Forbid numeric NaN in jsonpath

SQL standard doesn't define numeric Inf or NaN values.  It appears even more
ridiculous to support then in jsonpath assuming JSON doesn't support these
values as well.  This commit forbids returning NaN from .double(), which was
previously allowed.  NaN can't be result of inner-jsonpath computation over
non-NaNs.  So, we can not expect NaN in the jsonpath output.

Reported-by: Tom Lane
Discussion: https://postgr.es/m/203949.1591879542%40sss.pgh.pa.us
Author: Alexander Korotkov
Reviewed-by: Tom Lane
Backpatch-through: 12

3 files changed, 10 insertions, 25 deletions

diff --git a/src/backend/utils/adt/jsonb_util.c b/src/backend/utils/adt/jsonb_util.c
index 04b70c805b4..4eeffa14243 100644
--- a/src/backend/utils/adt/jsonb_util.c
+++ b/src/backend/utils/adt/jsonb_util.c
@@ -1773,14 +1773,6 @@ convertJsonbScalar(StringInfo buffer, JEntry *jentry, JsonbValue *scalarVal)
 			break;
 
 		case jbvNumeric:
-			/* replace numeric NaN with string "NaN" */
-			if (numeric_is_nan(scalarVal->val.numeric))
-			{
-				appendToBuffer(buffer, "NaN", 3);
-				*jentry = 3;
-				break;
-			}
-
 			numlen = VARSIZE_ANY(scalarVal->val.numeric);
 			padlen = padBufferToInt(buffer);
 
diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 25ec3dcd802..f146767bfc3 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -1044,15 +1044,16 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 				{
 					char	   *tmp = DatumGetCString(DirectFunctionCall1(numeric_out,
 																		  NumericGetDatum(jb->val.numeric)));
+					double		val;
 					bool		have_error = false;
 
-					(void) float8in_internal_opt_error(tmp,
-													   NULL,
-													   "double precision",
-													   tmp,
-													   &have_error);
+					val = float8in_internal_opt_error(tmp,
+													  NULL,
+													  "double precision",
+													  tmp,
+													  &have_error);
 
-					if (have_error)
+					if (have_error || isinf(val) || isnan(val))
 						RETURN_ERROR(ereport(ERROR,
 											 (errcode(ERRCODE_NON_NUMERIC_SQL_JSON_ITEM),
 											  errmsg("numeric argument of jsonpath item method .%s() is out of range for type double precision",
@@ -1073,7 +1074,7 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 													  tmp,
 													  &have_error);
 
-					if (have_error || isinf(val))
+					if (have_error || isinf(val) || isnan(val))
 						RETURN_ERROR(ereport(ERROR,
 											 (errcode(ERRCODE_NON_NUMERIC_SQL_JSON_ITEM),
 											  errmsg("string argument of jsonpath item method .%s() is not a valid representation of a double precision number",
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index f8a5deb2b99..57332111b42 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -1500,17 +1500,9 @@ ERROR:  string argument of jsonpath item method .double() is not a valid represe
 select jsonb_path_query('1e1000', '$.double()');
 ERROR:  numeric argument of jsonpath item method .double() is out of range for type double precision
 select jsonb_path_query('"nan"', '$.double()');
- jsonb_path_query 
-------------------
- "NaN"
-(1 row)
-
+ERROR:  string argument of jsonpath item method .double() is not a valid representation of a double precision number
 select jsonb_path_query('"NaN"', '$.double()');
- jsonb_path_query 
-------------------
- "NaN"
-(1 row)
-
+ERROR:  string argument of jsonpath item method .double() is not a valid representation of a double precision number
 select jsonb_path_query('"inf"', '$.double()');
 ERROR:  string argument of jsonpath item method .double() is not a valid representation of a double precision number
 select jsonb_path_query('"-inf"', '$.double()');