Shared memory

sharedmemory.c

///////////////////
// shared memory //
///////////////////
/**
 * Open a shared memory 
 * @return shared memory file descriptor
 * if(shmfd < 0) err
 */
int shmfd = shm_open( "MSG_NAME", O_CREAT | O_EXCL | O_RDWR, S_IRWXU | S_IRWXG);

/**
 * Truncate shared memory size
 * @param1: shared memory file descriptor
 * @param2: integer 			the ammount of data will be shared 
 * ex: (3 * sizeof(char)) will share 3 characters.
 */
int msg_size;
ftrucate(shmfd, msg_size)

/**
 * Requesting The shared segment
 * offset: where to start
 * if(!shared_msg) err;
 */
int offset = 0;
msg_type * shared_msg = (msg_type *) mmap(NULL, msg_size, PROT_READ | PROT_WRITE, MAP_SHARED, shmfd, offset);

/**
 * Unlink the shared memory (remove it)
 */
shm_unlink("MSG_NAME");