Fix incorrect translation of minus-infinity datetimes for json/jsonb.

Commit bda76c1c8cfb1d11751ba6be88f0242850481733 caused both plus and
minus infinity to be rendered as "infinity", which is not only wrong
but inconsistent with the pre-9.4 behavior of to_json().  Fix that by
duplicating the coding in date_out/timestamp_out/timestamptz_out more
closely.  Per bug #13687 from Stepan Perlov.  Back-patch to 9.4, like
the previous commit.

In passing, also re-pgindent json.c, since it had gotten a bit messed up by
recent patches (and I was already annoyed by indentation-related problems
in back-patching this fix ...)

src/backend/utils/adt/date.c

@@ -40,7 +40,6 @@
 #endif
 
 
-static void EncodeSpecialDate(DateADT dt, char *str);
 static int	time2tm(TimeADT time, struct pg_tm * tm, fsec_t *fsec);
 static int	timetz2tm(TimeTzADT *time, struct pg_tm * tm, fsec_t *fsec, int *tzp);
 static int	tm2time(struct pg_tm * tm, fsec_t fsec, TimeADT *result);
@@ -273,7 +272,7 @@ make_date(PG_FUNCTION_ARGS)
 /*
  * Convert reserved date values to string.
  */
-static void
+void
 EncodeSpecialDate(DateADT dt, char *str)
 {
 	if (DATE_IS_NOBEGIN(dt))

src/backend/utils/adt/json.c

@@ -33,9 +33,6 @@
 #include "utils/typcache.h"
 #include "utils/syscache.h"
 
-/* String to output for infinite dates and timestamps */
-#define DT_INFINITY "\"infinity\""
-
 /*
  * The context of the parser is maintained by the recursive descent
  * mechanism, but is passed explicitly to the error reporting routine
@@ -1435,19 +1432,16 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 				char		buf[MAXDATELEN + 1];
 
 				date = DatumGetDateADT(val);
-
+				/* Same as date_out(), but forcing DateStyle */
 				if (DATE_NOT_FINITE(date))
-				{
-					/* we have to format infinity ourselves */
-					appendStringInfoString(result,DT_INFINITY);
-				}
+					EncodeSpecialDate(date, buf);
 				else
 				{
 					j2date(date + POSTGRES_EPOCH_JDATE,
 						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
 					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
-					appendStringInfo(result, "\"%s\"", buf);
 				}
+				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMP:
@@ -1458,21 +1452,16 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 				char		buf[MAXDATELEN + 1];
 
 				timestamp = DatumGetTimestamp(val);
-
+				/* Same as timestamp_out(), but forcing DateStyle */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
-				{
-					/* we have to format infinity ourselves */
-					appendStringInfoString(result,DT_INFINITY);
-				}
+					EncodeSpecialTimestamp(timestamp, buf);
 				else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
-				{
 					EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
-					appendStringInfo(result, "\"%s\"", buf);
-				}
 				else
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
+				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMPTZ:
@@ -1484,22 +1473,17 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 				const char *tzn = NULL;
 				char		buf[MAXDATELEN + 1];
 
-				timestamp = DatumGetTimestamp(val);
-
+				timestamp = DatumGetTimestampTz(val);
+				/* Same as timestamptz_out(), but forcing DateStyle */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
-				{
-					/* we have to format infinity ourselves */
-					appendStringInfoString(result,DT_INFINITY);
-				}
+					EncodeSpecialTimestamp(timestamp, buf);
 				else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
-				{
 					EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
-					appendStringInfo(result, "\"%s\"", buf);
-				}
 				else
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
+				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_JSON:

src/backend/utils/adt/timestamp.c

@@ -75,7 +75,6 @@ typedef struct
 
 
 static TimeOffset time2t(const int hour, const int min, const int sec, const fsec_t fsec);
-static void EncodeSpecialTimestamp(Timestamp dt, char *str);
 static Timestamp dt2local(Timestamp dt, int timezone);
 static void AdjustTimestampForTypmod(Timestamp *time, int32 typmod);
 static void AdjustIntervalForTypmod(Interval *interval, int32 typmod);
@@ -1507,7 +1506,7 @@ make_interval(PG_FUNCTION_ARGS)
 /* EncodeSpecialTimestamp()
  * Convert reserved timestamp data type to string.
  */
-static void
+void
 EncodeSpecialTimestamp(Timestamp dt, char *str)
 {
 	if (TIMESTAMP_IS_NOBEGIN(dt))

src/include/utils/date.h

@@ -92,6 +92,7 @@ typedef struct
 
 /* date.c */
 extern double date2timestamp_no_overflow(DateADT dateVal);
+extern void EncodeSpecialDate(DateADT dt, char *str);
 
 extern Datum date_in(PG_FUNCTION_ARGS);
 extern Datum date_out(PG_FUNCTION_ARGS);

src/include/utils/datetime.h

@@ -319,6 +319,7 @@ extern void EncodeDateOnly(struct pg_tm * tm, int style, char *str);
 extern void EncodeTimeOnly(struct pg_tm * tm, fsec_t fsec, bool print_tz, int tz, int style, char *str);
 extern void EncodeDateTime(struct pg_tm * tm, fsec_t fsec, bool print_tz, int tz, const char *tzn, int style, char *str);
 extern void EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str);
+extern void EncodeSpecialTimestamp(Timestamp dt, char *str);
 
 extern int ValidateDate(int fmask, bool isjulian, bool is2digits, bool bc,
 			 struct pg_tm * tm);

src/test/regress/expected/json.out

@@ -418,18 +418,36 @@ select to_json(date 'Infinity');
  "infinity"
 (1 row)
 
+select to_json(date '-Infinity');
+   to_json   
+-------------
+ "-infinity"
+(1 row)
+
 select to_json(timestamp 'Infinity');
   to_json   
 ------------
  "infinity"
 (1 row)
 
+select to_json(timestamp '-Infinity');
+   to_json   
+-------------
+ "-infinity"
+(1 row)
+
 select to_json(timestamptz 'Infinity');
   to_json   
 ------------
  "infinity"
 (1 row)
 
+select to_json(timestamptz '-Infinity');
+   to_json   
+-------------
+ "-infinity"
+(1 row)
+
 --json_agg
 SELECT json_agg(q)
   FROM ( SELECT $$a$$ || x AS b, y AS c,

src/test/regress/sql/json.sql

@@ -116,8 +116,11 @@ COMMIT;
 select to_json(date '2014-05-28');
 
 select to_json(date 'Infinity');
+select to_json(date '-Infinity');
 select to_json(timestamp 'Infinity');
+select to_json(timestamp '-Infinity');
 select to_json(timestamptz 'Infinity');
+select to_json(timestamptz '-Infinity');
 
 --json_agg