From: Joseph Myers <joseph@codesourcery.com>
To: Zack Weinberg <zackw@panix.com>
Cc: "Albert ARIBAUD (3ADEV)" <albert.aribaud@3adev.fr>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [RFC PATCH 00/52] Make GLIBC Y2038-proof
Date: Fri, 08 Sep 2017 17:24:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.20.1709081715180.16313@digraph.polyomino.org.uk> (raw)
In-Reply-To: <CAKCAbMjgCjA-jMrCt9YDhw6dM5Y9MKJGn3=Bte-kF00Y-9SUdg@mail.gmail.com>
On Fri, 8 Sep 2017, Zack Weinberg wrote:
> > And as discussed, I disagree and don't think we should invent any such
> > typedef or deviate from this requirement, given that long is fully able to
> > represent all valid nanoseconds values
>
> Neither you, nor Rich, nor anyone else on the cited Austin Group
> discussion has addressed the actual issue, which is that this is a
> datum embedded in structures passed across the kernel/user boundary by
> reference, it is impossible to enumerate all such structures,
> therefore its type _must_ be a typedef so that it can be made to match
> the kernel's expectations, whatever those might be.
I don't see this as in any way an issue for having a definition of struct
timespec that conforms to ISO C and POSIX requirements. Code passing data
to the kernel knows the structures being used locally and needs to convert
it to the kernel's layout, which might be e.g. struct __kernel_timespec64.
I don't see that as different in essence from e.g. converting a local-time
broken down date/hours/minutes/seconds/nanoseconds value before passing it
to the kernel, if that's the form the particular application stores time
in. It just so happens that, as an optimization, we can arrange the
layout so that we both are POSIX-compatible and do not require any layout
conversions between timestamps coming *from* the kernel and struct
timespec.
> (And I don't particularly see why people seem to think this is an
> x32-specific issue. It potentially affects *any* 32-bit ABI on a
> 64-bit kernel.)
The kernel does the conversion just fine for a pure 32-bit struct timespec
- as it does for the entire compat interface - and could do them perfectly
well for a structure with 64-bit seconds and 32-bit (+ padding)
nanoseconds. It just so happens not to for the very specific case of x32.
> >> <sys/types.h>, matching the kernel's choice of 32 or 64 bits for this
> >> field (all _t names are reserved for future extension, so the typedef
> >> doesn't need to be _GNU_SOURCE-only). This "willful violation" (as the
> >
> > They are not reserved in ISO C, only in POSIX.
>
> <sys/types.h> doesn't exist in ISO C as far as I know, so how could it
> be? But any program that uses it opts into POSIX's specification for
My point is that you can't expose nsec_t, even as a typedef for long, in
<time.h> for C11.
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2017-09-08 17:24 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 22:42 Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 01/52] Y2038: add type __time64_t Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 02/52] Y2038: add function __difftime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 03/52] Y2038: add functions using struct tm Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 04/52] Y2038: add function __mktime64 (and timelocal) Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 05/52] Y2038: add function __timegm64 Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 06/52] Y2038: add struct __timespec64 Albert ARIBAUD (3ADEV)
2017-09-07 22:42 ` [RFC PATCH 07/52] Y2038: add function __clock_gettime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 08/52] Y2038: add function __clock_settime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 09/52] Y2038: add function __clock_getres64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 10/52] Y2038: add function __clock_nanosleep64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 11/52] Y2038: add function __timespec_get64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 12/52] Y2038: add function __futimens64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 13/52] Y2038: add function __utimensat64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 14/52] Y2038: add function __sigtimedwait64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 15/52] Y2038: add struct __timeval64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 16/52] Y2038: add function __futimes64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 17/52] Y2038: add function __lutimes64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 18/52] Y2038: add struct __itimerspec64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 19/52] Y2038: add function __timer_gettime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 20/52] Y2038: add function __timer_settime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:43 ` [RFC PATCH 21/52] Y2038: add function __timerfd_gettime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 22/52] Y2038: add function __timerfd_settime64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 23/52] Y2038: add struct __stat64_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 24/52] Y2038: add function __fstat64_t64 (and __fxstat64_t64) Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 25/52] Y2038: add function __stat64_t64 (and __xstat64_t64) Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 26/52] Y2038: add function __lstat64_t64 (and __lxstat64_t64) Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 27/52] Y2038: add function __fstatat64_t64 (and __fxstatat_t64) Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 28/52] Y2038: add function __time_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 29/52] Y2038: add function __stime_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 30/52] Y2038: add function __utimes_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 31/52] Y2038: add function __gettimeofday_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 32/52] Y2038: add function __settimeofday_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 33/52] Y2038: add function __mq_timedsend_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 34/52] Y2038: add function __mq_timedreceive_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:44 ` [RFC PATCH 35/52] Y2038: add function __msgctl_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 36/52] Y2038: add function __sched_rr_get_interval_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 37/52] Y2038: add function __nanosleep64_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 38/52] Y2038: add function __adjtime_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 39/52] Y2038: add function __utime_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 40/52] Y2038: add struct __itimerval_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 41/52] Y2038: add function __getitimer_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 42/52] Y2038: add function __setitimer_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 43/52] Y2038: add functions using futexes Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 44/52] Y2038: add function __getrusage_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 45/52] Y2038: add struct __ntp_timeval_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 46/52] Y2038: add function __ntp_gettime_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 47/52] Y2038: add function __ntp_gettimex_t64 Albert ARIBAUD (3ADEV)
2017-09-07 22:45 ` [RFC PATCH 48/52] Y2038: add function __adjtimex_t64 (and __ntp_adjtime_t64) Albert ARIBAUD (3ADEV)
2017-09-07 22:46 ` [RFC PATCH 49/52] Y2038: add function pselect Albert ARIBAUD (3ADEV)
2017-09-08 17:49 ` [RFC PATCH 50/52] Y2038: add function select Albert ARIBAUD (3ADEV)
2017-09-08 17:49 ` [RFC PATCH 51/52] Y2038: add RPC functions Albert ARIBAUD (3ADEV)
2017-09-08 17:49 ` [RFC PATCH 52/52] Y2038: add _TIME_BITS==64 support Albert ARIBAUD (3ADEV)
2017-09-08 19:47 ` Joseph Myers
2017-09-08 19:47 ` [RFC PATCH 51/52] Y2038: add RPC functions Joseph Myers
2017-09-08 19:59 ` Paul Eggert
2017-09-09 14:37 ` Albert ARIBAUD
2017-09-11 6:33 ` Paul Eggert
2017-09-11 7:06 ` Paul Eggert
2017-09-11 14:07 ` Paul Eggert
2017-09-11 15:59 ` Albert ARIBAUD
2017-09-07 23:21 ` [RFC PATCH 00/52] Make GLIBC Y2038-proof Joseph Myers
2017-09-08 16:19 ` Zack Weinberg
2017-09-08 16:43 ` Joseph Myers
2017-09-08 16:54 ` Paul Eggert
2017-09-08 17:01 ` Zack Weinberg
2017-09-08 17:24 ` Joseph Myers [this message]
2017-09-08 18:32 ` Zack Weinberg
2017-09-08 17:42 ` Albert ARIBAUD
2017-09-08 17:59 ` Joseph Myers
2017-09-08 18:16 ` Albert ARIBAUD
2017-09-08 18:36 ` Zack Weinberg
2017-09-08 17:08 ` Albert ARIBAUD
2017-09-08 17:26 ` Joseph Myers
2017-09-08 19:19 ` Albert ARIBAUD
2017-09-08 4:23 ` Albert ARIBAUD
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.DEB.2.20.1709081715180.16313@digraph.polyomino.org.uk \
--to=joseph@codesourcery.com \
--cc=albert.aribaud@3adev.fr \
--cc=libc-alpha@sourceware.org \
--cc=zackw@panix.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).