Bug 1363011 - [Static Analysis] Buffer not null terminated in int NS_main(int argc, NS_tchar **argv). r=mhowell

Patch wrote by: Santiago Paez [:tiago]

Differential Revision: https://phabricator.services.mozilla.com/D25747

--HG--
extra : moz-landing-system : lando

toolkit/mozapps/update/updater/updater.cpp

@@ -2770,6 +2770,7 @@ int NS_main(int argc, NS_tchar **argv) {
   }
   // The directory containing the update information.
   NS_tstrncpy(gPatchDirPath, argv[1], MAXPATHLEN);
+  gPatchDirPath[MAXPATHLEN - 1] = NS_T('\0');
 
   // This check is also performed in workmonitor.cpp since the maintenance
   // service can be called directly.