all: make procd "ctrld stop" blocks until process exited

Since procd does not block when init scripts execute stop operation, it
causes ctrld command callers (the installer, users ...) thought that
ctrld process was exited, while it does not.

See: https://forum.openwrt.org/t/procd-shutdown-issues-questions/33759

cmd/cli/cli.go

@@ -449,6 +449,23 @@ func initCLI() {
 			if doTasks([]task{{s.Stop, true}}) {
 				p.router.Cleanup()
 				p.resetDNS()
+				if router.WaitProcessExited() {
+					ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
+					defer cancel()
+
+					for {
+						select {
+						case <-ctx.Done():
+							mainLog.Load().Error().Msg("timeout while waiting for service to stop")
+							return
+						default:
+						}
+						time.Sleep(time.Second)
+						if status, _ := s.Status(); status == service.StatusStopped {
+							break
+						}
+					}
+				}
 				mainLog.Load().Notice().Msg("Service stopped")
 			}
 		},

internal/router/openwrt/procd.go

@@ -18,6 +18,7 @@ start_service() {
     procd_set_param stdout 1            # forward stdout of the command to logd
     procd_set_param stderr 1            # same for stderr
     procd_set_param pidfile ${pid_file} # write a pid file on instance start and remove it on stop
+    procd_set_param term_timeout 10
     procd_close_instance
     echo "${name} has been started"
 }

internal/router/router.go

@@ -98,6 +98,11 @@ func IsOldOpenwrt() bool {
 	return cmd == ""
 }
 
+// WaitProcessExited reports whether the "ctrld stop" command have to wait until ctrld process exited.
+func WaitProcessExited() bool {
+	return Name() == openwrt.Name
+}
+
 var routerPlatform atomic.Pointer[router]
 
 type router struct {