[tz] localtime.c issue

[Paul_Koning at Dell.com]

On Jul 8, 2013, at 5:19 PM, Alan Barrett wrote:

> On Mon, 08 Jul 2013, Arthur David Olson wrote:
> [localtime.c]
>> --- 1514,1521 ----
>>     }
>>     {
>>         register int_fast32_t    seconds;
>> 
>> !         seconds = tdays * SECSPERDAY + 0.5;
>>         tdays = seconds / SECSPERDAY;
>>         rem += seconds - tdays * SECSPERDAY;
>>     }
> 
> If time_t is an integer type, then that will multiply tdays * SECSPERDAY using time_t arithmetic, convert to double to add 0.5, then convert to int_fast32_t for the assignment.  The conversion to and from double may lose precision, if double has less than 32 bits of mantissa precision (but that's unlikely).
> 
> Perhaps this will work without either a compiler warning or potential loss of precision:
> 
>           seconds = tdays * SECSPERDAY + (time_t)0.5;
> 
> --apb (Alan Barrett)

I rather doubt it.  Casting 0.5 to an integer type (as time_t is) ends up adding 0 or 1, but not 0.5.  

How about (tdays * SECSPERDAY * 2 + 1) / 2;   ?

	paul