F-ckin Leap Seconds, how do they work?

Peter Lothberg roll at Stupi.SE
Thu Jul 5 16:49:48 UTC 2012


> > On one of my BSD boxes. /usr/src/share/zoneinfo/leapseconds, I see no
> > "-"
> No, but they're allowed; see Figure 9 of RFC 5905:

Steve, 

I commented that it was stated that we where doing both positive and
negative corrections. Only positive corrections have been made, and
yes, negative are possible. 

I pointed out in a previous post that we can count 57, 58, 00 
or 57, 58, 59, 00 or 57, 58, 59, 60, 00. And actually, this is the
only thing operating-systems and applications need to be capable to
handle to make it a non_issue. 


>    LI Leap Indicator (leap): 2-bit integer warning of an impending leap
>    second to be inserted or deleted in the last minute of the current
>    month with values defined in Figure 9.
> 
>            +-------+----------------------------------------+
>            | Value | Meaning                                |
>            +-------+----------------------------------------+
>            | 0     | no warning                             |
>            | 1     | last minute of the day has 61 seconds  |
>            | 2     | last minute of the day has 59 seconds  |
>            | 3     | unknown (clock unsynchronized)         |
>            +-------+----------------------------------------+

That's NTP packet format, used to implemment NTP's represenation of
UTC, but not the definition of UTC... (What do I do if I receive a
packet with "3".) Or better, all the UTC(k) are free-running and the
(old) recomenadtion was to try to keep them within 1us, is that
unsyncronized -:)

And ooops, I did not catch that before, should it not say "last minute
of the month"?  

If I remember right the posix standard don't allow "60" in seconds...

-Peter




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