boost test and async IO : memory access violation at address : no mapping at fault address

Question

i am trying to setup a boost test for async I/O for tcpip.

my function to send tcp msg:

    int TcpClient::sendMsgToServer(string msg) {
    if (isConnected == true) {
        Logger::debug("Asynch send request for msg: " + msg, __LINE__,
                __FILE__);
        sendSequence++;
        msg.append("\r\n");
        int length = msg.length() + 2; //+2 is for \r\n
        char* buffer = (char*) msg.c_str();
        Logger::debug(buffer, __LINE__, __FILE__);
        m_Socket.async_send(boost::asio::buffer(buffer, length),
                boost::bind(&fingigcc::TcpClient::sendMsgToServerErrorHandler,
                        this, boost::asio::placeholders::error,
                        boost::asio::placeholders::bytes_transferred));
        std::string sentMsg = "Sent Msg: " + msg;
        Logger::debug(sentMsg, __LINE__, __FILE__);


        return 0;
    } else {
        return -1;
    }

}

    void TcpClient::sendMsgToServerErrorHandler(
            const boost::system::error_code& error, std::size_t bytes_transferred) {
        Logger::debug("Sending complete: ", __LINE__, __FILE__);
        sendResponseSequence++;
        int i = error.value();
        std::stringstream ss;
        ss.clear();
        ss << i;
        Logger::debug("RESULTCODE: " + ss.str(), __LINE__, __FILE__);
        if (i == 0) {
            Logger::debug("RESULT: " + error.message(), __LINE__, __FILE__);

        } else {
            Logger::crit(error.message(), __LINE__, __FILE__);
            m_Socket.close();
            isConnected = false;
            connectionStateChanged(isConnected);
        }

    }

now this function works fine if i just run it in the main thread ( not running doing a boost test)

my boost test function looks like this:

BOOST_AUTO_TEST_CASE( CommunicationCore_sendTcpIpMsg_test ) {

    CommunicationCoreFixture f;
    int compare = f.c->initializeTcpIpConnection(serverAddress, serverPort); // i initialize the connection here. runs fine with any issue
    sleep(2);
    compare = f.c->sendMsgToServer("IDENTIFY console-2");
    BOOST_MESSAGE("Sending returned value : " << compare);
    BOOST_CHECK(compare == 0);
}

and it fails with the following error:

    Entering test case "CommunicationCore_sendTcpIpMsg_test"
unknown location(0): fatal error in "CommunicationCore_sendTcpIpMsg_test": memory access violation at address: 0x01003255: no mapping at fault address
*****************Test is aborted

Is there anything i should be aware of while testing such async functions?

my build information is:

Platform: linux
Compiler: GNU C++ version 4.7.2
STL     : GNU libstdc++ version 20120920
Boost   : 1.49.0

---

EDIT:

I have tried modifying it in the following manner as well..but still getting the same error:

int TcpClient::sendMsgToServer(string msg) {
    if (isConnected == true) {
        Logger::debug("Asynch send request for msg: " + msg, __LINE__,
                __FILE__);
        sendSequence++;
        msg.append("\r\n");
    char *buffer = new char[msg.size() + 1];
    buffer[msg.size()] = 0;
    memcpy(buffer, msg.c_str(), msg.size());
    Logger::debug(buffer, __LINE__, __FILE__);

    m_Socket.async_send(boost::asio::buffer(buffer, (msg.size() + 1)),
            boost::bind(&fingigcc::TcpClient::sendMsgToServerErrorHandler,
                    this, boost::asio::placeholders::error,
                    boost::asio::placeholders::bytes_transferred));
        std::string sentMsg = "Sent Msg: " + msg;
        Logger::debug(sentMsg, __LINE__, __FILE__);


        return 0;
    } else {
        return -1;
    }

}

Answer 1

m_Socket.async_send(boost::asio::buffer(buffer, length) -- but msg object is local, and its c_str() result gets invalid after msg goes out of scope! So you actually pass a temporary buffer to an asynchronous operation. The buffer doesn't outlive this operation, so segfault is inevitable.