#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
int main()
{
    //define pipe
    int fd_parent[2];
    int fd_child[2];
    char first_str[] = "humb1e";
    char second_str[]="hacked_by_";
    pid_t p;
    //check if create successfully
    if (pipe(fd_parent) == -1) {
        fprintf(stderr, "Pipe Failed");
        return 1;
    }
    if (pipe(fd_child) == -1) {
        fprintf(stderr, "Pipe Failed");
        return 1;
    }
    p = fork();
    if (p < 0) {
        fprintf(stderr, "fork Failed");
        return 1;
    }
    // Parent process
    else if (p > 0) {
        char concat_str[100];

        close(fd_parent[0]); // Close reading end of first pipe

        // Write input string and close writing end of first
        // pipe.
        write(fd_parent[1], second_str, strlen(second_str) + 1);
        close(fd_parent[1]);

        // Wait for child to send a string
        wait(NULL);

        close(fd_child[1]); // Close writing end of second pipe

        // Read string from child, print it and close
        // reading end.
        read(fd_child[0], concat_str, 100);
        printf("Concatenated string:%s\n", concat_str);
        close(fd_child[0]);
    }

    // child process
    else {
        close(fd_parent[1]); // Close writing end of first pipe

        // Read a string using first pipe
        char concat_str[100];
        read(fd_parent[0], concat_str, 100);

        // Concatenate a fixed string with it
        int k = strlen(concat_str);
        int i;
        for (i = 0; i < strlen(first_str); i++)
            concat_str[k++] = first_str[i];

        concat_str[k] = '\0'; // string ends with '\0'

        // Close both reading ends
        close(fd_parent[0]);
        close(fd_child[0]);

        // Write concatenated string and close writing end
        write(fd_child[1], concat_str, strlen(concat_str) + 1);
        close(fd_child[1]);

        exit(0);
    }
    return 0;
}