From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 0/6] Use time_t
Date: Tue, 28 Feb 2017 12:32:01 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1702281211270.3767@virtualbox> (raw)
In-Reply-To: <xmqqlgsrmesc.fsf@gitster.mtv.corp.google.com>
Hi Junio,
On Mon, 27 Feb 2017, Junio C Hamano wrote:
> Johannes Schindelin <johannes.schindelin@gmx.de> writes:
>
> > One notable fallout of this patch series is that on 64-bit Linux (and
> > other platforms where `unsigned long` is 64-bit), we now limit the
> > range of dates to LONG_MAX (i.e. the *signed* maximum value). This
> > needs to be done as `time_t` can be signed (and indeed is at least on
> > my Ubuntu setup).
> >
> > Obviously, I think that we can live with that, and I hope that all
> > interested parties agree.
>
> s/ulong/time_t/ is definintely a good change, and it will take us to a
> place we would want to be in in some future.
Actually. I have to take back the part where I hoped that all interested
parties would agree. The problem is 32-bit Linux:
$ cat >a1.c <<-\EOF
#include <stdio.h>
#include <limits.h>
#include <time.h>
int main(int argc, char **argv)
{
printf("sizeof(long): %d, sizeof(time_t): %d, ulong_max: %lu\n",
(int)sizeof(long), (int)sizeof(time_t), ULONG_MAX);
return 0;
}
EOF
$ gcc -m32 -Wall -o a1 a1.c
$ ./a1
sizeof(long): 4, sizeof(time_t): 4, ulong_max: 4294967295
So. Not only is `long` a 32-bit on 32-bit Linux, but so is `time_t`. And
with that, switching from `ULONG_MAX` as the maximal time we can represent
in Git to `LONG_MAX` is kind of a serious problem.
> As long as there remains no platform we care about whose time_t and long
> are still 32-bit signed integer, there will be a fallout to them with
> this change.
Sorry, I do not understand the verb "remains" in conjunction with "no
platform"...
Do you mean to say that currently no platform we care about has 32-bit
signed time_t/long?
If so, I just demonstrated this to be unfortunately incorrect.
> It appears that we use uint64_t in many places in our code. So
> while philosophically time_t is the right type, uint64_t might be
> practically a safer alternative type to use at the endgame patch in
> this series.
Yes, I think you are right. We should use uint64_t instead of time_t, but
*semantically* we should not even use uint64_t. We should introduce our
own data type instead of repeating the mistake to use a data type that
does not convey its role to the reader.
Currently, I am favoring timestamp_t.
> I haven't seen it yet, but presumably the last one 6/6 is the endgame?
Maybe it took a while to get sent out, but it made it into public inbox:
http://public-inbox.org/git/75efe76cbb0636741a7c3aec9e21459bc1dc3cbe.1488231002.git.johannes.schindelin@gmx.de/
Ciao,
Johannes
next prev parent reply other threads:[~2017-02-28 11:36 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-27 21:30 [PATCH 0/6] Use time_t Johannes Schindelin
2017-02-27 21:30 ` [PATCH 1/6] t0006 & t5000: prepare for 64-bit time_t Johannes Schindelin
2017-02-27 22:55 ` Junio C Hamano
2017-02-27 21:30 ` [PATCH 2/6] Specify explicitly where we parse timestamps Johannes Schindelin
2017-02-27 22:37 ` Junio C Hamano
2017-02-27 22:51 ` Junio C Hamano
2017-02-28 10:49 ` Johannes Schindelin
2017-02-27 21:31 ` [PATCH 3/6] Introduce a new "printf format" for timestamps Johannes Schindelin
2017-03-01 18:20 ` Junio C Hamano
2017-03-01 19:53 ` Junio C Hamano
2017-02-27 21:31 ` [PATCH 4/6] Prepare for timestamps to use 64-bit signed types Johannes Schindelin
2017-02-27 21:31 ` [PATCH 5/6] ref-filter: avoid using `unsigned long` for catch-all data type Johannes Schindelin
2017-02-27 21:31 ` [PATCH 6/6] Use time_t where appropriate Johannes Schindelin
2017-02-27 22:48 ` [PATCH 0/6] Use time_t Junio C Hamano
2017-02-28 11:32 ` Johannes Schindelin [this message]
2017-02-28 14:28 ` Jeff King
2017-02-28 15:01 ` Johannes Schindelin
2017-02-28 16:38 ` René Scharfe
2017-02-28 18:55 ` Junio C Hamano
2017-02-28 20:04 ` Jeff King
2017-02-28 20:54 ` Johannes Schindelin
2017-02-28 21:31 ` Jeff King
2017-02-28 21:31 ` René Scharfe
2017-02-28 23:10 ` Johannes Schindelin
2017-03-01 0:59 ` René Scharfe
2017-02-28 17:26 ` Junio C Hamano
2017-02-28 20:01 ` Jeff King
2017-02-28 22:27 ` Junio C Hamano
2017-02-28 22:33 ` Jeff King
2017-03-01 17:23 ` Junio C Hamano
2017-04-02 19:06 ` [PATCH v2 0/8] Introduce timestamp_t for timestamps Johannes Schindelin
2017-04-02 19:06 ` [PATCH v2 1/8] ref-filter: avoid using `unsigned long` for catch-all data type Johannes Schindelin
2017-04-03 4:22 ` Torsten Bögershausen
2017-04-03 22:47 ` Johannes Schindelin
2017-04-02 19:06 ` [PATCH v2 2/8] t0006 & t5000: prepare for 64-bit timestamps Johannes Schindelin
2017-04-02 19:06 ` [PATCH v2 3/8] t0006 & t5000: skip "far in the future" test when time_t is too limited Johannes Schindelin
2017-04-02 19:06 ` [PATCH v2 4/8] Specify explicitly where we parse timestamps Johannes Schindelin
2017-04-03 4:26 ` Torsten Bögershausen
2017-04-03 22:50 ` Johannes Schindelin
2017-04-02 19:06 ` [PATCH v2 5/8] Introduce a new "printf format" for timestamps Johannes Schindelin
2017-04-02 19:06 ` [PATCH v2 6/8] Introduce a new data type " Johannes Schindelin
2017-04-02 19:07 ` [PATCH v2 7/8] Abort if the system time cannot handle one of our timestamps Johannes Schindelin
2017-04-02 19:07 ` [PATCH v2 8/8] Use uintmax_t for timestamps Johannes Schindelin
2017-04-20 20:52 ` [PATCH v3 0/8] Introduce timestamp_t " Johannes Schindelin
2017-04-20 20:52 ` [PATCH v3 1/8] ref-filter: avoid using `unsigned long` for catch-all data type Johannes Schindelin
2017-04-20 20:52 ` [PATCH v3 2/8] t0006 & t5000: prepare for 64-bit timestamps Johannes Schindelin
2017-04-20 20:58 ` [PATCH v3 3/8] t0006 & t5000: skip "far in the future" test when time_t is too limited Johannes Schindelin
2017-04-20 20:58 ` [PATCH v3 4/8] Specify explicitly where we parse timestamps Johannes Schindelin
2017-04-20 20:58 ` [PATCH v3 5/8] Introduce a new "printf format" for timestamps Johannes Schindelin
2017-04-20 20:58 ` [PATCH v3 6/8] Introduce a new data type " Johannes Schindelin
2017-04-20 20:58 ` [PATCH v3 7/8] Abort if the system time cannot handle one of our timestamps Johannes Schindelin
2017-04-20 20:59 ` [PATCH v3 8/8] Use uintmax_t for timestamps Johannes Schindelin
2017-04-21 6:05 ` [PATCH v3 0/8] Introduce timestamp_t " Junio C Hamano
2017-04-21 10:44 ` Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 0/9] " Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 1/9] ref-filter: avoid using `unsigned long` for catch-all data type Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 2/9] t0006 & t5000: prepare for 64-bit timestamps Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 3/9] t0006 & t5000: skip "far in the future" test when time_t is too limited Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 4/9] Specify explicitly where we parse timestamps Johannes Schindelin
2017-04-24 3:19 ` Junio C Hamano
2017-04-21 10:45 ` [PATCH v4 5/9] Introduce a new "printf format" for timestamps Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 6/9] Introduce a new data type " Johannes Schindelin
2017-04-21 10:45 ` [PATCH v4 7/9] Abort if the system time cannot handle one of our timestamps Johannes Schindelin
2017-04-24 3:16 ` Junio C Hamano
2017-04-24 13:57 ` Johannes Schindelin
2017-04-25 2:37 ` Junio C Hamano
2017-04-25 3:56 ` Junio C Hamano
2017-04-21 10:46 ` [PATCH v4 8/9] Use uintmax_t for timestamps Johannes Schindelin
2017-04-24 3:24 ` Junio C Hamano
2017-04-24 10:28 ` Johannes Schindelin
2017-04-25 3:59 ` Junio C Hamano
2017-04-25 20:10 ` Johannes Schindelin
2017-04-26 1:52 ` Junio C Hamano
2017-04-26 3:45 ` Junio C Hamano
2017-04-26 9:32 ` Johannes Schindelin
2017-04-26 13:18 ` Junio C Hamano
2017-04-21 10:46 ` [PATCH v4 9/9] show_date_ident(): defer date overflow check Johannes Schindelin
2017-04-24 3:29 ` [PATCH v4 0/9] Introduce timestamp_t for timestamps Junio C Hamano
2017-04-24 6:15 ` Jacob Keller
2017-04-24 14:02 ` Johannes Schindelin
2017-04-24 11:37 ` Jeff King
2017-04-25 20:13 ` Johannes Schindelin
2017-04-24 14:00 ` Johannes Schindelin
2017-04-24 13:57 ` [PATCH v5 0/8] " Johannes Schindelin
2017-04-24 13:57 ` [PATCH v5 1/8] ref-filter: avoid using `unsigned long` for catch-all data type Johannes Schindelin
2017-04-24 13:57 ` [PATCH v5 2/8] t0006 & t5000: prepare for 64-bit timestamps Johannes Schindelin
2017-04-24 13:58 ` [PATCH v5 3/8] t0006 & t5000: skip "far in the future" test when time_t is too limited Johannes Schindelin
2017-04-24 13:58 ` [PATCH v5 4/8] Specify explicitly where we parse timestamps Johannes Schindelin
2017-04-25 5:59 ` Junio C Hamano
2017-04-24 13:58 ` [PATCH v5 5/8] Introduce a new "printf format" for timestamps Johannes Schindelin
2017-04-24 13:58 ` [PATCH v5 6/8] Introduce a new data type " Johannes Schindelin
2017-04-26 16:43 ` Johannes Sixt
2017-04-26 19:18 ` Johannes Schindelin
2017-04-26 22:32 ` René Scharfe
2017-04-24 13:58 ` [PATCH v5 7/8] Abort if the system time cannot handle one of our timestamps Johannes Schindelin
2017-04-24 13:58 ` [PATCH v5 8/8] Use uintmax_t for timestamps Johannes Schindelin
2017-04-26 16:36 ` Johannes Sixt
2017-04-26 19:09 ` Johannes Schindelin
2017-04-25 21:54 ` [PATCH v5 0/8] Introduce timestamp_t " René Scharfe
2017-04-25 22:22 ` Johannes Schindelin
2017-04-26 22:09 ` René Scharfe
2017-04-26 1:56 ` Junio C Hamano
2017-04-26 19:20 ` [PATCH v6 " Johannes Schindelin
2017-04-26 19:26 ` [PATCH v6 1/8] ref-filter: avoid using `unsigned long` for catch-all data type Johannes Schindelin
2017-04-26 19:26 ` [PATCH v6 2/8] t0006 & t5000: prepare for 64-bit timestamps Johannes Schindelin
2017-04-26 19:26 ` [PATCH v6 3/8] t0006 & t5000: skip "far in the future" test when time_t is too limited Johannes Schindelin
2017-04-26 19:26 ` [PATCH v6 4/8] Specify explicitly where we parse timestamps Johannes Schindelin
2017-04-26 19:29 ` [PATCH v6 5/8] Introduce a new "printf format" for timestamps Johannes Schindelin
2017-04-26 19:29 ` [PATCH v6 6/8] Introduce a new data type " Johannes Schindelin
2017-05-20 5:47 ` [PATCH] name-rev: change a "long" variable to timestamp_t Junio C Hamano
2017-05-22 13:39 ` Johannes Schindelin
2017-04-26 19:29 ` [PATCH v6 7/8] Abort if the system time cannot handle one of our timestamps Johannes Schindelin
2017-04-26 19:29 ` [PATCH v6 8/8] Use uintmax_t for timestamps Johannes Schindelin
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
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.DEB.2.20.1702281211270.3767@virtualbox \
--to=johannes.schindelin@gmx.de \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.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.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
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).