plugins/ipc/PluginScriptableObjectUtils.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et :
 * 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/. */

#ifndef dom_plugins_PluginScriptableObjectUtils_h
#define dom_plugins_PluginScriptableObjectUtils_h

#include "PluginModuleParent.h"
#include "PluginModuleChild.h"
#include "PluginInstanceParent.h"
#include "PluginInstanceChild.h"
#include "PluginScriptableObjectParent.h"
#include "PluginScriptableObjectChild.h"

#include "npapi.h"
#include "npfunctions.h"
#include "npruntime.h"

#include "nsDebug.h"

namespace mozilla {
namespace plugins {

inline PluginInstanceParent* GetInstance(NPObject* aObject) {
  NS_ASSERTION(aObject->_class == PluginScriptableObjectParent::GetClass(),
               "Bad class!");

  ParentNPObject* object = reinterpret_cast<ParentNPObject*>(aObject);
  if (object->invalidated) {
    NS_WARNING("Calling method on an invalidated object!");
    return nullptr;
  }
  if (!object->parent) {
    return nullptr;
  }
  return object->parent->GetInstance();
}

inline NPObject* NPObjectFromVariant(const Variant& aRemoteVariant) {
  switch (aRemoteVariant.type()) {
    case Variant::TPPluginScriptableObjectParent: {
      PluginScriptableObjectParent* actor =
          const_cast<PluginScriptableObjectParent*>(
              reinterpret_cast<const PluginScriptableObjectParent*>(
                  aRemoteVariant.get_PPluginScriptableObjectParent()));
      return actor->GetObject(true);
    }

    case Variant::TPPluginScriptableObjectChild: {
      PluginScriptableObjectChild* actor =
          const_cast<PluginScriptableObjectChild*>(
              reinterpret_cast<const PluginScriptableObjectChild*>(
                  aRemoteVariant.get_PPluginScriptableObjectChild()));
      return actor->GetObject(true);
    }

    default:
      MOZ_ASSERT_UNREACHABLE("Shouldn't get here!");
      return nullptr;
  }
}

inline NPObject* NPObjectFromVariant(const NPVariant& aVariant) {
  NS_ASSERTION(NPVARIANT_IS_OBJECT(aVariant), "Wrong variant type!");
  return NPVARIANT_TO_OBJECT(aVariant);
}

inline const NPNetscapeFuncs* GetNetscapeFuncs(
    PluginInstanceParent* aInstance) {
  PluginModuleParent* module = aInstance->Module();
  if (!module) {
    NS_WARNING("Null module?!");
    return nullptr;
  }
  return module->GetNetscapeFuncs();
}

inline const NPNetscapeFuncs* GetNetscapeFuncs(NPObject* aObject) {
  NS_ASSERTION(aObject->_class == PluginScriptableObjectParent::GetClass(),
               "Bad class!");

  PluginInstanceParent* instance = GetInstance(aObject);
  if (!instance) {
    return nullptr;
  }

  return GetNetscapeFuncs(instance);
}

inline void ReleaseRemoteVariant(Variant& aVariant) {
  switch (aVariant.type()) {
    case Variant::TPPluginScriptableObjectParent: {
      PluginScriptableObjectParent* actor =
          const_cast<PluginScriptableObjectParent*>(
              reinterpret_cast<const PluginScriptableObjectParent*>(
                  aVariant.get_PPluginScriptableObjectParent()));
      actor->Unprotect();
      break;
    }

    case Variant::TPPluginScriptableObjectChild: {
      NS_ASSERTION(XRE_GetProcessType() == GeckoProcessType_Plugin,
                   "Should only be running in the child!");
      PluginScriptableObjectChild* actor =
          const_cast<PluginScriptableObjectChild*>(
              reinterpret_cast<const PluginScriptableObjectChild*>(
                  aVariant.get_PPluginScriptableObjectChild()));
      actor->Unprotect();
      break;
    }

    default:
      break;  // Intentional fall-through for other variant types.
  }

  aVariant = mozilla::void_t();
}

bool ConvertToVariant(const Variant& aRemoteVariant, NPVariant& aVariant,
                      PluginInstanceParent* aInstance = nullptr);

template <class InstanceType>
bool ConvertToRemoteVariant(const NPVariant& aVariant, Variant& aRemoteVariant,
                            InstanceType* aInstance,
                            bool aProtectActors = false);

class ProtectedVariant {
 public:
  ProtectedVariant(const NPVariant& aVariant, PluginInstanceParent* aInstance) {
    mOk = ConvertToRemoteVariant(aVariant, mVariant, aInstance, true);
  }

  ProtectedVariant(const NPVariant& aVariant, PluginInstanceChild* aInstance) {
    mOk = ConvertToRemoteVariant(aVariant, mVariant, aInstance, true);
  }

  ~ProtectedVariant() { ReleaseRemoteVariant(mVariant); }

  bool IsOk() { return mOk; }

  operator const Variant&() { return mVariant; }

 private:
  Variant mVariant;
  bool mOk;
};

class ProtectedVariantArray {
 public:
  ProtectedVariantArray(const NPVariant* aArgs, uint32_t aCount,
                        PluginInstanceParent* aInstance)
      : mUsingShadowArray(false) {
    for (uint32_t index = 0; index < aCount; index++) {
      Variant* remoteVariant = mArray.AppendElement();
      if (!(remoteVariant &&
            ConvertToRemoteVariant(aArgs[index], *remoteVariant, aInstance,
                                   true))) {
        mOk = false;
        return;
      }
    }
    mOk = true;
  }

  ProtectedVariantArray(const NPVariant* aArgs, uint32_t aCount,
                        PluginInstanceChild* aInstance)
      : mUsingShadowArray(false) {
    for (uint32_t index = 0; index < aCount; index++) {
      Variant* remoteVariant = mArray.AppendElement();
      if (!(remoteVariant &&
            ConvertToRemoteVariant(aArgs[index], *remoteVariant, aInstance,
                                   true))) {
        mOk = false;
        return;
      }
    }
    mOk = true;
  }

  ~ProtectedVariantArray() {
    nsTArray<Variant>& vars = EnsureAndGetShadowArray();
    uint32_t count = vars.Length();
    for (uint32_t index = 0; index < count; index++) {
      ReleaseRemoteVariant(vars[index]);
    }
  }

  operator const nsTArray<Variant>&() { return EnsureAndGetShadowArray(); }

  bool IsOk() { return mOk; }

 private:
  nsTArray<Variant>& EnsureAndGetShadowArray() {
    if (!mUsingShadowArray) {
      mShadowArray.SwapElements(mArray);
      mUsingShadowArray = true;
    }
    return mShadowArray;
  }

  // We convert the variants fallibly, but pass them to Call*()
  // methods as an infallible array
  nsTArray<Variant> mArray;
  nsTArray<Variant> mShadowArray;
  bool mOk;
  bool mUsingShadowArray;
};

template <class ActorType>
struct ProtectedActorTraits {
  static bool Nullable();
};

template <class ActorType, class Traits = ProtectedActorTraits<ActorType> >
class ProtectedActor {
 public:
  explicit ProtectedActor(ActorType* aActor) : mActor(aActor) {
    if (!Traits::Nullable()) {
      NS_ASSERTION(mActor, "This should never be null!");
    }
  }

  ~ProtectedActor() {
    if (Traits::Nullable() && !mActor) return;
    mActor->Unprotect();
  }

  ActorType* operator->() { return mActor; }

  explicit operator bool() { return !!mActor; }

 private:
  ActorType* mActor;
};

template <>
struct ProtectedActorTraits<PluginScriptableObjectParent> {
  static bool Nullable() { return true; }
};

template <>
struct ProtectedActorTraits<PluginScriptableObjectChild> {
  static bool Nullable() { return false; }
};

} /* namespace plugins */
} /* namespace mozilla */

#include "PluginScriptableObjectUtils-inl.h"

#endif /* dom_plugins_PluginScriptableObjectUtils_h */