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      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  * Copyright (C) 2013 Apple Inc. All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are
      7  * met:
      8  *
      9  *     * Redistributions of source code must retain the above copyright
     10  * notice, this list of conditions and the following disclaimer.
     11  *     * Redistributions in binary form must reproduce the above
     12  * copyright notice, this list of conditions and the following disclaimer
     13  * in the documentation and/or other materials provided with the
     14  * distribution.
     15  *     * Neither the name of Google Inc. nor the names of its
     16  * contributors may be used to endorse or promote products derived from
     17  * this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "config.h"
     33 #include "core/dom/default/PlatformMessagePortChannel.h"
     34 
     35 #include "core/dom/MessagePort.h"
     36 #include "core/dom/ScriptExecutionContext.h"
     37 
     38 namespace WebCore {
     39 
     40 PassOwnPtr<PlatformMessagePortChannel::EventData> PlatformMessagePortChannel::EventData::create(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray> channels)
     41 {
     42     return adoptPtr(new EventData(message, channels));
     43 }
     44 
     45 PlatformMessagePortChannel::EventData::EventData(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray> channels)
     46     : m_message(message)
     47     , m_channels(channels)
     48 {
     49 }
     50 
     51 void MessagePortChannel::createChannel(PassRefPtr<MessagePort> port1, PassRefPtr<MessagePort> port2)
     52 {
     53     RefPtr<PlatformMessagePortChannel::MessagePortQueue> queue1 = PlatformMessagePortChannel::MessagePortQueue::create();
     54     RefPtr<PlatformMessagePortChannel::MessagePortQueue> queue2 = PlatformMessagePortChannel::MessagePortQueue::create();
     55 
     56     OwnPtr<MessagePortChannel> channel1 = adoptPtr(new MessagePortChannel(PlatformMessagePortChannel::create(queue1, queue2)));
     57     OwnPtr<MessagePortChannel> channel2 = adoptPtr(new MessagePortChannel(PlatformMessagePortChannel::create(queue2, queue1)));
     58 
     59     channel1->m_channel->m_entangledChannel = channel2->m_channel;
     60     channel2->m_channel->m_entangledChannel = channel1->m_channel;
     61 
     62     port1->entangle(channel2.release());
     63     port2->entangle(channel1.release());
     64 }
     65 
     66 MessagePortChannel::MessagePortChannel(PassRefPtr<PlatformMessagePortChannel> channel)
     67     : m_channel(channel)
     68 {
     69 }
     70 
     71 MessagePortChannel::~MessagePortChannel()
     72 {
     73     close();
     74 }
     75 
     76 bool MessagePortChannel::entangleIfOpen(MessagePort* port)
     77 {
     78     // We can't call member functions on our remote pair while holding our mutex or we'll deadlock,
     79     // but we need to guard against the remote port getting closed/freed, so create a standalone reference.
     80     RefPtr<PlatformMessagePortChannel> remote = m_channel->entangledChannel();
     81     if (!remote)
     82         return false;
     83     remote->setRemotePort(port);
     84     return true;
     85 }
     86 
     87 void MessagePortChannel::disentangle()
     88 {
     89     RefPtr<PlatformMessagePortChannel> remote = m_channel->entangledChannel();
     90     if (remote)
     91         remote->setRemotePort(0);
     92 }
     93 
     94 void MessagePortChannel::postMessageToRemote(PassRefPtr<SerializedScriptValue> message, PassOwnPtr<MessagePortChannelArray> channels)
     95 {
     96     MutexLocker lock(m_channel->m_mutex);
     97     if (!m_channel->m_outgoingQueue)
     98         return;
     99     bool wasEmpty = m_channel->m_outgoingQueue->appendAndCheckEmpty(PlatformMessagePortChannel::EventData::create(message, channels));
    100     if (wasEmpty && m_channel->m_remotePort)
    101         m_channel->m_remotePort->messageAvailable();
    102 }
    103 
    104 bool MessagePortChannel::tryGetMessageFromRemote(RefPtr<SerializedScriptValue>& message, OwnPtr<MessagePortChannelArray>& channels)
    105 {
    106     MutexLocker lock(m_channel->m_mutex);
    107     OwnPtr<PlatformMessagePortChannel::EventData> result = m_channel->m_incomingQueue->tryGetMessage();
    108     if (!result)
    109         return false;
    110 
    111     message = result->message();
    112     channels = result->channels();
    113 
    114     return true;
    115 }
    116 
    117 void MessagePortChannel::close()
    118 {
    119     RefPtr<PlatformMessagePortChannel> remote = m_channel->entangledChannel();
    120     if (!remote)
    121         return;
    122     m_channel->closeInternal();
    123     remote->closeInternal();
    124 }
    125 
    126 bool MessagePortChannel::isConnectedTo(MessagePort* port)
    127 {
    128     // FIXME: What guarantees that the result remains the same after we release the lock?
    129     MutexLocker lock(m_channel->m_mutex);
    130     return m_channel->m_remotePort == port;
    131 }
    132 
    133 bool MessagePortChannel::hasPendingActivity()
    134 {
    135     // FIXME: What guarantees that the result remains the same after we release the lock?
    136     MutexLocker lock(m_channel->m_mutex);
    137     return !m_channel->m_incomingQueue->isEmpty();
    138 }
    139 
    140 MessagePort* MessagePortChannel::locallyEntangledPort(const ScriptExecutionContext* context)
    141 {
    142     MutexLocker lock(m_channel->m_mutex);
    143     // See if both contexts are run by the same thread (are the same context, or are both documents).
    144     if (m_channel->m_remotePort) {
    145         // The remote port's ScriptExecutionContext is guaranteed not to change here - MessagePort::contextDestroyed()
    146         // will close the port before the context goes away, and close() will block because we are holding the mutex.
    147         ScriptExecutionContext* remoteContext = m_channel->m_remotePort->scriptExecutionContext();
    148         if (remoteContext == context || (remoteContext && remoteContext->isDocument() && context->isDocument()))
    149             return m_channel->m_remotePort;
    150     }
    151     return 0;
    152 }
    153 
    154 PassRefPtr<PlatformMessagePortChannel> PlatformMessagePortChannel::create(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing)
    155 {
    156     return adoptRef(new PlatformMessagePortChannel(incoming, outgoing));
    157 }
    158 
    159 PlatformMessagePortChannel::PlatformMessagePortChannel(PassRefPtr<MessagePortQueue> incoming, PassRefPtr<MessagePortQueue> outgoing)
    160     : m_incomingQueue(incoming)
    161     , m_outgoingQueue(outgoing)
    162     , m_remotePort(0)
    163 {
    164 }
    165 
    166 PlatformMessagePortChannel::~PlatformMessagePortChannel()
    167 {
    168 }
    169 
    170 void PlatformMessagePortChannel::setRemotePort(MessagePort* port)
    171 {
    172     MutexLocker lock(m_mutex);
    173     // Should never set port if it is already set.
    174     ASSERT(!port || !m_remotePort);
    175     m_remotePort = port;
    176 }
    177 
    178 PassRefPtr<PlatformMessagePortChannel> PlatformMessagePortChannel::entangledChannel()
    179 {
    180     // FIXME: What guarantees that the result remains the same after we release the lock?
    181     // This lock only guarantees that the returned pointer will not be pointing to released memory,
    182     // but not that it will still be pointing to this object's entangled port channel.
    183     MutexLocker lock(m_mutex);
    184     return m_entangledChannel;
    185 }
    186 
    187 void PlatformMessagePortChannel::closeInternal()
    188 {
    189     MutexLocker lock(m_mutex);
    190     // Disentangle ourselves from the other end. We still maintain a reference to our incoming queue, since previously-existing messages should still be delivered.
    191     m_remotePort = 0;
    192     m_entangledChannel = 0;
    193     m_outgoingQueue = 0;
    194 }
    195 
    196 } // namespace WebCore
    197