1 files changed, 15 insertions, 34 deletions

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 3c137ead1d0..951b6554007 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -806,14 +806,17 @@ json_lex_string(JsonLexContext *lex)
 					 * For UTF8, replace the escape sequence by the actual
 					 * utf8 character in lex->strval. Do this also for other
 					 * encodings if the escape designates an ASCII character,
-					 * otherwise raise an error. We don't ever unescape a
-					 * \u0000, since that would result in an impermissible nul
-					 * byte.
+					 * otherwise raise an error.
 					 */
 
 					if (ch == 0)
 					{
-						appendStringInfoString(lex->strval, "\\u0000");
+						/* We can't allow this, since our TEXT type doesn't */
+						ereport(ERROR,
+								(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
+							   errmsg("unsupported Unicode escape sequence"),
+						   errdetail("\\u0000 cannot be converted to text."),
+								 report_json_context(lex)));
 					}
 					else if (GetDatabaseEncoding() == PG_UTF8)
 					{
@@ -833,8 +836,8 @@ json_lex_string(JsonLexContext *lex)
 					else
 					{
 						ereport(ERROR,
-								(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
-								 errmsg("invalid input syntax for type json"),
+								(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
+							   errmsg("unsupported Unicode escape sequence"),
 								 errdetail("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8."),
 								 report_json_context(lex)));
 					}
@@ -1284,8 +1287,8 @@ json_categorize_type(Oid typoid,
 
 	/*
 	 * We need to get the output function for everything except date and
-	 * timestamp types, array and composite types, booleans,
-	 * and non-builtin types  where there's a cast to json.
+	 * timestamp types, array and composite types, booleans, and non-builtin
+	 * types where there's a cast to json.
 	 */
 
 	switch (typoid)
@@ -1335,11 +1338,12 @@ json_categorize_type(Oid typoid,
 				/* but let's look for a cast to json, if it's not built-in */
 				if (typoid >= FirstNormalObjectId)
 				{
-					Oid castfunc;
+					Oid			castfunc;
 					CoercionPathType ctype;
 
 					ctype = find_coercion_pathway(JSONOID, typoid,
-												  COERCION_EXPLICIT, &castfunc);
+												  COERCION_EXPLICIT,
+												  &castfunc);
 					if (ctype == COERCION_PATH_FUNC && OidIsValid(castfunc))
 					{
 						*tcategory = JSONTYPE_CAST;
@@ -2382,30 +2386,7 @@ escape_json(StringInfo buf, const char *str)
 				appendStringInfoString(buf, "\\\"");
 				break;
 			case '\\':
-
-				/*
-				 * Unicode escapes are passed through as is. There is no
-				 * requirement that they denote a valid character in the
-				 * server encoding - indeed that is a big part of their
-				 * usefulness.
-				 *
-				 * All we require is that they consist of \uXXXX where the Xs
-				 * are hexadecimal digits. It is the responsibility of the
-				 * caller of, say, to_json() to make sure that the unicode
-				 * escape is valid.
-				 *
-				 * In the case of a jsonb string value being escaped, the only
-				 * unicode escape that should be present is \u0000, all the
-				 * other unicode escapes will have been resolved.
-				 */
-				if (p[1] == 'u' &&
-					isxdigit((unsigned char) p[2]) &&
-					isxdigit((unsigned char) p[3]) &&
-					isxdigit((unsigned char) p[4]) &&
-					isxdigit((unsigned char) p[5]))
-					appendStringInfoCharMacro(buf, *p);
-				else
-					appendStringInfoString(buf, "\\\\");
+				appendStringInfoString(buf, "\\\\");
 				break;
 			default:
 				if ((unsigned char) *p < ' ')