CS3413/Assignment2/main.c

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

void print_prompt() {
    printf("[%d]> ", getpid());
}

void one_child() {
    print_prompt();
    printf("Hello, I am a parent process\n");
    if (fork() == 0) { // Child process
        print_prompt();
        printf("Hello, I am a child process\n");
        exit(0);
    } else { // Parent process
        wait(NULL);
    }
}

void add_numbers() {
    int number = 1;
    int send_to_child[2];
    int receive_from_child[2];
    pipe(send_to_child);
    pipe(receive_from_child);

    if (fork() == 0) { // Child process
        int subtotal = 0;
        while (number != 0) {
            // Read the numbers from the send_to_child pipe
            read(send_to_child[0], &number, sizeof(int));
            // Add the number to the subtotal
            subtotal += number;

            print_prompt();
            printf("The subtotal is %d\n", subtotal);

            // Write the sum to the receive_from_child pipe
            write(receive_from_child[1], &subtotal, sizeof(int));
        }
        exit(0);
    } else { // Parent process
        int total = 0;
        while (number != 0) {
            print_prompt();
            printf("Please input a number, 0 to terminate:  ");
            // Read the number from the user, and convert it to an int
            char buffer[100];
            fgets(buffer, 100, stdin);
            number = atoi(buffer);

            // Display what was entered
            print_prompt();
            printf("You entered %d\n", number);

            // Write to child process
            write(send_to_child[1], &number, sizeof(int));

            // Read the total from the child process
            read(receive_from_child[0], &total, sizeof(int));
        }
        wait(NULL);
        print_prompt();
        printf("The total is %d\n", total);
    }
    close(send_to_child[0]);
    close(send_to_child[1]);
    close(receive_from_child[0]);
    close(receive_from_child[1]);
}

int main() {
    bool is_looping = true;

    // Listen loop
    while (is_looping) {
        print_prompt();

        char input[100];
        fgets(input, 100, stdin); // Input for commands
        if (strcmp(input, "stop\n") == 0) { // Stop command
            is_looping = false;
        }
        if (strcmp(input, "onechild\n") == 0) { // One child command
            one_child();
        }
        if (strcmp(input, "addnumbers\n") == 0) { // Add numbers command
            add_numbers();
        }
        if (strcmp(input, "exec\n") == 0) {
            char *args[2];
            args[0] = "/bin/ls";
            args[1] = NULL;
            execv(args[0], args);
        }
    }
}

void temp() {
    char input[5][100];
    char buffer[500];
    //Print prompt
    print_prompt();
    if (fgets(buffer, 500, stdin) == NULL) {
        exit(0);
    }
    //split buffer on spaces into input array
    sscanf(buffer, "%s %s %s %s %s", input[0], input[1], input[2], input[3], input[4]);
}