[LEAPSECS] Crunching Bulletin B numbers (POSIX time)

Poul-Henning Kamp phk at phk.freebsd.dk
Mon Feb 21 05:19:33 EST 2011

In message <20110221100216.GA9800 at davros.org>, "Clive D.W. Feather" writes:

>Paul Sheer said:

>> These systems don't care whether the event really did happen at

>> 12:34:56pm nor whether the clock was a few minutes slow that day.


>> But they DO care that they are talking about the SAME event!!!


>In which case they will have some arrangement to synchronize their clocks.

You are missing the point.

If the isolated system creates a file and timestamps it with a time_t
value of FOO, that translates to a given UTC instant YYYY-MM-DD/HH:MM:SS

The same numeric time_t must translate to the same UTC instant on an
other POSIX system, connected or otherwise.

It doesn't matter if they agree when this instant happened, but the
*representation* must be the same.

That is why, we cannot have some POSIX systems inserting leap-seconds in
to time_t and some POSIX systems not doing so.

Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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