Process variadic arguments consistently in json functions

json_build_object and json_build_array and the jsonb equivalents did not
correctly process explicit VARIADIC arguments. They are modified to use
the new extract_variadic_args() utility function which abstracts away
the details of the call method.

Michael Paquier, reviewed by Tom Lane and Dmitry Dolgov.

Backpatch to 9.5 for the jsonb fixes and 9.4 for the json fixes, as
that's where they originated.

3 files changed, 152 insertions, 60 deletions

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 7c3992661f5..72f4781c461 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -18,6 +18,7 @@
 #include "catalog/pg_cast.h"
 #include "catalog/pg_type.h"
 #include "executor/spi.h"
+#include "funcapi.h"
 #include "lib/stringinfo.h"
 #include "libpq/pqformat.h"
 #include "mb/pg_wchar.h"
@@ -2035,10 +2036,17 @@ json_build_object(PG_FUNCTION_ARGS)
 {
 	int			nargs = PG_NARGS();
 	int			i;
-	Datum		arg;
 	const char *sep = "";
 	StringInfo	result;
-	Oid			val_type;
+	Datum	   *args;
+	bool	   *nulls;
+	Oid		   *types;
+
+	/* fetch argument values to build the object */
+	nargs = extract_variadic_args(fcinfo, 0, false, &args, &types, &nulls);
+
+	if (nargs < 0)
+		PG_RETURN_NULL();
 
 	if (nargs % 2 != 0)
 		ereport(ERROR,
@@ -2052,52 +2060,22 @@ json_build_object(PG_FUNCTION_ARGS)
 
 	for (i = 0; i < nargs; i += 2)
 	{
-		/*
-		 * Note: since json_build_object() is declared as taking type "any",
-		 * the parser will not do any type conversion on unknown-type literals
-		 * (that is, undecorated strings or NULLs).  Such values will arrive
-		 * here as type UNKNOWN, which fortunately does not matter to us,
-		 * since unknownout() works fine.
-		 */
 		appendStringInfoString(result, sep);
 		sep = ", ";
 
 		/* process key */
-		val_type = get_fn_expr_argtype(fcinfo->flinfo, i);
-
-		if (val_type == InvalidOid)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("could not determine data type for argument %d",
-							i + 1)));
-
-		if (PG_ARGISNULL(i))
+		if (nulls[i])
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 					 errmsg("argument %d cannot be null", i + 1),
 					 errhint("Object keys should be text.")));
 
-		arg = PG_GETARG_DATUM(i);
-
-		add_json(arg, false, result, val_type, true);
+		add_json(args[i], false, result, types[i], true);
 
 		appendStringInfoString(result, " : ");
 
 		/* process value */
-		val_type = get_fn_expr_argtype(fcinfo->flinfo, i + 1);
-
-		if (val_type == InvalidOid)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("could not determine data type for argument %d",
-							i + 2)));
-
-		if (PG_ARGISNULL(i + 1))
-			arg = (Datum) 0;
-		else
-			arg = PG_GETARG_DATUM(i + 1);
-
-		add_json(arg, PG_ARGISNULL(i + 1), result, val_type, false);
+		add_json(args[i + 1], nulls[i + 1], result, types[i + 1], false);
 	}
 
 	appendStringInfoChar(result, '}');
@@ -2120,12 +2098,19 @@ json_build_object_noargs(PG_FUNCTION_ARGS)
 Datum
 json_build_array(PG_FUNCTION_ARGS)
 {
-	int			nargs = PG_NARGS();
+	int			nargs;
 	int			i;
-	Datum		arg;
 	const char *sep = "";
 	StringInfo	result;
-	Oid			val_type;
+	Datum	   *args;
+	bool	   *nulls;
+	Oid		   *types;
+
+	/* fetch argument values to build the array */
+	nargs = extract_variadic_args(fcinfo, 0, false, &args, &types, &nulls);
+
+	if (nargs < 0)
+		PG_RETURN_NULL();
 
 	result = makeStringInfo();
 
@@ -2133,30 +2118,9 @@ json_build_array(PG_FUNCTION_ARGS)
 
 	for (i = 0; i < nargs; i++)
 	{
-		/*
-		 * Note: since json_build_array() is declared as taking type "any",
-		 * the parser will not do any type conversion on unknown-type literals
-		 * (that is, undecorated strings or NULLs).  Such values will arrive
-		 * here as type UNKNOWN, which fortunately does not matter to us,
-		 * since unknownout() works fine.
-		 */
 		appendStringInfoString(result, sep);
 		sep = ", ";
-
-		val_type = get_fn_expr_argtype(fcinfo->flinfo, i);
-
-		if (val_type == InvalidOid)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("could not determine data type for argument %d",
-							i + 1)));
-
-		if (PG_ARGISNULL(i))
-			arg = (Datum) 0;
-		else
-			arg = PG_GETARG_DATUM(i);
-
-		add_json(arg, PG_ARGISNULL(i), result, val_type, false);
+		add_json(args[i], nulls[i], result, types[i], false);
 	}
 
 	appendStringInfoChar(result, ']');
diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index 8573b58e7c4..d0d95f2adb3 100644
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -1420,6 +1420,54 @@ SELECT json_build_array('a',1,'b',1.2,'c',true,'d',null,'e',json '{"x": 3, "y":
  ["a", 1, "b", 1.2, "c", true, "d", null, "e", {"x": 3, "y": [1,2,3]}]
 (1 row)
 
+SELECT json_build_array('a', NULL); -- ok
+ json_build_array 
+------------------
+ ["a", null]
+(1 row)
+
+SELECT json_build_array(VARIADIC NULL::text[]); -- ok
+ json_build_array 
+------------------
+ 
+(1 row)
+
+SELECT json_build_array(VARIADIC '{}'::text[]); -- ok
+ json_build_array 
+------------------
+ []
+(1 row)
+
+SELECT json_build_array(VARIADIC '{a,b,c}'::text[]); -- ok
+ json_build_array 
+------------------
+ ["a", "b", "c"]
+(1 row)
+
+SELECT json_build_array(VARIADIC ARRAY['a', NULL]::text[]); -- ok
+ json_build_array 
+------------------
+ ["a", null]
+(1 row)
+
+SELECT json_build_array(VARIADIC '{1,2,3,4}'::text[]); -- ok
+   json_build_array   
+----------------------
+ ["1", "2", "3", "4"]
+(1 row)
+
+SELECT json_build_array(VARIADIC '{1,2,3,4}'::int[]); -- ok
+ json_build_array 
+------------------
+ [1, 2, 3, 4]
+(1 row)
+
+SELECT json_build_array(VARIADIC '{{1,4},{2,5},{3,6}}'::int[][]); -- ok
+  json_build_array  
+--------------------
+ [1, 4, 2, 5, 3, 6]
+(1 row)
+
 SELECT json_build_object('a',1,'b',1.2,'c',true,'d',null,'e',json '{"x": 3, "y": [1,2,3]}');
                              json_build_object                              
 ----------------------------------------------------------------------------
@@ -1435,6 +1483,65 @@ SELECT json_build_object(
  {"a" : {"b" : false, "c" : 99}, "d" : {"e" : [9,8,7], "f" : {"relkind":"r","name":"pg_class"}}}
 (1 row)
 
+SELECT json_build_object('{a,b,c}'::text[]); -- error
+ERROR:  argument list must have even number of elements
+HINT:  The arguments of json_build_object() must consist of alternating keys and values.
+SELECT json_build_object('{a,b,c}'::text[], '{d,e,f}'::text[]); -- error, key cannot be array
+ERROR:  key value must be scalar, not array, composite, or json
+SELECT json_build_object('a', 'b', 'c'); -- error
+ERROR:  argument list must have even number of elements
+HINT:  The arguments of json_build_object() must consist of alternating keys and values.
+SELECT json_build_object(NULL, 'a'); -- error, key cannot be NULL
+ERROR:  argument 1 cannot be null
+HINT:  Object keys should be text.
+SELECT json_build_object('a', NULL); -- ok
+ json_build_object 
+-------------------
+ {"a" : null}
+(1 row)
+
+SELECT json_build_object(VARIADIC NULL::text[]); -- ok
+ json_build_object 
+-------------------
+ 
+(1 row)
+
+SELECT json_build_object(VARIADIC '{}'::text[]); -- ok
+ json_build_object 
+-------------------
+ {}
+(1 row)
+
+SELECT json_build_object(VARIADIC '{a,b,c}'::text[]); -- error
+ERROR:  argument list must have even number of elements
+HINT:  The arguments of json_build_object() must consist of alternating keys and values.
+SELECT json_build_object(VARIADIC ARRAY['a', NULL]::text[]); -- ok
+ json_build_object 
+-------------------
+ {"a" : null}
+(1 row)
+
+SELECT json_build_object(VARIADIC ARRAY[NULL, 'a']::text[]); -- error, key cannot be NULL
+ERROR:  argument 1 cannot be null
+HINT:  Object keys should be text.
+SELECT json_build_object(VARIADIC '{1,2,3,4}'::text[]); -- ok
+   json_build_object    
+------------------------
+ {"1" : "2", "3" : "4"}
+(1 row)
+
+SELECT json_build_object(VARIADIC '{1,2,3,4}'::int[]); -- ok
+ json_build_object  
+--------------------
+ {"1" : 2, "3" : 4}
+(1 row)
+
+SELECT json_build_object(VARIADIC '{{1,4},{2,5},{3,6}}'::int[][]); -- ok
+      json_build_object      
+-----------------------------
+ {"1" : 4, "2" : 5, "3" : 6}
+(1 row)
+
 -- empty objects/arrays
 SELECT json_build_array();
  json_build_array 
diff --git a/src/test/regress/sql/json.sql b/src/test/regress/sql/json.sql
index 346e5b8363f..587bcb8dd4a 100644
--- a/src/test/regress/sql/json.sql
+++ b/src/test/regress/sql/json.sql
@@ -412,6 +412,14 @@ select value, json_typeof(value)
 -- json_build_array, json_build_object, json_object_agg
 
 SELECT json_build_array('a',1,'b',1.2,'c',true,'d',null,'e',json '{"x": 3, "y": [1,2,3]}');
+SELECT json_build_array('a', NULL); -- ok
+SELECT json_build_array(VARIADIC NULL::text[]); -- ok
+SELECT json_build_array(VARIADIC '{}'::text[]); -- ok
+SELECT json_build_array(VARIADIC '{a,b,c}'::text[]); -- ok
+SELECT json_build_array(VARIADIC ARRAY['a', NULL]::text[]); -- ok
+SELECT json_build_array(VARIADIC '{1,2,3,4}'::text[]); -- ok
+SELECT json_build_array(VARIADIC '{1,2,3,4}'::int[]); -- ok
+SELECT json_build_array(VARIADIC '{{1,4},{2,5},{3,6}}'::int[][]); -- ok
 
 SELECT json_build_object('a',1,'b',1.2,'c',true,'d',null,'e',json '{"x": 3, "y": [1,2,3]}');
 
@@ -419,6 +427,19 @@ SELECT json_build_object(
        'a', json_build_object('b',false,'c',99),
        'd', json_build_object('e',array[9,8,7]::int[],
            'f', (select row_to_json(r) from ( select relkind, oid::regclass as name from pg_class where relname = 'pg_class') r)));
+SELECT json_build_object('{a,b,c}'::text[]); -- error
+SELECT json_build_object('{a,b,c}'::text[], '{d,e,f}'::text[]); -- error, key cannot be array
+SELECT json_build_object('a', 'b', 'c'); -- error
+SELECT json_build_object(NULL, 'a'); -- error, key cannot be NULL
+SELECT json_build_object('a', NULL); -- ok
+SELECT json_build_object(VARIADIC NULL::text[]); -- ok
+SELECT json_build_object(VARIADIC '{}'::text[]); -- ok
+SELECT json_build_object(VARIADIC '{a,b,c}'::text[]); -- error
+SELECT json_build_object(VARIADIC ARRAY['a', NULL]::text[]); -- ok
+SELECT json_build_object(VARIADIC ARRAY[NULL, 'a']::text[]); -- error, key cannot be NULL
+SELECT json_build_object(VARIADIC '{1,2,3,4}'::text[]); -- ok
+SELECT json_build_object(VARIADIC '{1,2,3,4}'::int[]); -- ok
+SELECT json_build_object(VARIADIC '{{1,4},{2,5},{3,6}}'::int[][]); -- ok
 
 
 -- empty objects/arrays