unbound/compat/gmtime_r.c

   1 /*
   2  * Taken from FreeBSD src / lib / libc / stdtime / localtime.c 1.43 revision.
   3  * localtime.c 7.78.
   4  * tzfile.h 1.8
   5  * adapted to be replacement gmtime_r.
   6  */
   7 #include "config.h"
   8
   9 #ifdef HAVE_TIME_H
  10 #include <time.h>
  11 #endif
  12
  13 #define MONSPERYEAR 12
  14 #define DAYSPERNYEAR 365
  15 #define DAYSPERLYEAR 366
  16 #define SECSPERMIN 60
  17 #define SECSPERHOUR (60*60)
  18 #define SECSPERDAY (24*60*60)
  19 #define DAYSPERWEEK 7
  20 #define TM_SUNDAY       0
  21 #define TM_MONDAY       1
  22 #define TM_TUESDAY      2
  23 #define TM_WEDNESDAY    3
  24 #define TM_THURSDAY     4
  25 #define TM_FRIDAY       5
  26 #define TM_SATURDAY     6
  27
  28 #define TM_YEAR_BASE    1900
  29
  30 #define EPOCH_YEAR      1970
  31 #define EPOCH_WDAY      TM_THURSDAY
  32
  33 #define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
  34
  35 static const int        mon_lengths[2][MONSPERYEAR] = {
  36         { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
  37         { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
  38 };
  39
  40 static const int        year_lengths[2] = {
  41         DAYSPERNYEAR, DAYSPERLYEAR
  42 };
  43
  44 static void
  45 timesub(timep, offset, tmp)
  46 const time_t * const                    timep;
  47 const long                              offset;
  48 struct tm * const               tmp;
  49 {
  50         long                    days;
  51         long                    rem;
  52         long                    y;
  53         int                     yleap;
  54         const int *             ip;
  55
  56         days = *timep / SECSPERDAY;
  57         rem = *timep % SECSPERDAY;
  58         rem += (offset);
  59         while (rem < 0) {
  60                 rem += SECSPERDAY;
  61                 --days;
  62         }
  63         while (rem >= SECSPERDAY) {
  64                 rem -= SECSPERDAY;
  65                 ++days;
  66         }
  67         tmp->tm_hour = (int) (rem / SECSPERHOUR);
  68         rem = rem % SECSPERHOUR;
  69         tmp->tm_min = (int) (rem / SECSPERMIN);
  70         /*
  71         ** A positive leap second requires a special
  72         ** representation.  This uses "... ??:59:60" et seq.
  73         */
  74         tmp->tm_sec = (int) (rem % SECSPERMIN) ;
  75         tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
  76         if (tmp->tm_wday < 0)
  77                 tmp->tm_wday += DAYSPERWEEK;
  78         y = EPOCH_YEAR;
  79 #define LEAPS_THRU_END_OF(y)    ((y) / 4 - (y) / 100 + (y) / 400)
  80         while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
  81                 long    newy;
  82
  83                 newy = y + days / DAYSPERNYEAR;
  84                 if (days < 0)
  85                         --newy;
  86                 days -= (newy - y) * DAYSPERNYEAR +
  87                         LEAPS_THRU_END_OF(newy - 1) -
  88                         LEAPS_THRU_END_OF(y - 1);
  89                 y = newy;
  90         }
  91         tmp->tm_year = y - TM_YEAR_BASE;
  92         tmp->tm_yday = (int) days;
  93         ip = mon_lengths[yleap];
  94         for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
  95                 days = days - (long) ip[tmp->tm_mon];
  96         tmp->tm_mday = (int) (days + 1);
  97         tmp->tm_isdst = 0;
  98 }
  99
 100 /*
 101 * Re-entrant version of gmtime.
 102 */
 103 struct tm * gmtime_r(const time_t* timep, struct tm *tm)
 104 {
 105         timesub(timep, 0L, tm);
 106         return tm;
 107 }