extensions: Use V8 Maybe APIs in NativeHandler

extensions/renderer/module_system.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/module_system.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 177 matching lines @@
 
 ModuleSystem::NativesEnabledScope::~NativesEnabledScope() {
   module_system_->natives_enabled_--;
   CHECK_GE(module_system_->natives_enabled_, 0);
 }
 
 void ModuleSystem::HandleException(const v8::TryCatch& try_catch) {
   exception_handler_->HandleUncaughtException(try_catch);
 }
 
-v8::Local<v8::Value> ModuleSystem::Require(const std::string& module_name) {
-  if (module_name.size() >= v8::String::kMaxLength)
-    return v8::Undefined(GetIsolate());
+v8::MaybeLocal<v8::Object> ModuleSystem::Require(
+    const std::string& module_name) {
+  v8::Local<v8::String> v8_module_name;
+  if (!ToV8String(GetIsolate(), module_name, &v8_module_name))
+    return v8::MaybeLocal<v8::Object>();
   v8::EscapableHandleScope handle_scope(GetIsolate());
-  return handle_scope.Escape(RequireForJsInner(
-      ToV8StringUnsafe(GetIsolate(), module_name.c_str())));
+  v8::Local<v8::Value> value = RequireForJsInner(
+      v8_module_name);

[not at google - send to devlin, 2015/06/24 16:43:03]

This should fit on 1 line; run "git cl format" before submitting.

+  if (value.IsEmpty() || !value->IsObject())
+    return v8::MaybeLocal<v8::Object>();
+  return handle_scope.Escape(value.As<v8::Object>());
 }
 
 void ModuleSystem::RequireForJs(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   if (!args[0]->IsString()) {
     NOTREACHED() << "require() called with a non-string argument";
     return;
   }
   v8::Local<v8::String> module_name = args[0].As<v8::String>();
   args.GetReturnValue().Set(RequireForJsInner(module_name));
@@ skipping 173 matching lines @@
     return;
   }
   std::string name = *v8::String::Utf8Value(v8_module_name);
 
   // Switch to our v8 context because we need functions created while running
   // the require()d module to belong to our context, not the current one.
   v8::Context::Scope context_scope(context);
   NativesEnabledScope natives_enabled_scope(module_system);
 
   v8::TryCatch try_catch(info.GetIsolate());
-  v8::Local<v8::Value> module_value = (module_system->*require_function)(name);
-  if (try_catch.HasCaught()) {
+  v8::Local<v8::Value> module_value;
+  if (!(module_system->*require_function)(name).ToLocal(&module_value)) {
     module_system->HandleException(try_catch);
     return;
   }
-  if (module_value.IsEmpty() || !module_value->IsObject()) {
-    // require_function will have already logged this, we don't need to.
-    return;
-  }
 
   v8::Local<v8::Object> module = v8::Local<v8::Object>::Cast(module_value);
   v8::Local<v8::Value> field_value;
   if (!GetProperty(context, parameters, kModuleField, &field_value)) {
     module_system->HandleException(try_catch);
     return;
   }
   v8::Local<v8::String> field;
   if (!field_value->ToString(context).ToLocal(&field)) {
     module_system->HandleException(try_catch);
@@ skipping 112 matching lines @@
   if (!source_map_->Contains(module_name))
     return v8::Undefined(GetIsolate());
   return handle_scope.Escape(
       v8::Local<v8::Value>(source_map_->GetSource(GetIsolate(), module_name)));
 }
 
 void ModuleSystem::RequireNative(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   CHECK_EQ(1, args.Length());
   std::string native_name = *v8::String::Utf8Value(args[0]);
-  args.GetReturnValue().Set(RequireNativeFromString(native_name));
+  v8::Local<v8::Object> object;
+  if (RequireNativeFromString(native_name).ToLocal(&object))
+    args.GetReturnValue().Set(object);
 }
 
-v8::Local<v8::Value> ModuleSystem::RequireNativeFromString(
+v8::MaybeLocal<v8::Object> ModuleSystem::RequireNativeFromString(
     const std::string& native_name) {
   if (natives_enabled_ == 0) {
     // HACK: if in test throw exception so that we can test the natives-disabled
     // logic; however, under normal circumstances, this is programmer error so
     // we could crash.
     if (exception_handler_) {
-      return GetIsolate()->ThrowException(
+      GetIsolate()->ThrowException(
           ToV8StringUnsafe(GetIsolate(), "Natives disabled"));
+      return v8::MaybeLocal<v8::Object>();
     }
     Fatal(context_, "Natives disabled for requireNative(" + native_name + ")");
-    return v8::Undefined(GetIsolate());
+    return v8::MaybeLocal<v8::Object>();
   }
 
   if (overridden_native_handlers_.count(native_name) > 0u) {
-    return RequireForJsInner(
+    v8::Local<v8::Value> value = RequireForJsInner(
         ToV8StringUnsafe(GetIsolate(), native_name.c_str()));
+    if (value.IsEmpty() || !value->IsObject())
+      return v8::MaybeLocal<v8::Object>();

[not at google - send to devlin, 2015/06/24 16:43:03]

This should probably be a DCHECK since the code is only hit during testing. No
need to fail gracefully.

+    return value.As<v8::Object>();
   }
 
   NativeHandlerMap::iterator i = native_handler_map_.find(native_name);
   if (i == native_handler_map_.end()) {
     Fatal(context_,
           "Couldn't find native for requireNative(" + native_name + ")");
-    return v8::Undefined(GetIsolate());
+    return v8::MaybeLocal<v8::Object>();
   }
   return i->second->NewInstance();
 }
 
 void ModuleSystem::RequireAsync(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   CHECK_EQ(1, args.Length());
   std::string module_name = *v8::String::Utf8Value(args[0]);
   v8::Local<v8::Context> v8_context = context_->v8_context();
   v8::Local<v8::Promise::Resolver> resolver(
@@ skipping 163 matching lines @@
 
 void ModuleSystem::ClobberExistingNativeHandler(const std::string& name) {
   NativeHandlerMap::iterator existing_handler = native_handler_map_.find(name);
   if (existing_handler != native_handler_map_.end()) {
     clobbered_native_handlers_.push_back(existing_handler->second);
     native_handler_map_.erase(existing_handler);
   }
 }
 
 }  // namespace extensions