Message-Queue-IPC-System/Message_queue_demo.cpp at main · hannahgsimon/Message-Queue-IPC-System · GitHub

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/*
 A message queue manipulation utility
*/
#include "Message_que.h"
#include <iostream>
#include <cstdlib>
#include <unistd.h>
using namespace std;

typedef struct {
    long int m_type;
    char m_text[1024];
} MESSAGE;

extern char *optarg;
extern int optind, opterr, optopt;

int
main(int argc, char *argv[])
{
    int c;
    // Added 'n' (nondestructive read) and 'd' (delete queue)
    char optstring[] = "sri:m:nd";

    opterr = 0;
    bool snd_msg = false, get_msg = false, rmv_que = false, peek_msg = false;
    char *the_message;

    // Allocate msg - clear text
    MESSAGE my_msg;
    memset(my_msg.m_text, 0x0, 1024);

    // Allocate - acquire msg queue
    Message_que MQ('M');
    if (!MQ.Exist('M'))
        MQ.Create();
    else
        MQ.Acquire();

    // Process command line args
    while ((c = getopt(argc, argv, optstring)) != -1)
        switch (c) {
        case 's':
            snd_msg = true;
            break;
        case 'r':
            get_msg = true;
            break;
        case 'n':
            // nondestructive read (peek)
            peek_msg = true;
            break;
        case 'd':
            // remove the message queue
            rmv_que = true;
            break;
        case 'i':
            my_msg.m_type = atol(optarg);
            break;
        case 'm':
            strcpy(my_msg.m_text, optarg);
            break;
        default:
            break;
        }

    if (snd_msg && my_msg.m_type > 0) {
        MQ.Enque(&my_msg, strlen(my_msg.m_text) + 1);
        cerr << "Added : " << my_msg.m_text << endl;
    } else if (get_msg && my_msg.m_type > 0) {
        MQ.Deque(&my_msg, 1024, my_msg.m_type);
        cerr << "Message: " << my_msg.m_text << endl;
    } else if (peek_msg && my_msg.m_type > 0) {
        int nbytes = MQ.Deque(&my_msg, 1024, my_msg.m_type);
        cerr << "Message (peek): " << my_msg.m_text << endl;
        // Re-enqueue the same message so it stays in the queue
        MQ.Enque(&my_msg, nbytes);
    } else if (rmv_que) {
        MQ.Remove();
        cerr << "Message queue removed" << endl;
    } else {
        cerr << "Invalid command line option(s)" << endl;
    }

    return 0;
}