newlib/libc/time/lcltime_r.c

   1 /*
   2  * localtime_r.c
   3  * Original Author: Adapted from tzcode maintained by Arthur David Olson.
   4  * Modifications:
   5  * - Changed to mktm_r and added __tzcalc_limits - 04/10/02, Jeff Johnston
   6  * - Fixed bug in mday computations - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
   7  * - Fixed bug in __tzcalc_limits - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
   8  * - Implement localtime_r() with gmtime_r() and the conditional code moved
   9  *   from _mktm_r() - 05/09/14, Freddie Chopin <freddie_chopin@op.pl>
  10  *
  11  * Converts the calendar time pointed to by tim_p into a broken-down time
  12  * expressed as local time. Returns a pointer to a structure containing the
  13  * broken-down time.
  14  */
  15
  16 #include "local.h"
  17
  18 struct tm *
  19 localtime_r (const time_t *__restrict tim_p,
  20         struct tm *__restrict res)
  21 {
  22   long offset;
  23   int hours, mins, secs;
  24   int year;
  25   __tzinfo_type *const tz = __gettzinfo ();
  26   const int *ip;
  27
  28   res = gmtime_r (tim_p, res);
  29
  30   year = res->tm_year + YEAR_BASE;
  31   ip = __month_lengths[isleap(year)];
  32
  33   TZ_LOCK;
  34   _tzset_unlocked ();
  35   if (_daylight)
  36     {
  37       if (year == tz->__tzyear || __tzcalc_limits (year))
  38         res->tm_isdst = (tz->__tznorth
  39           ? (*tim_p >= tz->__tzrule[0].change
  40           && *tim_p < tz->__tzrule[1].change)
  41           : (*tim_p >= tz->__tzrule[0].change
  42           || *tim_p < tz->__tzrule[1].change));
  43       else
  44         res->tm_isdst = -1;
  45     }
  46   else
  47     res->tm_isdst = 0;
  48
  49   offset = (res->tm_isdst == 1
  50     ? tz->__tzrule[1].offset
  51     : tz->__tzrule[0].offset);
  52
  53   hours = (int) (offset / SECSPERHOUR);
  54   offset = offset % SECSPERHOUR;
  55
  56   mins = (int) (offset / SECSPERMIN);
  57   secs = (int) (offset % SECSPERMIN);
  58
  59   res->tm_sec -= secs;
  60   res->tm_min -= mins;
  61   res->tm_hour -= hours;
  62
  63   if (res->tm_sec >= SECSPERMIN)
  64     {
  65       res->tm_min += 1;
  66       res->tm_sec -= SECSPERMIN;
  67     }
  68   else if (res->tm_sec < 0)
  69     {
  70       res->tm_min -= 1;
  71       res->tm_sec += SECSPERMIN;
  72     }
  73   if (res->tm_min >= MINSPERHOUR)
  74     {
  75       res->tm_hour += 1;
  76       res->tm_min -= MINSPERHOUR;
  77     }
  78   else if (res->tm_min < 0)
  79     {
  80       res->tm_hour -= 1;
  81       res->tm_min += MINSPERHOUR;
  82     }
  83   if (res->tm_hour >= HOURSPERDAY)
  84     {
  85       ++res->tm_yday;
  86       ++res->tm_wday;
  87       if (res->tm_wday > 6)
  88         res->tm_wday = 0;
  89       ++res->tm_mday;
  90       res->tm_hour -= HOURSPERDAY;
  91       if (res->tm_mday > ip[res->tm_mon])
  92         {
  93           res->tm_mday -= ip[res->tm_mon];
  94           res->tm_mon += 1;
  95           if (res->tm_mon == 12)
  96             {
  97               res->tm_mon = 0;
  98               res->tm_year += 1;
  99               res->tm_yday = 0;
 100             }
 101         }
 102     }
 103   else if (res->tm_hour < 0)
 104     {
 105       res->tm_yday -= 1;
 106       res->tm_wday -= 1;
 107       if (res->tm_wday < 0)
 108         res->tm_wday = 6;
 109       res->tm_mday -= 1;
 110       res->tm_hour += 24;
 111       if (res->tm_mday == 0)
 112         {
 113           res->tm_mon -= 1;
 114           if (res->tm_mon < 0)
 115             {
 116               res->tm_mon = 11;
 117               res->tm_year -= 1;
 118               res->tm_yday = 364 + isleap(res->tm_year + YEAR_BASE);
 119             }
 120           res->tm_mday = ip[res->tm_mon];
 121         }
 122     }
 123   TZ_UNLOCK;
 124
 125   return (res);
 126 }