gecko-dev/js/ipc/JavaScriptChild.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=4 sw=2 et tw=80:
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "JavaScriptChild.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/ipc/MessageChannel.h"
#include "nsContentUtils.h"
#include "xpcprivate.h"
#include "jsfriendapi.h"
#include "AccessCheck.h"

using namespace JS;
using namespace mozilla;
using namespace mozilla::jsipc;

using mozilla::AutoSafeJSContext;

static void UpdateChildWeakPointersBeforeSweepingZoneGroup(JSContext* cx,
                                                           void* data) {
  static_cast<JavaScriptChild*>(data)->updateWeakPointers();
}

static void TraceChild(JSTracer* trc, void* data) {
  static_cast<JavaScriptChild*>(data)->trace(trc);
}

JavaScriptChild::~JavaScriptChild() {
  JSContext* cx = dom::danger::GetJSContext();
  JS_RemoveWeakPointerZonesCallback(
      cx, UpdateChildWeakPointersBeforeSweepingZoneGroup);
  JS_RemoveExtraGCRootsTracer(cx, TraceChild, this);
}

bool JavaScriptChild::init() {
  JSContext* cx = dom::danger::GetJSContext();
  JS_AddWeakPointerZonesCallback(
      cx, UpdateChildWeakPointersBeforeSweepingZoneGroup, this);
  JS_AddExtraGCRootsTracer(cx, TraceChild, this);
  return true;
}

void JavaScriptChild::trace(JSTracer* trc) {
  objects_.trace(trc, strongReferenceObjIdMinimum_);
}

void JavaScriptChild::updateWeakPointers() {
  objects_.sweep();
  unwaivedObjectIds_.sweep();
  waivedObjectIds_.sweep();
}

JSObject* JavaScriptChild::scopeForTargetObjects() {
  // CPOWs from the parent need to point into the child's privileged junk
  // scope so that they can benefit from XrayWrappers in the child.
  return xpc::PrivilegedJunkScope();
}

mozilla::ipc::IPCResult JavaScriptChild::RecvDropTemporaryStrongReferences(
    const uint64_t& upToObjId) {
  strongReferenceObjIdMinimum_ = upToObjId + 1;
  return IPC_OK();
}

PJavaScriptChild* mozilla::jsipc::NewJavaScriptChild() {
  JavaScriptChild* child = new JavaScriptChild();
  if (!child->init()) {
    delete child;
    return nullptr;
  }
  return child;
}

void mozilla::jsipc::ReleaseJavaScriptChild(PJavaScriptChild* child) {
  static_cast<JavaScriptChild*>(child)->decref();
}