linux socketpair

相对于无名管道来说，socketpair也是使用在亲缘进程之间，不过它提供了能够全双工通信的通道

man socketpair:

       #include <sys/types.h>          /* See NOTES */
       #include <sys/socket.h>

       int socketpair(int domain, int type, int protocol, int sv[2]);

　　该sv保存的两个文件描述符，能写也能读

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>

int main()
{
    int sockfd[2] = {0};

    if (-1 == socketpair(PF_UNIX, SOCK_STREAM, 0, sockfd))
    {
        fprintf(stderr, "socketpair: %d, %s
", errno, strerror(errno));
        exit(1);
    }

    pid_t pid = fork();

    if (pid < 0)
    {
        fprintf(stderr, "fork: %d, %s
", errno, strerror(errno));
        exit(1);
    }
    if (pid == 0)
    {
        close(sockfd[1]);
        char buf[] = "data from child program";
        write(sockfd[0], buf, strlen(buf));

        char szRecv[200] = {0};
        read(sockfd[0], szRecv, 200);
        printf("in child program, get data: %s
", szRecv);
        
        close(sockfd[0]);
    }
    else
    {
        close(sockfd[0]);

        char szRecv[200] = {0};
        read(sockfd[1], szRecv, 200);
        printf("in parent program, get data: %s
", szRecv);

        char buf[] = "data from parent program";
        write(sockfd[1], buf, strlen(buf));

        close(sockfd[1]);
        wait(NULL);
    }
    
	return 0;
}