bug 517923: support serializing ns*Strings that represent NULL, use this mechanism in PluginInstanceParent/PluginModuleChild. also add basic crash-handling to *Channel code and some NS_OVERRIDE annotations.

ipc/glue/SyncChannel.cpp

@@ -59,18 +59,26 @@ SyncChannel::Send(Message* msg, Message* reply)
 {
     NS_ABORT_IF_FALSE(!ProcessingSyncMessage(),
                       "violation of sync handler invariant");
-    NS_ASSERTION(ChannelConnected == mChannelState,
-                 "trying to Send() to a channel not yet open");
-    NS_PRECONDITION(msg->is_sync(), "can only Send() sync messages here");
+    NS_ABORT_IF_FALSE(msg->is_sync(), "can only Send() sync messages here");
+
+    if (!Connected())
+        // trying to Send() to a closed or error'd channel
+        return false;
 
     MutexAutoLock lock(mMutex);
 
     mPendingReply = msg->type() + 1;
-    /*assert*/AsyncChannel::Send(msg);
+    if (!AsyncChannel::Send(msg))
+        // FIXME more sophisticated error handling
+        return false;
 
     // wait for the next sync message to arrive
     mCvar.Wait();
 
+    if (!Connected())
+        // FIXME more sophisticated error handling
+        return false;
+
     // we just received a synchronous message from the other side.
     // If it's not the reply we were awaiting, there's a serious
     // error: either a mistimed/malformed message or a sync in-message
@@ -156,6 +164,22 @@ SyncChannel::OnMessageReceived(const Message& msg)
     }
 }
 
+void
+SyncChannel::OnChannelError()
+{
+    {
+        MutexAutoLock lock(mMutex);
+
+        mChannelState = ChannelError;
+
+        if (AwaitingSyncReply()) {
+            mCvar.Notify();
+        }
+    }
+
+    return AsyncChannel::OnChannelError();
+}
+
 void
 SyncChannel::OnSendReply(Message* aReply)
 {