lib/model: Don't create folder root when paused (fixes #4903) (#4904)

lib/model/model.go

@@ -1505,7 +1505,18 @@ func (m *Model) GetIgnores(folder string) ([]string, []string, error) {
 func (m *Model) SetIgnores(folder string, content []string) error {
 	cfg, ok := m.cfg.Folders()[folder]
 	if !ok {
-		return fmt.Errorf("Folder %s does not exist", folder)
+		return fmt.Errorf("folder %s does not exist", cfg.Description())
+	}
+
+	err := cfg.CheckPath()
+	if err == config.ErrPathMissing {
+		if err = cfg.CreateRoot(); err != nil {
+			return fmt.Errorf("failed to create folder root: %v", err)
+		}
+		err = cfg.CheckPath()
+	}
+	if err != nil && err != config.ErrMarkerMissing {
+		return err
 	}
 
 	if err := ignore.WriteIgnores(cfg.Filesystem(), ".stignore", content); err != nil {
@@ -2629,7 +2640,6 @@ func (m *Model) CommitConfiguration(from, to config.Configuration) bool {
 			// A folder was added.
 			if cfg.Paused {
 				l.Infoln("Paused folder", cfg.Description())
-				cfg.CreateRoot()
 			} else {
 				l.Infoln("Adding folder", cfg.Description())
 				m.AddFolder(cfg)

lib/model/model_test.go

@@ -3527,6 +3527,80 @@ func TestPausedFolders(t *testing.T) {
 	}
 }
 
+func TestIssue4094(t *testing.T) {
+	db := db.OpenMemory()
+	// Create a separate wrapper not to pollute other tests.
+	wrapper, path := createTmpWrapper(config.Configuration{})
+	defer os.Remove(path)
+	m := NewModel(wrapper, protocol.LocalDeviceID, "syncthing", "dev", db, nil)
+	m.ServeBackground()
+	defer m.Stop()
+
+	// Force the model to wire itself and add the folders
+	folderPath := "testdata/nonexistent"
+	defer os.RemoveAll(folderPath)
+	cfg := defaultCfgWrapper.RawCopy()
+	fcfg := config.FolderConfiguration{
+		ID:     "folder1",
+		Path:   folderPath,
+		Paused: true,
+		Devices: []config.FolderDeviceConfiguration{
+			{DeviceID: device1},
+		},
+	}
+	cfg.Folders = []config.FolderConfiguration{fcfg}
+	p, err := wrapper.Replace(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	p.Wait()
+
+	if err := m.SetIgnores(fcfg.ID, []string{"foo"}); err != nil {
+		t.Fatalf("failed setting ignores: %v", err)
+	}
+
+	if _, err := fcfg.Filesystem().Lstat(".stignore"); err != nil {
+		t.Fatalf("failed stating .stignore: %v", err)
+	}
+}
+
+func TestIssue4903(t *testing.T) {
+	db := db.OpenMemory()
+	// Create a separate wrapper not to pollute other tests.
+	wrapper, path := createTmpWrapper(config.Configuration{})
+	defer os.Remove(path)
+	m := NewModel(wrapper, protocol.LocalDeviceID, "syncthing", "dev", db, nil)
+	m.ServeBackground()
+	defer m.Stop()
+
+	// Force the model to wire itself and add the folders
+	folderPath := "testdata/nonexistent"
+	defer os.RemoveAll(folderPath)
+	cfg := defaultCfgWrapper.RawCopy()
+	fcfg := config.FolderConfiguration{
+		ID:     "folder1",
+		Path:   folderPath,
+		Paused: true,
+		Devices: []config.FolderDeviceConfiguration{
+			{DeviceID: device1},
+		},
+	}
+	cfg.Folders = []config.FolderConfiguration{fcfg}
+	p, err := wrapper.Replace(cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	p.Wait()
+
+	if err := fcfg.CheckPath(); err != config.ErrPathMissing {
+		t.Fatalf("expected path missing error, got: %v", err)
+	}
+
+	if _, err := fcfg.Filesystem().Lstat("."); !fs.IsNotExist(err) {
+		t.Fatalf("Expected missing path error, got: %v", err)
+	}
+}
+
 func addFakeConn(m *Model, dev protocol.DeviceID) *fakeConnection {
 	fc := &fakeConnection{id: dev, model: m}
 	m.AddConnection(fc, protocol.HelloResult{})