Ensure old device ID remains active on the client if new device ID registration fails

core/init.go

@@ -74,7 +74,7 @@ func LibmuttonInit(inputCB func(prompt string) string, clientSpecificIniData [][
 			return errors.New("unable to initialize libmutton directories: " + err.Error())
 		}
 		// write config file
-		if len(clientSpecificIniData) > 0 { // TODO test passing empty clientSpecificIniData
+		if len(clientSpecificIniData) > 0 {
 			err = cfg.WriteConfig(append(clientSpecificIniData, [][3]string{{"LIBMUTTON", "offlineMode", "true"}}...), nil, false)
 			if err != nil {
 				return errors.New("unable to write config file: " + err.Error())

synccycles/init.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/rwinkhart/go-boilerplate/back"
 	"github.com/rwinkhart/libmutton/global"
 	"github.com/rwinkhart/libmutton/syncclient"
 )
@@ -23,32 +24,44 @@ func DeviceIDGen(oldDeviceID string) (string, string, error) {
 	newDeviceID := deviceIDPrefix + "-" + deviceIDSuffix
 
 	// create new device ID file (locally)
-	fileToClose, err := os.OpenFile(global.ConfigDir+global.PathSeparator+"devices"+global.PathSeparator+newDeviceID, os.O_CREATE|os.O_WRONLY, 0600)
+	newDeviceIDPath := global.ConfigDir + global.PathSeparator + "devices" + global.PathSeparator + newDeviceID
+	oldDeviceIDPath := global.ConfigDir + global.PathSeparator + "devices" + global.PathSeparator + oldDeviceID
+	f, err := os.OpenFile(newDeviceIDPath, os.O_CREATE|os.O_WRONLY, 0600)
 	if err != nil {
 		return "", "", errors.New("unable to create local device ID file: " + err.Error())
 	}
-	_ = fileToClose.Close() // error ignored; if the file could be created, it can probably be closed
+	_ = f.Close() // error ignored; if the file could be created, it can probably be closed
 
-	// remove old device ID file (locally; may not exist)
-	err = os.RemoveAll(global.ConfigDir + global.PathSeparator + "devices" + global.PathSeparator + oldDeviceID)
-	if err != nil {
-		return "", "", errors.New("unable to remove old device ID file (locally): " + err.Error())
+	cleanupOnFail := func() {
+		// remove new device ID file
+		os.RemoveAll(newDeviceIDPath)
+		// restore old device ID file (if it has already been removed due to DirInit)
+		if isAccessible, _ := back.TargetIsFile(oldDeviceIDPath, true); !isAccessible {
+			f, _ := os.OpenFile(oldDeviceIDPath, os.O_CREATE|os.O_WRONLY, 0600)
+			_ = f.Close() // error ignored; if the file could be created, it can probably be closed
+		}
 	}
 
 	// register new device ID with server and fetch remote EntryRoot and OS type
 	// also removes the old device ID file (remotely)
+	// if registration fails, remove the new device ID file locally and return before removing the old one
 	sshClient, _, _, _, err := syncclient.GetSSHClient()
 	if err != nil {
+		cleanupOnFail()
 		return "", "", errors.New("unable to connect to SSH client: " + err.Error())
 	}
 	output, err := syncclient.GetSSHOutput(sshClient, "libmuttonserver register", newDeviceID+"\n"+oldDeviceID)
 	if err != nil {
+		cleanupOnFail()
 		return "", "", errors.New("unable to register device ID with server: " + err.Error())
 	}
 	sshEntryRootSSHIsWindows := strings.Split(output, global.FSSpace)
-	err = sshClient.Close()
+	_ = sshClient.Close() // ignore error; non-critical/unlikely/not much could be done about it
+
+	// remove old device ID file (locally; may not exist)
+	err = os.RemoveAll(oldDeviceIDPath)
 	if err != nil {
-		return "", "", errors.New("unable to close SSH client: " + err.Error())
+		return "", "", errors.New("unable to remove old device ID file (locally): " + err.Error())
 	}
 
 	return sshEntryRootSSHIsWindows[0], sshEntryRootSSHIsWindows[1], nil