I cannot load a KBD layout from wow64 (returning Null)

Question

Hi,

I am trying to obtain a pointer to the descriptor of my current keyboard layout in \Windows\syswow64\kbdsp.dll. All this through an unmanaged 32bits dll loaded by a x86 .net application in a x64 windows 7 installation.

In a brief, I do:

kbdLibrary = LoadLibrary(getLayoutFilename());
pKbdLayerDescriptor = (KbdLayerDescriptor)GetProcAddress(kbdLibrary, "KbdLayerDescriptor");
pKbd = pKbdLayerDescriptor();

But pKbd->pVkToWcharTable is null after the last call in x64 architectures. However, if I run the same application in a x86 Windows installation then it works fine....

 

I can figure out that the pointer returned is out of the wow64 mapped memory, but is there any approach to deal with this problem?

 

Thanks

 

 

Answer 1

ok, the returned layer descriptor is a 64bits pointers even if it's in WoW64. Problem solved.

Answer 2

Edit:

Ahh, I finally got it work.
Is it possible to define at runtime, based on if the application is runned on x86 or x64?

 

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Hi LQBWEB, I've been twisting my mind around the same problem.

Could you post a solution here?

I check the:

#if defined(BUILD_WOW6432)
    #define KBD_LONG_POINTER __ptr64
#else
    #define KBD_LONG_POINTER
#endif

Then..

typedef struct _VK_TO_WCHAR_TABLE {
    PVK_TO_WCHARS1 pVkToWchars;
    BYTE           nModifications;
    BYTE           cbSize;
} VK_TO_WCHAR_TABLE, *KBD_LONG_POINTER PVK_TO_WCHAR_TABLE;

Isn't PVK_TO_WCHAR_TABLE a __ptr64?

Answer 3

Hi,

I'm using the same piece of code and I'm still having some problems.

Can anyone of you post the final answer ?

This is what I have :

if(pKbdLayerDescriptor != NULL)
	{
	    int * __ptr64 pPtr64;
	    pKbd = pKbdLayerDescriptor();

	    printf("Size pVkToWcharTable : %d Size PVK_TO_WCHAR_TABLE : %d Size__ptr64 : %d  0x%X\n", sizeof(pKbd->pVkToWcharTable),
              sizeof(PVK_TO_WCHAR_TABLE),
              sizeof(pPtr64),
              pKbd->pVkToWcharTable);
	}

And the result :

Size pVkToWcharTable : 4 Size PVK_TO_WCHAR_TABLE : 4 Size__ptr64 : 4  0x0

As you can see, it keeps dealing with 32 bits pointers...

I'm using Code Blocks with GNU GCC compiler, i have set #define BUILD_WOW6432 before any includes.

Thanks for any help!

Regards

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Answer 4

For a 32-bit app, __ptr64 has no effect -  it is truncated to 32 bits . See here.

So the solution found by the OP probably was just to compile in x64 mode.

Also, not sure that we can help with the GCC.

-- pa