[PATCH 2/5] time: Implement c23 timespec_get base

[Florian Weimer]

* Yonggang Luo via Libc-alpha:

> diff --git a/time/timespec_get.c b/time/timespec_get.c
> index 9b1d4f22ed..a57b1ee0b8 100644
> --- a/time/timespec_get.c
> +++ b/time/timespec_get.c
> @@ -22,10 +22,52 @@
>  int
>  timespec_get (struct timespec *ts, int base)
>  {
> -  if (base == TIME_UTC)
> +	clockid_t clockid = -1;
> +	switch (base) {
> +	default:
> +		break;
> +	case TIME_UTC:
> +		clockid = CLOCK_REALTIME;
> +		break;
> +	case TIME_MONOTONIC:
> +		clockid = CLOCK_MONOTONIC;
> +		break;
> +	case TIME_PROCESS_CPUTIME_ID:
> +		clockid = CLOCK_PROCESS_CPUTIME_ID;
> +		break;
> +	case TIME_THREAD_CPUTIME_ID:
> +		clockid = CLOCK_THREAD_CPUTIME_ID;
> +		break;
> +	case TIME_MONOTONIC_RAW:
> +		clockid = CLOCK_MONOTONIC_RAW;
> +		break;
> +	case TIME_REALTIME_COARSE:
> +		clockid = CLOCK_REALTIME_COARSE;
> +		break;
> +	case TIME_MONOTONIC_COARSE:
> +		clockid = CLOCK_MONOTONIC_COARSE;
> +		break;
> +	case TIME_BOOTTIME:
> +		clockid = CLOCK_BOOTTIME;
> +		break;
> +	case TIME_REALTIME_ALARM:
> +		clockid = CLOCK_REALTIME_ALARM;
> +		break;
> +	case TIME_BOOTTIME_ALARM:
> +		clockid = CLOCK_BOOTTIME_ALARM;
> +		break;
> +	case TIME_SGI_CYCLE:
> +		clockid = CLOCK_SGI_CYCLE;
> +		break;
> +	case TIME_TAI:
> +		clockid = CLOCK_TAI;
> +		break;
> +	}
> +  if (clockid >= 0)
>      {
> -      __clock_gettime (CLOCK_REALTIME, ts);
> -      return base;
> +      if (__clock_gettime (clockid, ts) >= 0) {
> +        return base;
> +      }
>      }
>    return 0;
>  }

This was recently discussed on the libc-coord list:

  Relation between C timespec_get time bases and POSIX clockid_t values.
  <https://www.openwall.com/lists/libc-coord/2023/04/25/1>

I'm not sure if we should extend this because it's just a bizarre WG14
not-invent-here interface, designed to be incompatible with existing
implementation practice.

Thanks,
Florian