Re: [PATCH v3] Define in_int32_t_range to check if the 64 bit time_t syscall should be used

["Arnd Bergmann" <arnd@arndb.de>]

On Tue, Nov 8, 2022, at 12:17, Florian Weimer wrote:
> * Arnd Bergmann:
>> On Tue, Nov 8, 2022, at 05:49, YunQiang Su wrote:
>>> Currently glibc uses in_time_t_range to detects time_t overflow,
>>> and if it occurs fallbacks to 64 bit syscall version.
>>>
>>> The function name is confusing because internally time_t might be
>>> either 32 bits or 64 bits (depending on __TIMESIZE).
>>>
>>> This patch refactors the in_time_t_range by replacing it with
>>> in_int32_t_range for the case to check if the 64 bit time_t syscall
>>> should be used.
>>>
>>> The in_time_t range is used to detect overflow of the
>>> syscall return value.
>>
>> It looks like the fallback logic has another flaw, I don't
>> see how this works on kernels with COMPAT_32BIT_TIME disabled,
>> as these only have the time64 syscalls available.
>
> Isn't that an invalid kernel configuration?

No, this is what we will use anyway after 2038 (possibly
earlier), so the option is useful to ensure that all userspace
has been converted away from the time32 interfaces.

     Arnd