From f10db388c59ddac14a770bd2d4df3df2267ca434 Mon Sep 17 00:00:00 2001
From: fanrenhoo <fanrenhoo@sina.com>
Date: Mon, 25 Apr 2022 11:32:49 +0800
Subject: [PATCH] variable: make lc_messages read only (#33708)

close pingcap/tidb#33707
---
 sessionctx/variable/noop.go        | 2 +-
 sessionctx/variable/sysvar_test.go | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/sessionctx/variable/noop.go b/sessionctx/variable/noop.go
index 449a9aef63..4f2cdac1aa 100644
--- a/sessionctx/variable/noop.go
+++ b/sessionctx/variable/noop.go
@@ -296,7 +296,7 @@ var noopSysVars = []*SysVar{
 	{Scope: ScopeGlobal, Name: SlowQueryLog, Value: "0"},
 	{Scope: ScopeSession, Name: "debug_sync", Value: ""},
 	{Scope: ScopeGlobal, Name: InnodbStatsAutoRecalc, Value: "1"},
-	{Scope: ScopeGlobal | ScopeSession, Name: "lc_messages", Value: "en_US"},
+	{Scope: ScopeGlobal | ScopeSession, Name: "lc_messages", Value: "en_US", ReadOnly: true},
 	{Scope: ScopeGlobal | ScopeSession, Name: "bulk_insert_buffer_size", Value: "8388608", IsHintUpdatable: true},
 	{Scope: ScopeGlobal | ScopeSession, Name: BinlogDirectNonTransactionalUpdates, Value: Off, Type: TypeBool},
 	{Scope: ScopeGlobal, Name: "innodb_change_buffering", Value: "all"},
diff --git a/sessionctx/variable/sysvar_test.go b/sessionctx/variable/sysvar_test.go
index 0d694d8b9a..ec1bed29ac 100644
--- a/sessionctx/variable/sysvar_test.go
+++ b/sessionctx/variable/sysvar_test.go
@@ -819,6 +819,14 @@ func TestLcTimeNamesReadOnly(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestLcMessagesReadOnly(t *testing.T) {
+	sv := GetSysVar("lc_messages")
+	vars := NewSessionVars()
+	vars.GlobalVarsAccessor = NewMockGlobalAccessor4Tests()
+	_, err := sv.Validate(vars, "newvalue", ScopeGlobal)
+	require.Error(t, err)
+}
+
 func TestDDLWorkers(t *testing.T) {
 	svWorkerCount, svBatchSize := GetSysVar(TiDBDDLReorgWorkerCount), GetSysVar(TiDBDDLReorgBatchSize)
 	vars := NewSessionVars()