ipn/ipnlocal: add file sharing to windows shell

Updates: tailscale/winmin#33

Signed-off-by: Aleksandar Pesic <peske.nis@gmail.com>

cmd/tailscaled/depaware.txt

@@ -134,6 +134,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/util/dnsname                                   from tailscale.com/ipn/ipnstate+
   LW    tailscale.com/util/endian                                    from tailscale.com/net/netns+
    L    tailscale.com/util/lineread                                  from tailscale.com/control/controlclient+
+        tailscale.com/util/osshare                                   from tailscale.com/cmd/tailscaled+
         tailscale.com/util/pidowner                                  from tailscale.com/ipn/ipnserver
         tailscale.com/util/racebuild                                 from tailscale.com/logpolicy
         tailscale.com/util/systemd                                   from tailscale.com/control/controlclient+

cmd/tailscaled/install_windows.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/sys/windows/svc/mgr"
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/osshare"
 )
 
 func init() {
@@ -79,6 +80,9 @@ func installSystemDaemonWindows(args []string) (err error) {
 }
 
 func uninstallSystemDaemonWindows(args []string) (ret error) {
+	// Remove file sharing from Windows shell (noop in non-windows)
+	osshare.SetFileSharingEnabled(false, logger.Discard)
+
 	m, err := mgr.Connect()
 	if err != nil {
 		return fmt.Errorf("failed to connect to Windows service manager: %v", err)

cmd/tailscaled/tailscaled.go

@@ -40,6 +40,7 @@ import (
 	"tailscale.com/types/flagtype"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/netmap"
+	"tailscale.com/util/osshare"
 	"tailscale.com/version"
 	"tailscale.com/version/distro"
 	"tailscale.com/wgengine"
@@ -160,7 +161,12 @@ func main() {
 		log.Fatalf("--socket is required")
 	}
 
-	if err := run(); err != nil {
+	err := run()
+
+	// Remove file sharing from Windows shell (noop in non-windows)
+	osshare.SetFileSharingEnabled(false, logger.Discard)
+
+	if err != nil {
 		// No need to log; the func already did
 		os.Exit(1)
 	}