[time-nuts] Mac OS and iOS leap second handling

[Hal Murray]

eric at scace.org said:
> proper display of 23:59:60, etc on the system clock & return of same to
> appropriate function calls. 

I doubt if you will find that on any system with a Unix/POSIX background.  
86400 seconds per day is just wired in too deeply to change.


>    (In contrast, Microsoft docs claim Win 2018 Oct and Win Server 2019 now
> have leap second support.) 

What does "support" mean?

It wouldn't surprise me if it means that their NTP implementation knows about 
leap seconds and steps the clock back so that 23:59:59 repeats.

There are a couple of alternative implementations.  The idea is to avoid time 
going backwards.

One is to run the clock at half speed for 2 seconds.

Another is to stop the clock at midnight but bump it a tiny bit each time 
somebody reads the clock. You can turn it back to normal in a bit over a 
second.


-- 
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