Fix super_read_only for DROP TRIGGER

Summary:
Feature: Super Read-Only

This was contributed by: Laurynas Biveinis <[email protected]>

Fix for issue #10 (super read only does not prevent DROP TRIGGER).

- add super read only handling to mysql_create_and_drop_trigger;
- tweak error message in trans_begin to note whether regular or super
  read only is effective;
- add MTR tests for the above changes and for multi-table update which
  was implemented but not covered in MTR.

I will squash this commit, in future branches, with:
https://reviews.facebook.net/D16197

Test Plan:
mtr sys_vars.super_read_only_basic

I will run the automated tests on this diff now.

Reviewers: inaam-rana, liang.guo.752, pivanof

Reviewed By: pivanof

Subscribers: jtolmer

Differential Revision: https://reviews.facebook.net/D30309

mysql-test/suite/sys_vars/r/super_read_only_basic.result

@@ -213,15 +213,27 @@ connection con1;
 create table t1 (a int);
 insert into t1 values(1);
 create table t2 select * from t1;
+update t1, t2 set t1.a=2, t2.a=2;
+start transaction read write;
+commit;
+create trigger trig1 before insert on t1 for each row set new.a = new.a;
 connection default;
 #
 # Make sure it blocks SUPER
 #
 set global super_read_only=1;
+create trigger trig2 before insert on t2 for each row set new.a = new.a;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
 create table t3 (a int);
 ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
 drop table t3;
 ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
+update t1, t2 set t1.a=3, t2.a=3;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
+start transaction read write;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
+drop trigger trig1;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
 #
 # Make sure it still blocks for non-super
 #
@@ -236,6 +248,12 @@ create table t3 (a int);
 ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
 insert into t1 values(1);
 ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
+update t1, t2 set t1.a=3, t2.a=3;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
+start transaction read write;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
+drop trigger trig1;
+ERROR HY000: The MySQL server is running with the --read-only (super) option so it cannot execute this statement
 #
 # Cleanup
 #

mysql-test/suite/sys_vars/t/super_read_only_basic.test

@@ -159,6 +159,13 @@ insert into t1 values(1);
 
 create table t2 select * from t1;
 
+update t1, t2 set t1.a=2, t2.a=2;
+
+start transaction read write;
+commit;
+
+create trigger trig1 before insert on t1 for each row set new.a = new.a;
+
 --echo connection default;
 connection default;
 
@@ -169,12 +176,23 @@ connection default;
 
 set global super_read_only=1;
 
+--error ER_OPTION_PREVENTS_STATEMENT
+create trigger trig2 before insert on t2 for each row set new.a = new.a;
+
 --error ER_OPTION_PREVENTS_STATEMENT
 create table t3 (a int);
 
 --error ER_OPTION_PREVENTS_STATEMENT
 drop table t3;
 
+--error ER_OPTION_PREVENTS_STATEMENT
+update t1, t2 set t1.a=3, t2.a=3;
+
+--error ER_OPTION_PREVENTS_STATEMENT
+start transaction read write;
+
+--error ER_OPTION_PREVENTS_STATEMENT
+drop trigger trig1;
 
 --echo #
 --echo # Make sure it still blocks for non-super
@@ -192,6 +210,14 @@ create table t3 (a int);
 --error ER_OPTION_PREVENTS_STATEMENT
 insert into t1 values(1);
 
+--error ER_OPTION_PREVENTS_STATEMENT
+update t1, t2 set t1.a=3, t2.a=3;
+
+--error ER_OPTION_PREVENTS_STATEMENT
+start transaction read write;
+
+--error ER_OPTION_PREVENTS_STATEMENT
+drop trigger trig1;
 
 --echo #
 --echo # Cleanup

sql/sql_trigger.cc

@@ -444,6 +444,9 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
   if (!create)
   {
     bool if_exists= thd->lex->drop_if_exists;
+    bool enforce_ro= true;
+    if (!opt_super_readonly)
+      enforce_ro= !(thd->security_ctx->master_access & SUPER_ACL);
 
     /*
       Protect the query table list from the temporary and potentially
@@ -458,11 +461,11 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
     */
     thd->lex->sql_command= backup.sql_command;
 
-    if (opt_readonly && !(thd->security_ctx->master_access & SUPER_ACL) &&
-        !thd->slave_thread)
+    if (opt_readonly && enforce_ro && !thd->slave_thread)
     {
-      my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--read-only");
-      goto end;
+        my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0),
+                 opt_super_readonly ? "--read-only (super)" : "--read-only");
+        goto end;
     }
 
     if (add_table_for_trigger(thd, thd->lex->spname, if_exists, & tables))

sql/transaction.cc

@@ -176,7 +176,8 @@ bool trans_begin(THD *thd, uint flags)
       enforce_ro = !(thd->security_ctx->master_access & SUPER_ACL);
     if (opt_readonly && enforce_ro)
     {
-      my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--read-only");
+      my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0),
+               opt_super_readonly ? "--read-only (super)" : "--read-only");
       DBUG_RETURN(true);
     }
     thd->tx_read_only= false;