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.

1 files changed, 27 insertions, 70 deletions

diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c
index a39d084ce8f..70ee928e58d 100644
--- a/src/backend/utils/adt/jsonb.c
+++ b/src/backend/utils/adt/jsonb.c
@@ -16,6 +16,7 @@
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "catalog/pg_type.h"
+#include "funcapi.h"
 #include "libpq/pqformat.h"
 #include "parser/parse_coerce.h"
 #include "utils/builtins.h"
@@ -1170,16 +1171,24 @@ to_jsonb(PG_FUNCTION_ARGS)
 Datum
 jsonb_build_object(PG_FUNCTION_ARGS)
 {
-	int			nargs = PG_NARGS();
+	int			nargs;
 	int			i;
-	Datum		arg;
-	Oid			val_type;
 	JsonbInState result;
+	Datum	   *args;
+	bool	   *nulls;
+	Oid		   *types;
+
+	/* build argument values to build the object */
+	nargs = extract_variadic_args(fcinfo, 0, true, &args, &types, &nulls);
+
+	if (nargs < 0)
+		PG_RETURN_NULL();
 
 	if (nargs % 2 != 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("invalid number of arguments: object must be matched key value pairs")));
+				 errmsg("argument list must have even number of elements"),
+				 errhint("The arguments of jsonb_build_object() must consist of alternating keys and values.")));
 
 	memset(&result, 0, sizeof(JsonbInState));
 
@@ -1188,54 +1197,15 @@ jsonb_build_object(PG_FUNCTION_ARGS)
 	for (i = 0; i < nargs; i += 2)
 	{
 		/* process key */
-
-		if (PG_ARGISNULL(i))
+		if (nulls[i])
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 					 errmsg("argument %d: key must not be null", i + 1)));
-		val_type = get_fn_expr_argtype(fcinfo->flinfo, i);
-
-		/*
-		 * turn a constant (more or less literal) value that's of unknown type
-		 * into text. Unknowns come in as a cstring pointer.
-		 */
-		if (val_type == UNKNOWNOID && get_fn_expr_arg_stable(fcinfo->flinfo, i))
-		{
-			val_type = TEXTOID;
-			arg = CStringGetTextDatum(PG_GETARG_POINTER(i));
-		}
-		else
-		{
-			arg = PG_GETARG_DATUM(i);
-		}
-		if (val_type == InvalidOid || val_type == UNKNOWNOID)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			   errmsg("could not determine data type for argument %d", i + 1)));
 
-		add_jsonb(arg, false, &result, val_type, true);
+		add_jsonb(args[i], false, &result, types[i], true);
 
 		/* process value */
-
-		val_type = get_fn_expr_argtype(fcinfo->flinfo, i + 1);
-		/* see comments above */
-		if (val_type == UNKNOWNOID && get_fn_expr_arg_stable(fcinfo->flinfo, i + 1))
-		{
-			val_type = TEXTOID;
-			if (PG_ARGISNULL(i + 1))
-				arg = (Datum) 0;
-			else
-				arg = CStringGetTextDatum(PG_GETARG_POINTER(i + 1));
-		}
-		else
-		{
-			arg = PG_GETARG_DATUM(i + 1);
-		}
-		if (val_type == InvalidOid || val_type == UNKNOWNOID)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			   errmsg("could not determine data type for argument %d", i + 2)));
-		add_jsonb(arg, PG_ARGISNULL(i + 1), &result, val_type, false);
+		add_jsonb(args[i + 1], nulls[i + 1], &result, types[i + 1], false);
 	}
 
 	result.res = pushJsonbValue(&result.parseState, WJB_END_OBJECT, NULL);
@@ -1265,38 +1235,25 @@ jsonb_build_object_noargs(PG_FUNCTION_ARGS)
 Datum
 jsonb_build_array(PG_FUNCTION_ARGS)
 {
-	int			nargs = PG_NARGS();
+	int			nargs;
 	int			i;
-	Datum		arg;
-	Oid			val_type;
 	JsonbInState result;
+	Datum	   *args;
+	bool	   *nulls;
+	Oid		   *types;
+
+	/* build argument values to build the array */
+	nargs = extract_variadic_args(fcinfo, 0, true, &args, &types, &nulls);
+
+	if (nargs < 0)
+		PG_RETURN_NULL();
 
 	memset(&result, 0, sizeof(JsonbInState));
 
 	result.res = pushJsonbValue(&result.parseState, WJB_BEGIN_ARRAY, NULL);
 
 	for (i = 0; i < nargs; i++)
-	{
-		val_type = get_fn_expr_argtype(fcinfo->flinfo, i);
-		/* see comments in jsonb_build_object above */
-		if (val_type == UNKNOWNOID && get_fn_expr_arg_stable(fcinfo->flinfo, i))
-		{
-			val_type = TEXTOID;
-			if (PG_ARGISNULL(i))
-				arg = (Datum) 0;
-			else
-				arg = CStringGetTextDatum(PG_GETARG_POINTER(i));
-		}
-		else
-		{
-			arg = PG_GETARG_DATUM(i);
-		}
-		if (val_type == InvalidOid || val_type == UNKNOWNOID)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			   errmsg("could not determine data type for argument %d", i + 1)));
-		add_jsonb(arg, PG_ARGISNULL(i), &result, val_type, false);
-	}
+		add_jsonb(args[i], nulls[i], &result, types[i], false);
 
 	result.res = pushJsonbValue(&result.parseState, WJB_END_ARRAY, NULL);