Thread: Shared memory program

Hi,

I have one requirement to store an array of structure at shared memory. Also the shared memory should have one counter to store number of elements in the array.

I tried to look at some placed but didn't find anything relevant.

So my first question, is it possible that we can store two things on same shared memory. And second if not then how to achieve the same?

Thanks

Originally Posted by maven

I have one requirement to store an array of structure at shared memory. Also the shared memory should have one counter to store number of elements in the array.

You can write a struct which meets these requirements. Then you can share a pointer to the struct with any function that needs access to it.

ok.

I tried it like this. Used below structure and struct "forShm" to insert in shared memory. I am able to copy data and do all. But while reading seems it is getting some garbage. I believe i messed up something.

Code:

typedef struct userList
{
  char userName[64];
  int  socketFd;
  int  gpReady;
}listUsers;

struct forShm
{
  listUsers userInfo[10];
  int  numUsers;
  int  numGpUsers;
};

             shmid = shmget((key_t)1234, sizeof(struct forShm)*10, 0666 | IPC_CREAT);
             sh_mem = shmat(shmid, (void *)0, 0);
             fromShm = (struct forShm*)sh_mem;

             strcpy(fromShm->userInfo[count].userName,tokName);
             fromShm->userInfo[count].socketFd = sockfd;
             count=count+1;
             fromShm->numUsers = count;