*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.64.2.2 2002/08/22 05:27:41 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.64.2.3 2002/09/30 20:57:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
TimestampTz result;
struct tm tt,
*tm = &tt;
- time_t utime;
- j2date((dateVal + date2j(2000, 1, 1)), &(tm->tm_year), &(tm->tm_mon), &(tm->tm_mday));
+ j2date((dateVal + date2j(2000, 1, 1)),
+ &(tm->tm_year), &(tm->tm_mon), &(tm->tm_mday));
if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
{
-#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)
+ int tz;
+
tm->tm_hour = 0;
tm->tm_min = 0;
tm->tm_sec = 0;
- tm->tm_isdst = -1;
+ tz = DetermineLocalTimeZone(tm);
- tm->tm_year -= 1900;
- tm->tm_mon -= 1;
- utime = mktime(tm);
- if (utime == -1)
- elog(ERROR, "Unable to convert date to tm");
-
- result = utime + ((date2j(1970, 1, 1) - date2j(2000, 1, 1)) * 86400.0);
-#else
- result = dateVal * 86400.0 + CTimeZone;
-#endif
+ result = dateVal * 86400.0 + tz;
}
else
{
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.87.2.1 2002/02/25 16:22:48 thomas Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.87.2.2 2002/09/30 20:57:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/* 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 mainly to centralize uses of mktime() and defend
- * against mktime() bugs on various platforms...
+ * 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.
*/
int
DetermineLocalTimeZone(struct tm * tm)
int tz;
if (HasCTZSet)
+ {
+ tm->tm_isdst = 0; /* for lack of a better idea */
tz = CTimeZone;
+ }
else if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
{
#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)
/* indicate timezone unknown */
tmp->tm_isdst = -1;
- mktime(tmp);
-
- tm->tm_isdst = tmp->tm_isdst;
+ 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 */
- if (tmp->tm_isdst >= 0)
+ /* tm_gmtoff is Sun/DEC-ism */
tz = -(tmp->tm_gmtoff);
- else
- tz = 0; /* assume UTC if mktime failed */
#elif defined(HAVE_INT_TIMEZONE)
- tz = ((tmp->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
+ tz = ((tmp->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : 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 * 24 + tm->tm_hour) * 60) * 60;
+ 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);
+ 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 * 24 + tmp->tm_hour) * 60) * 60;
+ /*
+ * 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);
+ 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 * 24 + tmp->tm_hour) * 60) * 60;
+ delta2 = mysec - locsec;
+ if (delta2 != delta1)
+ {
+ mysec += (delta2 - delta1);
+ mytime = (time_t) mysec;
+ tmp = localtime(&mytime);
+ 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 * 24 + tmp->tm_hour) * 60) * 60;
+ delta2 = mysec - locsec;
+ }
+ tm->tm_isdst = tmp->tm_isdst;
+ tz = (int) delta2;
+ }
#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
tm->tm_isdst = 0;
tz = CTimeZone;
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