Re: time_t on NetBSD/i386

[Bruno Haible]

Jim Meyering wrote:
> >> time_t is 64 bits in recent NetBSD versions even on i386 platform,
> >> therefore these assertations fail on it:
> >>
> >> in lib/mktime.c:
> >> verify (long_int_year_and_yday_are_wide_enough,
> >>     INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
> >
> > I'm disabling this assertion; the code seems to be correct also with
> > 64-bit 'time_t'.
> 
> I'm still leery of disabling it, but can't put my finger on a precise
> problem, so this isn't an official objection.
> 
> I'm nearly certain you understand the issue, but your sentence above
> suggests it is worth clarifying:
> the possible problem is not with 64-bit time_t per se,
> but rather with the combination of that *and* a "long int"
> type that is no wider than "int".

Yes. The naming of the variable 'long_int_year_and_yday_are_wide_enough'
sounds as if Paul intended to be able to pass time_t values into 'year1'
and 'yday1'. But this does not happen: all inputs are 'int'.

Or maybe Paul meant that the entire time_t range can occur as result of
mktime() with given 'int' inputs (in other words, that mktime is
surjective)? I cannot see the rationale for such a requirement.

> > This one is harder. It has already been reported for QNX [1][2].
> > [1] http://lists.gnu.org/archive/html/bug-gnulib/2008-01/msg00161.html
> > [2] http://lists.gnu.org/archive/html/bug-gnulib/2009-07/msg00111.html
> >
> > Here is a proposed patch. I checked all uses of 'time_t' in getdate.y and
> > found only two conversions from time_t to 'long int', in the 'relunit' rule:
> >
> >   | tSDECIMAL_NUMBER tSEC_UNIT
> >       { $$ = RELATIVE_TIME_0; $$.seconds = $1.tv_sec; $$.ns = $1.tv_nsec; }
> >   | tUDECIMAL_NUMBER tSEC_UNIT
> >       { $$ = RELATIVE_TIME_0; $$.seconds = $1.tv_sec; $$.ns = $1.tv_nsec; }
> >
> > So this patch should handle it. Jim, Eric, opinions?
> 
> I confess I'm not sure it's ok, but if something breaks,
> we'll fix it and be sure to add a test case next time.
> 
> So go ahead.

The kind of breakage that we have to expect here is in the corner cases, with
specially crafted input. It's not guaranteed that such a bug will visibly
"break" something. But I have read the entire file and found no other conversion
from time_t to 'long int'.

So, committed and pushed.

Bruno