Subject: hangs the whole configure script

From: "Herbert, Marc" <[email-masked]>
Date: Tue, 8 Nov 2011 16:45:55 +0000

When "configure" is run by a user with an UID bigger than 21bits, BSD
pax 3.4 aborts when trying to create the conftest.tar test archive and
leaves an empty or corrupted conftest.tar file behind. In the next
step, pax tries to extract this incomplete or corrupted archive and

 *this hangs the whole ./configure script forever*

  => I do not think "normal" is enough as a severity

configure:NNN: pax -r <conftest.tar
pax: Cannot identify format. Searching...
pax: End of archive volume 1 reached

ATTENTION! pax archive volume change required.
Ready for archive volume: 1
Input archive name or "." to quit pax.
Archive name > 

Note: GNU cpio 2.9 pretends to pass the test but it is a LIE: it
silently truncates any big UID to its lower 21 bits. I don't know what
can be the consequences of this lie.

Some background
---------------

- POSIX 1988 "ustar" format is defined with *fixed size* fields. There
  is notably a 21 bits limit (2097151) for the uid and the gid.

- POSIX 2001 "pax" format (also sometimes known as... "posix") has
  additional attributes of unlimited length. However, as of today
  support for this format is scarce. GNU tar 1.20 claims support yet
  breaks on big user IDs. Despite its name, BSD pax 3.4 does not offer
  any 2001 "pax" support at all, see discussion here:
  <https://bugzilla.redhat.com/show_bug.cgi?id=503860>

Only a couple of non-portable formats ("star", "gnutar", ...) seem to
actually support big user IDs today.

I think there is currently a design issue in automake/m4/tar.m4
considering that a ustar archive should should *never* succeed when
./configure is run from a big user ID.

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