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+/* -*- 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
+
+#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/UniquePtr.h"
+#include "mozilla/ipc/MessageChannel.h"
+#include "mozilla/ipc/MessageLink.h"
+#include "mozilla/ipc/SharedMemory.h"
+#include "mozilla/ipc/Shmem.h"
+#include "nsPrintfCString.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 {
+
+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 IRefCountedProtocol;
+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;
+
+ virtual uint32_t AllManagedActorsCount() 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() = 0;
+
+ // 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() = 0;
+
+ 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__)
+
+/*
+ * IPC_FAIL_UNSAFE_PRINTF(actor, format, ...)
+ *
+ * Create a failure IPCResult with a dynamic reason-string.
+ *
+ * @note This macro causes data collection because IPC failure reasons may be
+ * sent to crash-stats, where they are publicly visible. Firefox data stewards
+ * must do data review on usages of this macro.
+ */
+#define IPC_FAIL_UNSAFE_PRINTF(actor, format, ...) \
+ mozilla::ipc::IPCResult::FailUnsafePrintfImpl( \
+ WrapNotNull(actor), __func__, nsPrintfCString(format, ##__VA_ARGS__))
+
+/**
+ * All message deserializers and message handlers should return this type via
+ * the 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.
+ *
+ * Note that merely constructing a failure-result, whether directly or via the
+ * IPC_FAIL macros, causes the associated error message to be processed
+ * immediately.
+ */
+class IPCResult {
+ public:
+ static IPCResult Ok() { return IPCResult(true); }
+
+ // IPC failure messages can sometimes end up in telemetry. As such, to avoid
+ // accidentally exfiltrating sensitive information without a data review, we
+ // require that they be constant strings.
+ template <size_t N, size_t M>
+ static IPCResult Fail(NotNull<IProtocol*> aActor, const char (&aWhere)[N],
+ const char (&aWhy)[M]) {
+ return FailImpl(aActor, aWhere, aWhy);
+ }
+ template <size_t N>
+ static IPCResult Fail(NotNull<IProtocol*> aActor, const char (&aWhere)[N]) {
+ return FailImpl(aActor, aWhere, "");
+ }
+
+ MOZ_IMPLICIT operator bool() const { return mSuccess; }
+
+ // Only used by IPC_FAIL_UNSAFE_PRINTF (q.v.). Do not call this directly. (Or
+ // at least get data-review's approval if you do.)
+ template <size_t N>
+ static IPCResult FailUnsafePrintfImpl(NotNull<IProtocol*> aActor,
+ const char (&aWhere)[N],
+ nsPrintfCString const& aWhy) {
+ return FailImpl(aActor, aWhere, aWhy.get());
+ }
+
+ private:
+ static IPCResult FailImpl(NotNull<IProtocol*> aActor, const char* aWhere,
+ const char* aWhy);
+
+ explicit IPCResult(bool aResult) : mSuccess(aResult) {}
+ bool mSuccess;
+};
+
+class UntypedEndpoint;
+
+template <class PFooSide>
+class Endpoint;
+
+template <class PFooSide>
+class ManagedEndpoint;
+
+/**
+ * All refcounted protocols should inherit this class.
+ */
+class IRefCountedProtocol : public IProtocol {
+ public:
+ NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+ using IProtocol::IProtocol;
+};
+
+/**
+ * All top-level protocols should inherit this class.
+ *
+ * IToplevelProtocol tracks all top-level protocol actors created from
+ * this protocol actor.
+ */
+class IToplevelProtocol : public IRefCountedProtocol {
+ template <class PFooSide>
+ friend class Endpoint;
+
+ protected:
+ explicit IToplevelProtocol(const char* aName, ProtocolId aProtoId,
+ Side aSide);
+ ~IToplevelProtocol() = default;
+
+ public:
+ // 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 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<RefPtr<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, mozilla::ipc::Side aSide,
+ const char* aFilter);
+#endif
+
+inline bool LoggingEnabledFor(const char* aTopLevelProtocol,
+ mozilla::ipc::Side aSide) {
+#if defined(DEBUG) || defined(FUZZING)
+ return LoggingEnabledFor(aTopLevelProtocol, aSide,
+ 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, std::forward<F>(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
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-09 00:43:53 +0000