lib/ansi/localtime.c

   1 /*
   2  * localtime - convert a calendar time into broken down time
   3  */
   4 /* $Header$ */
   5
   6 #include        <time.h>
   7 #include        "loc_time.h"
   8
   9 /* We must be careful, since an int can't represent all the seconds in a day.
  10  * Hence the adjustment of minutes when adding timezone and dst information.
  11  * This assumes that both must be expressable in multiples of a minute.
  12  * Furthermore, it is assumed that both fit into an integer when expressed as
  13  * minutes (this is about 22 days, so this should not cause any problems).
  14  */
  15 struct tm *
  16 localtime(const time_t *timer)
  17 {
  18         struct tm *timep;
  19         unsigned dst;
  20
  21         _tzset();
  22         timep = gmtime(timer);                  /* tm->tm_isdst == 0 */
  23         timep->tm_min -= _timezone / 60;
  24         timep->tm_sec -= _timezone % 60;
  25         mktime(timep);
  26
  27         dst = _dstget(timep);
  28         if (dst) {
  29                 timep->tm_min += dst / 60;
  30                 timep->tm_sec += dst % 60;
  31                 mktime(timep);
  32         }
  33         return timep;
  34 }