704486 - Javascript Date doesn't account for double summer time during WW2 correctly

Status: RESOLVED DUPLICATE of bug 1346211

(Core :: JavaScript Engine, defect)

Description

[u430174]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0.1) Gecko/20100101 Firefox/8.0.1
Build ID: 20111122085954

Steps to reproduce:

Numerous dates between 1941 and 1945 don't account for summer time. At least not in Europe/Zagreb timezone (GMT+01:00).

Environment:
Arch linux (also reproducible in Ubuntu 11.04)
Firefox 8.0.1 (http://www.archlinux.org/packages/extra/x86_64/firefox)
"uname -srm": Linux 3.1.1-1-ARCH x86_64

Timezone: Europe/Zagreb GMT+01:00



Actual results:

var d = new Date(Date.UTC(1942, 5, 11, 22, 0, 0, 0));
// firebug reports "Date {Thu Jun 11 1942 23:00:00 GMT+0100 (CEST)}"
// so date is reported as CEST but not accounted for

d.getFullYear(); // 1942
d.getMonth(); // 5 - Jun
d.getDate(); // 11
d.getHours(); // 23
d.getMinutes(); // 0
d.getSeconds(); // 0
d.getMilliseconds(); // 0
d.getTimezoneOffset(); // -60



Expected results:

var d = new Date(Date.UTC(1942, 5, 11, 22, 0, 0, 0));

d.getFullYear(); // 1942
d.getMonth(); // 5 - Jun
d.getDate(); // 12
d.getHours(); // 0
d.getMinutes(); // 0
d.getSeconds(); // 0
d.getMilliseconds(); // 0
d.getTimezoneOffset(); // -120

// Chrome15, IE9 and code in Java all behave as expected.
// Firefox works as expected for other years (e.g. 1990)

Comment 1

[u430174]

Here is the same thing, only easier to read:

var d = new Date(Date.UTC(1942, 5, 11, 22, 0, 0, 0));

// Firefox 8.0.1, Rhino 1.7 release 3 2011 10 16
d.toString(); // Thu Jun 11 1942 23:00:00 GMT+0100 (CET)

// Chrome15, IE8, nodejs 0.6.2, and code in Java and Ruby
d.toString(); // Fri Jun 12 1942 00:00:00 GMT+0200 (CEST)

Comment 2

[u430174]

Wops. I was a bit hasty with my last comment. I missed a small detail. Rhino reports CET time, while Firefox reports CEST. Here is that same examples again in Firefox and in Rhino. Of course Rhino is the least of my worries. :)

var d = new Date(Date.UTC(1942, 5, 11, 22, 0, 0, 0));

// Firefox 8.0.1
d.toString(); Thu Jun 11 1942 23:00:00 GMT+0100 (CEST)

// Rhino 1.7 release 3 2011 10 16
d.toString(); Thu Jun 11 1942 23:00:00 GMT+0100 (CET)

Comment 3

[Jo Hermans]

That information doesn't come from Firefox - it's delivered by the operating system or the C library. I think that they all use the same information (Windows too ?), which is the "tz" timezone database. But you shouldn't compare results from different platforms, they don't always have the same version of the data.

http://en.wikipedia.org/wiki/Tz_database

I tried to find an online copy of the file, and  I found one here : <http://www.openbsd.org/cgi-bin/cvsweb/src/share/zoneinfo/datfiles/europe?rev0=1.45;content-type=text%2Fplain>. As far as I can see (I'm not an expert here), I don't see a 1941 rule in the C-Eur section - I don't know what happened on Jun 11 1942.

Comment 4

[Jan de Mooij [:jandem]]

I had a deja vu feeling; bug 637244 is also about DST during WW2. Not sure if it's the same problem though.

Comment 5

[u430174]

I figured that tzdata could be the culprit. If anyone finds it useful, I'm using the following version of tzdata package: http://www.archlinux.org/packages/core/x86_64/tzdata.

However, if I run given test in Firefox, Rhino, Chrome and in Java _on the same computer_, I still get those time differences. One would expect that Java and Chrome both use the same tzdata as Firefox.

Comment 6

[Boris Zbarsky [:bzbarsky]]

> One would expect that Java and Chrome both use the same tzdata as Firefox.

I believe Java, at least, ships its own timezone information instead of using the system's....

Comment 7

[u430174]

That appears to be true. See http://www.oracle.com/technetwork/java/javase/timezones-137583.html.

Comment 8

[u430174]

Attachment: Firefox 8.0.1 output for dates between 1941 and 1945

Comment 9

[u430174]

Attachment: Chromium 15 output for dates between 1941 and 1945

Comment 10

[u430174]

Attachment: Side by side diff of Firefox and Chromium output for dates between 1941 and 1945

Comment 11

[u430174]

I've attached output when running following snippet in Firefox 8.0.1 and Chromium 15:

8<---------------------------------------------------------
var show = function(year, days) {
    var days = year % 4 == 0 ? 366 : 365;
    for(var d = 0; d < days; d++) {
        var root = new Date(Date.UTC(year, 0, 1, 22, 0, 0, 0));
        root.setUTCDate(root.getUTCDate() + d);

        console.log(root.toString());
    }
};

show(1941);
show(1942);
show(1943);
show(1944);
show(1945);
--------------------------------------------------------->8

I got `firefox_chromium_diff.txt' by running: `diff --side-by-side --suppress-common-lines firefox_1941-1945.txt chromium_1941-1945.txt'.

Hope that helps us determine a bug.

Comment 12

[u430174]

Turns out I found vague information in a link that Jo Hermans provided. Namely:

8<---------------------------------------------------------
# Serbia
# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
Zone	Europe/Belgrade	1:22:00	-	LMT	1884
			1:00	-	CET	1941 Apr 18 23:00
			1:00	C-Eur	CE%sT	1945
			1:00	-	CET	1945 May 8 2:00s
			1:00	1:00	CEST	1945 Sep 16  2:00s
# Metod Kozelj reports that the legal date of
# transition to EU rules was 1982-11-27, for all of Yugoslavia at the time.
# Shanks & Pottenger don't give as much detail, so go with Kozelj.
			1:00	-	CET	1982 Nov 27
			1:00	EU	CE%sT
Link Europe/Belgrade Europe/Ljubljana	# Slovenia
Link Europe/Belgrade Europe/Podgorica	# Montenegro
Link Europe/Belgrade Europe/Sarajevo	# Bosnia and Herzegovina
Link Europe/Belgrade Europe/Skopje	# Macedonia
Link Europe/Belgrade Europe/Zagreb	# Croatia
--------------------------------------------------------->8

Dates don't match but at least Europe/Zagreb and 1941 is there. :) If I'd only know exact tzdata that I have installed I'd look into it more closely. All I know is package version (2011n-1): http://www.archlinux.org/packages/core/x86_64/tzdata.

Does anyone know command line utility that reads `/usr/share/zoneinfo/Europe/Zagreb' file?

Here is file dump:
$ file /usr/share/zoneinfo/Europe/Zagreb
/usr/share/zoneinfo/Europe/Zagreb: timezone data, version 2, 6 gmt time flags, 6 std time flags, no leap seconds, 120 transition times, 6 abbreviation chars

Comment 13

[David Mandelin [:dmandelin]]

It doesn't look like there is anything incredibly convenient for reading the tz files. I found a list of related stuff here: http://www.twinsun.com/tz/tz-link.htm but none of it looked like it would easily dump out a text form of the data. 

(Removing tracking flags because this doesn't look like a Fx bug--I tried it on my Win 7 machine and got the right answer.)

Comment 14

[u430174]

Attachment: Firefox output for dates between 1941 and 1945 on Windows 7

Comment 15

[u430174]

Attachment: Chrome output for dates between 1941 and 1945 on Windows 7

Comment 16

[u430174]

I tried the same test on Windows 7 and got different results. Output from Firefox and Chrome match. The only conclusion I can make is that Chrome (as well as Java) use different tzdata then one provided by OS. Only Firefox uses native tzdata and that data appears to be incorrect on Linux.

You can close/discard this bug as it isn't in Firefox. Sorry to have wasted your time.

If you don't mind I'll use this page as a reference in order to report a bug in the actual source. Apparently here: http://www.twinsun.com/tz/tz-link.htm

Comment 17

[David Mandelin [:dmandelin]]

(In reply to disponiblekonto from comment #16)
> You can close/discard this bug as it isn't in Firefox. Sorry to have wasted
> your time.

No problem--thanks for trying to help us--it was a good bug report.

> If you don't mind I'll use this page as a reference in order to report a bug
> in the actual source. Apparently here: http://www.twinsun.com/tz/tz-link.htm

Sure.

Comment 18

[u430174]

This appears to be a bug in Firefox after all. Bug is related to Firefox not accounting for _double_ summer time during WWII.

See http://thread.gmane.org/gmane.comp.time.tz/4550 thread for more information. I'll summarize discussion here.

During WWII:
 - US suspended summer time
 - The British used double summer time (+ 1 hour in winter, +2 in summer)
 - by data that I'm getting Europe/Zagreb also used double summer time

I got data that led me to such conclusion by running following command:
8<---------------------------------------------------------
$ zdump -v -c1940,1946 Europe/Zagreb
Europe/Zagreb  -9223372036854775808 = NULL
Europe/Zagreb  -9223372036854689408 = NULL
Europe/Zagreb  Fri Apr 18 21:59:59 1941 UTC = Fri Apr 18 22:59:59 1941 CET isdst=0
Europe/Zagreb  Fri Apr 18 22:00:00 1941 UTC = Sat Apr 19 00:00:00 1941 CEST isdst=1
Europe/Zagreb  Mon Nov  2 00:59:59 1942 UTC = Mon Nov  2 02:59:59 1942 CEST isdst=1
Europe/Zagreb  Mon Nov  2 01:00:00 1942 UTC = Mon Nov  2 02:00:00 1942 CET isdst=0
Europe/Zagreb  Mon Mar 29 00:59:59 1943 UTC = Mon Mar 29 01:59:59 1943 CET isdst=0
Europe/Zagreb  Mon Mar 29 01:00:00 1943 UTC = Mon Mar 29 03:00:00 1943 CEST isdst=1
Europe/Zagreb  Mon Oct  4 00:59:59 1943 UTC = Mon Oct  4 02:59:59 1943 CEST isdst=1
Europe/Zagreb  Mon Oct  4 01:00:00 1943 UTC = Mon Oct  4 02:00:00 1943 CET isdst=0
Europe/Zagreb  Mon Apr  3 00:59:59 1944 UTC = Mon Apr  3 01:59:59 1944 CET isdst=0
Europe/Zagreb  Mon Apr  3 01:00:00 1944 UTC = Mon Apr  3 03:00:00 1944 CEST isdst=1
Europe/Zagreb  Mon Oct  2 00:59:59 1944 UTC = Mon Oct  2 02:59:59 1944 CEST isdst=1
Europe/Zagreb  Mon Oct  2 01:00:00 1944 UTC = Mon Oct  2 02:00:00 1944 CET isdst=0
Europe/Zagreb  Tue May  8 00:59:59 1945 UTC = Tue May  8 01:59:59 1945 CET isdst=0
Europe/Zagreb  Tue May  8 01:00:00 1945 UTC = Tue May  8 03:00:00 1945 CEST isdst=1
Europe/Zagreb  Sun Sep 16 00:59:59 1945 UTC = Sun Sep 16 02:59:59 1945 CEST isdst=1
Europe/Zagreb  Sun Sep 16 01:00:00 1945 UTC = Sun Sep 16 02:00:00 1945 CET isdst=0
Europe/Zagreb  9223372036854689407 = NULL
Europe/Zagreb  9223372036854775807 = NULL
--------------------------------------------------------->8

Here you can clearly see that double summer time (+2h) was in place from Apr 16 1941 until 2 Nov 1942.

Further more by using command line `date' utility I got expected output.
8<---------------------------------------------------------
$ LANG=hr_HR.utf-8 TZ=Europe/Zagreb date -d '1942-11-11 22:00 UTC' +'%c %z'
Wed Nov 11 23:00:00 1942 +0100
--------------------------------------------------------->8

`date' surely uses native tzdata - the same that Firefox uses. Since `date' works as expected I can only assume Firefox doesn't account for weird double summer time situation that occurred during WWII.

Comment 19

[Boris Zbarsky [:bzbarsky]]

Thanks for looking that up!  Reopening bug.

Comment 20

[u430174]

I actually meant to show example with 1942-06-11 that shows `date' command accounts for double summer time. I'm sorry for potential confusion from my previous post.

8<---------------------------------------------------------
$ LANG=hr_HR.utf-8 TZ=Europe/Zagreb date -d '1942-06-11 22:00 UTC' +'%c %z'
Fri Jun 12 00:00:00 1942 +0200
--------------------------------------------------------->8

Comment 21

[u430174]

Any progress towards fixing this bug? I'd be happy to provide other information if one is needed.

Comment 22

[David Mandelin [:dmandelin]]

I haven't had a chance to get back to this yet but I'll bump it in my list.

Comment 24

[André Bargull [:anba]]

Dup'ing forward to bug 1346211 which should have fixed this problem. Please reopen if the issue is still present. Thanks!