FreeBSD handles leapsecond correctly

Matthias Andree matthias.andree at
Mon Jan 2 06:00:58 PST 2006

Poul-Henning Kamp <phk at> writes:

> Notice how CLOCK_REALTIME recycles the 1136073599 second.

Well, it is in accordance with POSIX, but that doesn't mean its

How does the POSIX "consistency" babble, and particularly the FreeBSD 5
or 6 implementation, make sure that "make(1)" or other application
doesn't see a file created on 2005-12-31T23:59:60.1Z as older than a
file created 0.9 seconds earlier, on 2005-12-31T23:59:59.2Z, because of
the time warp caused by POSIX's demand to ignore leap seconds?

Are there plans to add monotonous TAI clock interfaces to FreeBSD 7 so
we have an alternative to the differential CLOCK_MONOTONIC and the jumpy
CLOCK_REALTIME? Is any reader of this message aware of efforts to
standardize such a TAI clock?

The FreeBSD 6 zoneinfo stuff seems to be ready for leap seconds, if only
someone uses -L leapseconds with zic. It appears some systems (SUSE
Linux) have been doing such for a subdirectory right/
(i. e. TZ=right/Europe/Berlin) for half a decade now.

Matthias Andree

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