1 files changed, 11 insertions, 47 deletions

diff --git a/src/timezone/localtime.c b/src/timezone/localtime.c
index 0f65f3c648e..fa3c059038c 100644
--- a/src/timezone/localtime.c
+++ b/src/timezone/localtime.c
@@ -53,14 +53,7 @@ static const char wildabbr[] = WILDABBR;
 static const char gmt[] = "GMT";
 
 /*
- * PG: We cache the result of trying to load the TZDEFRULES zone here.
- * tzdefrules_loaded is 0 if not tried yet, +1 if good, -1 if failed.
- */
-static struct state *tzdefrules_s = NULL;
-static int	tzdefrules_loaded = 0;
-
-/*
- * The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
+ * The DST rules to use if a POSIX TZ string has no rules.
  * Default to US rules as of 2017-05-07.
  * POSIX does not specify the default DST rules;
  * for historical reasons, US rules are a common default.
@@ -986,14 +979,15 @@ tzparse(const char *name, struct state *sp, bool lastditch)
 		return false;
 
 	/*
-	 * The IANA code always tries tzload(TZDEFRULES) here.  We do not want to
-	 * do that; it would be bad news in the lastditch case, where we can't
-	 * assume pg_open_tzfile() is sane yet.  Moreover, the only reason to do
-	 * it unconditionally is to absorb the TZDEFRULES zone's leap second info,
-	 * which we don't want to do anyway.  Without that, we only need to load
-	 * TZDEFRULES if the zone name specifies DST but doesn't incorporate a
-	 * POSIX-style transition date rule, which is not a common case.
+	 * The IANA code always tries to tzload(TZDEFRULES) here.  We do not want
+	 * to do that; it would be bad news in the lastditch case, where we can't
+	 * assume pg_open_tzfile() is sane yet.  Moreover, if we did load it and
+	 * it contains leap-second-dependent info, that would cause problems too.
+	 * Finally, IANA has deprecated the TZDEFRULES feature, so it presumably
+	 * will die at some point.  Desupporting it now seems like good
+	 * future-proofing.
 	 */
+	load_ok = false;
 	sp->goback = sp->goahead = false;	/* simulate failed tzload() */
 	sp->leapcnt = 0;			/* intentionally assume no leap seconds */
 
@@ -1027,38 +1021,8 @@ tzparse(const char *name, struct state *sp, bool lastditch)
 		}
 		else
 			dstoffset = stdoffset - SECSPERHOUR;
-		if (*name == '\0')
-		{
-			/*
-			 * The POSIX zone name does not provide a transition-date rule.
-			 * Here we must load the TZDEFRULES zone, if possible, to serve as
-			 * source data for the transition dates.  Unlike the IANA code, we
-			 * try to cache the data so it's only loaded once.
-			 */
-			if (tzdefrules_loaded == 0)
-			{
-				/* Allocate on first use */
-				if (tzdefrules_s == NULL)
-					tzdefrules_s = (struct state *) malloc(sizeof(struct state));
-				if (tzdefrules_s != NULL)
-				{
-					if (tzload(TZDEFRULES, NULL, tzdefrules_s, false) == 0)
-						tzdefrules_loaded = 1;
-					else
-						tzdefrules_loaded = -1;
-					/* In any case, we ignore leap-second data from the file */
-					tzdefrules_s->leapcnt = 0;
-				}
-			}
-			load_ok = (tzdefrules_loaded > 0);
-			if (load_ok)
-				memcpy(sp, tzdefrules_s, sizeof(struct state));
-			else
-			{
-				/* If we can't load TZDEFRULES, fall back to hard-wired rule */
-				name = TZDEFRULESTRING;
-			}
-		}
+		if (*name == '\0' && !load_ok)
+			name = TZDEFRULESTRING;
 		if (*name == ',' || *name == ';')
 		{
 			struct rule start;