storage: local storage tolerates broken symlink when Walk (#51170)

close #49423

br/pkg/storage/local.go

@@ -130,7 +130,11 @@ func (l *LocalStorage) WalkDir(_ context.Context, opt *WalkOption, fn func(strin
 		if !f.Mode().IsRegular() {
 			stat, err := os.Stat(filepath.Join(l.base, path))
 			if err != nil {
-				return errors.Trace(err)
+				// error may happen because of file deleted after walk started, or other errors
+				// like #49423. We just return 0 size and let the caller handle it in later
+				// logic.
+				log.Warn("failed to get file size", zap.String("path", path), zap.Error(err))
+				return fn(path, 0)
 			}
 			size = stat.Size()
 		}

br/pkg/storage/local_test.go

@@ -237,3 +237,23 @@ func TestLocalFileReadRange(t *testing.T) {
 	n, _ := r.Read(smallBuf)
 	require.Equal(t, "23", string(smallBuf[:n]))
 }
+
+func TestWalkBrokenSymLink(t *testing.T) {
+	ctx := context.Background()
+	dir := t.TempDir()
+	err := os.Symlink(filepath.Join(dir, "non-existing-file"), filepath.Join(dir, "file-that-should-be-ignored"))
+	require.NoError(t, err)
+
+	sb, err := ParseBackend("file://"+filepath.ToSlash(dir), nil)
+	require.NoError(t, err)
+	store, err := New(ctx, sb, nil)
+	require.NoError(t, err)
+
+	files := map[string]int64{}
+	err = store.WalkDir(ctx, nil, func(path string, size int64) error {
+		files[path] = size
+		return nil
+	})
+	require.NoError(t, err)
+	require.Equal(t, map[string]int64{"file-that-should-be-ignored": 0}, files)
+}