Bug#1146517: libipc-shareable-perl: FTBFS on ppc64el and ppc64: shm_segments() reads the wrong field of struct shmid_ds

[Edmund Lodewijks]

Source: libipc-shareable-perl
Version: 1.19-1
Severity: serious
Tags: ftbfs patch upstream
Justification: fails to build from source
Forwarded: https://github.com/stevieb9/ipc-shareable/issues/66
X-Debbugs-Cc: gregoa at debian.org


1.19-1 fails to build on ppc64el and ppc64, and builds everywhere else:

   https://buildd.debian.org/status/package.php?p=libipc-shareable-perl
  
https://buildd.debian.org/status/logs.php?pkg=libipc-shareable-perl&arch=ppc64el

   t/72-shm_segments.t  (Wstat: 6912 Tests: 47 Failed: 27)
   t/74-seg_map.t       (Wstat: 512  Tests: 12 Failed: 2)

lib/IPC/Shareable.pm unpacks struct shmid_ds at a hard-coded offset for
shm_segsz, assuming the asm-generic field order. PowerPC puts the three
time fields first, so on ppc64el/ppc64 the offset lands on shm_atime;
the oversized value makes the following shmread() fail and the segment
never reaches %segments. IPC/Shareable/SharedMem.pm has the same bug in
stat().

Reported upstream as #66, together with an alternative that drops the
offset tables entirely and reads the fields through IPC::SysV's XS
instead. Upstream has not replied yet, so the attached minimal fix is
what I would suggest for Debian; it is the least likely to conflict with
whichever route upstream takes.

Both solutions were built and tested on ppc64el under sbuild. No 
upstream reply yet.

Filed separately from #1142815, which is the unrelated t/47-seg_size.t
memory problem (upstream #65).

Kind regards,

     Edmund Lodewijks


-- 
Edmund Lodewijks <edmund at proteamail.com>
TZ: UTC+2 / GMT+2

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