[LEAPSECS] POSIX? (was Time math libraries, UTC to TAI)

[Rob Seaman]

Warner is staging a spirited defense of POSIX. Such a stalwart champion deserves a more worthy cause.

> POSIX time_t says they don't exist. Therefore, they don't exist.


POSIX, meet physics.

> There's millions of lines of code written to POSIX with the mistaken assumption that they are implementing time correctly. Changing it all, or even a large part of it, is unlikely to happen.


A lot of code could have been changed while the ITU fiddled, e.g., Mac OS X was launched in 2001.

> UTC may well be superior to POSIX's notion, but that’s entirely besides the point.

It is the only point.

> While it might result in a better world if POSIX were able to change, it isn’t.

Placing POSIX in the same “too stupid to fail” basket as the U.S. Electoral College seems a weak strategy.

> The marketplace has effectively voted with its feet, and change would be too expensive.

But change is what is proposed. That being the case, the simplest change would be to define a new timescale. Call it “GNU” for "GNU is Not UTC”. Add one statement to the POSIX standard:

“After <date> all references to UTC in the POSIX documents, or to timekeeping generally, will be taken to refer to the GNU time scale, defined by <document>.”

Or simply adopt GPS or TAI, which already have the precise behavior desired. Commercial devices already exist (and are already widely deployed) that implement high precision GPS and TAI.

Rob Seaman
University of Arizona



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