all: use correct binary path when running upgrade

For safety reason, ctrld will create a backup of the current binary when
running upgrade command.

However, on systems where ctrld status is got by parsing ps command
output, the current binary path is important and must be the same with
the original binary. Depends on kernel version, using os.Executable may
return new backup binary path, aka "ctrld_previous", not the original
"ctrld" binary. This causes upgrade command see ctrld as not running
after restart -> upgrade failed.

Fixing this by recording the binary path before creating new service, so
the ctrld service status can be checked correctly.

cmd/cli/cli.go

@@ -850,7 +850,14 @@ NOTE: Uninstalling will set DNS to values provided by DHCP.`,
 			checkHasElevatedPrivilege()
 		},
 		Run: func(cmd *cobra.Command, args []string) {
-			s, err := newService(&prog{}, svcConfig)
+			bin, err := os.Executable()
+			if err != nil {
+				mainLog.Load().Fatal().Err(err).Msg("failed to get current ctrld binary path")
+			}
+			sc := &service.Config{}
+			*sc = *svcConfig
+			sc.Executable = bin
+			s, err := newService(&prog{}, sc)
 			if err != nil {
 				mainLog.Load().Error().Msg(err.Error())
 				return
@@ -859,10 +866,6 @@ NOTE: Uninstalling will set DNS to values provided by DHCP.`,
 			if _, err := s.Status(); errors.Is(err, service.ErrNotInstalled) {
 				svcInstalled = false
 			}
-			bin, err := os.Executable()
-			if err != nil {
-				mainLog.Load().Fatal().Err(err).Msg("failed to get current ctrld binary path")
-			}
 			oldBin := bin + "_previous"
 			baseUrl := upgradeChannel[upgradeChannelDefault]
 			if len(args) > 0 {

cmd/cli/service.go

@@ -21,7 +21,7 @@ func newService(i service.Interface, c *service.Config) (service.Service, error)
 	}
 	switch {
 	case router.IsOldOpenwrt(), router.IsNetGearOrbi():
-		return &procd{&sysV{s}}, nil
+		return &procd{sysV: &sysV{s}, svcConfig: c}, nil
 	case router.IsGLiNet():
 		return &sysV{s}, nil
 	case s.Platform() == "unix-systemv":
@@ -89,18 +89,24 @@ func (s *sysV) Status() (service.Status, error) {
 // like old GL.iNET Opal router.
 type procd struct {
 	*sysV
+	svcConfig *service.Config
 }
 
 func (s *procd) Status() (service.Status, error) {
 	if !s.installed() {
 		return service.StatusUnknown, service.ErrNotInstalled
 	}
-	exe, err := os.Executable()
-	if err != nil {
-		return service.StatusUnknown, nil
+	bin := s.svcConfig.Executable
+	if bin == "" {
+		exe, err := os.Executable()
+		if err != nil {
+			return service.StatusUnknown, nil
+		}
+		bin = exe
 	}
+
 	// Looking for something like "/sbin/ctrld run ".
-	shellCmd := fmt.Sprintf("ps | grep -q %q", exe+" [r]un ")
+	shellCmd := fmt.Sprintf("ps | grep -q %q", bin+" [r]un ")
 	if err := exec.Command("sh", "-c", shellCmd).Run(); err != nil {
 		return service.StatusStopped, nil
 	}

internal/router/service_merlin.go

@@ -49,11 +49,15 @@ func (s *merlinSvc) Platform() string {
 }
 
 func (s *merlinSvc) configPath() string {
-	path, err := os.Executable()
-	if err != nil {
-		return ""
+	bin := s.Config.Executable
+	if bin == "" {
+		path, err := os.Executable()
+		if err != nil {
+			return ""
+		}
+		bin = path
 	}
-	return path + ".startup"
+	return bin + ".startup"
 }
 
 func (s *merlinSvc) template() *template.Template {