Re: [musl] Re: parse-datetime test failure

[Rich Felker <dalias@libc.org>]

On Wed, Nov 11, 2020 at 07:38:00PM -0800, Paul Eggert wrote:
> On 11/11/20 8:20 AM, Bruno Haible wrote:
> >It works fine on Alpine Linux 3.7 (32-bit, 64-bit) and 3.9 (64-bit).
> >
> >On Alpine Linux 3.10 and 3.12 (64-bit) it fails:
> >../../gltests/test-parse-datetime.c:448: assertion 'result.tv_sec == 1 * 60 * 60 + 2 * 60 + 3 && result.tv_nsec == 123456789' failed
> >Aborted
> >
> >So, to me it looks like a regression between Alpine Linux 3.9 and 3.10.
> 
> It's arguably a bug in the test case, since Alpine uses musl libc
> which does not support time zone abbreviations longer than 6 bytes,
> whereas the test case uses an time zone abbreviation of 2000 bytes
> (to test a bug in an old Gnulib version when running on GNU/Linux).
> POSIX does not define behavior if you go over the limit.
> 
> I worked around the problem by changing the test case to not go over
> the limit as determined by sysconf (_SC_TZNAME_MAX), in the first
> attached patch. Plus I refactored and/or slightly improved the
> Gnulib overflow checking while I was in the neighborhood (last two
> attached patches).
> 
> Arguably this is a quality-of-implementation issue here, since
> Alpine and/or musl goes beserk with long timezone abbreviations
> whereas every other implementation I know of either works or
> silently substitutes localtime or UTC (which is good enough for this
> test case). But I'll leave that issue to the Alpine and/or musl libc
> folks.
> 
> I'll cc this to the musl bug reporting list. Although the Gnulib
> test failure has been fixed, it may be the symptom of a more-severe
> bug in musl. For those new to the problem, this thread starts here:
> 
> https://lists.gnu.org/r/bug-gnulib/2020-11/msg00039.html

Thanks. I believe you've just re-discovered a known bug that's fixed
in musl commit 33338ebc853d37c80f0f236cc7a92cb0acc6aace, which will be
included in the upcoming 1.2.2 release.

Rich