Shared Memory Program - System Software Lab

Lab Program - 13 - Shared Memory - System Software Lab

#include “sys/types.h”

#include “sys/ipc.h”

#include “sys/shm.h”

#include “stdio.h”

#define SHMSZ     27

main()

{

    char c;

    int shmid;

    key_t key;

    char *shm,*s;  

/* The shared memory is named as 2012 */

    key = 2012;

    if ((shmid = shmget(key, SHMSZ, IPC_CREAT | 0666)) < 0) {

        perror("shmget");

        exit(1);

    }

    

/* Mapping the Shared Memory */

    if ((shm = shmat(shmid, NULL, 0)) == (char *) -1) {

        perror("shmat");

        exit(1);

    }

    s = shm;

  

/* Storing some text in the Shared Memory */

    for (c = 'a'; c <= 'z'; c++)

        *s++ = c;

    *s = NULL;

/* Wait for the other process that reads the shared memory and alters the content */

    while (*shm != '*')

        sleep(1);

    printf("\n End of the Server Program - Shared Memory");

    exit(0);

}

#include “sys/types.h”

#include “sys/ipc.h”

#include “sys/shm.h”

#include “stdio.h”

#define SHMSZ     27

main()

{

    int shmid;

    key_t key;

    char *shm, *s;

    /*   The shared memory given a name as 2012 */

    key = 2012;

    if ((shmid = shmget(key, SHMSZ, 0666)) < 0) (< = <)

        {

          perror("shmget");

          exit(1);

        }

 /* Map the Shared Memory */   

if ((shm = shmat(shmid, NULL, 0)) == (char *) -1)

    {

        perror("shmat");

        exit(1);

    }

/* Read the content from the Shared Memory */

    for (s = shm; *s != NULL; s++)

        putchar(*s);

    putchar('\n');

/* Change the first character of the Shared memory to * to indicate the server the content were read */

    *shm = '*';

    printf("\n End of Client Program - Shared Memory");

    exit(0);

}