Re: [PATCH] libc/time: Add CLOCK_TAI

On Jul 15 15:01, brian.inglis--- via Newlib wrote:
> On 2025-07-15 02:43, Corinna Vinschen via Newlib wrote:
> > On Jul 14 14:38, Brian Inglis via Newlib wrote:
> > > On 2025-07-14 09:45, Corinna Vinschen via Newlib wrote:
> > > > On Jul 11 06:35, Sebastian Huber wrote:
> > > > > FreeBSD also provides this clock identifier, maybe it should be
> > > > > #if __BSD_VISIBLE
> > > > > #define CLOCK_TAI		(11)
> > > > > #endif
> > > > > ?
> > > 
> > > > Probably, but I seriously wonder how to implement CLOCK_TAI on Cygwin.
> > > 
> > > > IIUC, if you don't do anything special, the CLOCK_REALTIME and CLOCK_TAI
> > > > return the same value, because the leap second is set to 0 at kernel
> > > > startup.  Maybe that's enough...
> > > 
> > > If you are running an NTP server you just have to ask for the system variable:
> > > [...]
> > What we could do is to define CLOCK_TAI as CLOCK_REALTIME + 37 in the DLL
> > for the time being, and the DLL could check if a file "/etc/leapsecs"
> > exists and read it to compensate for new leap secs.  We can add such a
> > file to the distro when a new leap sec has been defined.
> 
> It may be better to just use the standard approach and standard file name
> which is /etc/leap-seconds.list, often symlinked from /etc/ntp/ which may
> itself be symlinked from /var/lib/ntp/.

Actually, yesterday I hacked some POC code in my local Cygwin sandbox
using the file /usr/share/zoneinfo/leapseconds from tzdata.  If the file
isn't present, the DLL uses the current leap secs offset of 37 secs.
Seems to work nicely.

So I'm looking forward to Sebastian adding the CLOCK_TAI macro to time.h.


Corinna