Add support for bsdtar

[tpgxyz]

Short description of the problem

Currently mock supports tar from GNU, while bsdtar from libarchive is not supported

Output of rpm -q mock

Steps to reproduce issue

1. Set up bsdtar as default tar
2. Observe mock failure

Do not forget to mention full commandline with the mock command you executed.

Any additional notes

Consider adding output of mock --debug-config this can help developers to reproduce the issue.

[xsuchy]

What would be the benefit? I am afraid that this is soooo low prio, that it will not happen unless someone (you) send a patch.

[praiskup]

GNU tar is supposed to be the default on GNU/Linux distro. Btw.:

$ rpm -q mock
mock-1.4.9-1.fc27.noarch

[praiskup]

Is this issue related to mock scm plugin?

[tpgxyz]

@xsuchy @praiskup All calls to tar inside mock code are not compatible with bsdtar https://github.com/libarchive/libarchive

[Conan-Kudo]

To give a more detailed explanation here:

OpenMandriva is in the process of switching to rpm.org rpm and DNF. As a part of this, their build system build engine is changing to mock. However, they replaced GNU tar with libarchive's tar back in OpenMandriva Lx 3, and libarchive's tar works slightly differently.

A proper patch for this would probably involve making it configurable to use either tar (expecting GNU tar) or bsdtar for libarchive's tar. What would be required for that, I don't yet know, but that's what I think would be required.

[praiskup]

Thanks @Conan-Kudo, it is starting to make sense. As a sum-up, those are the missing bits

• what are the concrete differences in behavior between tar and bsdtar we face here
• how OpenMandriva replaced package named 'tar' with 'bsdtar', who provides /bin/tar there
• what it means "configurable" to use either tar or bsdtar (on mock.spec level, or ./configure?,
  it's no longer there..)

What would be required for that, I don't yet know, but that's what I think would be required.

Where this is discussed?

[Conan-Kudo]

@praiskup

what it means "configurable" to use either tar or bsdtar (on mock.spec level, or ./configure?,
it's no longer there..)

This probably would be a switch in the site-defaults.cfg/mock target config, since we don't have any other configuration mechanism.

Where this is discussed?

I'm not sure what you mean?

[praiskup]

On Tuesday, April 24, 2018 11:21:42 AM CEST Neal Gompa (ニール・ゴンパ) wrote: > > What would be required for that, I don't yet ... > > Where this is discussed? I'm not sure what you mean?

I thought that it is being discussed somewhere, and you'll know sooner or later. Having some reference links would be nice.

[Conan-Kudo]

No, this was discussed on IRC in #OpenMandriva-Cooker some time ago. The switch to bsdtar occurred two years ago, and GNU tar is no longer in the base system package set at all.

There was an attempt to patch mock to forcibly switch it to bsdtar, but it didn't work, so currently we have a relatively unmaintained version of the gnutar package providing it as gtar (like on macOS and BSD) and we patch mock to use gtar instead of tar.

[praiskup]

On Tuesday, April 24, 2018 11:36:41 AM CEST Neal Gompa (ニール・ゴンパ) wrote: No, this was discussed on IRC in `#OpenMandriva-Cooker` some time ago. The switch to `bsdtar` occurred two years ago, and GNU tar is no longer in the base system package set at all.

So at least `bsdtar` is generally available on every such box, which provides `/bin/tar`, which is OK.

There was an attempt to patch mock to forcibly switch it to `bsdtar`, but it didn't work, so currently we have a relatively unmaintained version of the [`gnutar`](https://github.com/OpenMandrivaAssociation/gnutar/blob/master/gnutar.spec) package providing it as `gtar` (like on macOS and BSD) and we patch `mock` to use `gtar` instead of `tar`.

I really need to see links to discussions about this, because otherwise I only can guess what concrete problems with bsdtar are... really really guessing now, I grepped through mock's devel branch: $ git grep 'tar ' mock/py/mockbuild/scm.py: self.write_tar = opts['write_tar'] mock/py/mockbuild/scm.py: self.log.debug(".write_tar detected, will write tarball on the fly") mock/py/mockbuild/scm.py: self.write_tar = True mock/py/mockbuild/scm.py: cmd = "tar caf " + tarball + " " + taropts + " " + tardir ... so I see one portability problem, and that's 'taropts' which contains '--exclude-vcs' option. Is this this the core of the problem?

[Conan-Kudo]

I think so. @berolinux and @tpgxyz can give more details. I wasn't really there for most of it, as we operate in different time zones.

[praiskup]

It would answer the question I asked before, that this is related only to scm plugin.
This makes me feel that 'mock' should runtime depend on 'gtar' on such architectures,
and that the scm plugin should just go and use /bin/gtar instead of /bin/tar. I can
invent some more magic solution, but this should be just enough..

[Conan-Kudo]

@praiskup The thing is, we don't use mock-scm: https://github.com/OpenMandrivaSoftware/docker-builder/blob/master/config-generator.sh

[praiskup]

On Tuesday, April 24, 2018 12:22:50 PM CEST Neal Gompa (ニール・ゴンパ) wrote: The thing is, we don't use `mock-scm`

That's even better. /bin/yum would say, "Nothing to do.", or what am I missing?

[tpgxyz]

@praiskup @xsuchy Yes @Conan-Kudo well descibed what i had on my mind, when i filled this issue.

Problem is that mock uses switches from gnu's version of tar. Unfortunately these options does not exists in BSD's (or POSIX compiliant) tar from libarchive (https://www.libarchive.org/)

Mostly libarchive's tar does not support exclude-foo-bar. Instead of this option is support excludes pattern i.e
--exclude='*foo*'

Currently gtar compatible options were found in mock's root_cache.py

[praiskup]

Thanks, that makes it clear now. I forgot about root_cache.py. Please consider
whether #180 fix is enough.

[xsuchy]

@praiskup bsdtar exists even in fedora:
https://apps.fedoraproject.org/packages/bsdtar

so you can try it yourself (or compare man pages)

[praiskup]

On Tuesday, April 24, 2018 8:15:56 PM CEST Miroslav Suchý wrote: so you can try it yourself (or compare man pages)

I know something about those packages :-)

[xsuchy]

oops, I did not realized :))