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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim: set ts=8 sts=4 et sw=4 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef __MINITRANSCEIVER_H_
#define __MINITRANSCEIVER_H_
#include "chrome/common/ipc_message.h"
#include "mozilla/Assertions.h"
struct msghdr;
namespace mozilla {
namespace ipc {
enum class DataBufferClear { None, AfterReceiving };
/**
* This simple implementation handles the transmissions of IPC
* messages.
*
* It works according to a strict request-response paradigm, no
* concurrent messaging is allowed. Sending a message from A to B must
* be followed by another one from B to A. Because of this we don't
* need to handle data crossing the boundaries of a
* message. Transmission is done via blocking I/O to avoid the
* complexity of asynchronous I/O.
*/
class MiniTransceiver {
public:
/**
* \param aFd should be a blocking, no O_NONBLOCK, fd.
* \param aClearDataBuf is true to clear data buffers after
* receiving a message.
*/
explicit MiniTransceiver(
int aFd, DataBufferClear aDataBufClear = DataBufferClear::None);
bool Send(IPC::Message& aMsg);
inline bool SendInfallible(IPC::Message& aMsg, const char* aCrashMessage) {
bool Ok = Send(aMsg);
if (!Ok) {
MOZ_CRASH_UNSAFE(aCrashMessage);
}
return Ok;
}
/**
* \param aMsg will hold the content of the received message.
* \return false if the fd is closed or with an error.
*/
bool Recv(IPC::Message& aMsg);
inline bool RecvInfallible(IPC::Message& aMsg, const char* aCrashMessage) {
bool Ok = Recv(aMsg);
if (!Ok) {
MOZ_CRASH_UNSAFE(aCrashMessage);
}
return Ok;
}
int GetFD() { return mFd; }
private:
/**
* Set control buffer to make file descriptors ready to be sent
* through a socket.
*/
void PrepareFDs(msghdr* aHdr, IPC::Message& aMsg);
/**
* Collect buffers of the message and make them ready to be sent.
*
* \param aHdr is the structure going to be passed to sendmsg().
* \param aMsg is the Message to send.
*/
size_t PrepareBuffers(msghdr* aHdr, IPC::Message& aMsg);
/**
* Collect file descriptors received.
*
* \param aAllFds is where to store file descriptors.
* \param aMaxFds is how many file descriptors can be stored in aAllFds.
* \return the number of received file descriptors.
*/
unsigned RecvFDs(msghdr* aHdr, int* aAllFds, unsigned aMaxFds);
/**
* Received data from the socket.
*
* \param aDataBuf is where to store the data from the socket.
* \param aBufSize is the size of the buffer.
* \param aMsgSize returns how many bytes were readed from the socket.
* \param aFdsBuf is the buffer to return file desriptors received.
* \param aMaxFds is the number of file descriptors that can be held.
* \param aNumFds returns the number of file descriptors received.
* \return true if sucess, or false for error.
*/
bool RecvData(char* aDataBuf, size_t aBufSize, uint32_t* aMsgSize,
int* aFdsBuf, unsigned aMaxFds, unsigned* aNumFds);
int mFd; // The file descriptor of the socket for IPC.
#ifdef DEBUG
enum State {
STATE_NONE,
STATE_SENDING,
STATE_RECEIVING,
};
State mState;
#endif
// Clear all received data in temp buffers to avoid data leaking.
DataBufferClear mDataBufClear;
};
} // namespace ipc
} // namespace mozilla
#endif // __MINITRANSCEIVER_H_