recver.cpp

#include "shared_memory_communicator.hpp"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

enum
{
	MSG_DV_TYPE_START = 0,
	MSG_DV_TYPE_MSG1,
	MSG_DV_TYPE_MSG2,
	MSG_DV_TYPE_MSG3,
	MSG_DV_TYPE_MSG4,
	MSG_DV_TYPE_MSG5,
	MSG_DV_TYPE_MSG6,
	MSG_DV_TYPE_MSG7,
	MSG_DV_TYPE_MSG8,
	MSG_DV_TYPE_END
};

#define DV_MSG_KEY			0x61766C79

struct MsgStr
{
    long type;
    char msg[128];
};

int main(int argc, char** argv)
{
    SharedMemoryCommunicator shm(DV_MSG_KEY, MSG_DV_TYPE_MSG1);
    MsgStr msgStr;
    memset(&msgStr, 0, sizeof(MsgStr));
    msgStr.type = MSG_DV_TYPE_MSG1;
    int ret = shm.recvMessage(&msgStr, sizeof(msgStr));
    printf("RET=%d : MSG=%s\n", ret, msgStr.msg);
    return 0;
}

sender.cpp

#include "shared_memory_communicator.hpp"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

enum
{
	MSG_DV_TYPE_START = 0,
	MSG_DV_TYPE_MSG1,
	MSG_DV_TYPE_MSG2,
	MSG_DV_TYPE_MSG3,
	MSG_DV_TYPE_MSG4,
	MSG_DV_TYPE_MSG5,
	MSG_DV_TYPE_MSG6,
	MSG_DV_TYPE_MSG7,
	MSG_DV_TYPE_MSG8,
	MSG_DV_TYPE_END
};

#define DV_MSG_KEY			0x61766C79

struct MsgStruct
{
    long type;
    char buf[128];
};

int main(int argc, char** argv)
{
    SharedMemoryCommunicator shm(DV_MSG_KEY, MSG_DV_TYPE_MSG1);
    char msg[] = "ABCDEFG";
    MsgStruct msgStr;
    memset(&msgStr, 0, sizeof(msgStr));
    msgStr.type = MSG_DV_TYPE_MSG1;
    strcpy(msgStr.buf, msg);
    shm.sendMessage(&msgStr, sizeof(msgStr));
    /*
    int queueId;
    key_t key = DV_MSG_KEY;
    queueId = msgget(key, 0);
    if(queueId < 0)
    {
        queueId = msgget(key, IPC_CREAT|0666);
        printf("Created queue id: %d\n", queueId);
    }

    printf("Queue id:%d\n", queueId);
*/
    return 0;
}

shared_memory_communicator.cpp

#include "shared_memory_communicator.hpp"

#include <iostream>
#include <stdio.h>
#include <linux/errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

SharedMemoryCommunicator::SharedMemoryCommunicator(int msgKey, int messageType)
    : msgKey(msgKey)
    , messageQueueId(0)
    , messageType(messageType)
{
    this->messageQueueId = msgget(this->msgKey, 0);
    if(this->messageQueueId < 0)
    {
        this->messageQueueId = msgget(this->msgKey, IPC_CREAT|0666);
        std::cout << "Created message queue " << this->messageQueueId << std::endl;
    }
    std::cout << "Connected to message queue " << this->messageQueueId << std::endl;
}

int SharedMemoryCommunicator::sendMessage(void* data, int size)
{
    return msgsnd(this->messageQueueId, data, size - sizeof(long), 0);
}

int SharedMemoryCommunicator::recvMessage(void* data, int size)
{
    return msgrcv(this->messageQueueId, data, size - sizeof(long), this->messageType, 0);
}

shared_memory_communicator.hpp

#ifndef __SHARED_MEMORY_COMMUNICATOR_HPP__
#define __SHARED_MEMORY_COMMUNICATOR_HPP__

class SharedMemoryCommunicator
{
    int msgKey;
    int messageQueueId;
    int messageType;

public:
    SharedMemoryCommunicator(int msgKey, int messageType);

    int sendMessage(void* data, int size);
    int recvMessage(void* data, int size);
};

#endif