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__penter and /Gh on VC++ 6.0

I'm wondering if anyone has had any experience with the function hook system on VC++ that uses the /Gh compiler option to bung __penter calls at the beginning of each native function in an application. I'm having real trouble getting it to work.

Anyone out there that could give me a hand (and possibly a working example!) would be most appreciated..

-hd

nietod

You should be able to do something like.

void cdecl _penter(void)
{
__asm
{
PUSHA ; Save all the general purpose registers.

; your code here.

POPA ; Restore all the general purpose registers.
}
}

What is it that you want to do? What sort of problems are you having?

Ishani

ASKER

i'm not getting the linker to recognize the declaration of penter at all.

it complains of an unresolved external symbol, no matter how I declare penter or even if I write it in an external library and link it in (as the MS CAP example does)

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nietod

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Ishani

ASKER

spot on. although i'm still a bit puzzled:

why _penter and not __penter? even the MSDN docs show a sample implimentation as

void __cdecl __penter(void)...

what does declaring it as a C style name actually do? has this got something to do with name scambling?

thanks muchly for your help.

-hd

nietod

the C compiler will add a "_" to the start of the name as part of its name decoration. So while the linker looks for a function with two "_"'s you only specify one.

>> what does declaring it as a C style name actually do
It removes the C++ name decoration used for overloading. this is a "code" that is appended to the end of the function name to express the parameters passed to the function. This code is used to insure that different overloads of a particular function have unique names.