src: guard against calling Init() multiple times

This function should only be called once. Calling it multiple times
would currently break Node.js (e.g. re-registering builtin modules
would break the linked list for them).

PR-URL: https://github.com/nodejs/node/pull/26458
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/node.cc

@@ -608,9 +608,14 @@ int ProcessGlobalArgs(std::vector<std::string>* args,
   return 0;
 }
 
+static std::atomic_bool init_called{false};
+
 int Init(std::vector<std::string>* argv,
          std::vector<std::string>* exec_argv,
          std::vector<std::string>* errors) {
+  // Make sure Init() is called only once.
+  CHECK(!init_called.exchange(true));
+
   // Register built-in modules
   binding::RegisterBuiltinModules();