Thank you. The patch had been overlooked, but now is applied. I'm going to
see if there are other places with the same error.
Paul
On Fri, Feb 8, 2013 at 6:42 AM, Egger Clemens <[email protected]>wrote:
> Hi Paul,
>
> any feedback for me regarding this patch?
>
> Best regards,
> Clemens Egger
>
>
> > -----Original Message-----
> > From: Egger Clemens
> > Sent: Wednesday, 23 January, 2013 1:16 PM
> > To: OWFS Developer's list
> > Subject: Patch - DS1921 Thermochron iButton - reading udate values
> > depends on local time zone
> >
> > Hi,
> >
> > working with the DS1921 Thermochron iButton I noticed that, when writing
> a
> > time value to clock/udate and reading it immediately afterwards, the
> > returned value differs notably to the written value. This is dependent
> on the
> > local time zone and whether it's daylight saving time or not. My
> environment
> > variable TZ usually reads "Europe/Berlin". In the following example
> there's a
> > difference of 3600 seconds i.e. 1 hour between the two values.
> >
> > $ ./owwrite -s 3000 21.D5542E000000/clock/udate 1352387000; ./owread -s
> > 3000 21.D5542E000000/clock/udate
> > 1352383400
> >
> > Looking at the source code, I discovered that the function mktime is
> used to
> > convert a struct tm to time_t. However mktime uses the local time zone
> > which explains the time shift.
> >
> > The following workaround makes the time shift disappear: just set the TZ
> > environment variable to UTC when invoking the server.
> > TZ=UTC ./owserver -u -p 3000
> >
> > There's a function timegm which is basically the opposite part to
> gmtime. The
> > latter is already used in the code when writing a udate value to the
> iButton.
> > In my opinion timegm would be more suitable than mktime. I developed a
> > patch to fix this issue, see attachment.
> >
> > BTW: I already submitted this patch last year Nov 8 to this list, but I
> never got
> > any feedback - just in case this sounds familiar.
> >
> > Best regards
> > Clemens Egger
>
>
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