From: Florian Weimer <fweimer@redhat.com>
To: "Arnd Bergmann" <arnd@arndb.de>
Cc: "YunQiang Su" <yunqiang.su@cipunited.com>,
"Xi Ruoyao" <libc-alpha@sourceware.org>,
aurelien@aurel32.net,
"Adhemerval Zanella Netto" <adhemerval.zanella@linaro.org>,
"Jiaxun Yang" <jiaxun.yang@flygoat.com>,
"Maciej W. Rozycki" <macro@orcam.me.uk>,
syq@debian.org
Subject: Re: [PATCH v3] Define in_int32_t_range to check if the 64 bit time_t syscall should be used
Date: Tue, 08 Nov 2022 12:39:37 +0100 [thread overview]
Message-ID: <87sfitisjq.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <80f469a6-f432-419d-9cdc-91f2366639d3@app.fastmail.com> (Arnd Bergmann's message of "Tue, 08 Nov 2022 12:33:45 +0100")
* Arnd Bergmann:
> 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.
What happened to not breaking userspace?
Those with 32-bit applications will want to run their legacy stuff in a
time-shifted environment, so these system calls must remain supported
outside specialized applications.
Thanks,
Florian
next prev parent reply other threads:[~2022-11-08 11:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-04 1:39 [PATCH] Use in_int32_t_range to check need 64bit syscall YunQiang Su
2022-11-08 4:49 ` [PATCH v3] Define in_int32_t_range to check if the 64 bit time_t syscall should be used YunQiang Su
2022-11-08 10:39 ` Arnd Bergmann
2022-11-08 11:17 ` Florian Weimer
2022-11-08 11:33 ` Arnd Bergmann
2022-11-08 11:39 ` Florian Weimer [this message]
2022-11-08 11:55 ` Adhemerval Zanella Netto
2022-11-08 12:28 ` Arnd Bergmann
2022-11-08 12:51 ` Adhemerval Zanella Netto
2022-11-08 13:27 ` Arnd Bergmann
2022-11-08 13:49 ` Adhemerval Zanella Netto
2022-11-08 14:07 ` Arnd Bergmann
2022-11-08 14:27 ` Adhemerval Zanella Netto
2022-11-08 19:47 ` Adhemerval Zanella Netto
2022-11-08 23:29 ` Rich Felker
2022-11-17 17:35 ` Adhemerval Zanella Netto
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