Open db file in readonly mode for commands which shouldn't update db file

Signed-off-by: Benjamin Wang <wachao@vmware.com>

cmd/bbolt/main.go

@@ -202,7 +202,7 @@ func (cmd *CheckCommand) Run(args ...string) error {
 	}
 
 	// Open database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}
@@ -279,7 +279,7 @@ func (cmd *InfoCommand) Run(args ...string) error {
 	}
 
 	// Open the database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}
@@ -651,7 +651,7 @@ func (cmd *PagesCommand) Run(args ...string) error {
 	}
 
 	// Open database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}
@@ -745,7 +745,7 @@ func (cmd *StatsCommand) Run(args ...string) error {
 	}
 
 	// Open database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}
@@ -880,7 +880,7 @@ func (cmd *BucketsCommand) Run(args ...string) error {
 	}
 
 	// Open database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}
@@ -945,7 +945,7 @@ func (cmd *KeysCommand) Run(args ...string) error {
 	}
 
 	// Open database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}
@@ -1040,7 +1040,7 @@ func (cmd *GetCommand) Run(args ...string) error {
 	}
 
 	// Open database.
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return err
 	}

cmd/bbolt/main_test.go

@@ -11,6 +11,7 @@ import (
 	"strconv"
 	"testing"
 
+	"github.com/stretchr/testify/require"
 	bolt "go.etcd.io/bbolt"
 	main "go.etcd.io/bbolt/cmd/bbolt"
 )
@@ -21,6 +22,8 @@ func TestInfoCommand_Run(t *testing.T) {
 	db.DB.Close()
 	defer db.Close()
 
+	defer requireDBNoChange(t, dbData(t, db.Path), db.Path)
+
 	// Run the info command.
 	m := NewMain()
 	if err := m.Run("info", db.Path); err != nil {
@@ -39,6 +42,8 @@ func TestStatsCommand_Run_EmptyDatabase(t *testing.T) {
 	defer db.Close()
 	db.DB.Close()
 
+	defer requireDBNoChange(t, dbData(t, db.Path), db.Path)
+
 	// Generate expected result.
 	exp := "Aggregate statistics for 0 buckets\n\n" +
 		"Page count statistics\n" +
@@ -116,6 +121,8 @@ func TestStatsCommand_Run(t *testing.T) {
 	}
 	db.DB.Close()
 
+	defer requireDBNoChange(t, dbData(t, db.Path), db.Path)
+
 	// Generate expected result.
 	exp := "Aggregate statistics for 3 buckets\n\n" +
 		"Page count statistics\n" +
@@ -163,6 +170,8 @@ func TestBucketsCommand_Run(t *testing.T) {
 	}
 	db.DB.Close()
 
+	defer requireDBNoChange(t, dbData(t, db.Path), db.Path)
+
 	expected := "bar\nbaz\nfoo\n"
 
 	// Run the command.
@@ -198,6 +207,8 @@ func TestKeysCommand_Run(t *testing.T) {
 	}
 	db.DB.Close()
 
+	defer requireDBNoChange(t, dbData(t, db.Path), db.Path)
+
 	expected := "foo-0\nfoo-1\nfoo-2\n"
 
 	// Run the command.
@@ -234,6 +245,8 @@ func TestGetCommand_Run(t *testing.T) {
 	}
 	db.DB.Close()
 
+	defer requireDBNoChange(t, dbData(t, db.Path), db.Path)
+
 	expected := "val-foo-1\n"
 
 	// Run the command.
@@ -420,7 +433,7 @@ func fillBucket(b *bolt.Bucket, prefix []byte) error {
 }
 
 func chkdb(path string) ([]byte, error) {
-	db, err := bolt.Open(path, 0666, nil)
+	db, err := bolt.Open(path, 0666, &bolt.Options{ReadOnly: true})
 	if err != nil {
 		return nil, err
 	}
@@ -453,3 +466,17 @@ func walkBucket(parent *bolt.Bucket, k []byte, v []byte, w io.Writer) error {
 		return walkBucket(parent, k, v, w)
 	})
 }
+
+func dbData(t *testing.T, filePath string) []byte {
+	data, err := os.ReadFile(filePath)
+	require.NoError(t, err)
+	return data
+}
+
+func requireDBNoChange(t *testing.T, oldData []byte, filePath string) {
+	newData, err := os.ReadFile(filePath)
+	require.NoError(t, err)
+
+	noChange := bytes.Equal(oldData, newData)
+	require.True(t, noChange)
+}