Hello Patrick,
Thanks for the analysis. I changed the rrule parsing routine to allow returning
a adjusted DTSTART so the engine now correctly detects this iCalendar's
timezone as GMT. I just pushed these changes into the luz branch on synthesis
indefero.
Best Regards,
Lukas
On May 4, 2010, at 22:40 , Patrick Ohly wrote:
> On Mon, 2010-04-26 at 13:40 +0100, Patrick Ohly wrote:
>> On Wed, 2010-04-21 at 09:39 +0200, Patrick Ohly wrote:
>>> I have a meeting in my Evolution calendar which I synchronize with
>>> SyncEvolution. I noticed that the outgoing VEVENT has start and end
>>> time
>>> converted to UTC times which are one hour off.
>>>
>>> Here's the stripped down event:
>>>
>>> BEGIN:VCALENDAR
>>> PRODID:-//Ximian//NONSGML Evolution Calendar//EN
>>> VERSION:2.0
>>> METHOD:PUBLISH
>>> BEGIN:VTIMEZONE
>>> TZID:GMT Standard Time
>>> BEGIN:STANDARD
>>> DTSTART:16010101T020000
>>> TZOFFSETFROM:+0100
>>> TZOFFSETTO:+0000
>>> RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
>>> END:STANDARD
>>> BEGIN:DAYLIGHT
>>> DTSTART:16010101T010000
>>> TZOFFSETFROM:+0000
>>> TZOFFSETTO:+0100
>>> RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
>>> END:DAYLIGHT
>>> END:VTIMEZONE
>>> BEGIN:VEVENT
>>> SUMMARY:test event
>>> DTSTART;TZID=GMT Standard Time:20100421T150000
>>> DTEND;TZID=GMT Standard Time:20100421T160000
>>> UID:040000008200E00074C5B7101A82E0080000000000B5A586D0A4CA01000000000000000010
>>> CLASS:PUBLIC
>>> PRIORITY:5
>>> DTSTAMP:20100415T035521Z
>>> TRANSP:OPAQUE
>>> STATUS:CONFIRMED
>>> SEQUENCE:4
>>> END:VEVENT
>>> END:VCALENDAR
>>
>> This fails because RRULE2toInternal() in rrule.cpp fails to convert the
>> RRULE properties into the internal format. It bombs out here:
>>
>> switch (freq)
>> {
>> ...
>> case 'Y' :
>> if (byday == "" ||
>> (byday.length() == 2 && byday[0] ==
>> RRULE_weekdays[startwday][0] &&
>> byday[1] ==
>> RRULE_weekdays[startwday][1]))
>> {
>> ...
>> }
>> else
>> {
>> goto incompat;
>> }
>>
>> It reaches the "goto incompat" because byday == "-1SU".
>>
>> Recurrence rules with "last day in month ..." are common for VTIMEZONEs.
>> Beat, is that really something that is not handled by the Synthesis code
>> at the moment? What would be necessary to add support for it?
>
> I'm still wondering about this.
>
> In the meantime I looked into VTIMEZONEs which parse successfully. What
> I found is that FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 (as in the example
> above) is supported, by converting it to the equivalent
> FREQ=MONTHLY;INTERVAL=12;BYDAY=-1SU.
>
> However, there is a sanity check that compares the start month:
> if (DayMonthCombi( freq, byday,bymonth,startmonth )) {
> freq = 'M'; // a different model will be chosen for this case,
> interval= 12*interval; // which is in fact aequivalent
> bymonth = "";
> } // if
>
> In the example above, DTSTART=16010101T020000 and thus startmonth !=
> bymonth. DayMonthCombi() then returns false.
>
> Does the month in DTSTART really matter in this case? I would expect
> that the first recurrence will be in the month specified in BYMONTH
> which is >= than the month in DTSTART, so one could apply the conversion
> to FREQ=MONTHLY;INTERVAL=12;BYDAY=-1SU by setting the month in DTSTART
> to the value from BYMONTH.
>
> Does that make sense?
>
> --
> Best Regards, Patrick Ohly
>
> The content of this message is my personal opinion only and although
> I am an employee of Intel, the statements I make here in no way
> represent Intel's position on the issue, nor am I authorized to speak
> on behalf of Intel on this matter.
>
>
>
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Lukas Zeller (l...@synthesis.ch)
-
Synthesis AG, SyncML Solutions & Sustainable Software Concepts
i...@synthesis.ch, http://www.synthesis.ch
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