[C++知识库]System V共享内存实现进程间通信

System V共享内存实现进程间通信

#ifndef __11_SHM_HPP__
#define __11_SHM_HPP__

#include<iostream>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>

using namespace std;

const char *pathname = "./";
const int PROJ_ID = 0x6664;

inline int error(const char *errstr)
{
    printf("%s\n", errstr);
    return -1;
}

class sharememory
{
private:
    key_t key;
    int shmid;
    int shm_size;
    char *shm_addr;
    int shm_destroy();
public:
    sharememory(int shmflg, int _shm_size = 1024);
    ~sharememory();
    char *read_shm();
    void write_shm(const char *msg);
};

sharememory::sharememory(int shmflg, int _shm_size):shm_size(_shm_size)
{
    if ((key = ftok(pathname, PROJ_ID)) < 0)
        error("ftok");
    
    if ((shmid = shmget(key, shm_size, shmflg)) < 0)
        error("shmget");

    shm_addr = (char *)(shmat(shmid, NULL, 0));
}

sharememory::~sharememory()
{
    shmdt(shm_addr);
    shm_destroy();
}

char *sharememory::read_shm()
{
    return shm_addr;
}

void sharememory::write_shm(const char *msg)
{
    strcpy(shm_addr, msg);
}

int sharememory::shm_destroy()
{
    if (shmctl(shmid, IPC_RMID, NULL) < 0)
        error("shmctl");
    return 0;
}

#endif

server.cpp

#include "11-shm.hpp"

int main(int argc, char *argv[])
{
    sharememory server(IPC_CREAT | IPC_EXCL | 0666, 1024);
    while (true)
    {
        char *buf = new char[1024];
        cin >> buf;
        server.write_shm(buf);
        sleep(1);
        if (buf[0] == '$')
            break;
    }
    cout << "exit..." << endl;
    server.~sharememory();
    return 0;
}

client.cpp

#include "11-shm.hpp"

int main(int argc, char *argv[])
{
    sharememory client(IPC_CREAT, 1024);
    char *msg = new char[1024];
    while (true)
    {
        msg = client.read_shm();
        if (msg == NULL)
            exit;
        cout << msg << endl;
        sleep(1);
    }
    client.~sharememory();
    delete[] msg;
    return 0;
}