Portable Archive Interchange (cpio, pax, tar)

pax lack of support for "pax" format fails LSB

Reported by Wayne Pollock on 2009-10-20
14
This bug affects 2 people
Affects Status Importance Assigned to Milestone
MirCPIO
Undecided
Unassigned

Bug Description

The SUS/POSIX standard tool pax is required for LSB 3.2 compliance. The
version of this tool on Linux (all systems I've tested) provide ustar format
but not 'pax" format. "pax" format is required by LSB; it is needed to backup
ACLs and extended attributes including SE Linux labels.

libarchive does support pax format. It should be easy to create a front-end
for pax that uses libarchive (which comes with bsdcpio front-end, but not in
the Fedora 10 package). SUSv3 and SYSv4 (and POSIX all required this format to
be supported, and LSB 3.2 does as well.) Not supporting it means no standard
tool can make archives with EAs; more importantly it means Fedora (and
presumably Red Hat) is not compliant with the LSB.

How reproducible:
Always

Steps to Reproduce:
try "pax -x pax" ...

Actual results:
pax: Unknown -x format: pax

Expected results:
should work.

Additional:

I originally reported this against Fedora. The maintainer, <email address hidden>, confirms no distro
supports this and has written a patch. (See Fedora bug #503860.) But libarchive supports this
so I think it should be fairly easy to lift that code, or just invoke that .so from pax?

affects: ubuntu → ubuntu-meta (Ubuntu)
Richard Hansen (a7x) wrote :

There are two separate but related issues here:
  1. the pax utility doesn't support the pax format (a LSB conformance bug in pax)
  2. the pax utility isn't installed by default (a LSB conformance bug in ubuntu-meta)
This bug report seems to be about the first issue, so I'm moving this to pax. A separate bug should be opened for the second issue.

affects: ubuntu-meta (Ubuntu) → pax (Ubuntu)
Thorsten Glaser (mirabilos) wrote :

True. I’ve planned to add support to this upstream eventually. (Reassigning this bugreport to the upstream codebase.) I’ve added ar already, and pax is not unlike ustar, so it ought to not be _that_ difficult. Still needs quite some time, and standardese parsing, so don’t hold your breath for it ☺

affects: pax (Ubuntu) → paxmirabilis
Changed in paxmirabilis:
status: New → Confirmed
ruario (e-launchpad-ruari-com) wrote :

Perhaps worth looking at the pax provided by the The Heirloom Toolchest <http://heirloom.sourceforge.net/tools.html> as an alternative? This claims to be POSIX.1-2001/SUSV3 compliant and is under Open Source licenses.

I complied it up locally and "pax -x pax -f test.tar somefile" seems to work as expected.

Thorsten Glaser (mirabilos) wrote :

No, it’s relatively easy to add the format to paxtar, it just needs time to be done.
(Also, the heirloom stuff doesn’t integrate tar and the other improvements, and
I don’t want to have to audit its mix of licences. Switching implementations isn’t
something easily done.)

The LSB people agreed to not press this issue, and may even waive the pax format
(which doesn’t mean we won’t eventually add it, as I really want it, too).

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