Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 746 insertions, 0 deletions

diff --git a/ipc/glue/ProtocolUtils.h b/ipc/glue/ProtocolUtils.h
new file mode 100644
index 0000000000..aa398453ae
--- /dev/null
+++ b/ipc/glue/ProtocolUtils.h
@@ -0,0 +1,746 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 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 https://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ipc_ProtocolUtils_h
+#define mozilla_ipc_ProtocolUtils_h 1
+
+#include <cstddef>
+#include <cstdint>
+#include <utility>
+#include "IPCMessageStart.h"
+#include "base/basictypes.h"
+#include "base/process.h"
+#include "chrome/common/ipc_message.h"
+#include "mojo/core/ports/port_ref.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/FunctionRef.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Scoped.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/ipc/MessageChannel.h"
+#include "mozilla/ipc/MessageLink.h"
+#include "mozilla/ipc/SharedMemory.h"
+#include "mozilla/ipc/Shmem.h"
+#include "nsTHashMap.h"
+#include "nsDebug.h"
+#include "nsISupports.h"
+#include "nsTArrayForwardDeclare.h"
+#include "nsTHashSet.h"
+
+// XXX Things that could be moved to ProtocolUtils.cpp
+#include "base/process_util.h"  // for CloseProcessHandle
+#include "prenv.h"              // for PR_GetEnv
+
+#if defined(ANDROID) && defined(DEBUG)
+#  include <android/log.h>
+#endif
+
+template <typename T>
+class nsPtrHashKey;
+
+// WARNING: this takes into account the private, special-message-type
+// enum in ipc_channel.h.  They need to be kept in sync.
+namespace {
+// XXX the max message ID is actually kuint32max now ... when this
+// changed, the assumptions of the special message IDs changed in that
+// they're not carving out messages from likely-unallocated space, but
+// rather carving out messages from the end of space allocated to
+// protocol 0.  Oops!  We can get away with this until protocol 0
+// starts approaching its 65,536th message.
+enum {
+  // Message types used by DataPipe
+  DATA_PIPE_CLOSED_MESSAGE_TYPE = kuint16max - 18,
+  DATA_PIPE_BYTES_CONSUMED_MESSAGE_TYPE = kuint16max - 17,
+
+  // Message types used by NodeChannel
+  ACCEPT_INVITE_MESSAGE_TYPE = kuint16max - 16,
+  REQUEST_INTRODUCTION_MESSAGE_TYPE = kuint16max - 15,
+  INTRODUCE_MESSAGE_TYPE = kuint16max - 14,
+  BROADCAST_MESSAGE_TYPE = kuint16max - 13,
+  EVENT_MESSAGE_TYPE = kuint16max - 12,
+
+  // Message types used by MessageChannel
+  MANAGED_ENDPOINT_DROPPED_MESSAGE_TYPE = kuint16max - 11,
+  MANAGED_ENDPOINT_BOUND_MESSAGE_TYPE = kuint16max - 10,
+  IMPENDING_SHUTDOWN_MESSAGE_TYPE = kuint16max - 9,
+  BUILD_IDS_MATCH_MESSAGE_TYPE = kuint16max - 8,
+  BUILD_ID_MESSAGE_TYPE = kuint16max - 7,  // unused
+  CHANNEL_OPENED_MESSAGE_TYPE = kuint16max - 6,
+  SHMEM_DESTROYED_MESSAGE_TYPE = kuint16max - 5,
+  SHMEM_CREATED_MESSAGE_TYPE = kuint16max - 4,
+  GOODBYE_MESSAGE_TYPE = kuint16max - 3,
+  CANCEL_MESSAGE_TYPE = kuint16max - 2,
+
+  // kuint16max - 1 is used by ipc_channel.h.
+};
+
+}  // namespace
+
+class MessageLoop;
+class PickleIterator;
+class nsISerialEventTarget;
+
+namespace mozilla {
+class SchedulerGroup;
+
+namespace dom {
+class ContentParent;
+}  // namespace dom
+
+namespace net {
+class NeckoParent;
+}  // namespace net
+
+namespace ipc {
+
+// Scoped base::ProcessHandle to ensure base::CloseProcessHandle is called.
+struct ScopedProcessHandleTraits {
+  typedef base::ProcessHandle type;
+
+  static type empty() { return base::kInvalidProcessHandle; }
+
+  static void release(type aProcessHandle) {
+    if (aProcessHandle && aProcessHandle != base::kInvalidProcessHandle) {
+      base::CloseProcessHandle(aProcessHandle);
+    }
+  }
+};
+typedef mozilla::Scoped<ScopedProcessHandleTraits> ScopedProcessHandle;
+
+class ProtocolFdMapping;
+class ProtocolCloneContext;
+
+// Used to pass references to protocol actors across the wire.
+// Actors created on the parent-side have a positive ID, and actors
+// allocated on the child side have a negative ID.
+struct ActorHandle {
+  int mId;
+};
+
+// What happens if Interrupt calls race?
+enum RacyInterruptPolicy { RIPError, RIPChildWins, RIPParentWins };
+
+enum class LinkStatus : uint8_t {
+  // The actor has not established a link yet, or the actor is no longer in use
+  // by IPC, and its 'Dealloc' method has been called or is being called.
+  //
+  // NOTE: This state is used instead of an explicit `Freed` state when IPC no
+  // longer holds references to the current actor as we currently re-open
+  // existing actors. Once we fix these poorly behaved actors, this loopback
+  // state can be split to have the final state not be the same as the initial
+  // state.
+  Inactive,
+
+  // A live link is connected to the other side of this actor.
+  Connected,
+
+  // The link has begun being destroyed. Messages may still be received, but
+  // cannot be sent. (exception: sync/intr replies may be sent while Doomed).
+  Doomed,
+
+  // The link has been destroyed, and messages will no longer be sent or
+  // received.
+  Destroyed,
+};
+
+typedef IPCMessageStart ProtocolId;
+
+// Generated by IPDL compiler
+const char* ProtocolIdToName(IPCMessageStart aId);
+
+class IToplevelProtocol;
+class ActorLifecycleProxy;
+class WeakActorLifecycleProxy;
+class IPDLResolverInner;
+class UntypedManagedEndpoint;
+
+class IProtocol : public HasResultCodes {
+ public:
+  enum ActorDestroyReason {
+    FailedConstructor,
+    Deletion,
+    AncestorDeletion,
+    NormalShutdown,
+    AbnormalShutdown,
+    ManagedEndpointDropped
+  };
+
+  typedef base::ProcessId ProcessId;
+  typedef IPC::Message Message;
+
+  IProtocol(ProtocolId aProtoId, Side aSide)
+      : mId(0),
+        mProtocolId(aProtoId),
+        mSide(aSide),
+        mLinkStatus(LinkStatus::Inactive),
+        mLifecycleProxy(nullptr),
+        mManager(nullptr),
+        mToplevel(nullptr) {}
+
+  IToplevelProtocol* ToplevelProtocol() { return mToplevel; }
+  const IToplevelProtocol* ToplevelProtocol() const { return mToplevel; }
+
+  // The following methods either directly forward to the toplevel protocol, or
+  // almost directly do.
+  int32_t Register(IProtocol* aRouted);
+  int32_t RegisterID(IProtocol* aRouted, int32_t aId);
+  IProtocol* Lookup(int32_t aId);
+  void Unregister(int32_t aId);
+
+  Shmem::SharedMemory* CreateSharedMemory(size_t aSize, bool aUnsafe,
+                                          int32_t* aId);
+  Shmem::SharedMemory* LookupSharedMemory(int32_t aId);
+  bool IsTrackingSharedMemory(Shmem::SharedMemory* aSegment);
+  bool DestroySharedMemory(Shmem& aShmem);
+
+  MessageChannel* GetIPCChannel();
+  const MessageChannel* GetIPCChannel() const;
+
+  // Get the nsISerialEventTarget which all messages sent to this actor will be
+  // processed on. Unless stated otherwise, all operations on IProtocol which
+  // don't occur on this `nsISerialEventTarget` are unsafe.
+  nsISerialEventTarget* GetActorEventTarget();
+
+  // Actor lifecycle and other properties.
+  ProtocolId GetProtocolId() const { return mProtocolId; }
+  const char* GetProtocolName() const { return ProtocolIdToName(mProtocolId); }
+
+  int32_t Id() const { return mId; }
+  IProtocol* Manager() const { return mManager; }
+
+  ActorLifecycleProxy* GetLifecycleProxy() { return mLifecycleProxy; }
+  WeakActorLifecycleProxy* GetWeakLifecycleProxy();
+
+  Side GetSide() const { return mSide; }
+  bool CanSend() const { return mLinkStatus == LinkStatus::Connected; }
+  bool CanRecv() const {
+    return mLinkStatus == LinkStatus::Connected ||
+           mLinkStatus == LinkStatus::Doomed;
+  }
+
+  // Remove or deallocate a managee given its type.
+  virtual void RemoveManagee(int32_t, IProtocol*) = 0;
+  virtual void DeallocManagee(int32_t, IProtocol*) = 0;
+
+  Maybe<IProtocol*> ReadActor(IPC::MessageReader* aReader, bool aNullable,
+                              const char* aActorDescription,
+                              int32_t aProtocolTypeId);
+
+  virtual Result OnMessageReceived(const Message& aMessage) = 0;
+  virtual Result OnMessageReceived(const Message& aMessage,
+                                   UniquePtr<Message>& aReply) = 0;
+  virtual Result OnCallReceived(const Message& aMessage,
+                                UniquePtr<Message>& aReply) = 0;
+  bool AllocShmem(size_t aSize, Shmem* aOutMem);
+  bool AllocUnsafeShmem(size_t aSize, Shmem* aOutMem);
+  bool DeallocShmem(Shmem& aMem);
+
+  void FatalError(const char* const aErrorMsg);
+  virtual void HandleFatalError(const char* aErrorMsg);
+
+ protected:
+  virtual ~IProtocol();
+
+  friend class IToplevelProtocol;
+  friend class ActorLifecycleProxy;
+  friend class IPDLResolverInner;
+  friend class UntypedManagedEndpoint;
+
+  void SetId(int32_t aId);
+
+  // We have separate functions because the accessibility code manually
+  // calls SetManager.
+  void SetManager(IProtocol* aManager);
+
+  // Sets the manager for the protocol and registers the protocol with
+  // its manager, setting up channels for the protocol as well.  Not
+  // for use outside of IPDL.
+  void SetManagerAndRegister(IProtocol* aManager);
+  void SetManagerAndRegister(IProtocol* aManager, int32_t aId);
+
+  // Helpers for calling `Send` on our underlying IPC channel.
+  bool ChannelSend(UniquePtr<IPC::Message> aMsg);
+  bool ChannelSend(UniquePtr<IPC::Message> aMsg,
+                   UniquePtr<IPC::Message>* aReply);
+  template <typename Value>
+  void ChannelSend(UniquePtr<IPC::Message> aMsg,
+                   IPC::Message::msgid_t aReplyMsgId,
+                   ResolveCallback<Value>&& aResolve,
+                   RejectCallback&& aReject) {
+    if (CanSend()) {
+      GetIPCChannel()->Send(std::move(aMsg), Id(), aReplyMsgId,
+                            std::move(aResolve), std::move(aReject));
+    } else {
+      WarnMessageDiscarded(aMsg.get());
+      aReject(ResponseRejectReason::SendError);
+    }
+  }
+
+  // Collect all actors managed by this object in an array. To make this safer
+  // to iterate, `ActorLifecycleProxy` references are returned rather than raw
+  // actor pointers.
+  virtual void AllManagedActors(
+      nsTArray<RefPtr<ActorLifecycleProxy>>& aActors) const = 0;
+
+  // Internal method called when the actor becomes connected.
+  void ActorConnected();
+
+  // Called immediately before setting the actor state to doomed, and triggering
+  // async actor destruction. Messages may be sent from this callback, but no
+  // later.
+  // FIXME(nika): This is currently unused!
+  virtual void ActorDoom() {}
+  void DoomSubtree();
+
+  // Called when the actor has been destroyed due to an error, a __delete__
+  // message, or a __doom__ reply.
+  virtual void ActorDestroy(ActorDestroyReason aWhy) {}
+  void DestroySubtree(ActorDestroyReason aWhy);
+
+  // Called when IPC has acquired its first reference to the actor. This method
+  // may take references which will later be freed by `ActorDealloc`.
+  virtual void ActorAlloc() {}
+
+  // Called when IPC has released its final reference to the actor. It will call
+  // the dealloc method, causing the actor to be actually freed.
+  //
+  // The actor has been freed after this method returns.
+  virtual void ActorDealloc() {
+    if (Manager()) {
+      Manager()->DeallocManagee(mProtocolId, this);
+    }
+  }
+
+  static const int32_t kNullActorId = 0;
+  static const int32_t kFreedActorId = 1;
+
+ private:
+#ifdef DEBUG
+  void WarnMessageDiscarded(IPC::Message* aMsg);
+#else
+  void WarnMessageDiscarded(IPC::Message*) {}
+#endif
+
+  int32_t mId;
+  ProtocolId mProtocolId;
+  Side mSide;
+  LinkStatus mLinkStatus;
+  ActorLifecycleProxy* mLifecycleProxy;
+  IProtocol* mManager;
+  IToplevelProtocol* mToplevel;
+};
+
+#define IPC_OK() mozilla::ipc::IPCResult::Ok()
+#define IPC_FAIL(actor, why) \
+  mozilla::ipc::IPCResult::Fail(WrapNotNull(actor), __func__, (why))
+#define IPC_FAIL_NO_REASON(actor) \
+  mozilla::ipc::IPCResult::Fail(WrapNotNull(actor), __func__)
+
+/**
+ * All message deserializer and message handler should return this
+ * type via above macros. We use a less generic name here to avoid
+ * conflict with mozilla::Result because we have quite a few using
+ * namespace mozilla::ipc; in the code base.
+ */
+class IPCResult {
+ public:
+  static IPCResult Ok() { return IPCResult(true); }
+  static IPCResult Fail(NotNull<IProtocol*> aActor, const char* aWhere,
+                        const char* aWhy = "");
+  MOZ_IMPLICIT operator bool() const { return mSuccess; }
+
+ private:
+  explicit IPCResult(bool aResult) : mSuccess(aResult) {}
+  bool mSuccess;
+};
+
+class UntypedEndpoint;
+
+template <class PFooSide>
+class Endpoint;
+
+template <class PFooSide>
+class ManagedEndpoint;
+
+/**
+ * All top-level protocols should inherit this class.
+ *
+ * IToplevelProtocol tracks all top-level protocol actors created from
+ * this protocol actor.
+ */
+class IToplevelProtocol : public IProtocol {
+  template <class PFooSide>
+  friend class Endpoint;
+
+ protected:
+  explicit IToplevelProtocol(const char* aName, ProtocolId aProtoId,
+                             Side aSide);
+  ~IToplevelProtocol() = default;
+
+ public:
+  // All top-level protocols are refcounted.
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  // Shadow methods on IProtocol which are implemented directly on toplevel
+  // actors.
+  int32_t Register(IProtocol* aRouted);
+  int32_t RegisterID(IProtocol* aRouted, int32_t aId);
+  IProtocol* Lookup(int32_t aId);
+  void Unregister(int32_t aId);
+
+  Shmem::SharedMemory* CreateSharedMemory(size_t aSize, bool aUnsafe,
+                                          int32_t* aId);
+  Shmem::SharedMemory* LookupSharedMemory(int32_t aId);
+  bool IsTrackingSharedMemory(Shmem::SharedMemory* aSegment);
+  bool DestroySharedMemory(Shmem& aShmem);
+
+  MessageChannel* GetIPCChannel() { return &mChannel; }
+  const MessageChannel* GetIPCChannel() const { return &mChannel; }
+
+  void SetOtherProcessId(base::ProcessId aOtherPid);
+
+  virtual void OnChannelClose() = 0;
+  virtual void OnChannelError() = 0;
+  virtual void ProcessingError(Result aError, const char* aMsgName) {}
+
+  bool Open(ScopedPort aPort, const nsID& aMessageChannelId,
+            base::ProcessId aOtherPid,
+            nsISerialEventTarget* aEventTarget = nullptr);
+
+  bool Open(IToplevelProtocol* aTarget, nsISerialEventTarget* aEventTarget,
+            mozilla::ipc::Side aSide = mozilla::ipc::UnknownSide);
+
+  // Open a toplevel actor such that both ends of the actor's channel are on
+  // the same thread. This method should be called on the thread to perform
+  // the link.
+  //
+  // WARNING: Attempting to send a sync or intr message on the same thread
+  // will crash.
+  bool OpenOnSameThread(IToplevelProtocol* aTarget,
+                        mozilla::ipc::Side aSide = mozilla::ipc::UnknownSide);
+
+  /**
+   * This sends a special message that is processed on the IO thread, so that
+   * other actors can know that the process will soon shutdown.
+   */
+  void NotifyImpendingShutdown();
+
+  void Close();
+  void CloseWithError();
+
+  void SetReplyTimeoutMs(int32_t aTimeoutMs);
+
+  void DeallocShmems();
+  bool ShmemCreated(const Message& aMsg);
+  bool ShmemDestroyed(const Message& aMsg);
+
+  virtual bool ShouldContinueFromReplyTimeout() { return false; }
+
+  // WARNING: This function is called with the MessageChannel monitor held.
+  virtual void IntentionalCrash() { MOZ_CRASH("Intentional IPDL crash"); }
+
+  // The code here is only useful for fuzzing. It should not be used for any
+  // other purpose.
+#ifdef DEBUG
+  // Returns true if we should simulate a timeout.
+  // WARNING: This is a testing-only function that is called with the
+  // MessageChannel monitor held. Don't do anything fancy here or we could
+  // deadlock.
+  virtual bool ArtificialTimeout() { return false; }
+
+  // Returns true if we want to cause the worker thread to sleep with the
+  // monitor unlocked.
+  virtual bool NeedArtificialSleep() { return false; }
+
+  // This function should be implemented to sleep for some amount of time on
+  // the worker thread. Will only be called if NeedArtificialSleep() returns
+  // true.
+  virtual void ArtificialSleep() {}
+#else
+  bool ArtificialTimeout() { return false; }
+  bool NeedArtificialSleep() { return false; }
+  void ArtificialSleep() {}
+#endif
+
+  bool IsOnCxxStack() const;
+
+  virtual void ProcessRemoteNativeEventsInInterruptCall() {}
+
+  virtual void OnChannelReceivedMessage(const Message& aMsg) {}
+
+  void OnIPCChannelOpened() { ActorConnected(); }
+
+  base::ProcessId OtherPidMaybeInvalid() const { return mOtherPid; }
+
+ private:
+  int32_t NextId();
+
+  template <class T>
+  using IDMap = nsTHashMap<nsUint32HashKey, T>;
+
+  base::ProcessId mOtherPid;
+
+  // NOTE NOTE NOTE
+  // Used to be on mState
+  int32_t mLastLocalId;
+  IDMap<IProtocol*> mActorMap;
+  IDMap<Shmem::SharedMemory*> mShmemMap;
+
+  MessageChannel mChannel;
+};
+
+class IShmemAllocator {
+ public:
+  virtual bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) = 0;
+  virtual bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) = 0;
+  virtual bool DeallocShmem(mozilla::ipc::Shmem& aShmem) = 0;
+};
+
+#define FORWARD_SHMEM_ALLOCATOR_TO(aImplClass)                             \
+  virtual bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem)       \
+      override {                                                           \
+    return aImplClass::AllocShmem(aSize, aShmem);                          \
+  }                                                                        \
+  virtual bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) \
+      override {                                                           \
+    return aImplClass::AllocUnsafeShmem(aSize, aShmem);                    \
+  }                                                                        \
+  virtual bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override {        \
+    return aImplClass::DeallocShmem(aShmem);                               \
+  }
+
+inline bool LoggingEnabled() {
+#if defined(DEBUG) || defined(FUZZING)
+  return !!PR_GetEnv("MOZ_IPC_MESSAGE_LOG");
+#else
+  return false;
+#endif
+}
+
+#if defined(DEBUG) || defined(FUZZING)
+bool LoggingEnabledFor(const char* aTopLevelProtocol, const char* aFilter);
+#endif
+
+inline bool LoggingEnabledFor(const char* aTopLevelProtocol) {
+#if defined(DEBUG) || defined(FUZZING)
+  return LoggingEnabledFor(aTopLevelProtocol, PR_GetEnv("MOZ_IPC_MESSAGE_LOG"));
+#else
+  return false;
+#endif
+}
+
+MOZ_NEVER_INLINE void LogMessageForProtocol(const char* aTopLevelProtocol,
+                                            base::ProcessId aOtherPid,
+                                            const char* aContextDescription,
+                                            uint32_t aMessageId,
+                                            MessageDirection aDirection);
+
+MOZ_NEVER_INLINE void ProtocolErrorBreakpoint(const char* aMsg);
+
+// IPC::MessageReader and IPC::MessageWriter call this function for FatalError
+// calls which come from serialization/deserialization.
+MOZ_NEVER_INLINE void PickleFatalError(const char* aMsg, IProtocol* aActor);
+
+// The code generator calls this function for errors which come from the
+// methods of protocols.  Doing this saves codesize by making the error
+// cases significantly smaller.
+MOZ_NEVER_INLINE void FatalError(const char* aMsg, bool aIsParent);
+
+// The code generator calls this function for errors which are not
+// protocol-specific: errors in generated struct methods or errors in
+// transition functions, for instance.  Doing this saves codesize by
+// by making the error cases significantly smaller.
+MOZ_NEVER_INLINE void LogicError(const char* aMsg);
+
+MOZ_NEVER_INLINE void ActorIdReadError(const char* aActorDescription);
+
+MOZ_NEVER_INLINE void BadActorIdError(const char* aActorDescription);
+
+MOZ_NEVER_INLINE void ActorLookupError(const char* aActorDescription);
+
+MOZ_NEVER_INLINE void MismatchedActorTypeError(const char* aActorDescription);
+
+MOZ_NEVER_INLINE void UnionTypeReadError(const char* aUnionName);
+
+MOZ_NEVER_INLINE void ArrayLengthReadError(const char* aElementName);
+
+MOZ_NEVER_INLINE void SentinelReadError(const char* aElementName);
+
+/**
+ * Annotate the crash reporter with the error code from the most recent system
+ * call. Returns the system error.
+ */
+void AnnotateSystemError();
+
+// The ActorLifecycleProxy is a helper type used internally by IPC to maintain a
+// maybe-owning reference to an IProtocol object. For well-behaved actors
+// which are not freed until after their `Dealloc` method is called, a
+// reference to an actor's `ActorLifecycleProxy` object is an owning one, as the
+// `Dealloc` method will only be called when all references to the
+// `ActorLifecycleProxy` are released.
+//
+// Unfortunately, some actors may be destroyed before their `Dealloc` method
+// is called. For these actors, `ActorLifecycleProxy` acts as a weak pointer,
+// and will begin to return `nullptr` from its `Get()` method once the
+// corresponding actor object has been destroyed.
+//
+// When calling a `Recv` method, IPC will hold a `ActorLifecycleProxy` reference
+// to the target actor, meaning that well-behaved actors can behave as though a
+// strong reference is being held.
+//
+// Generic IPC code MUST treat ActorLifecycleProxy references as weak
+// references!
+class ActorLifecycleProxy {
+ public:
+  NS_INLINE_DECL_REFCOUNTING_ONEVENTTARGET(ActorLifecycleProxy)
+
+  IProtocol* Get() { return mActor; }
+
+  WeakActorLifecycleProxy* GetWeakProxy();
+
+ private:
+  friend class IProtocol;
+
+  explicit ActorLifecycleProxy(IProtocol* aActor);
+  ~ActorLifecycleProxy();
+
+  ActorLifecycleProxy(const ActorLifecycleProxy&) = delete;
+  ActorLifecycleProxy& operator=(const ActorLifecycleProxy&) = delete;
+
+  IProtocol* MOZ_NON_OWNING_REF mActor;
+
+  // Hold a reference to the actor's manager's ActorLifecycleProxy to help
+  // prevent it from dying while we're still alive!
+  RefPtr<ActorLifecycleProxy> mManager;
+
+  // When requested, the current self-referencing weak reference for this
+  // ActorLifecycleProxy.
+  RefPtr<WeakActorLifecycleProxy> mWeakProxy;
+};
+
+// Unlike ActorLifecycleProxy, WeakActorLifecycleProxy only holds a weak
+// reference to both the proxy and the actual actor, meaning that holding this
+// type will not attempt to keep the actor object alive.
+//
+// This type is safe to hold on threads other than the actor's thread, but is
+// _NOT_ safe to access on other threads, as actors and ActorLifecycleProxy
+// objects are not threadsafe.
+class WeakActorLifecycleProxy final {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WeakActorLifecycleProxy)
+
+  // May only be called on the actor's event target.
+  // Will return `nullptr` if the actor has already been destroyed from IPC's
+  // point of view.
+  IProtocol* Get() const;
+
+  // Safe to call on any thread.
+  nsISerialEventTarget* ActorEventTarget() const { return mActorEventTarget; }
+
+ private:
+  friend class ActorLifecycleProxy;
+
+  explicit WeakActorLifecycleProxy(ActorLifecycleProxy* aProxy);
+  ~WeakActorLifecycleProxy();
+
+  WeakActorLifecycleProxy(const WeakActorLifecycleProxy&) = delete;
+  WeakActorLifecycleProxy& operator=(const WeakActorLifecycleProxy&) = delete;
+
+  // This field may only be accessed on the actor's thread, and will be
+  // automatically cleared when the ActorLifecycleProxy is destroyed.
+  ActorLifecycleProxy* MOZ_NON_OWNING_REF mProxy;
+
+  // The serial event target which owns the actor, and is the only thread where
+  // it is OK to access the ActorLifecycleProxy.
+  const nsCOMPtr<nsISerialEventTarget> mActorEventTarget;
+};
+
+class IPDLResolverInner final {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DESTROY(IPDLResolverInner,
+                                                     Destroy())
+
+  explicit IPDLResolverInner(UniquePtr<IPC::Message> aReply, IProtocol* aActor);
+
+  template <typename F>
+  void Resolve(F&& aWrite) {
+    ResolveOrReject(true, aWrite);
+  }
+
+ private:
+  void ResolveOrReject(bool aResolve,
+                       FunctionRef<void(IPC::Message*, IProtocol*)> aWrite);
+
+  void Destroy();
+  ~IPDLResolverInner();
+
+  UniquePtr<IPC::Message> mReply;
+  RefPtr<WeakActorLifecycleProxy> mWeakProxy;
+};
+
+}  // namespace ipc
+
+template <typename Protocol>
+class ManagedContainer {
+ public:
+  using iterator = typename nsTArray<Protocol*>::const_iterator;
+
+  iterator begin() const { return mArray.begin(); }
+  iterator end() const { return mArray.end(); }
+  iterator cbegin() const { return begin(); }
+  iterator cend() const { return end(); }
+
+  bool IsEmpty() const { return mArray.IsEmpty(); }
+  uint32_t Count() const { return mArray.Length(); }
+
+  void ToArray(nsTArray<Protocol*>& aArray) const {
+    aArray.AppendElements(mArray);
+  }
+
+  bool EnsureRemoved(Protocol* aElement) {
+    return mArray.RemoveElementSorted(aElement);
+  }
+
+  void Insert(Protocol* aElement) {
+    // Equivalent to `InsertElementSorted`, avoiding inserting a duplicate
+    // element.
+    size_t index = mArray.IndexOfFirstElementGt(aElement);
+    if (index == 0 || mArray[index - 1] != aElement) {
+      mArray.InsertElementAt(index, aElement);
+    }
+  }
+
+  void Clear() { mArray.Clear(); }
+
+ private:
+  nsTArray<Protocol*> mArray;
+};
+
+template <typename Protocol>
+Protocol* LoneManagedOrNullAsserts(
+    const ManagedContainer<Protocol>& aManagees) {
+  if (aManagees.IsEmpty()) {
+    return nullptr;
+  }
+  MOZ_ASSERT(aManagees.Count() == 1);
+  return *aManagees.cbegin();
+}
+
+template <typename Protocol>
+Protocol* SingleManagedOrNull(const ManagedContainer<Protocol>& aManagees) {
+  if (aManagees.Count() != 1) {
+    return nullptr;
+  }
+  return *aManagees.cbegin();
+}
+
+}  // namespace mozilla
+
+#endif  // mozilla_ipc_ProtocolUtils_h