publisher.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>

#define MAX_SUBSCRIBERS 3
#define MAX_MESSAGE_SIZE 1024

int main(int argc, char* argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <num_subscribers>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    int num_subscribers = atoi(argv[1]);
    if (num_subscribers <= 0 || num_subscribers > MAX_SUBSCRIBERS) {
        fprintf(stderr, "Invalid number of subscribers (1 to %d allowed).\n", MAX_SUBSCRIBERS);
        exit(EXIT_FAILURE);
    }

    char fifo_path[20];
    int i;

    // Create named pipes for each subscriber
    for (i = 1; i <= num_subscribers; i++) {
        snprintf(fifo_path, sizeof(fifo_path), "/tmp/ex1/s%d", i);
        mkfifo(fifo_path, 0666);
    }

    char message[MAX_MESSAGE_SIZE];
    ssize_t bytes_read;
    int pipe_fd;

    // Read messages from stdin and send to respective subscribers
    while ((bytes_read = read(STDIN_FILENO, message, MAX_MESSAGE_SIZE)) > 0) {
        for (i = 1; i <= num_subscribers; i++) {
            snprintf(fifo_path, sizeof(fifo_path), "/tmp/ex1/s%d", i);
            pipe_fd = open(fifo_path, O_WRONLY);
            if (pipe_fd != -1) {
                write(pipe_fd, message, bytes_read);
                close(pipe_fd);
            }
        }
    }

    // Close and remove named pipes
    for (i = 1; i <= num_subscribers; i++) {
        snprintf(fifo_path, sizeof(fifo_path), "/tmp/ex1/s%d", i);
        unlink(fifo_path);
    }

    return 0;
}