lib/config, lib/model: Configurable folder marker name (fixes #1126)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4483

lib/config/config.go

@@ -399,17 +399,21 @@ func convertV22V23(cfg *Configuration) {
 		// begin with.
 		permBits = 0700
 	}
+
+	// Upgrade code remains hardcoded for .stfolder despite configurable
+	// marker name in later versions.
+
 	for i := range cfg.Folders {
 		fs := cfg.Folders[i].Filesystem()
 		// Invalid config posted, or tests.
 		if fs == nil {
 			continue
 		}
-		if stat, err := fs.Stat(".stfolder"); err == nil && !stat.IsDir() {
-			err = fs.Remove(".stfolder")
+		if stat, err := fs.Stat(DefaultMarkerName); err == nil && !stat.IsDir() {
+			err = fs.Remove(DefaultMarkerName)
 			if err == nil {
-				err = fs.Mkdir(".stfolder", permBits)
-				fs.Hide(".stfolder") // ignore error
+				err = fs.Mkdir(DefaultMarkerName, permBits)
+				fs.Hide(DefaultMarkerName) // ignore error
 			}
 			if err != nil {
 				l.Infoln("Failed to upgrade folder marker:", err)

lib/config/config_test.go

@@ -85,13 +85,13 @@ func TestDefaultValues(t *testing.T) {
 
 func TestDeviceConfig(t *testing.T) {
 	for i := OldestHandledVersion; i <= CurrentVersion; i++ {
-		os.RemoveAll("testdata/.stfolder")
+		os.RemoveAll(filepath.Join("testdata", DefaultMarkerName))
 		wr, err := Load(fmt.Sprintf("testdata/v%d.xml", i), device1)
 		if err != nil {
 			t.Fatal(err)
 		}
 
-		_, err = os.Stat("testdata/.stfolder")
+		_, err = os.Stat(filepath.Join("testdata", DefaultMarkerName))
 		if i < 6 && err != nil {
 			t.Fatal(err)
 		} else if i >= 6 && err == nil {
@@ -120,6 +120,7 @@ func TestDeviceConfig(t *testing.T) {
 					Params: map[string]string{},
 				},
 				WeakHashThresholdPct: 25,
+				MarkerName:           DefaultMarkerName,
 			},
 		}
 

lib/config/folderconfiguration.go

@@ -20,6 +20,8 @@ var (
 	errMarkerMissing = errors.New("folder marker missing")
 )
 
+const DefaultMarkerName = ".stfolder"
+
 type FolderConfiguration struct {
 	ID                    string                      `xml:"id,attr" json:"id"`
 	Label                 string                      `xml:"label,attr" json:"label"`
@@ -47,6 +49,7 @@ type FolderConfiguration struct {
 	DisableTempIndexes    bool                        `xml:"disableTempIndexes" json:"disableTempIndexes"`
 	Paused                bool                        `xml:"paused" json:"paused"`
 	WeakHashThresholdPct  int                         `xml:"weakHashThresholdPct" json:"weakHashThresholdPct"` // Use weak hash if more than X percent of the file has changed. Set to -1 to always use weak hash.
+	MarkerName            string                      `xml:"markerName" json:"markerName"`
 
 	cachedFilesystem fs.Filesystem
 
@@ -91,6 +94,12 @@ func (f *FolderConfiguration) CreateMarker() error {
 	if err := f.CheckPath(); err != errMarkerMissing {
 		return err
 	}
+	if f.MarkerName != DefaultMarkerName {
+		// Folder uses a non-default marker so we shouldn't mess with it.
+		// Pretend we created it and let the subsequent health checks sort
+		// out the actual situation.
+		return nil
+	}
 
 	permBits := fs.FileMode(0777)
 	if runtime.GOOS == "windows" {
@@ -99,7 +108,7 @@ func (f *FolderConfiguration) CreateMarker() error {
 		permBits = 0700
 	}
 	fs := f.Filesystem()
-	err := fs.Mkdir(".stfolder", permBits)
+	err := fs.Mkdir(DefaultMarkerName, permBits)
 	if err != nil {
 		return err
 	}
@@ -108,7 +117,7 @@ func (f *FolderConfiguration) CreateMarker() error {
 	} else if err := dir.Sync(); err != nil {
 		l.Debugln("folder marker: fsync . failed:", err)
 	}
-	fs.Hide(".stfolder")
+	fs.Hide(DefaultMarkerName)
 
 	return nil
 }
@@ -120,7 +129,7 @@ func (f *FolderConfiguration) CheckPath() error {
 		return errPathMissing
 	}
 
-	_, err = f.Filesystem().Stat(".stfolder")
+	_, err = f.Filesystem().Stat(f.MarkerName)
 	if err != nil {
 		return errMarkerMissing
 	}
@@ -187,6 +196,10 @@ func (f *FolderConfiguration) prepare() {
 	if f.WeakHashThresholdPct == 0 {
 		f.WeakHashThresholdPct = 25
 	}
+
+	if f.MarkerName == "" {
+		f.MarkerName = DefaultMarkerName
+	}
 }
 
 type FolderDeviceConfigurationList []FolderDeviceConfiguration