pingpong.c

#include "kernel/types.h"
#include "kernel/stat.h"
#include "user/user.h"

int main(int argc, char *argv[])
{
    int p2c[2];
    int c2p[2];
    char *byte = "1";
    char buf[1];

TIP

创建两个管道：一个用于父进程向子进程发送，一个用于子进程向父进程发送

    if (pipe(p2c) < 0 || pipe(c2p) < 0)
    {
        printf("pipe failed\n");
        exit(1);
    }

    int pid = fork();
    if (pid < 0)
    {
        printf("fork failed\n");
        exit(1);
    }

    if (pid == 0)
    {

TIP

从父进程读取数据

        if (read(p2c[0], buf, 1) == 1)
        {
            printf("%d: received ping\n", getpid());
        }

TIP

向父进程发送数据

        write(c2p[1], &byte, 1);

        close(p2c[0]);
        close(c2p[1]);
        exit(0);
    }
    else
    {

TIP

向子进程发送数据

        write(p2c[1], &byte, 1);

TIP

等待子进程的响应

        if (read(c2p[0], buf, 1) == 1)
        {
            printf("%d: received pong\n", getpid());
        }

        close(p2c[1]);
        close(c2p[0]);
        wait(0);
    }

    exit(0);
}