64 bit shared memory segment C \ linux problems

I'm looking to do some IPC with shared memory segments in C \ Linux.

I go on creating it like normal :

typedef struct {
    int a[2];
} shm_segment;

...

shm_segment *shm;

int shm_id;
int shm_flags = IPC_CREAT | 0666
int shm_size = sizeof(struct shm_segment)
key_t key = 88899;
shm_id = shmget(key, shm_size, shm_flags); // ies this is in an if for error cheking but for example sake i omitted it

shm = (shm_segment*)shmat(shm_id, (void*)0, 0);

Last line is where it breaks, at compile it just gives a :

Warning cast to pointer from integer of a different size.

From what I've done before this code works perfectly on 32 bit machines (no warning) (have't tested 开发者_JAVA百科the exact same code, but the same), but on my 64 bit it gives this warning on compile.

And at run it segfaults. From the research i've done i believe casting from a void* to my pointer messes the pointer up, from 64 bit causes.

Any ideea how i can fix this guys? Or what is causing it?

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It sounds like you're missing the correct declaration of shmat(), so the compiler is assuming it returns int.

Make sure you have

#include <sys/shm.h>

in your includes.

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Get rid of the casts and include the proper headers:

#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/types.h>