Switch over to using the src/timezone functions for formatting timestamps

displayed in the postmaster log.  This avoids Windows-specific problems with
localized time zone names that are in the wrong encoding, and generally seems
like a good idea to forestall other potential platform-dependent issues.
To preserve the existing behavior that all backends will log in the same time
zone, create a new GUC variable log_timezone that can only be changed on a
system-wide basis, and reference log-related calculations to that zone instead
of the TimeZone variable.

This fixes the issue reported by Hiroshi Saito that timestamps printed by
xlog.c startup could be improperly localized on Windows.  We still need a
simpler patch for that problem in the back branches, however.

1 files changed, 109 insertions, 4 deletions

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 1f6839cbd17..8a04a975ca1 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.120 2007/01/05 22:19:27 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.121 2007/08/04 01:26:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -344,7 +344,7 @@ assign_timezone(const char *value, bool doit, GucSource source)
 			 */
 			if (doit)
 			{
-				const char *curzone = pg_get_timezone_name(global_timezone);
+				const char *curzone = pg_get_timezone_name(session_timezone);
 
 				if (curzone)
 					value = curzone;
@@ -381,7 +381,7 @@ assign_timezone(const char *value, bool doit, GucSource source)
 			if (doit)
 			{
 				/* Save the changed TZ */
-				global_timezone = new_tz;
+				session_timezone = new_tz;
 				HasCTZSet = false;
 			}
 		}
@@ -434,7 +434,112 @@ show_timezone(void)
 											  IntervalPGetDatum(&interval)));
 	}
 	else
-		tzn = pg_get_timezone_name(global_timezone);
+		tzn = pg_get_timezone_name(session_timezone);
+
+	if (tzn != NULL)
+		return tzn;
+
+	return "unknown";
+}
+
+
+/*
+ * LOG_TIMEZONE
+ *
+ * For log_timezone, we don't support the interval-based methods of setting a
+ * zone, which are only there for SQL spec compliance not because they're
+ * actually useful.
+ */
+
+/*
+ * assign_log_timezone: GUC assign_hook for log_timezone
+ */
+const char *
+assign_log_timezone(const char *value, bool doit, GucSource source)
+{
+	char	   *result;
+
+	if (pg_strcasecmp(value, "UNKNOWN") == 0)
+	{
+		/*
+		 * UNKNOWN is the value shown as the "default" for log_timezone in
+		 * guc.c.  We interpret it as being a complete no-op; we don't
+		 * change the timezone setting.  Note that if there is a known
+		 * timezone setting, we will return that name rather than UNKNOWN
+		 * as the canonical spelling.
+		 *
+		 * During GUC initialization, since the timezone library isn't set
+		 * up yet, pg_get_timezone_name will return NULL and we will leave
+		 * the setting as UNKNOWN.	If this isn't overridden from the
+		 * config file then pg_timezone_initialize() will eventually
+		 * select a default value from the environment.
+		 */
+		if (doit)
+		{
+			const char *curzone = pg_get_timezone_name(log_timezone);
+
+			if (curzone)
+				value = curzone;
+		}
+	}
+	else
+	{
+		/*
+		 * Otherwise assume it is a timezone name, and try to load it.
+		 */
+		pg_tz	   *new_tz;
+
+		new_tz = pg_tzset(value);
+
+		if (!new_tz)
+		{
+			ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("unrecognized time zone name: \"%s\"",
+							value)));
+			return NULL;
+		}
+
+		if (!tz_acceptable(new_tz))
+		{
+			ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("time zone \"%s\" appears to use leap seconds",
+							value),
+					 errdetail("PostgreSQL does not support leap seconds.")));
+			return NULL;
+		}
+
+		if (doit)
+		{
+			/* Save the changed TZ */
+			log_timezone = new_tz;
+		}
+	}
+
+	/*
+	 * If we aren't going to do the assignment, just return OK indicator.
+	 */
+	if (!doit)
+		return value;
+
+	/*
+	 * Prepare the canonical string to return.	GUC wants it malloc'd.
+	 */
+	result = strdup(value);
+
+	return result;
+}
+
+/*
+ * show_log_timezone: GUC show_hook for log_timezone
+ */
+const char *
+show_log_timezone(void)
+{
+	const char *tzn;
+
+	tzn = pg_get_timezone_name(log_timezone);
 
 	if (tzn != NULL)
 		return tzn;