cmd/tailscaled: fix state path for windows svc

Signed-off-by: James Tucker <james@tailscale.com>

cmd/tailscaled/tailscaled.go

@@ -158,13 +158,12 @@ func main() {
 		}
 	}
 
-	if beWindowsSubprocess() {
-		return
-	}
-
 	flag.Parse()
 	if flag.NArg() > 0 {
-		log.Fatalf("tailscaled does not take non-flag arguments: %q", flag.Args())
+		// Windows subprocess is spawned with /subprocess, so we need to avoid this check there.
+		if runtime.GOOS != "windows" || flag.Arg(0) != "/subproc" {
+			log.Fatalf("tailscaled does not take non-flag arguments: %q", flag.Args())
+		}
 	}
 
 	if printVersion {
@@ -193,6 +192,10 @@ func main() {
 		args.statepath = paths.DefaultTailscaledStateFile()
 	}
 
+	if beWindowsSubprocess() {
+		return
+	}
+
 	err := run()
 
 	// Remove file sharing from Windows shell (noop in non-windows)

cmd/tailscaled/tailscaled_windows.go

@@ -260,7 +260,7 @@ func startIPNServer(ctx context.Context, logid string) error {
 
 	linkMon, err := monitor.New(logf)
 	if err != nil {
-		return err
+		return fmt.Errorf("monitor: %w", err)
 	}
 	dialer := new(tsdial.Dialer)
 
@@ -367,7 +367,7 @@ func startIPNServer(ctx context.Context, logid string) error {
 	}
 	store, err := store.New(logf, statePathOrDefault())
 	if err != nil {
-		return err
+		return fmt.Errorf("store: %w", err)
 	}
 
 	ln, _, err := safesocket.Listen(args.socketpath, safesocket.WindowsLocalPort)