[LEAPSECS] How good could civil timekeeping be?

Michael Sokolov msokolov at ivan.Harhan.ORG
Thu Feb 14 17:45:37 EST 2008

Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:

> This is the point where the POSIX people shot us in the feet by

> ignoring leap-seconds.

Why care about POSIX at all? Why not use a non-POSIX UNIX system then?

> The time_t type, contains the number of SI seconds since 1970-01-01

> 00:00:00 UTC *ignoring all leapseconds*.

Dunno about POSIX, but in UNIX-in-4-capitals which predates POSIX,
time_t does NOT mean what you say. UNIX as opposed to POSIX time_t
measures the angle by which the hands of a wall clock have rotated since
since they displayed midnight 1970-01-01 in Greenwich. It is a wall
clock rotation angle and has absolutely nothing to do with SI seconds or
physical time interval.

> And down at a hairsbreadth, you cannot by looking at a time_t value,

> tell the leap second from the second right before it. (In some

> cases it's the second after, but that's clearly a bug since the

> leap second is the last second in the preceeding 24 hour UTC period.)

Rubber seconds solve this problem.


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