Re: [PATCH] login: Use unsigned 32-bit types for seconds-since-epoch

[Florian Weimer <fweimer@redhat.com>]

* Paul Eggert:

> On 4/3/24 11:39, Florian Weimer wrote:
>> For consistency,
>> if there is a 64-bit architecture that is coinstallable, define
>> __WORDSIZE_TIME64_COMPAT32 to 1 on the 32-bit architectyre as well.
>
> Could you explain the advantage of consistency here? User code almost
> invariably assignes ut_tv.tv_sec to time_t (this is true of every
> instance I found of ut_tv in Gnulib source code, for example). So
> changing this field's type on platforms where time_t is 32 bits will
> likely be ineffective in practice, and might cause more problems than
> it cures.

Few applications with a 32-bit time_t will work once there is a value in
this field with the MSB set.  So the relevant case is applications that
were built with -D_TIME_BITS=64, and there the consistent behavior with
the 64-bit architecture helps.

> Since the _TIME_BITS==32 world is going away anyway by 2038, it might
> be better to leave the field types unchanged in that world, to lessen
> compatibility glitches before that world gives up its ghost.

This is an on-disk format that doesn't change with -D_TIME_BITS=64.

Thanks,
Florian