Use nil pointer to indicate missing device ID (rather than FSMisc)

global/deviceIDs.go

@@ -7,19 +7,19 @@ import (
 )
 
 // GetCurrentDeviceID returns the current device ID or
-// FSMisc if there is no device ID (e.g. first run).
-func GetCurrentDeviceID() (string, error) {
+// nil if there is no device ID (e.g. first run).
+func GetCurrentDeviceID() (*string, error) {
 	deviceIDList, err := GenDeviceIDList()
 	if err != nil {
-		return "", errors.New("unable to generate device ID list: " + err.Error())
+		return nil, errors.New("unable to generate device ID list: " + err.Error())
 	}
 	var deviceID string
 	if len(deviceIDList) > 0 {
 		deviceID = (deviceIDList)[0].Name()
 	} else {
-		deviceID = FSMisc // indicates to server that no device ID is being replaced
+		return nil, nil // nil device ID indicates to server that no device ID is being replaced
 	}
-	return deviceID, nil
+	return &deviceID, nil
 }
 
 // GenDeviceIDList returns a slice of all registered device IDs.

global/init.go

@@ -9,36 +9,35 @@ import (
 
 // DirInit creates the libmutton directories.
 // Returns: oldDeviceID (from before the directory reset; will be FSMisc if there is no pre-existing ID).
-func DirInit(preserveOldCfgDir bool) (string, error) {
+func DirInit(preserveOldCfgDir bool) (*string, error) {
+	var err error
+
 	// create EntryRoot
-	if err := os.MkdirAll(EntryRoot, 0700); err != nil {
-		return "", errors.New("unable to create \"" + EntryRoot + "\": " + err.Error())
+	if err = os.MkdirAll(EntryRoot, 0700); err != nil {
+		return nil, errors.New("unable to create \"" + EntryRoot + "\": " + err.Error())
 	}
 
 	// get old device ID before its potential removal
-	oldDeviceID, err := GetCurrentDeviceID()
-	if err != nil {
-		oldDeviceID = FSMisc
-	}
+	oldDeviceID, _ := GetCurrentDeviceID() // error ignored; oldDeviceID is set to nil on error, which is the correct assumption
 
 	// remove existing config directory (if it exists and not in append mode)
 	if !preserveOldCfgDir {
 		isAccessible, _ := back.TargetIsFile(CfgDir, false) // error is ignored because dir/file status is irrelevant
 		if isAccessible {
 			if err = os.RemoveAll(CfgDir); err != nil {
-				return "", errors.New("unable to remove existing config directory: " + err.Error())
+				return nil, errors.New("unable to remove existing config directory: " + err.Error())
 			}
 		}
 	}
 
 	// create config directory w/devices subdirectory
 	if err = os.MkdirAll(CfgDir+PathSeparator+"devices", 0700); err != nil {
-		return "", errors.New("unable to create \"" + CfgDir + "\": " + err.Error())
+		return nil, errors.New("unable to create \"" + CfgDir + "\": " + err.Error())
 	}
 
 	// create password age directory
 	if err = os.MkdirAll(AgeDir, 0700); err != nil {
-		return "", errors.New("unable to create \"" + AgeDir + "\": " + err.Error())
+		return nil, errors.New("unable to create \"" + AgeDir + "\": " + err.Error())
 	}
 
 	return oldDeviceID, nil