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.

diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 60346efdcd104f96a38bf4c9b9c22adcad72230d..1a13aa4a4af49789589d0b1995708417a144e180 100644 (file)
--- 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 7e68d7e984ea79ee9093b8d2a440f45eca63782b..1ad99d330e5450d9d5c869b7ef8258350e8b31f7 100644 (file)
--- 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 186103252b35de6379dd6aedb9d292ff330df7e0..68099de86784ce15949fa0e24abf8d8f615fd245 100644 (file)
--- 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 af9b7f6ac7e93990749077df8914b48b5bdcfd06..5922d635dcece520a5a9555bebf90f1ea8ddbe5d 100644 (file)
--- 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);