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Consolidate several near-identical uses of mktime() into a single

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routine DetermineLocalTimeZone().  In that routine, be more wary of
broken mktime() implementations than the original code was: don't allow
mktime to change the already-set y/m/d/h/m/s information, and don't
use tm_gmtoff if mktime failed.  Possibly this will resolve some of
the complaints we've been hearing from users of Middle Eastern timezones
on RedHat.
This commit is contained in:
Tom Lane
2001-05-03 22:53:07 +00:00
parent 0cec2bb0cd
commit f5ba72ea04
4 changed files with 74 additions and 127 deletions
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108
src/backend/utils/adt/datetime.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.63 2001/04/03 18:05:53 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.64 2001/05/03 22:53:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -869,32 +869,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
if (fmask & DTK_M(DTZMOD))
return -1;
if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
{
#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)
tm->tm_year -= 1900;
tm->tm_mon -= 1;
tm->tm_isdst = -1;
mktime(tm);
tm->tm_year += 1900;
tm->tm_mon += 1;
#if defined(HAVE_TM_ZONE)
*tzp = -(tm->tm_gmtoff); /* tm_gmtoff is
* Sun/DEC-ism */
#elif defined(HAVE_INT_TIMEZONE)
*tzp = ((tm->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
#endif /* HAVE_INT_TIMEZONE */
#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
*tzp = CTimeZone;
#endif
}
else
{
tm->tm_isdst = 0;
*tzp = 0;
}
*tzp = DetermineLocalTimeZone(tm);
}
}
@ -902,6 +877,69 @@ DecodeDateTime(char **field, int *ftype, int nf,
} /* DecodeDateTime() */
/* 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...
*/
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;
mktime(tmp);
tm->tm_isdst = tmp->tm_isdst;
#if defined(HAVE_TM_ZONE)
/* tm_gmtoff is Sun/DEC-ism */
if (tmp->tm_isdst >= 0)
tz = -(tmp->tm_gmtoff);
else
tz = 0; /* assume GMT if mktime failed */
#elif defined(HAVE_INT_TIMEZONE)
tz = ((tmp->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
#endif /* HAVE_INT_TIMEZONE */
#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
tm->tm_isdst = 0;
tz = CTimeZone;
#endif
}
else
{
/* Given date is out of range, so assume GMT */
tm->tm_isdst = 0;
tz = 0;
}
return tz;
}
/* DecodeTimeOnly()
* Interpret parsed string as time fields only.
* Note that support for time zone is here for
@ -1119,22 +1157,8 @@ DecodeTimeOnly(char **field, int *ftype, int nf,
tmp->tm_min = tm->tm_min;
tmp->tm_sec = tm->tm_sec;
#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)
tmp->tm_year -= 1900;
tmp->tm_mon -= 1;
tmp->tm_isdst = -1;
mktime(tmp);
*tzp = DetermineLocalTimeZone(tmp);
tm->tm_isdst = tmp->tm_isdst;
#if defined(HAVE_TM_ZONE)
*tzp = -(tmp->tm_gmtoff); /* tm_gmtoff is Sun/DEC-ism */
#elif defined(HAVE_INT_TIMEZONE)
*tzp = ((tmp->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
#endif
#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
*tzp = CTimeZone;
#endif
}
return 0;