linux-ipc-共享内存

• 介绍
• • Demo

介绍

linux下共享内存方便多了，就四个api
shmget 创建/获取
shmat 映射到进程内
shmdt 取消映射
shmctl 删除共享内存

Demo

#include <iostream>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <unistd.h>
#include <memory.h>

int main()
{
    int id = shmget(1, 100, IPC_CREAT);
    if(id == -1)
    {
        perror("shmget err:");
        return -1;
    }

    pid_t pid = vfork();
    if(pid == 0)
    {
        //child
        void* addr = shmat(id, NULL, 0);
        if(addr == (void*)-1)
        {
            perror("shmat err:");
            return -1;
        }


        char buf[32] = { 0 };
        sprintf(buf, "asddsa123321");
        memcpy(addr, buf, sizeof(buf));

        shmdt(addr);

        exit(0);

    }
    else if(pid > 0)
    {
        //parent
        sleep(1);
        void* addr = shmat(id, NULL, 0);
        if(addr == (void*)-1)
        {
            perror("shmat err:");
            return -1;
        }


        char buf[32] = { 0 };
        memcpy(buf, addr, sizeof(buf));
        std::cout << buf << std::endl;

        wait(&pid);
        
        shmdt(addr);

        shmctl(id, IPC_RMID, 0);

    }
    else
    {
        //error
    }

    return 0;
}