signal: custom exit code status for interceptor

cmd/lnd/main.go

@@ -19,7 +19,7 @@ func main() {
 
 	// Load the configuration, and parse any command line options. This
 	// function will also set up logging properly.
-	loadedConfig, err := lnd.LoadConfig(shutdownInterceptor)
+	loadedConfig, err := lnd.LoadConfig(*shutdownInterceptor)
 	if err != nil {
 		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
 			// Print error if not due to help request.
@@ -34,9 +34,10 @@ func main() {
 	// Call the "real" main in a nested manner so the defers will properly
 	// be executed in the case of a graceful shutdown.
 	if err = lnd.Main(
-		loadedConfig, lnd.ListenerCfg{}, shutdownInterceptor,
+		loadedConfig, lnd.ListenerCfg{}, *shutdownInterceptor,
 	); err != nil {
 		_, _ = fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
+	os.Exit(shutdownInterceptor.GetExitCode())
 }

lnd.go

@@ -199,7 +199,6 @@ func Main(cfg *Config, lisCfg ListenerCfg, interceptor signal.Interceptor) error
 			ltndLog.Errorf("Could not close log rotator: %v", err)
 		}
 	}()
-
 	// Show version at startup.
 	ltndLog.Infof("Version: %s commit=%s, build=%s, logging=%s, debuglevel=%s",
 		build.Version(), build.Commit, build.Deployment,

mobile/bindings.go

@@ -75,7 +75,7 @@ func Start(extraArgs string, rpcReady Callback) {
 
 	// Load the configuration, and parse the extra arguments as command
 	// line options. This function will also set up logging properly.
-	loadedConfig, err := lnd.LoadConfig(shutdownInterceptor)
+	loadedConfig, err := lnd.LoadConfig(*shutdownInterceptor)
 	if err != nil {
 		atomic.StoreInt32(&lndStarted, 0)
 		_, _ = fmt.Fprintln(os.Stderr, err)
@@ -106,7 +106,7 @@ func Start(extraArgs string, rpcReady Callback) {
 		defer close(quit)
 
 		if err := lnd.Main(
-			loadedConfig, cfg, shutdownInterceptor,
+			loadedConfig, cfg, *shutdownInterceptor,
 		); err != nil {
 			if e, ok := err.(*flags.Error); ok &&
 				e.Type == flags.ErrHelp {

signal/signal.go

@@ -34,20 +34,24 @@ type Interceptor struct {
 
 	// quit is closed when instructing the main interrupt handler to exit.
 	quit chan struct{}
+
+	// exitCode is the exit code status when the main interrupt handler exits
+	exitCode chan int
 }
 
 // Intercept starts the interception of interrupt signals and returns an `Interceptor` instance.
 // Note that any previous active interceptor must be stopped before a new one can be created
-func Intercept() (Interceptor, error) {
+func Intercept() (*Interceptor, error) {
 	if !atomic.CompareAndSwapInt32(&started, 0, 1) {
-		return Interceptor{}, errors.New("intercept already started")
+		return &Interceptor{}, errors.New("intercept already started")
 	}
 
 	channels := Interceptor{
 		interruptChannel:       make(chan os.Signal, 1),
 		shutdownChannel:        make(chan struct{}),
 		shutdownRequestChannel: make(chan struct{}),
 		quit:                   make(chan struct{}),
+		exitCode:               make(chan int, 1),
 	}
 
 	signalsToCatch := []os.Signal{
@@ -59,7 +63,7 @@ func Intercept() (Interceptor, error) {
 	signal.Notify(channels.interruptChannel, signalsToCatch...)
 	go channels.mainInterruptHandler()
 
-	return channels, nil
+	return &channels, nil
 }
 
 // mainInterruptHandler listens for SIGINT (Ctrl+C) signals on the
@@ -95,16 +99,22 @@ func (c *Interceptor) mainInterruptHandler() {
 		select {
 		case signal := <-c.interruptChannel:
 			log.Infof("Received %v", signal)
+			// Adding exit status code 0 as this will quit after graceful shutdown
+			c.setExitCode(0)
 			shutdown()
 
 		case <-c.shutdownRequestChannel:
 			log.Infof("Received shutdown request.")
+			// Adding exit status code 0 as this will quit after graceful shutdown
+			c.setExitCode(1)
 			shutdown()
 
 		case <-c.quit:
 			log.Infof("Gracefully shutting down.")
 			close(c.shutdownChannel)
 			signal.Stop(c.interruptChannel)
+			// Adding exit status code 0 as this will quit after graceful shutdown
+			c.setExitCode(0)
 			return
 		}
 	}
@@ -147,3 +157,12 @@ func (c *Interceptor) RequestShutdown() {
 func (c *Interceptor) ShutdownChannel() <-chan struct{} {
 	return c.shutdownChannel
 }
+
+// GetExitCode fetches the exit code that has been set of the Interceptor
+func (c *Interceptor) GetExitCode() int {
+	return <-c.exitCode
+}
+
+func (c *Interceptor) setExitCode(exitCode int) {
+	c.exitCode <- exitCode
+}