Fix some odd behaviors when using a SQL-style simple GMT offset timezone.

Formerly, when using a SQL-spec timezone setting with a fixed GMT offset
(called a "brute force" timezone in the code), the session_timezone
variable was not updated to match the nominal timezone; rather, all code
was expected to ignore session_timezone if HasCTZSet was true.  This is
of course obviously fragile, though a search of the code finds only
timeofday() failing to honor the rule.  A bigger problem was that
DetermineTimeZoneOffset() supposed that if its pg_tz parameter was
pointer-equal to session_timezone, then HasCTZSet should override the
parameter.  This would cause datetime input containing an explicit zone
name to be treated as referencing the brute-force zone instead, if the
zone name happened to match the session timezone that had prevailed
before installing the brute-force zone setting (as reported in bug #8572).
The same malady could affect AT TIME ZONE operators.

To fix, set up session_timezone so that it matches the brute-force zone
specification, which we can do using the POSIX timezone definition syntax
"<abbrev>offset", and get rid of the bogus lookaside check in
DetermineTimeZoneOffset().  Aside from fixing the erroneous behavior in
datetime parsing and AT TIME ZONE, this will cause the timeofday() function
to print its result in the user-requested time zone rather than some
previously-set zone.  It might also affect results in third-party
extensions, if there are any that make use of session_timezone without
considering HasCTZSet, but in all cases the new behavior should be saner
than before.

Back-patch to all supported branches.

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 5d894ba77f74d02637008deedd4ca2919d8af6b8..3444ed4835468d435e1a16ce8bcd559c7b9d3295 100644 (file)
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -326,6 +326,7 @@ check_timezone(char **newval, void **extra, GucSource source)
 #else
                myextra.CTimeZone = -interval->time;
 #endif
+               myextra.session_timezone = pg_tzset_offset(myextra.CTimeZone);
                myextra.HasCTZSet = true;
 
                pfree(interval);
@@ -340,6 +341,7 @@ check_timezone(char **newval, void **extra, GucSource source)
                {
                        /* Here we change from SQL to Unix sign convention */
                        myextra.CTimeZone = -hours * SECS_PER_HOUR;
+                       myextra.session_timezone = pg_tzset_offset(myextra.CTimeZone);
                        myextra.HasCTZSet = true;
                }
                else

diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 202763b1c7fa195e865b28140d0c575e363e523b..4763a6fe588fa7396d20f4d34c19e1f12501b168 100644 (file)
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -1443,12 +1443,6 @@ DetermineTimeZoneOffset(struct pg_tm * tm, pg_tz *tzp)
                                after_isdst;
        int                     res;
 
-       if (tzp == session_timezone && HasCTZSet)
-       {
-               tm->tm_isdst = 0;               /* for lack of a better idea */
-               return CTimeZone;
-       }
-
        /*
         * First, generate the pg_time_t value corresponding to the given
         * y/m/d/h/m/s taken as GMT time.  If this overflows, punt and decide the

diff --git a/src/include/pgtime.h b/src/include/pgtime.h
index f6e2514fdcee7d3e992ec1088e7a5292cc818dfc..e840d0f0a3cd290ab03c48108cb4425a9adaa447 100644 (file)
--- a/src/include/pgtime.h
+++ b/src/include/pgtime.h
@@ -68,6 +68,7 @@ extern pg_tz *log_timezone;
 
 extern void pg_timezone_initialize(void);
 extern pg_tz *pg_tzset(const char *tzname);
+extern pg_tz *pg_tzset_offset(long gmtoffset);
 
 extern pg_tzenum *pg_tzenumerate_start(void);
 extern pg_tz *pg_tzenumerate_next(pg_tzenum *dir);

diff --git a/src/test/regress/expected/horology.out b/src/test/regress/expected/horology.out
index 553a158e2c79fed6358684eb767e0fa2d43b555c..2666deea88bd9838f48f2037378d31bc1b26f8fe 100644 (file)
--- a/src/test/regress/expected/horology.out
+++ b/src/test/regress/expected/horology.out
@@ -2935,3 +2935,33 @@ DETAIL:  Value must be an integer.
 SELECT to_timestamp('10000000000', 'FMYYYY');
 ERROR:  value for "YYYY" in source string is out of range
 DETAIL:  Value must be in the range -2147483648 to 2147483647.
+--
+-- Check behavior with SQL-style fixed-GMT-offset time zone (cf bug #8572)
+--
+SET TIME ZONE 'America/New_York';
+SET TIME ZONE '-1.5';
+SHOW TIME ZONE;
+       TimeZone       
+----------------------
+ @ 1 hour 30 mins ago
+(1 row)
+
+SELECT '2012-12-12 12:00'::timestamptz;
+           timestamptz           
+---------------------------------
+ Wed Dec 12 12:00:00 2012 -01:30
+(1 row)
+
+SELECT '2012-12-12 12:00 America/New_York'::timestamptz;
+           timestamptz           
+---------------------------------
+ Wed Dec 12 15:30:00 2012 -01:30
+(1 row)
+
+SELECT to_char('2012-12-12 12:00'::timestamptz, 'YYYY-MM-DD HH:MI:SS TZ');
+       to_char        
+----------------------
+ 2012-12-12 12:00:00 
+(1 row)
+
+RESET TIME ZONE;

diff --git a/src/test/regress/sql/horology.sql b/src/test/regress/sql/horology.sql
index ea794ecdd935f64a57ae462c867c6263dd6d8f2f..fe9a520cb91437638c6cf50f5ccd1a47607aae0b 100644 (file)
--- a/src/test/regress/sql/horology.sql
+++ b/src/test/regress/sql/horology.sql
@@ -461,3 +461,19 @@ SELECT to_timestamp('199711xy', 'YYYYMMDD');
 
 -- Input that doesn't fit in an int:
 SELECT to_timestamp('10000000000', 'FMYYYY');
+
+--
+-- Check behavior with SQL-style fixed-GMT-offset time zone (cf bug #8572)
+--
+
+SET TIME ZONE 'America/New_York';
+SET TIME ZONE '-1.5';
+
+SHOW TIME ZONE;
+
+SELECT '2012-12-12 12:00'::timestamptz;
+SELECT '2012-12-12 12:00 America/New_York'::timestamptz;
+
+SELECT to_char('2012-12-12 12:00'::timestamptz, 'YYYY-MM-DD HH:MI:SS TZ');
+
+RESET TIME ZONE;

diff --git a/src/timezone/pgtz.c b/src/timezone/pgtz.c
index 3dae9e5e9fd711a40ca4508b04a403da58caa397..d5bc83ecf81ecc89fc618b715b7e64711912e209 100644 (file)
--- a/src/timezone/pgtz.c
+++ b/src/timezone/pgtz.c
@@ -288,6 +288,46 @@ pg_tzset(const char *name)
        return &tzp->tz;
 }
 
+/*
+ * Load a fixed-GMT-offset timezone.
+ * This is used for SQL-spec SET TIME ZONE INTERVAL 'foo' cases.
+ * It's otherwise equivalent to pg_tzset().
+ *
+ * The GMT offset is specified in seconds, positive values meaning west of
+ * Greenwich (ie, POSIX not ISO sign convention).  However, we use ISO
+ * sign convention in the displayable abbreviation for the zone.
+ */
+pg_tz *
+pg_tzset_offset(long gmtoffset)
+{
+       long            absoffset = (gmtoffset < 0) ? -gmtoffset : gmtoffset;
+       char            offsetstr[64];
+       char            tzname[128];
+
+       snprintf(offsetstr, sizeof(offsetstr),
+                        "%02ld", absoffset / SECSPERHOUR);
+       absoffset %= SECSPERHOUR;
+       if (absoffset != 0)
+       {
+               snprintf(offsetstr + strlen(offsetstr),
+                                sizeof(offsetstr) - strlen(offsetstr),
+                                ":%02ld", absoffset / SECSPERMIN);
+               absoffset %= SECSPERMIN;
+               if (absoffset != 0)
+                       snprintf(offsetstr + strlen(offsetstr),
+                                        sizeof(offsetstr) - strlen(offsetstr),
+                                        ":%02ld", absoffset);
+       }
+       if (gmtoffset > 0)
+               snprintf(tzname, sizeof(tzname), "<-%s>+%s",
+                                offsetstr, offsetstr);
+       else
+               snprintf(tzname, sizeof(tzname), "<+%s>-%s",
+                                offsetstr, offsetstr);
+
+       return pg_tzset(tzname);
+}
+
 
 /*
  * Initialize timezone library