socketpair.c

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

int main(int argc, char **argv)
{
    int socket_fd[2];
    int status;
    pid_t pid;
    char buf[] = "hello world";
    char line[100];
    
    memset(line, 0, sizeof(line));
    int ret = socketpair(AF_UNIX, SOCK_STREAM, 0, socket_fd);
    /*
    socketpair(AF_UNIX, SOCK_STREAM, AF_LOCAL, socket_fd);
    
    int socketpair(int domain, int type, int protocol, int sv[2]);
    */
    if(ret == -1){  
        perror("socketpair error\n");
        return -1;
    }
 
    // 1, 2, 3번은 각각 stdin(0), stdout(1), stderr(2)의 다음 번호인 3, 4 할당
    printf("socket1 fd: %d\n", socket_fd[0]);
    printf("socket1 fd: %d\n", socket_fd[1]);
    
    if((pid = fork()) < 0) {
        perror("fork() error\n");
        return -1;
    } else if(pid == 0) {
        write(socket_fd[0], buf, strlen(buf) + 1);
        printf("data send : %s\n", buf);

        close(socket_fd[0]);
    } else {
        wait(&status);
        
        read(socket_fd[1], line, 100);
        printf("data recv : %s\n", line);
        close(socket_fd[1]);
    }

    return 0;
}