswith('xz'):
                        xml_content = lzma.open(repo_info['group']).read()
>                       ret = comps.fromxml_f(xml_content)
E                       TypeError: function accept string and optional xml_options dict

Is there a clever way to make this work?
fedora-infra/bodhi#5455

[kontura]

I think createrepo_c-1.0.0-1.fc39.x86_64 should default to zstd even for comps.

Nonetheless you can do:

xml_content = lzma.open("./comps.xml.xz").read()
ret = comps.fromxml_str(xml_content.decode())

[j-mracek]

I also think that createrepo_c should have the same default for all types of metadata types.

[mattiaverga]

Oh, yes, bodhi tests create repo with --xz, so they override the default compression.
However it seems before createrepo_c v1.x the comps.xml file was not compressed and just plain xml.

The above suggested solution
ret = comps.fromxml_str(xml_content.decode())
works when everything it's ok, but seems to not behave as expected when the content of comps.xml is invalid, returning a bad crash as Fatal Python error: Segmentation fault instead of raising an Exception, for example in this test:
https://github.com/fedora-infra/bodhi/actions/runs/5935123593/job/16093069432?pr=5455

[kontura]

Oh, yes, bodhi tests create repo with --xz, so they override the default compression. However it seems before createrepo_c v1.x the comps.xml file was not compressed and just plain xml.

This is one of the changes in 1.0.0 version. It used to create both compressed and uncompressed variants at the same time. Now there is only the compressed comps.

The above suggested solution ret = comps.fromxml_str(xml_content.decode()) works when everything it's ok, but seems to not behave as expected when the content of comps.xml is invalid, returning a bad crash as Fatal Python error: Segmentation fault instead of raising an Exception, for example in this test: https://github.com/fedora-infra/bodhi/actions/runs/5935123593/job/16093069432?pr=5455

Yes, that is a problem.

[kontura]

I made a PR to fix the crash: #104

[mattiaverga]

I've tested the above patch and now the test that previously crashed completes well.
However, I now get another segfault in the following test which is slightly different in what wrong content is passed in comps.xml.

[dralley]

Note that this isn't a fully new issue. Libcomps isn't very robust to invalid inputs in general #47

[kontura]

I have created another PR to patch some of the holes: #106
But yea there is likely more.