From f5ba72ea04e71a127031a4436781943008abfa7a Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 3 May 2001 22:53:07 +0000
Subject: [PATCH] Consolidate several near-identical uses of mktime() into a
single 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.
---
src/backend/utils/adt/datetime.c | 98 +++++++++++++++++++-----------
src/backend/utils/adt/formatting.c | 34 +----------
src/backend/utils/adt/timestamp.c | 55 +----------------
src/include/utils/datetime.h | 4 +-
4 files changed, 69 insertions(+), 122 deletions(-)
diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 60346efdcd1..1a13aa4a4af 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -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 $
*
*-------------------------------------------------------------------------
*/
@@ -869,37 +869,75 @@ 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))
- {
+ *tzp = DetermineLocalTimeZone(tm);
+ }
+ }
+
+ return 0;
+} /* 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)
- tm->tm_year -= 1900;
- tm->tm_mon -= 1;
- tm->tm_isdst = -1;
- mktime(tm);
- tm->tm_year += 1900;
- tm->tm_mon += 1;
+ /*
+ * 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)
- *tzp = -(tm->tm_gmtoff); /* tm_gmtoff is
- * Sun/DEC-ism */
+ /* 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)
- *tzp = ((tm->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
+ tz = ((tmp->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
#endif /* HAVE_INT_TIMEZONE */
#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
- *tzp = CTimeZone;
+ tm->tm_isdst = 0;
+ tz = CTimeZone;
#endif
- }
- else
- {
- tm->tm_isdst = 0;
- *tzp = 0;
- }
- }
+ }
+ else
+ {
+ /* Given date is out of range, so assume GMT */
+ tm->tm_isdst = 0;
+ tz = 0;
}
- return 0;
-} /* DecodeDateTime() */
+ return tz;
+}
/* DecodeTimeOnly()
@@ -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;
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 7e68d7e984e..1ad99d330e5 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -1,7 +1,7 @@
/* -----------------------------------------------------------------------
* formatting.c
*
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/formatting.c,v 1.36 2001/03/23 04:49:54 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/formatting.c,v 1.37 2001/05/03 22:53:07 tgl Exp $
*
*
* Portions Copyright (c) 1999-2000, PostgreSQL Global Development Group
@@ -2936,37 +2936,7 @@ to_timestamp(PG_FUNCTION_ARGS)
#ifdef DEBUG_TO_FROM_CHAR
NOTICE_TM;
#endif
- if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
- {
-
-#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)
- tm->tm_isdst = -1;
- tm->tm_year -= 1900;
- tm->tm_mon -= 1;
-
-#ifdef DEBUG_TO_FROM_CHAR
- elog(DEBUG_elog_output, "TO-FROM_CHAR: Call mktime()");
- NOTICE_TM;
-#endif
- mktime(tm);
- tm->tm_year += 1900;
- tm->tm_mon += 1;
-
-#if defined(HAVE_TM_ZONE)
- tz = -(tm->tm_gmtoff); /* tm_gmtoff is Sun/DEC-ism */
-#elif defined(HAVE_INT_TIMEZONE)
- tz = ((tm->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
-#endif
-
-#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
- tz = CTimeZone;
-#endif
- }
- else
- {
- tm->tm_isdst = 0;
- tz = 0;
- }
+ tz = DetermineLocalTimeZone(tm);
#ifdef DEBUG_TO_FROM_CHAR
NOTICE_TM;
#endif
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 186103252b3..68099de8678 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v 1.48 2001/05/03 19:00:36 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/timestamp.c,v 1.49 2001/05/03 22:53:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -990,32 +990,7 @@ timestamp_pl_span(PG_FUNCTION_ARGS)
if (tm->tm_mday > day_tab[isleap(tm->tm_year)][tm->tm_mon - 1])
tm->tm_mday = (day_tab[isleap(tm->tm_year)][tm->tm_mon - 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)
- tz = -(tm->tm_gmtoff); /* tm_gmtoff is
- * Sun/DEC-ism */
-#elif defined(HAVE_INT_TIMEZONE)
- tz = ((tm->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
-#endif
-
-#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
- tz = CTimeZone;
-#endif
- }
- else
- {
- tm->tm_isdst = 0;
- tz = 0;
- }
+ tz = DetermineLocalTimeZone(tm);
if (tm2timestamp(tm, fsec, &tz, &dt) != 0)
elog(ERROR, "Unable to add timestamp and interval");
@@ -1631,31 +1606,7 @@ timestamp_trunc(PG_FUNCTION_ARGS)
result = 0;
}
- 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)
- tz = -(tm->tm_gmtoff); /* tm_gmtoff is Sun/DEC-ism */
-#elif defined(HAVE_INT_TIMEZONE)
- tz = ((tm->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : TIMEZONE_GLOBAL);
-#endif
-
-#else /* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
- tz = CTimeZone;
-#endif
- }
- else
- {
- tm->tm_isdst = 0;
- tz = 0;
- }
+ tz = DetermineLocalTimeZone(tm);
if (tm2timestamp(tm, fsec, &tz, &result) != 0)
elog(ERROR, "Unable to truncate timestamp to '%s'", lowunits);
diff --git a/src/include/utils/datetime.h b/src/include/utils/datetime.h
index af9b7f6ac7e..5922d635dce 100644
--- a/src/include/utils/datetime.h
+++ b/src/include/utils/datetime.h
@@ -9,7 +9,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: datetime.h,v 1.17 2001/01/24 19:43:28 momjian Exp $
+ * $Id: datetime.h,v 1.18 2001/05/03 22:53:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -255,6 +255,8 @@ extern int DecodeDateDelta(char **field, int *ftype,
int nf, int *dtype,
struct tm * tm, double *fsec);
+extern int DetermineLocalTimeZone(struct tm * tm);
+
extern int EncodeDateOnly(struct tm * tm, int style, char *str);
extern int EncodeTimeOnly(struct tm * tm, double fsec, int *tzp, int style, char *str);
extern int EncodeDateTime(struct tm * tm, double fsec, int *tzp, char **tzn, int style, char *str);
--
GitLab