///******************************************************************/
///* IUT NICE-COTE D'AZUR - Departement INFORMATIQUE - R. CHIGNOLI  */
///* Module M311                              Theme IPC POSIX       */
///******************************************************************/
///* demo_shm.c : Demonstration d'utilisation d'un segment          */
///*              de memoire partagee                               */
///* UTILISATION : commande ( -create | -use )                      */
///* Utiliser ls, etc ... pour gerer les ressources                 */
///******************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <time.h>

/// Type de la zone mémoire
typedef struct memoire
{
    int valeur;
    int date;
} Memoire;

int main(int argc, char * argv[])
{
    struct memoire *zone;
    int mem_fd;

    if (argc != 2)
    {
        fprintf (stderr, "\nSyntaxe : %s ( -create | -use )\n\n", argv[0]);
        exit (1);
    }
    mem_fd = shm_open ("demo_mem", O_CREAT |O_RDWR, 0777);
    if (mem_fd == -1)
    {
        perror("shm_open");
        exit (1);
    }
    if (ftruncate(mem_fd, sizeof(struct memoire)) != 0)
    {
        perror("ftruncate");
        exit(2);
    }
    zone = mmap (NULL, 100, PROT_READ | PROT_WRITE, MAP_SHARED, mem_fd, 0);
    if (zone  ==  (void *) -1)
    {
        perror("mmap");
        exit (3);
    }
    if ((strcmp (argv[1], "-create")!= 0) && (strcmp (argv[1], "-use")!= 0))
    {
        fprintf (stderr, "\nSyntaxe : %s ( -create | -use )\n\n", argv[0]);
        exit (2);
    }
    if (strcmp (argv[1], "-create")== 0)
    {
        zone->valeur = 0;
        zone->date =time(NULL);
        printf("\nCREATE : VALEURS en memoire : valeur = %d - date = %s\n",
                zone->valeur, ctime ((time_t*)&zone->date));
    }
    else /// -use
    {
        printf("\nUSE : ANCIENNES VALEURS en memoire : valeur = %d - date = %s \n",
                zone->valeur, ctime ((time_t*)&zone->date));
        zone->valeur++;
        zone->date =time(NULL);
        printf("USE : NOUVELLES VALEURS en memoire : valeur = %d - date = %s \n",
        zone->valeur, ctime ((time_t*)&zone->date));
    }
    

    close(mem_fd);
    return 0;
}