[LEAPSECS] Crunching Bulletin B numbers (POSIX time)

Warner Losh imp at bsdimp.com
Wed Feb 23 13:02:17 EST 2011

On 02/23/2011 03:07, Tony Finch wrote:

> On Tue, 22 Feb 2011, Keith Winstein wrote:

> You made several good points though I have some minor niggles.


>> Calculations further in the future, though, still won't be "functional" and

>> will change their results when new leap seconds are loaded into the zoneinfo

>> files. This seems to be to be an artifact of having intercalary seconds in the

>> local time scale at all -- whether they are in time_t (as in POSIX) or in the

>> conversion to localtime (as here), it seems to be the same problem either way.

> It isn't that bad if the intercalation is predictable. Even better if it

> can be hard-coded, as in arithmetic calendars.


> Note that POSIX time has no intercalation: it is a version of traditional

> universal time. Specifying it in terms of UTC is mostly a red herring,

> especially since POSIX doesn't specify how time_t is synchronized.

Yes. It just specifies the times that a given time_t is labeled. The
method by which you tie your system clock to UTC is undefined.

Also, the scenario assumes 'hot operation' or 'hot spare' operation
where all systems know the current leap table. 'Cold spares' might not
have that in place.


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