Re: [Ntp] Leap second draft

[Martin Burnicki <[e-mail]>]

Tony Finch wrote:
> Warner Losh <[e-mail]> wrote:
>>
>> A reference to the POSIX standard would be likely be helpful.
>> http://pubs.opengroup.org/onlinepubs/9699919799/ has the definition, and
>> the reference on all the pages is "The Open Group Base Specifications Issue
>> 7, 2018 edition IEEE Std 1003.1-2017 (Revision of IEEE Std 1003.1-2008)"
> 
> A slightly more direct link is
> http://pubs.opengroup.org/onlinepubs/9699919799.2018edition/basedefs/V1_chap04.html#tag_04_16
> 
> The frames on the POSIX web site are annoying :-(
> 
>> POSIX does not assign a value to the leap second.
> 
> I think it does, because I can't see any caveat about plugging
> tm_sec == 60 into the expression for seconds since the epoch.
> 
> There's also explicit support for leap seconds in struct tm
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/time.h.html
> although it is not explicitly stated that the expression for seconds since
> the epoch uses the same definitions as the fields in struct tm...

The problem is not that struct tm can't store a specific point in time
that is a leap second. The problem is that if you take a system time
stamp in time_t format and call gmtime() or localtime() you never get a
struct tm back where the value of the second is 60.


Martin
-- 
Martin Burnicki

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