ipc/glue/MessageLink.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: sw=2 ts=4 et :
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #include "mozilla/ipc/MessageLink.h"
   9 #include "mojo/core/ports/event.h"
  10 #include "mojo/core/ports/node.h"
  11 #include "mozilla/ipc/MessageChannel.h"
  12 #include "mozilla/ipc/BrowserProcessSubThread.h"
  13 #include "mozilla/ipc/ProtocolUtils.h"
  14 #include "mozilla/ipc/NodeController.h"
  15 #include "chrome/common/ipc_channel.h"
  16 #include "base/task.h"
  17
  18 #include "mozilla/Assertions.h"
  19 #include "mozilla/DebugOnly.h"
  20 #include "nsDebug.h"
  21 #include "nsExceptionHandler.h"
  22 #include "nsISupportsImpl.h"
  23 #include "nsPrintfCString.h"
  24 #include "nsXULAppAPI.h"
  25
  26 using namespace mozilla;
  27
  28 namespace mozilla {
  29 namespace ipc {
  30
  31 MessageLink::MessageLink(MessageChannel* aChan) : mChan(aChan) {}
  32
  33 MessageLink::~MessageLink() {
  34 #ifdef DEBUG
  35   mChan = nullptr;
  36 #endif
  37 }
  38
  39 class PortLink::PortObserverThunk : public NodeController::PortObserver {
  40  public:
  41   PortObserverThunk(RefCountedMonitor* aMonitor, PortLink* aLink)
  42       : mMonitor(aMonitor), mLink(aLink) {}
  43
  44   void OnPortStatusChanged() override {
  45     MonitorAutoLock lock(*mMonitor);
  46     if (mLink) {
  47       mLink->OnPortStatusChanged();
  48     }
  49   }
  50
  51  private:
  52   friend class PortLink;
  53
  54   // The monitor from our PortLink's MessageChannel. Guards access to `mLink`.
  55   RefPtr<RefCountedMonitor> mMonitor;
  56
  57   // Cleared by `PortLink` in `PortLink::Clear()`.
  58   PortLink* MOZ_NON_OWNING_REF mLink;
  59 };
  60
  61 PortLink::PortLink(MessageChannel* aChan, ScopedPort aPort)
  62     : MessageLink(aChan), mNode(aPort.Controller()), mPort(aPort.Release()) {
  63   mChan->mMonitor->AssertCurrentThreadOwns();
  64
  65   mObserver = new PortObserverThunk(mChan->mMonitor, this);
  66   mNode->SetPortObserver(mPort, mObserver);
  67
  68   // Dispatch an event to the IO loop to trigger an initial
  69   // `OnPortStatusChanged` to deliver any pending messages. This needs to be run
  70   // asynchronously from a different thread (or in the case of a same-thread
  71   // channel, from the current thread), for now due to assertions in
  72   // `MessageChannel`.
  73   nsCOMPtr<nsIRunnable> openRunnable = NewRunnableMethod(
  74       "PortLink::Open", mObserver, &PortObserverThunk::OnPortStatusChanged);
  75   if (aChan->mIsSameThreadChannel) {
  76     aChan->mWorkerThread->Dispatch(openRunnable.forget());
  77   } else {
  78     XRE_GetIOMessageLoop()->PostTask(openRunnable.forget());
  79   }
  80 }
  81
  82 PortLink::~PortLink() {
  83   MOZ_RELEASE_ASSERT(!mObserver, "PortLink destroyed without being closed!");
  84 }
  85
  86 void PortLink::SendMessage(UniquePtr<Message> aMessage) {
  87   mChan->mMonitor->AssertCurrentThreadOwns();
  88
  89   if (aMessage->size() > IPC::Channel::kMaximumMessageSize) {
  90     CrashReporter::AnnotateCrashReport(
  91         CrashReporter::Annotation::IPCMessageName,
  92         nsDependentCString(aMessage->name()));
  93     CrashReporter::AnnotateCrashReport(
  94         CrashReporter::Annotation::IPCMessageSize,
  95         static_cast<unsigned int>(aMessage->size()));
  96     MOZ_CRASH("IPC message size is too large");
  97   }
  98   aMessage->AssertAsLargeAsHeader();
  99
 100   RefPtr<PortObserverThunk> observer = mObserver;
 101   if (!observer) {
 102     NS_WARNING("Ignoring message to closed PortLink");
 103     return;
 104   }
 105
 106   // Make local copies of relevant member variables, so we can unlock the
 107   // monitor for the rest of this function. This protects us in case `this` is
 108   // deleted during the call (although that shouldn't happen in practice).
 109   //
 110   // We don't want the monitor to be held when calling into ports, as we may be
 111   // re-entrantly called by our `PortObserverThunk` which will attempt to
 112   // acquire the monitor.
 113   RefPtr<RefCountedMonitor> monitor = mChan->mMonitor;
 114   RefPtr<NodeController> node = mNode;
 115   PortRef port = mPort;
 116
 117   bool ok = false;
 118   monitor->AssertCurrentThreadOwns();
 119   {
 120     MonitorAutoUnlock guard(*monitor);
 121     ok = node->SendUserMessage(port, std::move(aMessage));
 122   }
 123   if (!ok) {
 124     // The send failed, but double-check that we weren't closed racily while
 125     // sending, which could lead to an invalid state error.
 126     if (observer->mLink) {
 127       MOZ_CRASH("Invalid argument to SendUserMessage");
 128     }
 129     NS_WARNING("Message dropped as PortLink was closed");
 130   }
 131 }
 132
 133 void PortLink::Close() {
 134   mChan->mMonitor->AssertCurrentThreadOwns();
 135
 136   if (!mObserver) {
 137     // We're already being closed.
 138     return;
 139   }
 140
 141   Clear();
 142 }
 143
 144 void PortLink::Clear() {
 145   mChan->mMonitor->AssertCurrentThreadOwns();
 146
 147   // NOTE: We're calling into `ports` with our monitor held! Usually, this could
 148   // lead to deadlocks due to the PortObserverThunk acquiring the lock
 149   // re-entrantly, but is OK here as we're immediately clearing the port's
 150   // observer. We shouldn't have issues with any re-entrant calls on this thread
 151   // acquiring this MessageChannel's monitor.
 152   //
 153   // We also clear out the reference in `mObserver` back to this type so that
 154   // notifications from other threads won't try to call us again once we release
 155   // the monitor.
 156   mNode->SetPortObserver(mPort, nullptr);
 157   mObserver->mLink = nullptr;
 158   mObserver = nullptr;
 159   mNode->ClosePort(mPort);
 160 }
 161
 162 void PortLink::OnPortStatusChanged() {
 163   mChan->mMonitor->AssertCurrentThreadOwns();
 164
 165   // Check if the port's remoteness status has updated, and tell our channel if
 166   // it has.
 167   if (Maybe<PortStatus> status = mNode->GetStatus(mPort);
 168       status && status->peer_remote != mChan->IsCrossProcess()) {
 169     mChan->SetIsCrossProcess(status->peer_remote);
 170   }
 171
 172   while (mObserver) {
 173     UniquePtr<IPC::Message> message;
 174     if (!mNode->GetMessage(mPort, &message)) {
 175       Clear();
 176       mChan->OnChannelErrorFromLink();
 177       return;
 178     }
 179     if (!message) {
 180       return;
 181     }
 182
 183     mChan->OnMessageReceivedFromLink(std::move(message));
 184   }
 185 }
 186
 187 bool PortLink::IsClosed() const {
 188   if (Maybe<PortStatus> status = mNode->GetStatus(mPort)) {
 189     return !(status->has_messages || status->receiving_messages);
 190   }
 191   return true;
 192 }
 193
 194 }  // namespace ipc
 195 }  // namespace mozilla