PIPE 양방향 통신하기

#include <stdio.h>
#include <unistd.h>
#include <sys/times.h>
#include <limits.h>
#include <stdlib.h>
#include <time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string.h>

int main() {
    int fd1[2], fd2[2];
    pid_t pid;
    char buf[257];
    int len, status;

    if(pipe(fd1)== -1){
        perror("pipe");
        exit(1);
    }


    if(pipe(fd2)==-1){
        perror("pipe");
        exit(1);
    }

    switch(pid = fork()){
        case -1 :
            perror("fork");
            exit(1);
            break;

        case 0:
            close(fd1[1]);
            close(fd2[0]);
            write(1, "Child Process:", 15);
            len = read(fd1[0], buf, 256);
            write(1, buf, len);

            strcpy(buf, "Good\n");
            write(fd2[1], buf, strlen(buf));
            break;
        default:
            close(fd1[0]);
            close(fd2[1]);
            buf[0] = '\0';
            write(fd1[1], "Hello\n", 6);

            write(1, "Parent Process:", 15);
            len = read(fd2[0], buf, 256);
            write(1, buf, len);
            waitpid(pid, &status, 0);
            break;
    }

    return 0;
}