进程通信

此代码不一定可以使用！！！因为其实我自己都没有搞清楚很多东西。

用户端

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define SVKEY 1234
#define REQ 1
#define RESP 2

struct msgbuf {
    long mtype;
    pid_t pid;
};

int main() {
    int msqid;
    struct msgbuf buf;

    // 获取消息队列
    if ((msqid = msgget(SVKEY, 0666)) == -1) {
        perror("msgget");
        exit(EXIT_FAILURE);
    }

    // 发送请求消息
    buf.mtype = REQ;
    buf.pid = getpid();
    if (msgsnd(msqid, &buf, sizeof(pid_t), 0) == -1) {
        perror("msgsnd");
        exit(EXIT_FAILURE);
    }

    // 接收应答消息
    if (msgrcv(msqid, &buf, sizeof(pid_t), getpid(), 0) == -1) {
        perror("msgrcv");
        exit(EXIT_FAILURE);
    }

    printf("Received reply from server %d\n", buf.pid);

    return 0;
}

服务端

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define SVKEY 1234
#define REQ 1
#define RESP 2

struct msgbuf {
    long mtype;
    pid_t pid;
};

int main() {
    int msqid;
    struct msgbuf buf;

    // 创建消息队列
    if ((msqid = msgget(SVKEY, IPC_CREAT | 0666)) == -1) {
        perror("msgget");
        exit(EXIT_FAILURE);
    }

    // 服务端循环接收请求消息
    while (1) {
        // 接收请求消息
        if (msgrcv(msqid, &buf, sizeof(pid_t), REQ, 0) == -1) {
            perror("msgrcv");
            exit(EXIT_FAILURE);
        }

        printf("Serving for client %d\n", buf.pid);

        // 发送应答消息
        buf.mtype = buf.pid;
        buf.pid = getpid();
        if (msgsnd(msqid, &buf, sizeof(pid_t), 0) == -1) {
            perror("msgsnd");
            exit(EXIT_FAILURE);
        }
    }

    return 0;
}