Johannes Schindelin <johannes.schindelin@xxxxxx> writes:
> We are about to switch to a new data type for time stamps that is
> definitely not smaller or equal, but larger or equal to time_t.
>
> So before using the system functions to process or format timestamps,
> let's make extra certain that they can handle what we feed them.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
> ---
> date.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/date.c b/date.c
> index 92ab31aa441..75f6335cd09 100644
> --- a/date.c
> +++ b/date.c
> @@ -46,7 +46,10 @@ static time_t gm_time_t(timestamp_t time, int tz)
> minutes = tz < 0 ? -tz : tz;
> minutes = (minutes / 100)*60 + (minutes % 100);
> minutes = tz < 0 ? -minutes : minutes;
> - return time + minutes * 60;
> +
> + if (date_overflows(time + minutes * 60))
> + die("Timestamp too large for this system: %"PRItime, time);
> + return (time_t)time + minutes * 60;
> }
All the other calls to date_overflows() take a variable that holds
timestamp_t and presumably they are checking for integer wraparound
when the values are computed, but this one is not. Perhaps we want
to make it a bit more careful here? I wonder if something like this
is a good approach:
#define date_overflows(time) date_overflows_add(time, 0)
int date_overflows_add(timestamp_t base, timestamp_t minutes)
{
timestamp_t t;
if (unsigned_add_overflows(base, minutes))
return 1;
t = base + minutes;
if ((uintmax_t) t >= TIME_MAX)
return 1;
... what you have in date_overflows() ...
}