Ensure consistent file permissions on broken WAL

Signed-off-by: Lucas Rodriguez <[email protected]>

server/storage/wal/repair.go

@@ -67,7 +67,7 @@ func Repair(lg *zap.Logger, dirpath string) bool {
 
 		case errors.Is(err, io.ErrUnexpectedEOF):
 			brokenName := f.Name() + ".broken"
-			bf, bferr := os.Create(brokenName)
+			bf, bferr := os.OpenFile(brokenName, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, fileutil.PrivateFileMode)
 			if bferr != nil {
 				lg.Warn("failed to create backup file", zap.String("path", brokenName), zap.Error(bferr))
 				return false

server/storage/wal/repair_test.go

@@ -18,12 +18,14 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/zap/zaptest"
 
+	"go.etcd.io/etcd/client/pkg/v3/fileutil"
 	"go.etcd.io/etcd/server/v3/storage/wal/walpb"
 	"go.etcd.io/raft/v3/raftpb"
 )
@@ -77,6 +79,14 @@ func testRepair(t *testing.T, ents [][]raftpb.Entry, corrupt corruptFunc, expect
 	// repair the wal
 	require.True(t, Repair(lg, p), "'Repair' returned 'false', want 'true'")
 
+	// verify the broken wal has correct permissions
+	bf := filepath.Join(p, filepath.Base(w.tail().Name())+".broken")
+	fi, err := os.Stat(bf)
+	require.NoError(t, err)
+	expectedPerms := fmt.Sprintf("%o", os.FileMode(fileutil.PrivateFileMode))
+	actualPerms := fmt.Sprintf("%o", fi.Mode().Perm())
+	require.Equal(t, expectedPerms, actualPerms, "unexpected file permissions on .broken wal")
+
 	// read it back
 	w, err = Open(lg, p, walpb.Snapshot{})
 	require.NoError(t, err)