backward compatibility of .lock

erigon-lib/common/dir/rw_dir.go

@@ -72,15 +72,16 @@ func WriteFileWithFsync(name string, data []byte, perm os.FileMode) error {
 		return err
 	}
 	defer f.Close()
-	_, err = f.Write(data)
-	if err != nil {
+	if _, err = f.Write(data); err != nil {
 		return err
 	}
-	err = f.Sync()
-	if err != nil {
+	if err = f.Sync(); err != nil {
+		return err
+	}
+	if err = f.Close(); err != nil {
 		return err
 	}
-	return err
+	return nil
 }
 
 func Recreate(dir string) {

erigon-lib/downloader/torrent_files.go

@@ -177,43 +177,33 @@ func (tf *AtomicTorrentFS) ProhibitNewDownloads(t string) error {
 }
 
 func (tf *AtomicTorrentFS) prohibitNewDownloads(t string) error {
-	// open or create file ProhibitNewDownloadsFileName
-	f, err := os.OpenFile(filepath.Join(tf.dir, ProhibitNewDownloadsFileName), os.O_CREATE|os.O_RDONLY, 0644)
-	if err != nil {
-		return fmt.Errorf("open file: %w", err)
-	}
-	defer f.Close()
+	fPath := filepath.Join(tf.dir, ProhibitNewDownloadsFileName)
+	exist := dir.FileExist(fPath)
 	var prohibitedList []string
-	torrentListJsonBytes, err := io.ReadAll(f)
-	if err != nil {
-		return fmt.Errorf("read file: %w", err)
-	}
-	if len(torrentListJsonBytes) > 0 {
-		if err := json.Unmarshal(torrentListJsonBytes, &prohibitedList); err != nil {
-			return fmt.Errorf("unmarshal: %w", err)
+	if exist {
+		torrentListJsonBytes, err := os.ReadFile(fPath)
+		if err != nil {
+			return fmt.Errorf("read file: %w", err)
+		}
+		if len(torrentListJsonBytes) > 0 {
+			if err := json.Unmarshal(torrentListJsonBytes, &prohibitedList); err != nil {
+				return fmt.Errorf("unmarshal: %w", err)
+			}
 		}
 	}
 	if slices.Contains(prohibitedList, t) {
 		return nil
 	}
 	prohibitedList = append(prohibitedList, t)
-	f.Close()
 
-	// write new prohibited list by opening the file in truncate mode
-	f, err = os.OpenFile(filepath.Join(tf.dir, ProhibitNewDownloadsFileName), os.O_TRUNC|os.O_WRONLY, 0644)
-	if err != nil {
-		return fmt.Errorf("open file for writing: %w", err)
-	}
-	defer f.Close()
 	prohibitedListJsonBytes, err := json.Marshal(prohibitedList)
 	if err != nil {
 		return fmt.Errorf("marshal: %w", err)
 	}
-	if _, err := f.Write(prohibitedListJsonBytes); err != nil {
+	if err := dir.WriteFileWithFsync(fPath, prohibitedListJsonBytes, 0644); err != nil {
 		return fmt.Errorf("write: %w", err)
 	}
-
-	return f.Sync()
+	return nil
 }
 
 func (tf *AtomicTorrentFS) NewDownloadsAreProhibited(name string) (bool, error) {
@@ -223,7 +213,13 @@ func (tf *AtomicTorrentFS) NewDownloadsAreProhibited(name string) (bool, error)
 }
 
 func (tf *AtomicTorrentFS) newDownloadsAreProhibited(name string) (bool, error) {
-	f, err := os.OpenFile(filepath.Join(tf.dir, ProhibitNewDownloadsFileName), os.O_CREATE|os.O_APPEND|os.O_RDONLY, 0644)
+	fPath := filepath.Join(tf.dir, ProhibitNewDownloadsFileName)
+	exists := dir.FileExist(fPath)
+	if !exists {
+		return false, nil
+	}
+
+	f, err := os.OpenFile(fPath, os.O_RDONLY, 0644)
 	if err != nil {
 		return false, err
 	}
@@ -233,6 +229,9 @@ func (tf *AtomicTorrentFS) newDownloadsAreProhibited(name string) (bool, error)
 	if err != nil {
 		return false, fmt.Errorf("NewDownloadsAreProhibited: read file: %w", err)
 	}
+	if exists && len(torrentListJsonBytes) == 0 { // backward compatibility: if .lock exists and empty - it means everything is prohibited
+		return true, nil
+	}
 	if len(torrentListJsonBytes) > 0 {
 		if err := json.Unmarshal(torrentListJsonBytes, &prohibitedList); err != nil {
 			return false, fmt.Errorf("NewDownloadsAreProhibited: unmarshal: %w", err)

erigon-lib/downloader/torrent_files_test.go

@@ -0,0 +1,54 @@
+package downloader
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/ledgerwatch/erigon-lib/common/datadir"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFSProhibitBackwardCompat(t *testing.T) {
+	require := require.New(t)
+	dirs := datadir.New(t.TempDir())
+
+	//prev version of .lock - is empty .lock file which exitence prohibiting everything
+	t.Run("no prev version .lock", func(t *testing.T) {
+		tf := NewAtomicTorrentFS(dirs.Snap)
+		prohibited, err := tf.NewDownloadsAreProhibited("v1-004900-005000-headers.seg")
+		require.NoError(err)
+		require.False(prohibited)
+		prohibited, err = tf.NewDownloadsAreProhibited("v1-004900-005000-headers.seg.torrent")
+		require.NoError(err)
+		require.False(prohibited)
+	})
+	t.Run("prev version .lock support", func(t *testing.T) {
+		err := os.WriteFile(filepath.Join(dirs.Snap, ProhibitNewDownloadsFileName), nil, 0644)
+		require.NoError(err)
+
+		tf := NewAtomicTorrentFS(dirs.Snap)
+		prohibited, err := tf.NewDownloadsAreProhibited("v1-004900-005000-headers.seg")
+		require.NoError(err)
+		require.True(prohibited)
+		prohibited, err = tf.NewDownloadsAreProhibited("v1-004900-005000-headers.seg.torrent")
+		require.NoError(err)
+		require.True(prohibited)
+	})
+	t.Run("prev version .lock upgrade", func(t *testing.T) {
+		//old lock
+		err := os.WriteFile(filepath.Join(dirs.Snap, ProhibitNewDownloadsFileName), nil, 0644)
+		require.NoError(err)
+
+		tf := NewAtomicTorrentFS(dirs.Snap)
+		err = tf.prohibitNewDownloads("transactions") //upgrade
+		require.NoError(err)
+
+		prohibited, err := tf.NewDownloadsAreProhibited("v1-004900-005000-headers.seg")
+		require.NoError(err)
+		require.False(prohibited)
+		prohibited, err = tf.NewDownloadsAreProhibited("v1-004900-005000-headers.seg.torrent")
+		require.NoError(err)
+		require.False(prohibited)
+	})
+}