Date: Mon, 25 Sep 2000 08:06:42 +0100 From: Mark Ovens <marko@freebsd.org> To: Joao Carlos Mendes Luis <jonny@jonny.eng.br> Cc: questions@freebsd.org Subject: Re: mktime(3) Y2K bug? Message-ID: <20000925080642.E252@parish> In-Reply-To: <39CEC61F.DD8F23FB@jonny.eng.br>; from jonny@jonny.eng.br on Mon, Sep 25, 2000 at 12:27:27AM -0300 References: <39CD8FD9.F2B7419@jonny.eng.br> <20000924115101.A252@parish> <39CE8C9E.D7FA5FAA@jonny.eng.br> <20000925010622.F255@parish> <39CEC61F.DD8F23FB@jonny.eng.br>
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On Mon, Sep 25, 2000 at 12:27:27AM -0300, Joao Carlos Mendes Luis wrote:
> AAAAAAAAAAAAAAAAAAAAAAARGHHHHHHHHHHHH!!!
>
> I found the reason for the "bug". There will be NO 00:01 at Oct 1st
> in Brazil. It´s the beginning of Daylight Savings, according to the
> current zoneinfo file! Maybe we should just treat this as a feature,
> not as a bug... ;-)
>
I'd say it was a bug. From mktime(3):
A positive or zero value for tm_isdst causes mktime() to presume
initially that summer time (for example, Daylight Saving Time) is or
is not in effect for the specified time, respectively. A negative value
for tm_isdst causes the mktime() function to attempt to divine whether
summer time is in effect for the specified time. The tm_isdst and
tm_gmtoff members are forced to zero by timegm().
[snip]
Mktime() returns the specified calendar time; if the calendar time
cannot be represented, it returns -1;
Surely mktime() should be able to work out that for t == 970358460 the
calendar time is 01:01:00 BRT+1 and not 00:01:00 BRT?
> Mark Ovens wrote:
> >
> > On Sun, Sep 24, 2000 at 08:22:06PM -0300, Joao Carlos Mendes Luis wrote:
> > > I think I found more info. This seens to happen only with the
> > > America/Sao_Paulo zoneinfo into /etc/localtime, and TZ not set. If I
> > > change it to GMT+3, it works perfectly. Mark, could you please test
> > > this at your machine?
> > >
> >
> > Yes, it looks like the timezone file
> > (/usr/share/zoneinfo/America/Sao_Paulo) is broken/corrupt:
> >
> > /usr/share/zoneinfo/America{127}# tzsetup Sao_Paulo
> > /usr/share/zoneinfo/America{128}# date
> > Sun 24 Sep 2000 21:01:45 BRT
> > /usr/share/zoneinfo/America{129}# /usr/mark/time
> > t = -1
> > Wed Dec 31 20:59:59 1969
> > /usr/share/zoneinfo/America{130}# tzsetup ../GMT
> > /usr/share/zoneinfo/America{131}# date
> > Mon 25 Sep 2000 00:05:20 GMT
> > /usr/share/zoneinfo/America{132}# /usr/mark/time
> > t = 970358460
> > Sun Oct 1 00:01:00 2000
> > /usr/share/zoneinfo/America{133}#
> >
> > > Mark Ovens wrote:
> > > >
> > > > On Sun, Sep 24, 2000 at 02:23:37AM -0300, Joao Carlos Mendes Luis wrote:
> > > > > Hi,
> > > > >
> > > > > Try the following piece of code:
> > > > >
> > > > > #include <time.h>
> > > > >
> > > > > main()
> > > > > {
> > > > > struct tm tm;
> > > > > time_t t;
> > > > >
> > > > > bzero( &tm, sizeof tm );
> > > > > tm.tm_sec = 0;
> > > > > tm.tm_min = 1;
> > > > > tm.tm_hour = 0;
> > > > > tm.tm_mday = 1;
> > > > > tm.tm_mon = 9;
> > > > > tm.tm_year = 100;
> > > > > tm.tm_isdst = -1;
> > > > >
> > > > > t = mktime( &tm );
> > > > > printf( "t = %ld\n", t );
> > > > > printf( "%s", ctime( &t ) );
> > > > > }
> > > > >
> > > > >
> > > > > My results:
> > > > >
> > > > > FreeBSD:
> > > > >
> > > > > t = -1
> > > > > Wed Dec 31 20:59:59 1969
> > > > >
> > > >
> > > > Hmm, what version of FreeBSD? It works OK for me on 4.1-STABLE:
> > > >
> > > > /usr/marko{52}% cat > foo.c
> > > > #include <time.h>
> > > >
> > > > main()
> > > > {
> > > > struct tm tm;
> > > > time_t t;
> > > >
> > > > bzero( &tm, sizeof tm );
> > > > tm.tm_sec = 0;
> > > > tm.tm_min = 1;
> > > > tm.tm_hour = 0;
> > > > tm.tm_mday = 1;
> > > > tm.tm_mon = 9;
> > > > tm.tm_year = 100;
> > > > tm.tm_isdst = -1;
> > > >
> > > > t = mktime( &tm );
> > > > printf( "t = %ld\n", t );
> > > > printf( "%s", ctime( &t ) );
> > > > }
> > > > /usr/marko{53}% cc -o foo foo.c
> > > > /usr/marko{54}% ./foo
> > > > t = 970354860
> > > > Sun Oct 1 00:01:00 2000
> > > > /usr/marko{55}%
> > > >
> > > > > Solaris:
> > > > >
> > > > > t = 970369260
> > > > > Sun Oct 1 00:01:00 2000
> > > > >
> > > > > Linux:
> > > > >
> > > > > t = -1
> > > > > Wed Dec 31 20:59:59 1969
> > > > >
> > > > > If I change tm_year to 99, everything is ok.
> > > > >
> > > > > Is this a bug, or just something stupid I can´t see at 2am without
> > > > > enough coffe?
> > > > >
> > > > > I found this executing at(1) as "at 10/01/00", if that matters.
> > > > >
> > > > > TIA,
> > > > >
> > > > > Jonny
> > > > >
> > > > > --
> > > > > João Carlos Mendes Luís jonny@embratel.net.br
> > > > > Networking Engineer jonny@jonny.eng.br
> > > > > Internet via Embratel jcml@ieee.org
> > > > >
> > > > >
> > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > > > > with "unsubscribe freebsd-questions" in the body of the message
> > > >
> > > > --
> > > > 4.4 - The number of the Beastie
> > > > ________________________________________________________________
> > > > 51.44°N FreeBSD - The Power To Serve http://www.freebsd.org
> > > > 2.057°W My Webpage http://ukug.uk.freebsd.org/~mark
> > > > mailto:marko@freebsd.org http://www.radan.com
> > >
> > > --
> > >
> > > Jonny
> > >
> > > --
> > > João Carlos Mendes Luís jonny@embratel.net.br
> > > Networking Engineer jonny@jonny.eng.br
> > > Internet via Embratel jcml@ieee.org
> >
> > --
> > 4.4 - The number of the Beastie
> > ________________________________________________________________
> > 51.44°N FreeBSD - The Power To Serve http://www.freebsd.org
> > 2.057°W My Webpage http://ukug.uk.freebsd.org/~mark
> > mailto:marko@freebsd.org http://www.radan.com
>
> --
>
> Jonny
>
> --
> João Carlos Mendes Luís jonny@embratel.net.br
> Networking Engineer jonny@jonny.eng.br
> Internet via Embratel jcml@ieee.org
>
>
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-questions" in the body of the message
--
4.4 - The number of the Beastie
________________________________________________________________
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