[rb-general] Reproducing tarballs under various toolchains

[Daniel Shahaf]

Daniel Shahaf wrote on Thu, 20 Sep 2018 15:34 +0000:
> 1. Patch the site to mention bsdtar support for these flags

I took a shot at this but didn't come up with a good way to balance the
pragmatic information ("Here's what to do for gtar, for bsdtar, for
interoperability") with the theoretical background ("be able to
reproduce a tarball using a different tar(1) implementation than it was
originally created by") so I filed an issue:

https://salsa.debian.org/reproducible-builds/reproducible-website/issues/3

> 2. Ask bsdtar to support the gtar flag names

I looked into the history.

GNU tar had --owner,--group since before the 'release_1_14' tag in 2004.
Possibly for a long time before then.

FreeBSD's default tar gained the --uid option in FreeBSD 8.3, in 2012.
I don't know whether that was because FreeBSD transitioned to a
different tar implementation or because their tar implementation gainde
a new option.)

I would say that precedent lies with GNU tar and that FreeBSD tar
should add compatibility flags.

FreeBSD uses libarchive's bsdtar(1) as is.  For libarchive I found this:

[[[
https://github.com/libarchive/libarchive/issues/278#issuecomment-91880148
Comment #1 originally posted by kientzle on 2011-11-24T19:59:18.000Z:
> bsdtar already has --gid, --gname, --uid, --uname options that provide
> the same functionality.  If someone wants to implement GNU tar-compatible
> --owner and --group options, I'm happy to review patches, but this
> isn't a priority for me.
]]]

> 3. Ask gtar to support the bsdtar flag names

I haven't looked into this.

Cheers,

Daniel