From 4e5b771e980edfdad5c5414aa62c81d409d585a4 Mon Sep 17 00:00:00 2001
From: Rucha Deodhar <rucha.deodhar@mariadb.com>
Date: Tue, 2 May 2023 16:34:07 +0530
Subject: [PATCH] MDEV-30677: Incorrect result for "SELECT
 JSON_SCHEMA_VALID('{}', NULL)" Analysis: null_value is not set if any one of
 the arguments is NULL. So it returns 1. Fix: when either argument is NULL,
 set null_value to true, so that null can be returned

---
 mysql-test/main/func_json.result | 12 ++++++++++++
 mysql-test/main/func_json.test   |  7 +++++++
 sql/item_jsonfunc.cc             | 19 +++++++++++++------
 sql/item_jsonfunc.h              |  1 +
 4 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/mysql-test/main/func_json.result b/mysql-test/main/func_json.result
index afff2c58421..bdda00e256d 100644
--- a/mysql-test/main/func_json.result
+++ b/mysql-test/main/func_json.result
@@ -4704,4 +4704,16 @@ JSON_SCHEMA_VALID(json_object(), repeat('[', 10000000))
 0
 Warnings:
 Warning	4040	Limit of 32 on JSON nested structures depth is reached in argument 2 to function 'json_schema_valid' at position 32
+#
+# MDEV-30677: Incorrect result for "SELECT JSON_SCHEMA_VALID('{}', NULL)"
+#
+SELECT JSON_SCHEMA_VALID('{}', NULL);
+JSON_SCHEMA_VALID('{}', NULL)
+NULL
+SELECT JSON_SCHEMA_VALID(NULL, '{}');
+JSON_SCHEMA_VALID(NULL, '{}')
+NULL
+SELECT JSON_SCHEMA_VALID(NULL, NULL);
+JSON_SCHEMA_VALID(NULL, NULL)
+NULL
 # End of 11.1 test
diff --git a/mysql-test/main/func_json.test b/mysql-test/main/func_json.test
index e0da9819785..7fc2f05a57a 100644
--- a/mysql-test/main/func_json.test
+++ b/mysql-test/main/func_json.test
@@ -3586,4 +3586,11 @@ SELECT JSON_SCHEMA_VALID(repeat('[', 100000), json_object());
 
 SELECT JSON_SCHEMA_VALID(json_object(), repeat('[', 10000000));
 
+--echo #
+--echo # MDEV-30677: Incorrect result for "SELECT JSON_SCHEMA_VALID('{}', NULL)"
+--echo #
+SELECT JSON_SCHEMA_VALID('{}', NULL);
+SELECT JSON_SCHEMA_VALID(NULL, '{}');
+SELECT JSON_SCHEMA_VALID(NULL, NULL);
+
 --echo # End of 11.1 test
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 903776ddebf..fa0a8cbec7f 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -4729,18 +4729,22 @@ longlong Item_func_json_schema_valid::val_int()
   int is_valid= 1;
 
   if (!schema_parsed)
+  {
+    null_value= 1;
+     return 0;
+  }
+
+   val= args[1]->val_json(&tmp_val);
+
+   if (!val)
   {
     null_value= 1;
     return 0;
   }
+  null_value= 0;
 
-  val= args[1]->val_json(&tmp_val);
-
-  if (!val || !val->length())
-  {
-    null_value= 0;
+  if (!val->length())
     return 1;
-  }
 
   json_scan_start(&ve, val->charset(), (const uchar *) val->ptr(),
                   (const uchar *) val->end());
@@ -4799,7 +4803,10 @@ bool Item_func_json_schema_valid::fix_length_and_dec(THD *thd)
   String *js= args[0]->val_json(&tmp_js);
 
   if ((null_value= args[0]->null_value))
+  {
+    null_value= 1;
     return 0;
+  }
   json_scan_start(&je, js->charset(), (const uchar *) js->ptr(),
                   (const uchar *) js->ptr() + js->length());
   if (!create_object_and_handle_keyword(thd, &je, &keyword_list,
diff --git a/sql/item_jsonfunc.h b/sql/item_jsonfunc.h
index 4e857432b04..b352391c083 100644
--- a/sql/item_jsonfunc.h
+++ b/sql/item_jsonfunc.h
@@ -807,6 +807,7 @@ public:
     {
       val= NULL;
       schema_parsed= false;
+      set_maybe_null();
     }
   LEX_CSTRING func_name_cstring() const override
   {