Resend: Month 53 bug? (is there anybody who read this?)
Wim Vandeputte
bunbun at reptile.rug.ac.be
Fri Jan 9 14:32:48 UTC 1998
Hi there, I found a little quirck while playing around with the Y2K
problem. I got an apetite for overrun problems, and I was looking for
some variations.
I found a strange problem with the +%V flag of date on OpenBSD 2.2
Let me forward you the converation I had with Theo de Raadt
> ---------- Forwarded message ----------
> Date: Wed, 31 Dec 1997 00:03:40 +0100 (MET)
> From: Wim Vandeputte <bunbun at reptile.rug.ac.be>
> To: Theo de Raadt <deraadt at cvs.openbsd.org>
> Subject: Month 53 bug?
>
>
> eh, this is weird. OpenBSD 2.2 GENERIC#81 i386
>
> date +%W
> gives 52
>
> date +%V
> gives 53.
>
> is *this* 53'th week of the year?
>
> On SunOS 5.5 (Generic_103093-08 sun4d sparc SUNW,SPARCserver-1000) both
> give 52.
>
> On SunOS 5.5.1 (sun4u sparc SUNW,Ultra-1) %V gives 53, %W gives 52.
>
> On Linux, +%W gives 52, +%V gives 01
>
>
> The manpage of strftime says that if the week containing Jan 1 has four
> or more days in the new year, then it is week 1. This week gives:
> Thursday (1/1), Friday (2/1), Sat (3/1), Sun (4/1) = 4 days in the new year.
> So date +%V should produce 1 instead of 53, right?
>
> This must be some lib thing....
>
> *-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*
> Wim Vandeputte --Comfort is Treachery--
> --So pound the nails in tight--
>
>
> His first reply:
>
> From deraadt at cvs.openbsd.orgWed Dec 31 00:32:18 1997
> Date: Tue, 30 Dec 1997 16:05:14 -0700
> From: Theo de Raadt <deraadt at cvs.openbsd.org>
> To: Wim Vandeputte <bunbun at reptile.rug.ac.be>
> Cc: millert at cvs.openbsd.org
> Subject: Re: Month 53 bug?
>
> Hmm, interesting problem.
>
> It is possible that some of these systems have an old timezone
> library. And it is possible that our man page is wrong. Or that our
> code is wrong, since we don't have the very very latest version of the
> timezone code (we are about a year out of date with respect to the
> timezone code, but a cursory examination shows that not much has
> changed, and we've fixed a few bugs ourselves).
>
> > nor more days in the new year, then it is week 1. This week gives:
> > Thursday (1/1), Friday (2/1), Sat (3/1), Sun (4/1) = 4 days in the new year.
>
> Wait, isn't Sunday the first day of the next week? Then it's 3 days
> in the next week. Ie, look at this:
>
> October November December
> Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
> 1 2 3 4 1 1 2 3 4 5 6
> 5 6 7 8 9 10 11 2 3 4 5 6 7 8 7 8 9 10 11 12 13
> 12 13 14 15 16 17 18 9 10 11 12 13 14 15 14 15 16 17 18 19 20
> 19 20 21 22 23 24 25 16 17 18 19 20 21 22 21 22 23 24 25 26 27
> 26 27 28 29 30 31 23 24 25 26 27 28 29 28 29 30 31
> 30
>
> See?
>
> So I think we are right:
>
> I think SunOS 5.5 had it wrong,
> Linux has it wrong,
> and both SunOS 5.5.1 and OpenBSD 2.2 get it right.
>
> Do you now concur?
>
>
> ------------------------------------------------------------------------
>
> I wrote back:
>
>
> From bunbun at reptile.rug.ac.beWed Dec 31 00:34:13 1997
> Date: Wed, 31 Dec 1997 00:20:20 +0100 (MET)
> From: Wim Vandeputte <bunbun at reptile.rug.ac.be>
> To: Theo de Raadt <deraadt at cvs.openbsd.org>
> Subject: Re: Month 53 bug?
>
> On Tue, 30 Dec 1997, Theo de Raadt wrote:
>
> > Wait, isn't Sunday the first day of the next week? Then it's 3 days
> > in the next week. Ie, look at this:
>
> the man page (old or faulty?) says that "(Monday as the first day of the
> week)". ^^^^^^^^^^^^^-> the SunOS page says the same.
>
> That makes the week go from Mon -> Sun, thus still four days in this week
> in the next year.
>
> Confuse me :-) please (it's running late here :-)
>
>
> *-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*
> Wim Vandeputte --Comfort is Treachery--
> --So pound the nails in tight--
>
>
> His reply to this:
>
> From deraadt at cvs.openbsd.orgWed Dec 31 00:32:24 1997
> Date: Tue, 30 Dec 1997 16:17:40 -0700
> From: Theo de Raadt <deraadt at cvs.openbsd.org>
> To: Wim Vandeputte <bunbun at reptile.rug.ac.be>
> Cc: millert at cvs.openbsd.org
> Subject: Re: Month 53 bug?
>
> Please never remove cc:'s
>
> > > Wait, isn't Sunday the first day of the next week? Then it's 3 days
> > > in the next week. Ie, look at this:
> >
> > the man page (old or faulty?) says that "(Monday as the first day of the
> > week)". ^^^^^^^^^^^^^-> the SunOS page says the same.
> >
> > That makes the week go from Mon -> Sun, thus still four days in this week
> > in the next year.
>
> Ok. Perhaps this is a flaw then. We need to find out which way that
> needs to work, then. Do you want to do some more research by
> contacting the people who wrote the library in question?
>
> Yeah you do! Go for it: contact tz at elsie.nci.nih.gov and keep us
> informed OK?
>
> --------------------------------------------------
So I'm trying to determin *where* the problem could be. Any suggestions?
*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*-=-*
Wim Vandeputte --Comfort is Treachery--
--So pound the nails in tight--
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