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.

doc/src/sgml/datetime.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/datetime.sgml,v 2.46 2005/06/15 00:34:08 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/datetime.sgml,v 2.47 2005/09/09 02:31:48 tgl Exp $
 -->
 
  <appendix id="datetime-appendix">
@@ -990,9 +990,7 @@ $PostgreSQL: pgsql/doc/src/sgml/datetime.sgml,v 2.46 2005/06/15 00:34:08 momjian
    <para>
     <xref linkend="datetime-timezone-set-table"> shows the time zone
     names recognized by <productname>PostgreSQL</productname> as valid
-    settings for the <xref linkend="guc-timezone"> parameter, and as
-	parameters to the <literal>AT TIME ZONE function</> (see 
-	<xref linkend="functions-datetime-zoneconvert">).  Note that
+    settings for the <xref linkend="guc-timezone"> parameter.  Note that
     these names are conceptually as well as practically different from
     the names shown in <xref linkend="datetime-timezone-input-table">:
     most of these names imply a local daylight-savings time rule, whereas
@@ -1006,7 +1004,7 @@ $PostgreSQL: pgsql/doc/src/sgml/datetime.sgml,v 2.46 2005/06/15 00:34:08 momjian
    </para>
 
     <table id="datetime-timezone-set-table">
-     <title>Time Zone Names for Setting <varname>timezone</> and <literal>AT TIME ZONE</></title>
+     <title>Time Zone Names for Setting <varname>timezone</></title>
      <tgroup cols="1">
       <thead>
        <row>

doc/src/sgml/func.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.283 2005/08/25 01:29:55 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.284 2005/09/09 02:31:48 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -5730,9 +5730,9 @@ SELECT date_trunc('year', TIMESTAMP '2001-02-16 20:38:40');
     In these expressions, the desired time zone <replaceable>zone</> can be
     specified either as a text string (e.g., <literal>'PST'</literal>)
     or as an interval (e.g., <literal>INTERVAL '-08:00'</literal>).
-    In the text case, the available zone names are those shown in
-    <xref linkend="datetime-timezone-set-table">.  The time zone can
-    also be implied using the default time zone for that session.
+    In the text case, the available zone names are those shown in either
+    <xref linkend="datetime-timezone-set-table"> or
+    <xref linkend="datetime-timezone-input-table">.
    </para>
 
    <para>

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) {
+		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("could not determine current time")));
-		PG_RETURN_NULL();
+					 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))

src/backend/utils/adt/timestamp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.151 2005/08/25 05:01:43 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.152 2005/09/09 02:31:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1014,7 +1014,7 @@ dt2time(Timestamp jd, int *hour, int *min, int *sec, fsec_t *fsec)
  *	 0 on success
  *	-1 on out of range
  *
- * If attimezone is NULL, the global timezone (including possblly brute forced
+ * If attimezone is NULL, the global timezone (including possibly brute forced
  * timezone) will be used.
  */
 int
@@ -1113,8 +1113,8 @@ timestamp2tm(Timestamp dt, int *tzp, struct pg_tm *tm, fsec_t *fsec, char **tzn,
 	utime = (pg_time_t) dt;
 	if ((Timestamp) utime == dt)
 	{
-		struct pg_tm *tx = pg_localtime(&utime, (attimezone != NULL) ?
-										attimezone : global_timezone);
+		struct pg_tm *tx = pg_localtime(&utime,
+										attimezone ? attimezone : global_timezone);
 
 		tm->tm_year = tx->tm_year + 1900;
 		tm->tm_mon = tx->tm_mon + 1;
@@ -3952,44 +3952,60 @@ timestamp_zone(PG_FUNCTION_ARGS)
 	TimestampTz	result;
 	int			tz;
 	pg_tz      *tzp;
-	char        tzname[TZ_STRLEN_MAX+1];
+	char        tzname[TZ_STRLEN_MAX + 1];
 	int         len;
-	struct pg_tm tm;
-	fsec_t      fsec;
-	bool		fail;
 	
 	if (TIMESTAMP_NOT_FINITE(timestamp))
 		PG_RETURN_TIMESTAMPTZ(timestamp);
 
-	/* 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)
+	if (tzp)
 	{
+		/* Apply the timezone change */
+		struct pg_tm tm;
+		fsec_t      fsec;
+
+		if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, tzp) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+					 errmsg("timestamp out of range")));
+		tz = DetermineTimeZoneOffset(&tm, tzp);
+		if (tm2timestamp(&tm, fsec, &tz, &result) != 0)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("time zone \"%s\" not recognised",
+					 errmsg("could not convert to time zone \"%s\"",
 							tzname)));
-		PG_RETURN_NULL();
 	}
-
-	/* Apply the timezone change */
-	fail = (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, tzp) != 0);
-	if (!fail)
+	else
 	{
-		tz = DetermineTimeZoneOffset(&tm, tzp);
-		fail = (tm2timestamp(&tm, fsec, &tz, &result) != 0);
-	}
-	if (fail)
+		char	   *lowzone;
+		int			type,
+					val;
+
+		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("could not convert to time zone \"%s\"",
-				        tzname)));
-		PG_RETURN_NULL();
+					 errmsg("time zone \"%s\" not recognized", tzname)));
+			tz = 0;				/* keep compiler quiet */
+		}
+
+		result = dt2local(timestamp, tz);
 	}
 
 	PG_RETURN_TIMESTAMPTZ(result);
@@ -4109,37 +4125,59 @@ timestamptz_zone(PG_FUNCTION_ARGS)
 	Timestamp	result;
 	int			tz;
 	pg_tz	   *tzp;
-	char        tzname[TZ_STRLEN_MAX];
+	char        tzname[TZ_STRLEN_MAX + 1];
 	int         len;
-	struct pg_tm tm;
-	fsec_t      fsec = 0;
 
 	if (TIMESTAMP_NOT_FINITE(timestamp))
-		PG_RETURN_NULL();
+		PG_RETURN_TIMESTAMP(timestamp);
 
-	/* Find the specified zone */
-	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)
+	if (tzp)
 	{
+		/* Apply the timezone change */
+		struct pg_tm tm;
+		fsec_t      fsec;
+
+		if (timestamp2tm(timestamp, &tz, &tm, &fsec, NULL, tzp) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+					 errmsg("timestamp out of range")));
+		if (tm2timestamp(&tm, fsec, NULL, &result) != 0)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			 errmsg("time zone \"%s\" not recognized", tzname)));
-
-		PG_RETURN_NULL();
+					 errmsg("could not convert to time zone \"%s\"",
+							tzname)));
 	}
+	else
+	{
+		char	   *lowzone;
+		int			type,
+					val;
 
-	if (timestamp2tm(timestamp, &tz, &tm, &fsec, NULL, tzp) != 0 ||
-	    tm2timestamp(&tm, fsec, NULL, &result))
+		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("could not to convert to time zone \"%s\"", tzname)));
-		PG_RETURN_NULL();
+					 errmsg("time zone \"%s\" not recognized", tzname)));
+			tz = 0;				/* keep compiler quiet */
+		}
+
+		result = dt2local(timestamp, tz);
 	}
 
 	PG_RETURN_TIMESTAMP(result);

src/include/pgtime.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/include/pgtime.h,v 1.9 2005/07/22 03:46:34 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/include/pgtime.h,v 1.10 2005/09/09 02:31:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -58,7 +58,7 @@ extern const char *pg_get_timezone_name(pg_tz *tz);
 
 extern pg_tz *global_timezone;
 
-/* Maximum length of a timezone name */
+/* Maximum length of a timezone name (not including trailing null) */
 #define TZ_STRLEN_MAX 255
 
 #endif   /* _PGTIME_H */

src/timezone/pgtz.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.36 2005/06/26 23:32:34 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.37 2005/09/09 02:31:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -974,7 +974,7 @@ init_timezone_hashtable(void)
 
 	MemSet(&hash_ctl, 0, sizeof(hash_ctl));
 
-	hash_ctl.keysize = TZ_STRLEN_MAX;
+	hash_ctl.keysize = TZ_STRLEN_MAX + 1;
 	hash_ctl.entrysize = sizeof(pg_tz);
 
 	timezone_cache = hash_create("Timezones",
@@ -997,7 +997,7 @@ pg_tzset(const char *name)
 	pg_tz *tzp;
 	pg_tz tz;
 	
-	if (strlen(name) >= TZ_STRLEN_MAX)
+	if (strlen(name) > TZ_STRLEN_MAX)
 		return NULL;			/* not going to fit */
 
 	if (!timezone_cache)