signal: handle shutdown properly

This addresses issues related to the mobile lnd builds, where
calling `stopDaemon` and subsequently calling LndMobile's `Start`
results in crash.

cmd/lncli/cmd_open_channel.go

@@ -18,7 +18,6 @@ import (
 	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lnwallet/chanfunding"
-	"github.com/lightningnetwork/lnd/signal"
 	"github.com/urfave/cli"
 )
 
@@ -467,7 +466,7 @@ func openChannelPsbt(rpcCtx context.Context, ctx *cli.Context,
 	// the server.
 	go func() {
 		select {
-		case <-signal.ShutdownChannel():
+		case <-rpcCtx.Done():
 			fmt.Printf("\nInterrupt signal received.\n")
 			close(quit)
 

cmd/lncli/commands.go

@@ -41,14 +41,15 @@ const (
 )
 
 func getContext() context.Context {
-	if err := signal.Intercept(); err != nil {
+	shutdownInterceptor, err := signal.Intercept()
+	if err != nil {
 		_, _ = fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
 
 	ctxc, cancel := context.WithCancel(context.Background())
 	go func() {
-		<-signal.ShutdownChannel()
+		<-shutdownInterceptor.ShutdownChannel()
 		cancel()
 	}()
 	return ctxc

cmd/lnd/main.go

@@ -10,9 +10,16 @@ import (
 )
 
 func main() {
+	// Hook interceptor for os signals.
+	shutdownInterceptor, err := signal.Intercept()
+	if err != nil {
+		_, _ = fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
 	// Load the configuration, and parse any command line options. This
 	// function will also set up logging properly.
-	loadedConfig, err := lnd.LoadConfig()
+	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.
@@ -24,16 +31,10 @@ func main() {
 		os.Exit(0)
 	}
 
-	// Hook interceptor for os signals.
-	if err := signal.Intercept(); err != nil {
-		_, _ = fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
-	}
-
 	// 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{}, signal.ShutdownChannel(),
+	if err = lnd.Main(
+		loadedConfig, lnd.ListenerCfg{}, shutdownInterceptor,
 	); err != nil {
 		_, _ = fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)