Re: [bugs] appointments on the day of setting the clock back from DST to standard time are off by 1 h
- Date: Wed, 31 Oct 2018 23:07:00 +0100
- From: Lars Henriksen <LarsHenriksen@xxxxxxxxxx>
- Subject: Re: [bugs] appointments on the day of setting the clock back from DST to standard time are off by 1 h
On Wed, Oct 31, 2018 at 04:58:18PM +0100, Marco van Hulten wrote:
> Sorry, I am not able to reproduce the invalid apts specification in
> this manner. I have this in the broken apts file (adjusted the apt
> 10/28/2018 @ 02:59 -> 10/28/2018 @ 02:00|move clock one hour back
The appointment probably resulted from a known error in 4.3.0 that has been
corrected. It is not related DST. You can see it here:
I have found and corrected the paste error and a couple of other bugs to do
with DST. I am working on submitting patches to Github.
> So then I wondered how software in general handles the fact that all
> instances between 2:00 and 3:00 happen two times in this day. I guess
> the best is to save times in GMT and use timezone information from the
As you can see from the apts file, dates and times are saved in local time.
When loaded it is converted to Unix time which is seconds since 00:00:00, 1
January 1970 UTC. When displayed or saved it is converted back to local time.
The conversions and many time adjustments are performed by C library functions
which rely on a timezone database. But handling Unix time can be very confusing
and errorprone. To take the example you gave: an appointment with start time
02:00 and end time 03:00 on 28 October 2018 will get a duration of 2 hours in
Unix time (assuming the bug corrected).