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Incorrect timezone offset with current Russian rules - tzdata or glibc bug or normal?
- From: Andrei Borzenkov <arvidjaar at gmail dot com>
- To: tz at iana dot org, libc-help at sourceware dot org
- Date: Thu, 16 Oct 2014 21:46:22 +0400
- Subject: Incorrect timezone offset with current Russian rules - tzdata or glibc bug or normal?
- Authentication-results: sourceware.org; auth=none
I hit strange problem which looks like a bug and actually caused
serious problem due to different interpretation of current timezone
offset.
Current tzdata correctly - as far as I can tell - defines time today as
UTC-4 with summer time inactive:
/etc/localtime Sat Mar 26 23:00:00 2011 UT = Sun Mar 27 03:00:00 2011 MSK isdst=0 gmtoff=14400
/etc/localtime Sat Oct 25 21:59:59 2014 UT = Sun Oct 26 01:59:59 2014 MSK isdst=0 gmtoff=14400
/etc/localtime Sat Oct 25 22:00:00 2014 UT = Sun Oct 26 01:00:00 2014 MSK isdst=0 gmtoff=10800
/etc/localtime 9223372036854689407 = NULL
/etc/localtime 9223372036854775807 = NULL
But the valule of variable "timezone" (man timezone(3)) is set to
UTC-3 ...
bor@opensuse:~/tmp/sapttzz> ./sapttz
Name of local time zone:
no info (=TZ)
Technical description of local time zone:
UTC time +10800 sec
Daylight Saving Time at the current/given date is:
inaktiv
where offset is computed as simply
printf(" UTC time %+ld sec\n",- (long int)timezone);
if(tm->tm_isdst == 1)
printf(" aktiv\n");
else if(tm->tm_isdst == 0)
printf(" inaktiv\n");
else
printf(" unknown\n");
So basically any application which tries to compute current offset from
UTC as based offset (timezone) + dst offset (if isdst) will fail. Or
better, two programs running on the same system may have different idea
of current time.
What puzzles me - if I take previous timezone before last change
(before 2014f) the same program displays correct time. But visually
nothing has changed ...
/etc/localtime Sat Mar 26 22:59:59 2011 UT = Sun Mar 27 01:59:59 2011 MSK isdst=0 gmtoff=10800
/etc/localtime Sat Mar 26 23:00:00 2011 UT = Sun Mar 27 03:00:00 2011 MSK isdst=0 gmtoff=14400
/etc/localtime 9223372036854689407 = NULL
/etc/localtime 9223372036854775807 = NULL
bor@opensuse:~/tmp/sapttzz> ./sapttz
Name of local time zone:
no info (=TZ)
Technical description of local time zone:
UTC time +14400 sec
Daylight Saving Time at the current/given date is:
inaktiv
openSUSE 13.1 with glibc-2.18-4.21.1.x86_64
Any ideas?
TIA
-andrei