MDEV-30703: JSON_SCHEMA_VALID : Enum array must have at least one value

Analysis: Current implementation does not check the number of elements in
the enum array and whether they are unique or not.
Fix: Add a counter that counts number of elements and before inserting the
element in the enum hash check whether it exists.

mysql-test/main/func_json.result

@@ -4590,4 +4590,19 @@ JSON_SCHEMA_VALID(@invalid_schema, '{"number1":3, "obj2":{"key1":3}}')
 NULL
 Warnings:
 Warning	4038	Syntax error in JSON text in argument 1 to function 'json_schema_valid' at position 45
+#
+# MDEV-30703: JSON_SCHEMA_VALID : Enum array must have at least one value
+#
+SET @schema = '{
+                 "type":"array",
+                  "enum": []
+                }';
+SELECT JSON_SCHEMA_VALID(@schema, '2');
+ERROR HY000: Invalid value for keyword enum
+SET @schema = '{
+                 "type":"number",
+                  "enum": [2, 2]
+                }';
+SELECT JSON_SCHEMA_VALID(@schema, '2');
+ERROR HY000: Invalid value for keyword enum
 # End of 11.1 test

mysql-test/main/func_json.test

@@ -3357,6 +3357,7 @@ SET @schema_reference= '{"$defs": "http://example.com/custom-email-validator.jso
 SELECT JSON_SCHEMA_VALID(@schema_reference, '{}');
 
 
+
 --echo #
 --echo # MDEV-30795: JSON_SCHEMA_VALID bugs mentioned in comment
 --echo #
@@ -3474,4 +3475,23 @@ SET @invalid_schema= '{"type":"object"
                            }';
 SELECT JSON_SCHEMA_VALID(@invalid_schema, '{"number1":3, "obj2":{"key1":3}}');
 
+--echo #
+--echo # MDEV-30703: JSON_SCHEMA_VALID : Enum array must have at least one value
+--echo #
+
+SET @schema = '{
+                 "type":"array",
+                  "enum": []
+                }';
+--error ER_JSON_INVALID_VALUE_FOR_KEYWORD
+SELECT JSON_SCHEMA_VALID(@schema, '2');
+
+SET @schema = '{
+                 "type":"number",
+                  "enum": [2, 2]
+                }';
+--error ER_JSON_INVALID_VALUE_FOR_KEYWORD
+SELECT JSON_SCHEMA_VALID(@schema, '2');
+
+
 --echo # End of 11.1 test

sql/json_schema.cc

@@ -520,12 +520,10 @@ bool Json_schema_enum::validate(const json_engine_t *je,
 
   if (temp_je.value_type > JSON_VALUE_NUMBER)
   {
-    if (temp_je.value_type == JSON_VALUE_TRUE)
+    if (!(enum_scalar & (1 << temp_je.value_type)))
-      return !(enum_scalar & HAS_TRUE_VAL);
+      return true;
-    if (temp_je.value_type == JSON_VALUE_FALSE)
+    else
-      return !(enum_scalar & HAS_FALSE_VAL);
+      return false;
-    if (temp_je.value_type == JSON_VALUE_NULL)
-      return !(enum_scalar & HAS_NULL_VAL);
   }
   json_get_normalized_string(&temp_je, &a_res, &err);
   if (err)
@@ -546,6 +544,7 @@ bool Json_schema_enum::handle_keyword(THD *thd, json_engine_t *je,
                                       List<Json_schema_keyword>
                                            *all_keywords)
 {
+  int count= 0;
   if (my_hash_init(PSI_INSTRUMENT_ME,
                    &this->enum_values,
                    je->s.cs, 1024, 0, 0, (my_hash_get_key) get_key_name,
@@ -559,14 +558,16 @@ bool Json_schema_enum::handle_keyword(THD *thd, json_engine_t *je,
     {
       if (json_read_value(je))
         return true;
+      count++;
       if (je->value_type > JSON_VALUE_NUMBER)
       {
-        if (je->value_type == JSON_VALUE_TRUE)
+        if (!(enum_scalar & (1 << je->value_type)))
-          enum_scalar|= HAS_TRUE_VAL;
+          enum_scalar|= 1 << je->value_type;
-        else if (je->value_type == JSON_VALUE_FALSE)
+        else
-          enum_scalar|= HAS_FALSE_VAL;
+        {
-        else if (je->value_type == JSON_VALUE_NULL)
+          my_error(ER_JSON_INVALID_VALUE_FOR_KEYWORD, MYF(0), "enum");
-          enum_scalar|= HAS_NULL_VAL;
+          return true;
+        }
       }
       else
       {
@@ -586,12 +587,26 @@ bool Json_schema_enum::handle_keyword(THD *thd, json_engine_t *je,
         {
           norm_str[a_res.length()]= '\0';
           strncpy(norm_str, (const char*)a_res.ptr(), a_res.length());
+          if (!my_hash_search(&this->enum_values, (uchar*)norm_str,
+                              strlen(norm_str)))
+          {
             if (my_hash_insert(&this->enum_values, (uchar*)norm_str))
               return true;
           }
+          else
+          {
+            my_error(ER_JSON_INVALID_VALUE_FOR_KEYWORD, MYF(0), "enum");
+            return true;
+          }
         }
       }
-    return je->s.error ? true : false;
+    }
+    if (!count)
+    {
+     my_error(ER_JSON_INVALID_VALUE_FOR_KEYWORD, MYF(0), "enum");
+     return true;
+    }
+    return false;
   }
   else
   {

sql/json_schema.h

@@ -176,10 +176,7 @@ class Json_schema_const : public Json_schema_keyword
     }
 };
 
-enum enum_scalar_values {
+
-                         HAS_NO_VAL= 0, HAS_TRUE_VAL= 2,
-                         HAS_FALSE_VAL= 4, HAS_NULL_VAL= 8
-                        };
 class Json_schema_enum : public  Json_schema_keyword
 {
   private:
@@ -196,7 +193,7 @@ class Json_schema_enum : public  Json_schema_keyword
                         List<Json_schema_keyword> *all_keywords) override;
     Json_schema_enum()
     {
-      enum_scalar= HAS_NO_VAL;
+      enum_scalar= 0;
     }
     ~Json_schema_enum()
     {