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 config binding.

lib/internal/bootstrap_node.js

@@ -510,11 +510,9 @@
     return NativeModule._source.hasOwnProperty(id);
   };
 
-  const EXPOSE_INTERNALS = process.execArgv.some(function(arg) {
-    return arg.match(/^--expose[-_]internals$/);
-  });
+  const config = process.binding('config');
 
-  if (EXPOSE_INTERNALS) {
+  if (config.exposeInternals) {
     NativeModule.nonInternalExists = NativeModule.exists;
 
     NativeModule.isInternal = function(id) {

src/node.cc

@@ -214,6 +214,12 @@ bool config_preserve_symlinks = false;
 // Set in node.cc by ParseArgs when --redirect-warnings= is used.
 std::string config_warning_file;  // NOLINT(runtime/string)
 
+// Set in node.cc by ParseArgs when --expose-internals or --expose_internals is
+// used.
+// Used in node_config.cc to set a constant on process.binding('config')
+// that is used by lib/internal/bootstrap_node.js
+bool config_expose_internals = false;
+
 bool v8_initialized = false;
 
 // process-relative uptime base, initialized at start-up
@@ -3787,7 +3793,7 @@ static void ParseArgs(int* argc,
 #endif
     } else if (strcmp(arg, "--expose-internals") == 0 ||
                strcmp(arg, "--expose_internals") == 0) {
-      // consumed in js
+      config_expose_internals = true;
     } else if (strcmp(arg, "--") == 0) {
       index += 1;
       break;

src/node_config.cc

@@ -58,6 +58,9 @@ void InitConfig(Local<Object> target,
                                                 .ToLocalChecked();
     target->DefineOwnProperty(env->context(), name, value).FromJust();
   }
+
+  if (config_expose_internals)
+    READONLY_BOOLEAN_PROPERTY("exposeInternals");
 }  // InitConfig
 
 }  // namespace node

src/node_internals.h

@@ -65,6 +65,12 @@ extern std::string openssl_config;
 // that is used by lib/module.js
 extern bool config_preserve_symlinks;
 
+// Set in node.cc by ParseArgs when --expose-internals or --expose_internals is
+// used.
+// Used in node_config.cc to set a constant on process.binding('config')
+// that is used by lib/internal/bootstrap_node.js
+extern bool config_expose_internals;
+
 // Set in node.cc by ParseArgs when --redirect-warnings= is used.
 // Used to redirect warning output to a file rather than sending
 // it to stderr.

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

@@ -3,5 +3,9 @@
 
 require('../common');
 const assert = require('assert');
+const config = process.binding('config');
+
+console.log(config, process.argv);
 
 assert.strictEqual(typeof require('internal/freelist').FreeList, 'function');
+assert.strictEqual(config.exposeInternals, true);