Ian Lance Taylor-3 wrote:
>
> nazgul144 <nlscotty@xxxxxxxxxxx> writes:
>
>> I would like to do this in GCC,
>>
>> [code]
>>
>> void Hooks::NewSendFun()
>> {
>> __asm__ (
>> "mov [ppSendPacket],%esp\n\t"
>> "pusha\n\t"
>> "call SendPacketCallback\n\t"
>> "popa\n\t"
>> "jmp *%ulSendRet]\n\t"
>> );
>> }
>>
>> //and jmp from an address, like this
>> *(char*)ulSend = 0xE9;
>> //*(void **)((char *)ulSend + 1) = (void*)(((char*)(NewSendFun)) -
>> ((char *)ulSend + 5));
>> *(unsigned long*)(ulSend + 1) = ((unsigned long)NewSendFun -
>> (unsigned
>> long)ulSend - 5);
>> [/code]
>>
>> But none of it is working, ulSend(ret) is an unsigned long, the address
>> I'm
>> trying to hook,
>
> The chances of getting that work correctly are extremely remote. You
> are jumping away from the function without cleaning up the stack frame.
>
> Note that gcc will already turn sibling calls into jumps when possible
> when optimizing. I would recommend either relying on that optimization
> or simply writing assembler code directly.
>
> Ian
>
>
But how can I call the assembler function from my address?
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