Need to call original function from detoured function
- by peachykeen
I'm using Detours to hook into an executable's message function, but I need to run my own code and then call the original code. From what I've seen in the Detours docs, it definitely sounds like that should happen automatically. The original function prints a message to the screen, but as soon as I attach a detour it starts running my code and stops printing.
The original function code is roughly:
void CGuiObject::AppendMsgToBuffer(classA, unsigned long, unsigned long, int, classB);
My function is:
void CGuiObject_AppendMsgToBuffer( [same params, with names] );
I know the memory position the original function resides in, so using:
DWORD OrigPos = 0x0040592C;
DetourAttach( (void*)OrigPos, CGuiObject_AppendMsgToBuffer);
gets me into the function. This code works almost perfectly: my function is called with the proper parameters. However, execution leaves my function and the original code is not called. I've tried jmping back in, but that crashes the program (I'm assuming the code Detours moved to fit the hook is responsible for the crash).
Edit: I've managed to fix the first issue, with no returning to program execution. By calling the OrigPos value as a function, I'm able to go to the "trampoline" function and from there on to the original code. However, somewhere along the lines the registers are changing and that is causing the program to crash with a segfault as soon as I get back into the original code.
