Reading a cubin structure from a pointer

I am trying to read the contents a c++ structure(in windows) which has the following format

typedef struct __cudaFatCudaBinaryRec {
    unsigned long            magic;
    unsigned long            version;
    unsigned long            gpuInfoVersion;
    char*                   key;
    char*                   ident;
    char*                   usageMode;
    __cudaFatPtxEntry             *ptx;
    __cudaFatCubinE开发者_如何学Cntry           *cubin;
    __cudaFatDebugEntry           *debug;
    void*                  debugInfo;
    unsigned int                   flags;
    __cudaFatSymbol               *exported;
    __cudaFatSymbol               *imported;
    struct __cudaFatCudaBinaryRec *dependends;
    unsigned int                   characteristic;
    __cudaFatElfEntry             *elf;
} __cudaFatCudaBinary;

I have a pointer to this structure (void *ptr)

Now I am looking to read the contents of this structure.

__cudaFatCudaBinary *ptr2=(cudaFatCudaBinary*)ptr;
cout<<ptr->magic;//This works fine
cout<<ptr->key;//This crashes my program..bad pointer results..why?

The above is consistent with all non pointer and pointer members. What am I doing wrong?

ADDED:

ok let me elaborate on the problem. Yes, the address pointed to by "key" is NULL and so it is for all the pointer members. But I know for sure the structure has valid data. It is used by a driver function to generate a handle and it executes fine. All I need is to copy the entire image of the structure and store it in a text file. How would I do it? Why are some of the member fields null? I am thinking of a brute force way to find the address limits of the structure. But the values themselves seem to be invalid when read and I don't know how to go about it!

ADDED 2

Memory Dump of the structure

Thanks !

cout << ptr->key will print as a 0-terminated string whatever key points to, not the pointer itself. If key is NULL or otherwise invalid then this will be undefined behaviour. (In this case a "crash")

If you just want to print the pointer itself make sure you print it as a void* pointer:

cout << static_cast<void*>(ptr->key);

As of CUDA 4.0, the format of this struct drastically changed. The value of magic is now different and gpuInfoVersion is now a pointer to a struct that contains the actual data. For more information, you might want to read this thread.