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

Fri Dec 30 02:09:39 EST 2016

Rob,

You are way more polite than I might be.

I do believe, however, that NTF's General Timestamp API project might
help POSIX out here, in that it can map other timescales to UTC,
although going the other direction means one has to know how the POSIX
system handles leap seconds.

POSIX needs at least 2 more time-related signals, too.

H
--
Rob Seaman writes:
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> 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=E2=80=99s =
> 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=E2=80=99t.
> 
> Placing POSIX in the same =E2=80=9Ctoo stupid to fail=E2=80=9D 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 =E2=80=9CGNU=E2=80=9D for =
> "GNU is Not UTC=E2=80=9D. Add one statement to the POSIX standard:
> 
> =E2=80=9CAfter <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>.=E2=80=9D
> 
> 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
> 
> 
> 
> 
> --Apple-Mail=_628400EE-8D80-4E79-B462-C19C7BB5010B
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> 
> <html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
> charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
> -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
> class=3D""><div><div style=3D"word-wrap: break-word; -webkit-nbsp-mode: =
> space; -webkit-line-break: after-white-space;" class=3D""><span =
> style=3D"font-size: 13px;" class=3D"">Warner is staging a spirited =
> defense of POSIX. Such a stalwart champion deserves a more worthy =
> cause.</span></div><div style=3D"word-wrap: break-word; =
> -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
> class=3D""><span style=3D"font-size: 13px;" class=3D""><br =
> class=3D""></span></div><div style=3D"word-wrap: break-word; =
> -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
> class=3D""><div class=3D""><blockquote type=3D"cite" class=3D""><div =
> class=3D""><div class=3D""><span style=3D"font-size: 13px;" =
> class=3D"">POSIX time_t says they don't exist. Therefore, they don't =
> exist.<br class=3D""></span></div></div></blockquote></div><blockquote =
> class=3D"" style=3D"margin: 0px 0px 0px 40px; border: none; padding: =
> 0px;"><div class=3D""><span style=3D"font-size: 13px;" class=3D""><br =
> class=3D""></span></div></blockquote><span style=3D"font-size: 13px;" =
> class=3D"">POSIX, meet physics.</span><br class=3D""><div class=3D""><span=
>  style=3D"font-size: 13px;" class=3D""><br class=3D""></span><blockquote =
> type=3D"cite" class=3D""><span style=3D"font-size: 13px;" class=3D""><span=
>  class=3D"">There's millions of lines of code written</span> <span =
> class=3D"">to POSIX with the mistaken assumption that they are =
> implementing time </span><span =
> class=3D"">correctly. </span><span class=3D"">Changing it all, or =
> even a large part of it, is unlikely to </span><span =
> class=3D"">happen.</span></span></blockquote></div><div class=3D""><div =
> class=3D""><span style=3D"font-size: 13px;" class=3D""><br =
> class=3D""></span></div><span style=3D"font-size: 13px;" class=3D"">A =
> lot of code could have been changed while the ITU fiddled, =
> e.g., </span><span style=3D"font-size: 13px;" class=3D"">Mac OS X =
> was launched in 2001.</span></div><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><br class=3D""></span><blockquote =
> type=3D"cite" class=3D""><div class=3D""><span style=3D"font-size: =
> 13px;" class=3D""><span style=3D"font-style: normal; font-variant-caps: =
> normal; font-weight: normal; letter-spacing: normal; orphans: auto; =
> text-align: start; text-indent: 0px; text-transform: none; white-space: =
> normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
> float: none; display: inline !important;" class=3D"">UTC may well be =
> superior to POSIX's notion, but that=E2=80=99s </span><span =
> style=3D"font-style: normal; font-variant-caps: normal; font-weight: =
> normal; letter-spacing: normal; orphans: auto; text-align: start; =
> text-indent: 0px; text-transform: none; white-space: normal; widows: =
> auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; =
> display: inline !important;" class=3D"">entirely besides the =
> point.</span></span></div></blockquote><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><br class=3D""></span></div><span =
> style=3D"font-size: 13px;" class=3D"">It is the only =
> point.</span></div><div class=3D""><span style=3D"font-size: 13px;" =
> class=3D""><br class=3D""></span></div><div class=3D""><blockquote =
> type=3D"cite" class=3D""><div class=3D""><span style=3D"font-size: =
> 13px;" class=3D""><span style=3D"font-style: normal; font-variant-caps: =
> normal; font-weight: normal; letter-spacing: normal; orphans: auto; =
> text-align: start; text-indent: 0px; text-transform: none; white-space: =
> normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
> float: none; display: inline !important;" class=3D"">While it =
> might </span><span style=3D"font-style: normal; font-variant-caps: =
> normal; font-weight: normal; letter-spacing: normal; orphans: auto; =
> text-align: start; text-indent: 0px; text-transform: none; white-space: =
> normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
> float: none; display: inline !important;" class=3D"">result in a better =
> world if POSIX were able to change, it =
> isn=E2=80=99t.</span></span></div></blockquote><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><br class=3D""></span></div><span =
> style=3D"font-size: 13px;" class=3D"">Placing POSIX in the =
> same =E2=80=9Ctoo stupid to fail=E2=80=9D basket as the U.S. =
> Electoral College seems a weak strategy.</span></div><div class=3D""><span=
>  style=3D"font-size: 13px;" class=3D""><br class=3D""></span></div><div =
> class=3D""><blockquote type=3D"cite" class=3D""><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><span style=3D"font-style: normal; =
> font-variant-caps: normal; font-weight: normal; letter-spacing: normal; =
> orphans: auto; text-align: start; text-indent: 0px; text-transform: =
> none; white-space: normal; widows: auto; word-spacing: 0px; =
> -webkit-text-stroke-width: 0px; float: none; display: inline =
> !important;" class=3D"">The marketplace has effectively =
> voted </span><span style=3D"font-style: normal; font-variant-caps: =
> normal; font-weight: normal; letter-spacing: normal; orphans: auto; =
> text-align: start; text-indent: 0px; text-transform: none; white-space: =
> normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
> float: none; display: inline !important;" class=3D"">with its feet, and =
> change would be too expensive.</span></span></div></blockquote><div =
> class=3D""><span style=3D"font-size: 13px;" class=3D""><br =
> class=3D""></span></div><span style=3D"font-size: 13px;" class=3D"">But =
> change is what is proposed. That being the case, the simplest change =
> would be to define a new timescale. Call it =E2=80=9CGNU=E2=80=9D for =
> "GNU is Not UTC=E2=80=9D. Add one statement to the POSIX =
> standard:</span></div><div class=3D""><span style=3D"font-size: 13px;" =
> class=3D""><br class=3D""></span></div><blockquote style=3D"margin: 0 0 =
> 0 40px; border: none; padding: 0px;" class=3D""><div class=3D""><i =
> class=3D"" style=3D"font-size: 13px;">=E2=80=9CAfter <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>.=E2=80=9D</i></div></blockquote><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><br class=3D""></span></div><div =
> class=3D""><span style=3D"font-size: 13px;" class=3D"">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.</span></div><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><br class=3D""></span></div><div =
> class=3D""><span style=3D"font-size: 13px;" class=3D"">Rob =
> Seaman</span></div><div class=3D""><span style=3D"font-size: 13px;" =
> class=3D"">University of Arizona</span></div><div class=3D""><span =
> style=3D"font-size: 13px;" class=3D""><br class=3D""></span></div><div =
> class=3D""><span style=3D"font-size: 13px;" class=3D""><br =
> class=3D""></span></div></div></div><br class=3D""></body></html>=
> 
> --Apple-Mail=_628400EE-8D80-4E79-B462-C19C7BB5010B--
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