I'm working on an injectable DLL hack with a global keyboard hook, and although SetWindowsHookEx() returns as expected, when it comes time to unhook something fails, and GetLastError returns 0. I've attached only the relevant code, but I don't get any errors or warnings. I'm using VC++ 2008 Express Edition. Just say so if you need me to post the rest.

Core.cpp:[code]#include <windows.h>
#include <stdio.h>

// ...

BYTE StatsHackToggle = 0;
BYTE GoldHackToggle  = 0;

HHOOK MyKeyboardHook = 0;
DWORD bRet = 0, ErrCode = 0;

LRESULT CALLBACK KeyboardProc(int code, WPARAM wParam, LPARAM lParam);

// ...

BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved) {
switch (dwReason) {
case DLL_PROCESS_ATTACH:
// Register our keyboard hook.
MyKeyboardHook = SetWindowsHookEx(WH_KEYBOARD, (HOOKPROC)&KeyboardProc, hInstance, NULL);
if (MyKeyboardHook == NULL) { // Checking for errors...
DbgPrint("The call to SetWindowsHookEx() failed, [MyKeyboardHook] is null.", GetLastError());
}
break;
case DLL_PROCESS_DETACH:
// Unregister our keyboard hook.
bRet = UnhookWindowsHookEx(MyKeyboardHook);
if (bRet == NULL) { // Checking for errors...
DbgPrint("The call to UnhookWindowsHookEx() failed, [bRet] is null.", GetLastError());
}
break;
default:
break;
    }

return (TRUE);
}

LRESULT CALLBACK KeyboardProc(int code, WPARAM wParam, LPARAM lParam) {
if (code != HC_ACTION) {
return (CallNextHookEx(MyKeyboardHook, code, wParam, lParam));
}

// This is where the conditions for certain keys
// being pressed go. Use the virtual key-codes
// for the keys you wish to hook. For more information,
// do a search on "Virtual key-codes on MSDN.
switch (wParam) {
case VK_PRIOR: // StatsHack
if (StatsHackToggle == 0) { // on toggle
DbgPrint("StatsHack Toggle [ON]!", NULL);
bRet = PlaceDetour(ptrStatsHack,(DWORD)&StatsHack,NULL);
if (bRet == NULL) {
DbgPrint("The call to PlaceDetour() failed during toggling of StatsHack.", NULL);
StatsHackToggle = 0;
}

StatsHackToggle = 1;
} else { // off toggle
DbgPrint("StatsHack Toggle [OFF]!", NULL);
bRet = WriteMemory(ptrStatsHack,StatsHackOldData,6);
if (bRet == NULL) {
DbgPrint("The call to WriteMemory() failed during toggling of StatsHack.", NULL);
StatsHackToggle = 1;
}

StatsHackToggle = 0;
}
break;
case VK_NEXT: // GoldHack
if (GoldHackToggle == 0) { // on toggle
DbgPrint("GoldHack Toggle [ON]!", NULL);
bRet = PlaceDetour(ptrGoldHack,(DWORD)&GoldHack,6);
if (bRet == NULL) {
DbgPrint("The call to PlaceDetour() failed during the [ON] toggle of GoldHack.", NULL);
GoldHackToggle = 0;
}

GoldHackToggle = 1;
} else { // off toggle
DbgPrint("GoldHack Toggle [OFF]!", NULL);
bRet = WriteMemory(ptrGoldHack,GoldHackOldData,6);
if (bRet == NULL) {
DbgPrint("The call to WriteMemory() failed during the [OFF] toggle of GoldHack.", NULL);
GoldHackToggle = 1;
}

GoldHackToggle = 0;
}
break;
default:
break;
}

// Call the next hook in the system's hook chain.
return (CallNextHookEx(MyKeyboardHook, code, wParam, lParam));
}[/code]I would appreciate it if someone could tell me what I've done wrong...

It appears that you are doing nothing wrong at all--
However, for some reason when I set a global variable to a value within WinMain or DllMain, it always seems to be cleared, and i have to reset it in my windowproc. Check the value of MyKeyboardHook when calling UnhookWindowsHookEx.

I added [code]if (MyKeyboardHook == 0) {
DbgPrint("wtf", NULL);
}[/code]Right before the call to UnhookWindowsHookEx, but still nothing. Someone else suggested creating the Hook in a new thread and allowing it to idle, and it will automatically be unset when the thread terminates - but that still wouldn't explain why my hotkeys don't currently work, even though the only thing that appears to be wrong is the call to unhook...

[quote author=Dyndrilliac link=topic=17263.msg175786#msg175786 date=1200197370]
I added [code]if (MyKeyboardHook == 0) {
DbgPrint("wtf", NULL);
}[/code]Right before the call to UnhookWindowsHookEx, but still nothing. Someone else suggested creating the Hook in a new thread and allowing it to idle, and it will automatically be unset when the thread terminates - but that still wouldn't explain why my hotkeys don't currently work, even though the only thing that appears to be wrong is the call to unhook...
[/quote]
So your hotkeys never worked in the first place? Before trying the make-a-new-thread idea?
UnhookWindowsHookEx fails when you try to call from a different thread then SetWindowsHook was called from. If you never do solve this, try using SetWinEventHook instead. Maybe that'll work...
I haven't taken a good look at this, but maybe it'll help you: http://www.codeproject.com/KB/DLL/hooks.aspx
Other then that, I am clueless.