Fix the various forms of AT TIME ZONE to accept either timezones found

in the zic database or zone names found in the date token table.  This
preserves the old ability to do AT TIME ZONE 'PST' along with the new
ability to do AT TIME ZONE 'PST8PDT'.  Per gripe from Bricklen Anderson.
Also, fix some inconsistencies in usage of TZ_STRLEN_MAX --- the old
code had the potential for one-byte buffer overruns, though given
alignment considerations it's unlikely there was any real risk.

1 files changed, 38 insertions, 22 deletions

diff --git a/src/backend/utils/adt/date.c b/src/backend/utils/adt/date.c
index 477d7993e6f..b36ee180929 100644
--- a/src/backend/utils/adt/date.c
+++ b/src/backend/utils/adt/date.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.119 2005/07/23 14:25:33 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/date.c,v 1.120 2005/09/09 02:31:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2484,37 +2484,53 @@ timetz_zone(PG_FUNCTION_ARGS)
 	TimeTzADT  *t = PG_GETARG_TIMETZADT_P(1);
 	TimeTzADT  *result;
 	int			tz;
-	char        tzname[TZ_STRLEN_MAX];
+	char        tzname[TZ_STRLEN_MAX + 1];
 	int         len;
 	pg_tz	   *tzp;
-	struct pg_tm *tm;
-	pg_time_t   now;
 
-	/* Find the specified timezone */ 
-	len = (VARSIZE(zone) - VARHDRSZ > TZ_STRLEN_MAX) ?
-					TZ_STRLEN_MAX : VARSIZE(zone) - VARHDRSZ;
+	/*
+	 * Look up the requested timezone.  First we look in the timezone
+	 * database (to handle cases like "America/New_York"), and if that
+	 * fails, we look in the date token table (to handle cases like "EST").
+	 */ 
+	len = Min(VARSIZE(zone) - VARHDRSZ, TZ_STRLEN_MAX);
 	memcpy(tzname, VARDATA(zone), len);
-	tzname[len]=0;
+	tzname[len] = '\0';
 	tzp = pg_tzset(tzname);
-	if (!tzp) {
-		ereport(ERROR,
-			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-		 	 errmsg("time zone \"%s\" not recognized", tzname)));
-		PG_RETURN_NULL();
+	if (tzp)
+	{
+		/* Get the offset-from-GMT that is valid today for the selected zone */
+		pg_time_t   now;
+		struct pg_tm *tm;
+
+		now = time(NULL);
+		tm = pg_localtime(&now, tzp);
+		tz = -tm->tm_gmtoff;
 	}
+	else
+	{
+		char	   *lowzone;
+		int			type,
+					val;
 
-	/* Get the offset-from-GMT that is valid today for the selected zone */
-	if ((now = time(NULL)) < 0 ||
-	    (tm = pg_localtime(&now, tzp)) == NULL) {
-	   	ereport(ERROR,
-	   		(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			 errmsg("could not determine current time")));
-		PG_RETURN_NULL();
+		lowzone = downcase_truncate_identifier(VARDATA(zone),
+											   VARSIZE(zone) - VARHDRSZ,
+											   false);
+		type = DecodeSpecial(0, lowzone, &val);
+
+		if (type == TZ || type == DTZ)
+			tz = val * 60;
+		else
+		{
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("time zone \"%s\" not recognized", tzname)));
+			tz = 0;				/* keep compiler quiet */
+		}
 	}
 
-	result = (TimeTzADT *)palloc(sizeof(TimeTzADT));
+	result = (TimeTzADT *) palloc(sizeof(TimeTzADT));
 	
-	tz = -tm->tm_gmtoff;
 #ifdef HAVE_INT64_TIMESTAMP
 	result->time = t->time + (t->zone - tz) * USECS_PER_SEC;
 	while (result->time < INT64CONST(0))