[PATCH] clock:_TOD_To_seconds(): Fix year 2514 overflow

Sebastian Huber sebastian.huber at embedded-brains.de
Tue Apr 13 16:03:21 UTC 2021


Hello,

On 08/04/2021 15:41, Frank Kuehndel wrote:
> +/**
> + *  @brief Latest year to which a time of day can be initialized.
> + *
> + *  The following constant defines the latest year to which an
> + *  RTEMS time of day can be set using rtems_clock_set().
> + *
> + *  32 bits can accept as latest point in time 2106-Feb-7 6:28:15
> + *  but to simplify the implementation, is was decided to only
> + *  check that the year is not greater than the year of this constant.
> + *
> + *  The internal realtime clock can run centuries longer but in
> + *  contrast to the POSIX API, the RTEMS Classic API does not
> + *  support this for efficiency reasons.
> + */
> +#define TOD_LATEST_YEAR 2105

any objections to use this approach? If we want to support years after 
2105 in the Classic API, then we would need 64-bit values and 
calculations in several places. I think an RTEMS system which operates 
after 2105 is currently a bit unrealistic.

If we limit the time frame to the year 2100 we could simplify 
_TOD_Validate() a bit more since all years % 4 == 0 are leap years in 
the range 1988 to 2100 (exclusive).

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