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 const char* StringFromIPCSide(Side side) {
  32   switch (side) {
  33     case ChildSide:
  34       return "Child";
  35     case ParentSide:
  36       return "Parent";
  37     default:
  38       return "Unknown";
  39   }
  40 }
  41
  42 MessageLink::MessageLink(MessageChannel* aChan) : mChan(aChan) {}
  43
  44 MessageLink::~MessageLink() {
  45 #ifdef DEBUG
  46   mChan = nullptr;
  47 #endif
  48 }
  49
  50 class PortLink::PortObserverThunk : public NodeController::PortObserver {
  51  public:
  52   PortObserverThunk(RefCountedMonitor* aMonitor, PortLink* aLink)
  53       : mMonitor(aMonitor), mLink(aLink) {}
  54
  55   void OnPortStatusChanged() override {
  56     MonitorAutoLock lock(*mMonitor);
  57     if (mLink) {
  58       mLink->OnPortStatusChanged();
  59     }
  60   }
  61
  62  private:
  63   friend class PortLink;
  64
  65   // The monitor from our PortLink's MessageChannel. Guards access to `mLink`.
  66   RefPtr<RefCountedMonitor> mMonitor;
  67
  68   // Cleared by `PortLink` in `PortLink::Clear()`.
  69   PortLink* MOZ_NON_OWNING_REF mLink;
  70 };
  71
  72 PortLink::PortLink(MessageChannel* aChan, ScopedPort aPort)
  73     : MessageLink(aChan), mNode(aPort.Controller()), mPort(aPort.Release()) {
  74   mChan->mMonitor->AssertCurrentThreadOwns();
  75
  76   mObserver = new PortObserverThunk(mChan->mMonitor, this);
  77   mNode->SetPortObserver(mPort, mObserver);
  78
  79   // Dispatch an event to the IO loop to trigger an initial
  80   // `OnPortStatusChanged` to deliver any pending messages. This needs to be run
  81   // asynchronously from a different thread (or in the case of a same-thread
  82   // channel, from the current thread), for now due to assertions in
  83   // `MessageChannel`.
  84   nsCOMPtr<nsIRunnable> openRunnable = NewRunnableMethod(
  85       "PortLink::Open", mObserver, &PortObserverThunk::OnPortStatusChanged);
  86   if (aChan->mIsSameThreadChannel) {
  87     aChan->mWorkerThread->Dispatch(openRunnable.forget());
  88   } else {
  89     XRE_GetIOMessageLoop()->PostTask(openRunnable.forget());
  90   }
  91 }
  92
  93 PortLink::~PortLink() {
  94   MOZ_RELEASE_ASSERT(!mObserver, "PortLink destroyed without being closed!");
  95 }
  96
  97 void PortLink::SendMessage(UniquePtr<Message> aMessage) {
  98   mChan->mMonitor->AssertCurrentThreadOwns();
  99
 100   if (aMessage->size() > IPC::Channel::kMaximumMessageSize) {
 101     CrashReporter::AnnotateCrashReport(
 102         CrashReporter::Annotation::IPCMessageName,
 103         nsDependentCString(aMessage->name()));
 104     CrashReporter::AnnotateCrashReport(
 105         CrashReporter::Annotation::IPCMessageSize,
 106         static_cast<unsigned int>(aMessage->size()));
 107     MOZ_CRASH("IPC message size is too large");
 108   }
 109   aMessage->AssertAsLargeAsHeader();
 110
 111   RefPtr<PortObserverThunk> observer = mObserver;
 112   if (!observer) {
 113     NS_WARNING("Ignoring message to closed PortLink");
 114     return;
 115   }
 116
 117   // Make local copies of relevant member variables, so we can unlock the
 118   // monitor for the rest of this function. This protects us in case `this` is
 119   // deleted during the call (although that shouldn't happen in practice).
 120   //
 121   // We don't want the monitor to be held when calling into ports, as we may be
 122   // re-entrantly called by our `PortObserverThunk` which will attempt to
 123   // acquire the monitor.
 124   RefPtr<RefCountedMonitor> monitor = mChan->mMonitor;
 125   RefPtr<NodeController> node = mNode;
 126   PortRef port = mPort;
 127
 128   bool ok = false;
 129   monitor->AssertCurrentThreadOwns();
 130   {
 131     MonitorAutoUnlock guard(*monitor);
 132     ok = node->SendUserMessage(port, std::move(aMessage));
 133   }
 134   if (!ok) {
 135     // The send failed, but double-check that we weren't closed racily while
 136     // sending, which could lead to an invalid state error.
 137     if (observer->mLink) {
 138       MOZ_CRASH("Invalid argument to SendUserMessage");
 139     }
 140     NS_WARNING("Message dropped as PortLink was closed");
 141   }
 142 }
 143
 144 void PortLink::Close() {
 145   mChan->mMonitor->AssertCurrentThreadOwns();
 146
 147   if (!mObserver) {
 148     // We're already being closed.
 149     return;
 150   }
 151
 152   Clear();
 153 }
 154
 155 void PortLink::Clear() {
 156   mChan->mMonitor->AssertCurrentThreadOwns();
 157
 158   // NOTE: We're calling into `ports` with our monitor held! Usually, this could
 159   // lead to deadlocks due to the PortObserverThunk acquiring the lock
 160   // re-entrantly, but is OK here as we're immediately clearing the port's
 161   // observer. We shouldn't have issues with any re-entrant calls on this thread
 162   // acquiring this MessageChannel's monitor.
 163   //
 164   // We also clear out the reference in `mObserver` back to this type so that
 165   // notifications from other threads won't try to call us again once we release
 166   // the monitor.
 167   mNode->SetPortObserver(mPort, nullptr);
 168   mObserver->mLink = nullptr;
 169   mObserver = nullptr;
 170   mNode->ClosePort(mPort);
 171 }
 172
 173 void PortLink::OnPortStatusChanged() {
 174   mChan->mMonitor->AssertCurrentThreadOwns();
 175
 176   // Check if the port's remoteness status has updated, and tell our channel if
 177   // it has.
 178   if (Maybe<PortStatus> status = mNode->GetStatus(mPort);
 179       status && status->peer_remote != mChan->IsCrossProcess()) {
 180     mChan->SetIsCrossProcess(status->peer_remote);
 181   }
 182
 183   while (mObserver) {
 184     UniquePtr<IPC::Message> message;
 185     if (!mNode->GetMessage(mPort, &message)) {
 186       Clear();
 187       mChan->OnChannelErrorFromLink();
 188       return;
 189     }
 190     if (!message) {
 191       return;
 192     }
 193
 194     mChan->OnMessageReceivedFromLink(std::move(message));
 195   }
 196 }
 197
 198 bool PortLink::IsClosed() const {
 199   if (Maybe<PortStatus> status = mNode->GetStatus(mPort)) {
 200     return !(status->has_messages || status->receiving_messages);
 201   }
 202   return true;
 203 }
 204
 205 }  // namespace ipc
 206 }  // namespace mozilla