New subject: [Bug 740754] Timezone Europe/Italy leads to wrong dates on DST change at 00:00:00

11 Jan 2012

      https://bugzilla.novell.com/show_bug.cgi?id=740754

https://bugzilla.novell.com/show_bug.cgi?id=740754#c0

           Summary: Timezone Europe/Italy leads to wrong dates on DST
                    change at 00:00:00
    Classification: openSUSE
           Product: openSUSE 12.1
           Version: Final
          Platform: x86-64
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Other
        AssignedTo: bnc-team-screening@forge.provo.novell.com
        ReportedBy: andrea.turrini@gmail.com
         QAContact: qa@suse.de
          Found By: ---
           Blocker: ---

User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:10.0) Gecko/20100101
Firefox/10.0

As pointed out in an Italian forum about openSUSE, some web site checks the
validity of the date provided in a form using JavaScript performing a "tmp =
new Date (form_year, form_month-1, form_day)" and then checking whether
"form_year = tmp.getYear()" and so on.

This induces a wrong answer for some dates where DST occurred (format:
dd/mm/yyyy): 22/05/1966, 28/05/1967, 01/06/1969, 31/05/1970, 23/05/1971,
28/05/1972, 03/06/1973, 26/05/1974, 01/06/1975, 30/05/1976, 22/05/1977,
28/05/1978, 17/05/1979.

For instance, a "new Date(1972, 4, 28)" returns "May 27 1972, 23:00:00 GMT+0100
(CET)" instead of the correct date "May 28 1972...".

The point in common for all these dates is that the DST change happened at
00:00:00.
However there are other dates where the DST change happened at 00:00:00 that do
not induce the above error: 04/06/1916, 01/04/1917, 10/03/1918, 02/03/1919,
21/03/1920, 15/06/1940, 16/03/1947, 26/05/1968.

For all remaining years, either there was no DST change or it happened at a
time different from 00:00:00 (usually 02:00:00).

I performed the above tests using the addon FireBug and adding a "new
Date(...)" watch.

This problem occurs in Firefox as well as Chrome but not in Opera and
Konqueror, accordingly to reports from forum users.
Moreover, the same happens for other distributions (Mandriva, Fedora, Ubuntu)
but not on Windows (with the same version of Firefox, for instance), so it
seems to be something independent from the browser and OS but dependent on an
element that is common for several Linux distributions, such as the timezone
package.

If I zdump the Europe/Rome timezone relative to years 1972 (where error occurs)
and 1968 (where error does not occur), the result is essentially the same:

orodruin:/home/ori # zdump -v Europe/Rome|grep 1968
Europe/Rome  Sat May 25 22:59:59 1968 UTC = Sat May 25 23:59:59 1968 CET
isdst=0
Europe/Rome  Sat May 25 23:00:00 1968 UTC = Sun May 26 01:00:00 1968 CEST
isdst=1
Europe/Rome  Sat Sep 21 21:59:59 1968 UTC = Sat Sep 21 23:59:59 1968 CEST
isdst=1
Europe/Rome  Sat Sep 21 22:00:00 1968 UTC = Sat Sep 21 23:00:00 1968 CET
isdst=0
orodruin:/home/ori # zdump -v Europe/Rome|grep 1972
Europe/Rome  Sat May 27 22:59:59 1972 UTC = Sat May 27 23:59:59 1972 CET
isdst=0
Europe/Rome  Sat May 27 23:00:00 1972 UTC = Sun May 28 01:00:00 1972 CEST
isdst=1
Europe/Rome  Sat Sep 30 21:59:59 1972 UTC = Sat Sep 30 23:59:59 1972 CEST
isdst=1
Europe/Rome  Sat Sep 30 22:00:00 1972 UTC = Sat Sep 30 23:00:00 1972 CET
isdst=0

so timezone seems to be innocent.

I am almost sure this is not an openSUSE bug since probably it is an upstream
bug but I have no idea about the possible culprit and how to find it in order
to file the bug report in the right bugzilla.

Reproducible: Always

Steps to Reproduce:
1.
2.
3.

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[Bug 740754] New: Timezone Europe/Italy leads to wrong dates on DST change at 00:00:00

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