fs: use faster shallow object cloner

Author: mscdex

lib/fs.js

@@ -28,7 +28,7 @@ const constants = process.binding('constants').fs;
 const { S_IFMT, S_IFREG, S_IFLNK } = constants;
 const util = require('util');
 const pathModule = require('path');
-const { isUint8Array } = process.binding('util');
+const { isUint8Array, shallowClone: copyObject } = process.binding('util');
 
 const binding = process.binding('fs');
 const fs = exports;
@@ -93,13 +93,6 @@ function getOptions(options, defaultOptions) {
   return options;
 }
 
-function copyObject(source) {
-  const target = {};
-  for (const key in source)
-    target[key] = source[key];
-  return target;
-}
-
 function rethrow() {
   // TODO(thefourtheye) Throw error instead of warning in major version > 7
   process.emitWarning(

src/node_util.cc

@@ -147,6 +147,15 @@ void WatchdogHasPendingSigint(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+void ShallowClone(const FunctionCallbackInfo<Value>& args) {
+  if (!args[0]->IsObject()) {
+    Environment* env = Environment::GetCurrent(args);
+    return env->ThrowTypeError("obj must be an object");
+  }
+  args.GetReturnValue().Set(args[0].As<Object>()->Clone());
+}
+
+
 void Initialize(Local<Object> target,
                 Local<Value> unused,
                 Local<Context> context) {
@@ -192,6 +201,8 @@ void Initialize(Local<Object> target,
   env->SetMethod(target, "startSigintWatchdog", StartSigintWatchdog);
   env->SetMethod(target, "stopSigintWatchdog", StopSigintWatchdog);
   env->SetMethod(target, "watchdogHasPendingSigint", WatchdogHasPendingSigint);
+
+  env->SetMethod(target, "shallowClone", ShallowClone);
 }
 
 }  // namespace util