1 files changed, 288 insertions, 0 deletions
diff --git a/ipc/glue/Endpoint.h b/ipc/glue/Endpoint.h
new file mode 100644
index 0000000000..d7eea94dfc
--- /dev/null
+++ b/ipc/glue/Endpoint.h
@@ -0,0 +1,288 @@
+/* -*- 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 IPC_GLUE_ENDPOINT_H_
+#define IPC_GLUE_ENDPOINT_H_
+
+#include <utility>
+#include "CrashAnnotations.h"
+#include "base/process.h"
+#include "base/process_util.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/ipc/MessageLink.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/ipc/NodeController.h"
+#include "mozilla/ipc/ScopedPort.h"
+#include "nsXULAppAPI.h"
+#include "nscore.h"
+
+namespace IPC {
+template <class P>
+struct ParamTraits;
+}
+
+namespace mozilla {
+namespace ipc {
+
+namespace endpoint_detail {
+
+template <class T>
+static auto ActorNeedsOtherPidHelper(int)
+    -> decltype(std::declval<T>().OtherPid(), std::true_type{});
+template <class>
+static auto ActorNeedsOtherPidHelper(long) -> std::false_type;
+
+template <typename T>
+constexpr bool ActorNeedsOtherPid =
+    decltype(ActorNeedsOtherPidHelper<T>(0))::value;
+
+}  // namespace endpoint_detail
+
+struct PrivateIPDLInterface {};
+
+class UntypedEndpoint {
+ public:
+  using ProcessId = base::ProcessId;
+
+  UntypedEndpoint() = default;
+
+  UntypedEndpoint(const PrivateIPDLInterface&, ScopedPort aPort,
+                  const nsID& aMessageChannelId,
+                  ProcessId aMyPid = base::kInvalidProcessId,
+                  ProcessId aOtherPid = base::kInvalidProcessId)
+      : mPort(std::move(aPort)),
+        mMessageChannelId(aMessageChannelId),
+        mMyPid(aMyPid),
+        mOtherPid(aOtherPid) {}
+
+  UntypedEndpoint(const UntypedEndpoint&) = delete;
+  UntypedEndpoint(UntypedEndpoint&& aOther) = default;
+
+  UntypedEndpoint& operator=(const UntypedEndpoint&) = delete;
+  UntypedEndpoint& operator=(UntypedEndpoint&& aOther) = default;
+
+  // This method binds aActor to this endpoint. After this call, the actor can
+  // be used to send and receive messages. The endpoint becomes invalid.
+  //
+  // If specified, aEventTarget is the target the actor will be bound to, and
+  // must be on the current thread. Otherwise, GetCurrentSerialEventTarget() is
+  // used.
+  bool Bind(IToplevelProtocol* aActor,
+            nsISerialEventTarget* aEventTarget = nullptr) {
+    MOZ_RELEASE_ASSERT(IsValid());
+    MOZ_RELEASE_ASSERT(mMyPid == base::kInvalidProcessId ||
+                       mMyPid == base::GetCurrentProcId());
+    MOZ_RELEASE_ASSERT(!aEventTarget || aEventTarget->IsOnCurrentThread());
+    return aActor->Open(std::move(mPort), mMessageChannelId, mOtherPid,
+                        aEventTarget);
+  }
+
+  bool IsValid() const { return mPort.IsValid(); }
+
+ protected:
+  friend struct IPC::ParamTraits<UntypedEndpoint>;
+
+  ScopedPort mPort;
+  nsID mMessageChannelId{};
+  ProcessId mMyPid = base::kInvalidProcessId;
+  ProcessId mOtherPid = base::kInvalidProcessId;
+};
+
+/**
+ * An endpoint represents one end of a partially initialized IPDL channel. To
+ * set up a new top-level protocol:
+ *
+ * Endpoint<PFooParent> parentEp;
+ * Endpoint<PFooChild> childEp;
+ * nsresult rv;
+ * rv = PFoo::CreateEndpoints(&parentEp, &childEp);
+ *
+ * Endpoints can be passed in IPDL messages or sent to other threads using
+ * PostTask. Once an Endpoint has arrived at its destination process and thread,
+ * you need to create the top-level actor and bind it to the endpoint:
+ *
+ * FooParent* parent = new FooParent();
+ * bool rv1 = parentEp.Bind(parent, processActor);
+ * bool rv2 = parent->SendBar(...);
+ *
+ * (See Bind below for an explanation of processActor.) Once the actor is bound
+ * to the endpoint, it can send and receive messages.
+ *
+ * If creating endpoints for a [NeedsOtherPid] actor, you're required to also
+ * pass in parentPid and childPid, which are the pids of the processes in which
+ * the parent and child endpoints will be used.
+ */
+template <class PFooSide>
+class Endpoint final : public UntypedEndpoint {
+ public:
+  using UntypedEndpoint::IsValid;
+  using UntypedEndpoint::UntypedEndpoint;
+
+  base::ProcessId OtherPid() const {
+    static_assert(
+        endpoint_detail::ActorNeedsOtherPid<PFooSide>,
+        "OtherPid may only be called on Endpoints for actors which are "
+        "[NeedsOtherPid]");
+    MOZ_RELEASE_ASSERT(mOtherPid != base::kInvalidProcessId);
+    return mOtherPid;
+  }
+
+  // This method binds aActor to this endpoint. After this call, the actor can
+  // be used to send and receive messages. The endpoint becomes invalid.
+  //
+  // If specified, aEventTarget is the target the actor will be bound to, and
+  // must be on the current thread. Otherwise, GetCurrentSerialEventTarget() is
+  // used.
+  bool Bind(PFooSide* aActor, nsISerialEventTarget* aEventTarget = nullptr) {
+    return UntypedEndpoint::Bind(aActor, aEventTarget);
+  }
+};
+
+#if defined(XP_MACOSX)
+void AnnotateCrashReportWithErrno(CrashReporter::Annotation tag, int error);
+#else
+inline void AnnotateCrashReportWithErrno(CrashReporter::Annotation tag,
+                                         int error) {}
+#endif
+
+// This function is used internally to create a pair of Endpoints. See the
+// comment above Endpoint for a description of how it might be used.
+template <class PFooParent, class PFooChild>
+nsresult CreateEndpoints(const PrivateIPDLInterface& aPrivate,
+                         Endpoint<PFooParent>* aParentEndpoint,
+                         Endpoint<PFooChild>* aChildEndpoint) {
+  static_assert(
+      !endpoint_detail::ActorNeedsOtherPid<PFooParent> &&
+          !endpoint_detail::ActorNeedsOtherPid<PFooChild>,
+      "Pids are required when creating endpoints for [NeedsOtherPid] actors");
+
+  auto [parentPort, childPort] =
+      NodeController::GetSingleton()->CreatePortPair();
+  nsID channelId = nsID::GenerateUUID();
+  *aParentEndpoint =
+      Endpoint<PFooParent>(aPrivate, std::move(parentPort), channelId);
+  *aChildEndpoint =
+      Endpoint<PFooChild>(aPrivate, std::move(childPort), channelId);
+  return NS_OK;
+}
+
+template <class PFooParent, class PFooChild>
+nsresult CreateEndpoints(const PrivateIPDLInterface& aPrivate,
+                         base::ProcessId aParentDestPid,
+                         base::ProcessId aChildDestPid,
+                         Endpoint<PFooParent>* aParentEndpoint,
+                         Endpoint<PFooChild>* aChildEndpoint) {
+  MOZ_RELEASE_ASSERT(aParentDestPid != base::kInvalidProcessId);
+  MOZ_RELEASE_ASSERT(aChildDestPid != base::kInvalidProcessId);
+
+  auto [parentPort, childPort] =
+      NodeController::GetSingleton()->CreatePortPair();
+  nsID channelId = nsID::GenerateUUID();
+  *aParentEndpoint =
+      Endpoint<PFooParent>(aPrivate, std::move(parentPort), channelId,
+                           aParentDestPid, aChildDestPid);
+  *aChildEndpoint = Endpoint<PFooChild>(
+      aPrivate, std::move(childPort), channelId, aChildDestPid, aParentDestPid);
+  return NS_OK;
+}
+
+class UntypedManagedEndpoint {
+ public:
+  bool IsValid() const { return mInner.isSome(); }
+
+  UntypedManagedEndpoint(const UntypedManagedEndpoint&) = delete;
+  UntypedManagedEndpoint& operator=(const UntypedManagedEndpoint&) = delete;
+
+ protected:
+  UntypedManagedEndpoint() = default;
+  explicit UntypedManagedEndpoint(IProtocol* aActor);
+
+  UntypedManagedEndpoint(UntypedManagedEndpoint&& aOther) noexcept
+      : mInner(std::move(aOther.mInner)) {
+    aOther.mInner = Nothing();
+  }
+  UntypedManagedEndpoint& operator=(UntypedManagedEndpoint&& aOther) noexcept {
+    this->~UntypedManagedEndpoint();
+    new (this) UntypedManagedEndpoint(std::move(aOther));
+    return *this;
+  }
+
+  ~UntypedManagedEndpoint() noexcept;
+
+  bool BindCommon(IProtocol* aActor, IProtocol* aManager);
+
+ private:
+  friend struct IPDLParamTraits<UntypedManagedEndpoint>;
+
+  struct Inner {
+    // Pointers to the toplevel actor which will manage this connection. When
+    // created, only `mOtherSide` will be set, and will reference the
+    // toplevel actor which the other side is managed by. After being sent over
+    // IPC, only `mToplevel` will be set, and will be the toplevel actor for the
+    // channel which received the IPC message.
+    RefPtr<WeakActorLifecycleProxy> mOtherSide;
+    RefPtr<WeakActorLifecycleProxy> mToplevel;
+
+    int32_t mId = 0;
+    ProtocolId mType = LastMsgIndex;
+    int32_t mManagerId = 0;
+    ProtocolId mManagerType = LastMsgIndex;
+  };
+  Maybe<Inner> mInner;
+};
+
+/**
+ * A managed endpoint represents one end of a partially initialized managed
+ * IPDL actor. It is used for situations where the usual IPDL Constructor
+ * methods do not give sufficient control over the construction of actors, such
+ * as when constructing actors within replies, or constructing multiple related
+ * actors simultaneously.
+ *
+ * FooParent* parent = new FooParent();
+ * ManagedEndpoint<PFooChild> childEp = parentMgr->OpenPFooEndpoint(parent);
+ *
+ * ManagedEndpoints should be sent using IPDL messages or other mechanisms to
+ * the other side of the manager channel. Once the ManagedEndpoint has arrived
+ * at its destination, you can create the actor, and bind it to the endpoint.
+ *
+ * FooChild* child = new FooChild();
+ * childMgr->BindPFooEndpoint(childEp, child);
+ *
+ * WARNING: If the remote side of an endpoint has not been bound before it
+ * begins to receive messages, an IPC routing error will occur, likely causing
+ * a browser crash.
+ */
+template <class PFooSide>
+class ManagedEndpoint : public UntypedManagedEndpoint {
+ public:
+  ManagedEndpoint() = default;
+  ManagedEndpoint(ManagedEndpoint&&) noexcept = default;
+  ManagedEndpoint& operator=(ManagedEndpoint&&) noexcept = default;
+
+  ManagedEndpoint(const PrivateIPDLInterface&, IProtocol* aActor)
+      : UntypedManagedEndpoint(aActor) {}
+
+  bool Bind(const PrivateIPDLInterface&, PFooSide* aActor, IProtocol* aManager,
+            ManagedContainer<PFooSide>& aContainer) {
+    if (!BindCommon(aActor, aManager)) {
+      return false;
+    }
+    aContainer.Insert(aActor);
+    return true;
+  }
+
+  // Only invalid ManagedEndpoints can be equal, as valid endpoints are unique.
+  bool operator==(const ManagedEndpoint& _o) const {
+    return !IsValid() && !_o.IsValid();
+  }
+};
+
+}  // namespace ipc
+}  // namespace mozilla
+
+#endif  // IPC_GLUE_ENDPOINT_H_