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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef IPC_IPC_CHANNEL_NACL_H_
#define IPC_IPC_CHANNEL_NACL_H_
#include <deque>
#include <string>
#include "base/macros.h"
#include "base/memory/linked_ptr.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/process/process.h"
#include "base/threading/simple_thread.h"
#include "ipc/ipc_channel.h"
#include "ipc/ipc_channel_reader.h"
namespace IPC {
// Contains the results from one call to imc_recvmsg (data and file
// descriptors).
struct MessageContents;
// Similar to the ChannelPosix but for Native Client code.
// This is somewhat different because sendmsg/recvmsg here do not follow POSIX
// semantics. Instead, they are implemented by a custom embedding of
// NaClDescCustom. See NaClIPCAdapter for the trusted-side implementation.
//
// We don't need to worry about complicated set up and READWRITE mode for
// sharing handles. We also currently do not support passing file descriptors or
// named pipes, and we use background threads to emulate signaling when we can
// read or write without blocking.
class ChannelNacl : public Channel,
public internal::ChannelReader {
public:
// Mirror methods of Channel, see ipc_channel.h for description.
ChannelNacl(const IPC::ChannelHandle& channel_handle,
Mode mode,
Listener* listener);
~ChannelNacl() override;
// Channel implementation.
base::ProcessId GetPeerPID() const override;
base::ProcessId GetSelfPID() const override;
bool Connect() override;
void Close() override;
bool Send(Message* message) override;
AttachmentBroker* GetAttachmentBroker() override;
// Posted to the main thread by ReaderThreadRunner.
void DidRecvMsg(scoped_ptr<MessageContents> contents);
void ReadDidFail();
private:
class ReaderThreadRunner;
bool CreatePipe(const IPC::ChannelHandle& channel_handle);
bool ProcessOutgoingMessages();
void CallOnChannelConnected();
// ChannelReader implementation.
ReadState ReadData(char* buffer,
int buffer_len,
int* bytes_read) override;
bool ShouldDispatchInputMessage(Message* msg) override;
bool GetNonBrokeredAttachments(Message* msg) override;
bool DidEmptyInputBuffers() override;
void HandleInternalMessage(const Message& msg) override;
base::ProcessId GetSenderPID() override;
bool IsAttachmentBrokerEndpoint() override;
Mode mode_;
bool waiting_connect_;
// The pipe used for communication.
int pipe_;
// The "name" of our pipe. On Windows this is the global identifier for
// the pipe. On POSIX it's used as a key in a local map of file descriptors.
// For NaCl, we don't actually support looking up file descriptors by name,
// and it's only used for debug information.
std::string pipe_name_;
// We use a thread for reading, so that we can simply block on reading and
// post the received data back to the main thread to be properly interleaved
// with other tasks in the MessagePump.
//
// imc_recvmsg supports non-blocking reads, but there's no easy way to be
// informed when a write or read can be done without blocking (this is handled
// by libevent in Posix).
scoped_ptr<ReaderThreadRunner> reader_thread_runner_;
scoped_ptr<base::DelegateSimpleThread> reader_thread_;
// IPC::ChannelReader expects to be able to call ReadData on us to
// synchronously read data waiting in the pipe's buffer without blocking.
// Since we can't do that (see 1 and 2 above), the reader thread does blocking
// reads and posts the data over to the main thread in MessageContents. Each
// MessageContents object is the result of one call to "imc_recvmsg".
// DidRecvMsg breaks the MessageContents out in to the data and the file
// descriptors, and puts them on these two queues.
// TODO(dmichael): There's probably a more efficient way to emulate this with
// a circular buffer or something, so we don't have to do so
// many heap allocations. But it maybe isn't worth
// the trouble given that we probably want to implement 1 and
// 2 above in NaCl eventually.
// When ReadData is called, it pulls the bytes out of this queue in order.
std::deque<linked_ptr<std::vector<char> > > read_queue_;
// Queue of file descriptors extracted from imc_recvmsg messages.
// NOTE: The implementation assumes underlying storage here is contiguous, so
// don't change to something like std::deque<> without changing the
// implementation!
std::vector<int> input_fds_;
// This queue is used when a message is sent prior to Connect having been
// called. Normally after we're connected, the queue is empty.
std::deque<linked_ptr<Message> > output_queue_;
base::WeakPtrFactory<ChannelNacl> weak_ptr_factory_;
DISALLOW_IMPLICIT_CONSTRUCTORS(ChannelNacl);
};
} // namespace IPC
#endif // IPC_IPC_CHANNEL_NACL_H_
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