From 92b87b99dfbfab263b5387696505f0f163794b04 Mon Sep 17 00:00:00 2001
From: lance6716 <lance6716@gmail.com>
Date: Thu, 3 Dec 2020 16:48:20 +0800
Subject: [PATCH] export: don't write SHOW MASTER STATUS when lacking privilege
 (#208)

---
 v4/export/metadata.go      | 14 +++++++++-----
 v4/export/metadata_test.go | 16 ++++++++++++++++
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/v4/export/metadata.go b/v4/export/metadata.go
index d9cc6021..e3a9f90d 100644
--- a/v4/export/metadata.go
+++ b/v4/export/metadata.go
@@ -65,12 +65,14 @@ func (m *globalMetadata) recordGlobalMetaData(db *sql.Conn, serverType ServerTyp
 }
 
 func recordGlobalMetaData(db *sql.Conn, buffer *bytes.Buffer, serverType ServerType, afterConn bool, snapshot string) error {
-	// get master status info
-	buffer.WriteString("SHOW MASTER STATUS:")
-	if afterConn {
-		buffer.WriteString(" /* AFTER CONNECTION POOL ESTABLISHED */")
+	writeMasterStatusHeader := func() {
+		buffer.WriteString("SHOW MASTER STATUS:")
+		if afterConn {
+			buffer.WriteString(" /* AFTER CONNECTION POOL ESTABLISHED */")
+		}
+		buffer.WriteString("\n")
 	}
-	buffer.WriteString("\n")
+
 	switch serverType {
 	// For MySQL:
 	// mysql 5.6+
@@ -106,6 +108,7 @@ func recordGlobalMetaData(db *sql.Conn, buffer *bytes.Buffer, serverType ServerT
 		gtidSet := getValidStr(str, gtidSetFieldIndex)
 
 		if logFile != "" {
+			writeMasterStatusHeader()
 			fmt.Fprintf(buffer, "\tLog: %s\n\tPos: %s\n\tGTID:%s\n", logFile, pos, gtidSet)
 		}
 	// For MariaDB:
@@ -136,6 +139,7 @@ func recordGlobalMetaData(db *sql.Conn, buffer *bytes.Buffer, serverType ServerT
 		}
 
 		if logFile != "" {
+			writeMasterStatusHeader()
 			fmt.Fprintf(buffer, "\tLog: %s\n\tPos: %s\n\tGTID:%s\n", logFile, pos, gtidSet)
 		}
 	default:
diff --git a/v4/export/metadata_test.go b/v4/export/metadata_test.go
index 0cdf3ca5..ed1e0c91 100644
--- a/v4/export/metadata_test.go
+++ b/v4/export/metadata_test.go
@@ -4,6 +4,7 @@ package export
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/DATA-DOG/go-sqlmock"
@@ -269,3 +270,18 @@ func (s *testMetaDataSuite) TestTiDBSnapshotMetaData(c *C) {
 		"\tGTID:\n\n")
 	c.Assert(mock.ExpectationsWereMet(), IsNil)
 }
+
+func (s *testMetaDataSuite) TestNoPrivilege(c *C) {
+	db, mock, err := sqlmock.New()
+	c.Assert(err, IsNil)
+	defer db.Close()
+	conn, err := db.Conn(context.Background())
+	c.Assert(err, IsNil)
+
+	mock.ExpectQuery("SHOW MASTER STATUS").WillReturnError(errors.New("lack SUPER or REPLICATION CLIENT privilege"))
+
+	m := newGlobalMetadata(s.createStorage(c), "")
+	// some consistencyType will ignore this error, this test make sure no extra message is written
+	c.Assert(m.recordGlobalMetaData(conn, ServerTypeTiDB, false), NotNil)
+	c.Assert(m.buffer.String(), Equals, "")
+}