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.

6 files changed, 134 insertions, 82 deletions

diff --git a/doc/src/sgml/datetime.sgml b/doc/src/sgml/datetime.sgml
index 8866137441..aeeb129833 100644
--- a/doc/src/sgml/datetime.sgml
+++ b/doc/src/sgml/datetime.sgml
@@ -990,9 +990,7 @@ $PostgreSQL$
    <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 @@ $PostgreSQL$
    </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>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index b0ecbf6ac8..befe4c473b 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -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>
diff --git a/src/backend/utils/adt/date.c b/src/backend/utils/adt/date.c
index 1c1d84f017..aa0133492a 100644
--- a/src/backend/utils/adt/date.c
+++ b/src/backend/utils/adt/date.c
@@ -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))
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 3b3840bae1..df15e2dc31 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -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;
@@ -3948,48 +3948,64 @@ Datum
 timestamp_zone(PG_FUNCTION_ARGS)
 {
 	text	   *zone = PG_GETARG_TEXT_P(0);
-	Timestamp timestamp = PG_GETARG_TIMESTAMP(1);
+	Timestamp	timestamp = PG_GETARG_TIMESTAMP(1);
 	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)
 	{
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("time zone \"%s\" not recognised",
-				        tzname)));
-		PG_RETURN_NULL();
-	}
+		/* Apply the timezone change */
+		struct pg_tm tm;
+		fsec_t      fsec;
 
-	/* Apply the timezone change */
-	fail = (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, tzp) != 0);
-	if (!fail)
-	{
+		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);
-		fail = (tm2timestamp(&tm, fsec, &tz, &result) != 0);
+		if (tm2timestamp(&tm, fsec, &tz, &result) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("could not convert to time zone \"%s\"",
+							tzname)));
 	}
-	if (fail)
+	else
 	{
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("could not convert to time zone \"%s\"",
-				        tzname)));
-		PG_RETURN_NULL();
+		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("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)
 	{
-		ereport(ERROR,
-			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			 errmsg("time zone \"%s\" not recognized", tzname)));
+		/* Apply the timezone change */
+		struct pg_tm tm;
+		fsec_t      fsec;
 
-		PG_RETURN_NULL();
+		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("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))
-	{ 
-		ereport(ERROR,
-			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			errmsg("could not to convert to time zone \"%s\"", tzname)));
-		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 = dt2local(timestamp, tz);
 	}
 
 	PG_RETURN_TIMESTAMP(result);
diff --git a/src/include/pgtime.h b/src/include/pgtime.h
index 8bb5ab0e88..623701df85 100644
--- a/src/include/pgtime.h
+++ b/src/include/pgtime.h
@@ -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 */
diff --git a/src/timezone/pgtz.c b/src/timezone/pgtz.c
index e99a89eb0e..7986d39603 100644
--- a/src/timezone/pgtz.c
+++ b/src/timezone/pgtz.c
@@ -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)