-/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/dt_common.c,v 1.39 2007/05/21 07:04:00 meskes Exp $ */
+/* $PostgreSQL: pgsql/src/interfaces/ecpg/pgtypeslib/dt_common.c,v 1.40 2007/05/21 07:07:48 meskes Exp $ */
#include "postgres_fe.h"
abstime2tm(time(NULL), &tz, tm, NULL);
}
-/* DetermineLocalTimeZone()
- *
- * Given a struct tm in which tm_year, tm_mon, tm_mday, tm_hour, tm_min, and
- * tm_sec fields are set, attempt to determine the applicable local zone
- * (ie, regular or daylight-savings time) at that time. Set the struct tm's
- * tm_isdst field accordingly, and return the actual timezone offset.
- *
- * This subroutine exists to centralize uses of mktime() and defend against
- * mktime() bugs/restrictions on various platforms. This should be
- * the *only* call of mktime() in the backend.
- */
-static int
-DetermineLocalTimeZone(struct tm * tm)
-{
- int tz;
-
- if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
- {
-#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)
-
- /*
- * Some buggy mktime() implementations may change the year/month/day
- * when given a time right at a DST boundary. To prevent corruption
- * of the caller's data, give mktime() a copy...
- */
- struct tm tt,
- *tmp = &tt;
-
- *tmp = *tm;
- /* change to Unix conventions for year/month */
- tmp->tm_year -= 1900;
- tmp->tm_mon -= 1;
-
- /* indicate timezone unknown */
- tmp->tm_isdst = -1;
-
- if (mktime(tmp) != (time_t) -1 && tmp->tm_isdst >= 0)
- {
- /* mktime() succeeded, trust its result */
- tm->tm_isdst = tmp->tm_isdst;
-
-#if defined(HAVE_TM_ZONE)
- /* tm_gmtoff is Sun/DEC-ism */
- tz = -tmp->tm_gmtoff;
-#elif defined(HAVE_INT_TIMEZONE)
- tz = (tmp->tm_isdst > 0) ? TIMEZONE_GLOBAL - SECS_PER_HOUR : TIMEZONE_GLOBAL;
-#endif /* HAVE_INT_TIMEZONE */
- }
- else
- {
- /*
- * We have a buggy (not to say deliberately brain damaged)
- * mktime(). Work around it by using localtime() instead.
- *
- * First, generate the time_t value corresponding to the given
- * y/m/d/h/m/s taken as GMT time. This will not overflow (at
- * least not for time_t taken as signed) because of the range
- * check we did above.
- */
- long day,
- mysec,
- locsec,
- delta1,
- delta2;
- time_t mytime;
-
- day = (date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) -
- date2j(1970, 1, 1));
- mysec = tm->tm_sec + (tm->tm_min + (day * HOURS_PER_DAY + tm->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
- mytime = (time_t) mysec;
-
- /*
- * Use localtime to convert that time_t to broken-down time, and
- * reassemble to get a representation of local time.
- */
- tmp = localtime(&mytime);
- if (!tmp)
- {
- tm->tm_isdst = 0;
- return 0;
- }
- day = (date2j(tmp->tm_year + 1900, tmp->tm_mon + 1, tmp->tm_mday) -
- date2j(1970, 1, 1));
- locsec = tmp->tm_sec + (tmp->tm_min + (day * HOURS_PER_DAY + tmp->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
-
- /*
- * The local time offset corresponding to that GMT time is now
- * computable as mysec - locsec.
- */
- delta1 = mysec - locsec;
-
- /*
- * However, if that GMT time and the local time we are actually
- * interested in are on opposite sides of a daylight-savings-time
- * transition, then this is not the time offset we want. So,
- * adjust the time_t to be what we think the GMT time
- * corresponding to our target local time is, and repeat the
- * localtime() call and delta calculation. We may have to do it
- * twice before we have a trustworthy delta.
- *
- * Note: think not to put a loop here, since if we've been given
- * an "impossible" local time (in the gap during a spring-forward
- * transition) we'd never get out of the loop. Twice is enough to
- * give the behavior we want, which is that "impossible" times are
- * taken as standard time, while at a fall-back boundary ambiguous
- * times are also taken as standard.
- */
- mysec += delta1;
- mytime = (time_t) mysec;
- tmp = localtime(&mytime);
- if (!tmp)
- {
- tm->tm_isdst = 0;
- return 0;
- }
- day = (date2j(tmp->tm_year + 1900, tmp->tm_mon + 1, tmp->tm_mday) -
- date2j(1970, 1, 1));
- locsec = tmp->tm_sec + (tmp->tm_min + (day * HOURS_PER_DAY + tmp->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
- delta2 = mysec - locsec;
- if (delta2 != delta1)
- {
- mysec += (delta2 - delta1);
- mytime = (time_t) mysec;
- tmp = localtime(&mytime);
- if (!tmp)
- {
- tm->tm_isdst = 0;
- return 0;
- }
- day = (date2j(tmp->tm_year + 1900, tmp->tm_mon + 1, tmp->tm_mday) -
- date2j(1970, 1, 1));
- locsec = tmp->tm_sec + (tmp->tm_min + (day * HOURS_PER_DAY + tmp->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
- delta2 = mysec - locsec;
- }
- tm->tm_isdst = tmp->tm_isdst;
- tz = (int) delta2;
- }
-#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
- /* Assume UTC if no system timezone info available */
- tm->tm_isdst = 0;
- tz = 0;
-#endif
- }
- else
- {
- /* Given date is out of range, so assume UTC */
- tm->tm_isdst = 0;
- tz = 0;
- }
-
- return tz;
-}
-
static void
dt2time(double jd, int *hour, int *min, int *sec, fsec_t *fsec)
{
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