命名管道——进程通信案例

该案例是实现两个进程之间使用命名管道进行通信。

进程1：fifo01.c

#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<string.h>
#include<errno.h>
int main(int argc, char const *argv[])
{
    if(mkfifo("myfifo1",0664) == -1)
    {
        if(errno != EEXIST)
        {
            perror("Fail to mkfifo1");
            exit(1);
        }
    }
    if(mkfifo("myfifo2",0664) == -1)
    {
        if(errno != EEXIST)
        {
            perror("Fail to mkfifo1");
            exit(1);
        }
    }
    int fd_w = open("myfifo1",O_WRONLY);
    if(fd_w == -1)
    {
        perror("Fail to open myfifo1");
        exit(1);
    }
    int fd_r = open("myfifo2",O_RDONLY);
    if(fd_r == -1)
    {
        perror("Fail to open myfifo2");
        exit(1);
    }
    pid_t pid;
    pid = fork();
    if(pid < 0)
    {
        perror("fail to fork");
        exit(1);
    }
    else if(pid == 0)
    {
        while (1)
        {
            char buf[128] = "";
            fgets(buf,sizeof(buf),stdin);
            buf[strlen(buf) - 1] = '';
            if(write(fd_w,buf,strlen(buf)) == -1)
            {
                perror("Fail to write");
                exit(1);
            }
        }
        
    }
    else
    {
        while(1)
        {
            char buf[128] = "";
            if(read(fd_r,buf,sizeof(buf)) == -1)
            {
                perror("fail to read");
                exit(1);
            }
            printf("receive from fifo02:%s
",buf);
        }
    }
    close(fd_r);
    close(fd_w);
    return 0;
}

进程2：fifo02

#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<string.h>
int main(int argc, char const *argv[])
{
    int fd_r = open("myfifo1",O_RDONLY);
    if(fd_r == -1)
    {
        perror("fail to open");
        exit(1);
    }
    int fd_w = open("myfifo2",O_WRONLY);
    if(fd_w == -1)
    {
        perror("fail to write");
        exit(1);
    }
    pid_t pid;
    pid = fork();
    if(pid == -1)
    {
        perror("fail to fork");
        exit(1);
    }
    else if(pid == 0)
    {
        while (1)
        {
            char buf[128] = "";
            if(read(fd_r,buf,sizeof(buf)) == -1)
            {
                perror("fail to read");
                exit(1);
            }
            printf("received from fifo01:%s
",buf);
        }
        
    }
    else
    {
        while (1)
        {
            char buf[128] = "";
            fgets(buf,sizeof(buf),stdin);
            buf[strlen(buf) - 1] = '';
            if(write(fd_w,buf,strlen(buf)) == -1)
            {
                perror("fail to write");
                exit(1);
            }
        }
        
    }
    
    close(fd_w);
    close(fd_r);
    return 0;
}

运行结果：

 原理如下：