PR #1127 and PR #1150

PR#1127: Fix is_check_constraints.result to be compatibile with 10.3

The patch is done according to the original patch for MDEV-14474
1edd09c325 and not one which is merged on server
d526679efd.
This patch includes:
- Rename from `is_check_constraint` to `is_check_constraints` to tests
and results
- Per review, change the order of fields in IS check_constraints table by adding
the column `table_name` before `constraint_name`. According to the standard
2006 there is no `table_name` column.
- Original patch and one in `10.3` supports embedded server this patch doesn't
support. After the merge `10.3` will not support also.
- Don't use patch c8b8b01b61 to change the length of `CHECK_CLAUSE` field

PR#1150: MDEV-18440: Information_schema.check_constraints possible data leak

This patch is extension of PR 1127 and includes:
- Check for table grants
- Additional test according to the MDEV specification

mysql-test/suite/funcs_1/t/is_check_constraints.test

@@ -40,7 +40,7 @@ CREATE TABLE t1
  CONSTRAINT CHECK (tt > 32), CONSTRAINT CHECK (tt <50),# autogenerated names table constraints
  CONSTRAINT CHK_tt CHECK(tt<100) # named table constraint
 ) ENGINE=InnoDB;
- --sorted_result
+--sorted_result
 SELECT * from information_schema.check_constraints;
 
 ALTER TABLE t1
@@ -55,7 +55,7 @@ start_date DATE,
 end_date DATE,
 CONSTRAINT CHK_dates CHECK(start_date IS NULL) #table constraint
 )ENGINE=Innodb;
- --sorted_result
+--sorted_result
 SELECT * from information_schema.check_constraints;
 
 ALTER TABLE t1
@@ -70,12 +70,12 @@ a int,
 b int check (b>0), # field constraint named 'b'
 CONSTRAINT b check (b>10) # table constraint
 ) ENGINE=InnoDB;
- --sorted_result
+--sorted_result
 SELECT * from information_schema.check_constraints;
 
 DISCONNECT con1;
 CONNECT(con2, localhost, boo2,, test);
- --sorted_result
+--sorted_result
 SELECT * from information_schema.check_constraints;
 
 DISCONNECT con2;
@@ -90,3 +90,28 @@ DISCONNECT con1;
 --CONNECTION default
 DROP USER boo1;
 DROP USER boo2;
+
+--echo #
+--echo # MDEV-18440: Information_schema.check_constraints possible data leak
+--echo #
+
+CREATE USER foo;
+CREATE DATABASE db;
+USE db;
+CREATE TABLE t1 (a int, b int, CONSTRAINT CHECK (b > 0));
+INSERT INTO t1 VALUES (1, 2), (2, 3);
+GRANT SELECT (a) ON t1 TO foo;
+
+SHOW GRANTS FOR foo;
+--sorted_result
+SELECT * FROM information_schema.check_constraints;
+
+CONNECT(con1,localhost, foo,, db);
+SELECT a FROM t1;
+--sorted_result
+SELECT * FROM information_schema.check_constraints;
+
+--CONNECTION default
+
+DROP USER foo;
+DROP DATABASE db;