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On Fri, Feb 24, 2012 at 11:58:08AM -0800, Bill Unruh wrote:
> On Fri, 24 Feb 2012, Miroslav Lichvar wrote:
> >The timezones in /usr/share/zoneinfo/right are written so the system
> >clock needs to be in TAI-10s instead of UTC and they do include the
> >leapsecond data.
>
> Why not just use the leapseconds file? And
Because it's not a file normally present on systems, it has to be
maintained by admin. How many of the NTP stratum 1 operators know
there will be a leapsecond, that their refclock doesn't announce it
and they need an up to date leapseconds file? We'll see in June.
> >
> >Try this:
> >
> >$ TZ="right/UTC" date -d 'Dec 31 2008 23:59:60'
> >Wed Dec 31 23:59:60 UTC 2008
> >$ TZ="right/UTC" date -d 'Dec 31 2009 23:59:60'
> >date: invalid date `Dec 31 2009 23:59:60'
>
> And TZ="right/America/Vancouver" date -d 'Dec 31 2008 15:59:60'
> Wed Dec 31 15:59:60 PST 2008
Yes, it has to be a timezone with leap seconds occuring on midnight.
> >Note that there wasn't an upstream tzdata release which includes the
> >2012 leap second yet, but some distributions may have released a
> >patched tzdata-2011n.
>
> The latest leapseconds file tzdata2011n.tar.gz does not have this year's
> leapseconds in it yet. And by the time it comes out, the distros are going to
> take a few months to update and for users to install.
Some distros already have a patched tzdata.
$ TZ=right/UTC date -d 'Jun 30 2012 23:59:60'
Sat Jun 30 23:59:60 UTC 2012
The tzdata package is one of the most volatile packages (at least on
the systems I'm familiar with) and they are released in a matter of
days. There are sometimes changes in DST announced only few days
beforehand, releasing it after couple months would be unacceptable.
You can always put your own leapsecond timezone in the tz directory if
needed.
> Thus there are four
> steps. leapseconds file released. Distros recompile the tzdata including the
> "right" directory. Users knowing that they should use the "right" database,
> and the program knowing that the timezone file used needs to have the correct
> offset tested to see if there is a leapsecond. I think it is too complicated.
I agree, it's more complicated than the leapsecond format. But the tz
database seems to be the only source of leap second data on most
systems. I think we can add a check for a known leap second and log a
warning if it's not found in the timezone. The example in the
documentation uses the right/UTC timezone.
--
Miroslav Lichvar
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