src: use option parser for expose_internals

bootstrap_node.js was directly parsing process.execArgv to see if
internals should be exposed, even though the argv was already parsed by
node. This is unusual and unnecessary, change it to set the option value
from the parser onto the process object, as is done for the other CLI
options.

lib/internal/bootstrap_node.js

@@ -508,11 +508,10 @@
     return NativeModule._source.hasOwnProperty(id);
   };
 
-  const EXPOSE_INTERNALS = process.execArgv.some(function(arg) {
-    return arg.match(/^--expose[-_]internals$/);
-  });
+  const EXPOSE_INTERNALS = process._exposeInternals;
 
   if (EXPOSE_INTERNALS) {
+    delete process._exposeInternals;
     NativeModule.nonInternalExists = NativeModule.exists;
 
     NativeModule.isInternal = function(id) {

src/node.cc

@@ -163,6 +163,7 @@ static bool trace_sync_io = false;
 static bool track_heap_objects = false;
 static const char* eval_string = nullptr;
 static std::vector<std::string> preload_modules;
+static bool expose_internals = false;
 static const int v8_default_thread_pool_size = 4;
 static int v8_thread_pool_size = v8_default_thread_pool_size;
 static bool prof_process = false;
@@ -3333,6 +3334,13 @@ void SetupProcessObject(Environment* env,
     READONLY_PROPERTY(process, "_debugWaitConnect", True(env->isolate()));
   }
 
+  // --expose_internals, --expose-internals
+  // Note that this is not exposed as a process property, it is deleted when
+  // node's javascript bootstrap code runs.
+  if (expose_internals) {
+    READONLY_PROPERTY(process, "_exposeInternals", True(env->isolate()));
+  }
+
   // --security-revert flags
 #define V(code, _, __)                                                        \
   do {                                                                        \
@@ -3786,7 +3794,7 @@ static void ParseArgs(int* argc,
 #endif
     } else if (strcmp(arg, "--expose-internals") == 0 ||
                strcmp(arg, "--expose_internals") == 0) {
-      // consumed in js
+      expose_internals = true;
     } else if (strcmp(arg, "--") == 0) {
       index += 1;
       break;

test/parallel/test-internal-modules-expose.js

@@ -5,3 +5,4 @@ require('../common');
 const assert = require('assert');
 
 assert.strictEqual(typeof require('internal/freelist').FreeList, 'function');
+assert(!('_exposeInternals' in process), 'no process property is leaked');