snap: error on empty snapshot

snap/snapshotter.go

@@ -38,9 +38,10 @@ const (
 )
 
 var (
-	ErrNoSnapshot  = errors.New("snap: no available snapshot")
-	ErrCRCMismatch = errors.New("snap: crc mismatch")
-	crcTable       = crc32.MakeTable(crc32.Castagnoli)
+	ErrNoSnapshot    = errors.New("snap: no available snapshot")
+	ErrEmptySnapshot = errors.New("snap: empty snapshot")
+	ErrCRCMismatch   = errors.New("snap: crc mismatch")
+	crcTable         = crc32.MakeTable(crc32.Castagnoli)
 )
 
 type Snapshotter struct {
@@ -108,11 +109,16 @@ func loadSnap(dir, name string) (*raftpb.Snapshot, error) {
 		log.Printf("snap: corrupted snapshot file %v: %v", name, err)
 		return nil, err
 	}
+
+	if len(serializedSnap.Data) == 0 || serializedSnap.Crc == 0 {
+		log.Printf("snap: unexpected empty snapshot")
+		return nil, ErrEmptySnapshot
+	}
+
 	crc := crc32.Update(0, crcTable, serializedSnap.Data)
 	if crc != serializedSnap.Crc {
 		log.Printf("snap: corrupted snapshot file %v: crc mismatch", name)
-		err = ErrCRCMismatch
-		return nil, err
+		return nil, ErrCRCMismatch
 	}
 
 	var snap raftpb.Snapshot

snap/snapshotter_test.go

@@ -188,3 +188,23 @@ func TestNoSnapshot(t *testing.T) {
 		t.Errorf("err = %v, want %v", err, ErrNoSnapshot)
 	}
 }
+
+func TestEmptySnapshot(t *testing.T) {
+	dir := path.Join(os.TempDir(), "snapshot")
+	err := os.Mkdir(dir, 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	err = ioutil.WriteFile(path.Join(dir, "1.snap"), []byte("shit"), 0x700)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ss := New(dir)
+	_, err = ss.Load()
+	if err == nil || err != ErrEmptySnapshot {
+		t.Errorf("err = %v, want %v", err, ErrEmptySnapshot)
+	}
+}