[time-nuts] Leap Quirks
M. Warner Losh
imp at bsdimp.com
Sun Jan 4 08:14:32 UTC 2009
In message: <m3hc4gqdjb.fsf at lugabout.jhcloos.org>
James Cloos <cloos at jhcloos.com> writes:
: >>>>> "Warner" == M Warner Losh <imp at bsdimp.com> writes:
: Warner> So what you've done is created a new time scale that is a UTC
: Warner> from 1972 forward, but a simplified form of UTC prior to 1972
: Warner> that didn't match what UTC was doing then.
: Grrr! Except s/you/they/; I didn't invent.
Yea, I was speaking a bit rhetorically :-)
: So right isn't quite, err, right. I wonder whether the Olsen db can
: be fixed to account for that? right/UTC and posix/UTC currently are
: identical for all (time_t)LONG_MIN <= time_t < 78796800.
Yes. I'd forgotten that the Olsen db doesn't deal with rubber seconds
at all. It is a pain in the *** to try to do that, and of dubious
value. I tried once to create a library that coped with them, but
gave up when I realized it wasn't a useful problem to solve.
: Thanks for the reminder. I had forgotten that entirely. (And am
: only just vaguely remembering that I used to know that fact. [SIGH])
It is certainly underdocumented...
: Warner> Yet another hazard of high precision time keeping that few
: Warner> people get right
: Part of what makes this list's name so appropriate is just how hard
: it is, all things considered. That is also what makes it enjoyable.
Yes. Very enjoyable. Of course, I could live without all this
complexity, frankly, and be happier.
: Warner> An understandable simplification, to be true, and one that's
: Warner> often made...
: Often, I'm sure, because not all sources document/remember that fact.
Yea. In another life, I defined a datum as 'number of SI seconds
since 01-01-1972 00:00:00 UTC + 63072000'. Which is what we're
talking about here, no? This is number of seconds since 1970, with
the 'oddball' rubber seconds counting as SI seconds.
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