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, 49 insertions, 31 deletions

diff --git a/src/timezone/pgtz.c b/src/timezone/pgtz.c
index ac97e981530..26ff1ea1129 100644
--- a/src/timezone/pgtz.c
+++ b/src/timezone/pgtz.c
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.51 2007/05/31 15:13:06 petere Exp $
+ *	  $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.52 2007/08/04 01:26:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -27,8 +27,11 @@
 #include "utils/guc.h"
 #include "utils/hsearch.h"
 
-/* Current global timezone */
-pg_tz	   *global_timezone = NULL;
+/* Current session timezone (controlled by TimeZone GUC) */
+pg_tz	   *session_timezone = NULL;
+
+/* Current log timezone (controlled by log_timezone GUC) */
+pg_tz	   *log_timezone = NULL;
 
 
 static char tzdir[MAXPGPATH];
@@ -38,8 +41,8 @@ static bool scan_directory_ci(const char *dirname,
 							  const char *fname, int fnamelen,
 							  char *canonname, int canonnamelen);
 static const char *identify_system_timezone(void);
-static const char *select_default_timezone(void);
-static bool set_global_timezone(const char *tzname);
+static pg_tz *get_pg_tz_for_zone(const char *tzname);
+static pg_tz *select_default_timezone(void);
 
 
 /*
@@ -1196,51 +1199,51 @@ tz_acceptable(pg_tz *tz)
 
 
 /*
- * Set the global timezone. Verify that it's acceptable first.
+ * Get a pg_tz struct for the given timezone name.  Returns NULL if name
+ * is invalid or not an "acceptable" zone.
  */
-static bool
-set_global_timezone(const char *tzname)
+static pg_tz *
+get_pg_tz_for_zone(const char *tzname)
 {
-	pg_tz	   *tznew;
+	pg_tz	   *tz;
 
 	if (!tzname || !tzname[0])
-		return false;
+		return NULL;
 
-	tznew = pg_tzset(tzname);
-	if (!tznew)
-		return false;
+	tz = pg_tzset(tzname);
+	if (!tz)
+		return NULL;
 
-	if (!tz_acceptable(tznew))
-		return false;
+	if (!tz_acceptable(tz))
+		return NULL;
 
-	global_timezone = tznew;
-	return true;
+	return tz;
 }
 
 /*
- * Identify a suitable default timezone setting based on the environment,
- * and make it active.
+ * Identify a suitable default timezone setting based on the environment.
  *
  * We first look to the TZ environment variable.  If not found or not
  * recognized by our own code, we see if we can identify the timezone
  * from the behavior of the system timezone library.  When all else fails,
  * fall back to GMT.
  */
-static const char *
+static pg_tz *
 select_default_timezone(void)
 {
-	const char *def_tz;
+	pg_tz	   *def_tz;
 
-	def_tz = getenv("TZ");
-	if (set_global_timezone(def_tz))
+	def_tz = get_pg_tz_for_zone(getenv("TZ"));
+	if (def_tz)
 		return def_tz;
 
-	def_tz = identify_system_timezone();
-	if (set_global_timezone(def_tz))
+	def_tz = get_pg_tz_for_zone(identify_system_timezone());
+	if (def_tz)
 		return def_tz;
 
-	if (set_global_timezone("GMT"))
-		return "GMT";
+	def_tz = get_pg_tz_for_zone("GMT");
+	if (def_tz)
+		return def_tz;
 
 	ereport(FATAL,
 			(errmsg("could not select a suitable default timezone"),
@@ -1253,19 +1256,34 @@ select_default_timezone(void)
  *
  * This is called after initial loading of postgresql.conf.  If no TimeZone
  * setting was found therein, we try to derive one from the environment.
+ * Likewise for log_timezone.
  */
 void
 pg_timezone_initialize(void)
 {
-	/* Do we need to try to figure the timezone? */
+	pg_tz	   *def_tz = NULL;
+
+	/* Do we need to try to figure the session timezone? */
 	if (pg_strcasecmp(GetConfigOption("timezone"), "UNKNOWN") == 0)
 	{
-		const char *def_tz;
-
 		/* Select setting */
 		def_tz = select_default_timezone();
+		session_timezone = def_tz;
+		/* Tell GUC about the value. Will redundantly call pg_tzset() */
+		SetConfigOption("timezone", pg_get_timezone_name(def_tz),
+						PGC_POSTMASTER, PGC_S_ARGV);
+	}
+
+	/* What about the log timezone? */
+	if (pg_strcasecmp(GetConfigOption("log_timezone"), "UNKNOWN") == 0)
+	{
+		/* Select setting, but don't duplicate work */
+		if (!def_tz)
+			def_tz = select_default_timezone();
+		log_timezone = def_tz;
 		/* Tell GUC about the value. Will redundantly call pg_tzset() */
-		SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ARGV);
+		SetConfigOption("log_timezone", pg_get_timezone_name(def_tz),
+						PGC_POSTMASTER, PGC_S_ARGV);
 	}
 }