Keyboard Hook Problem

DLL main file:

Code:

---

#define EXPORT_HOOK_FUNCS
#include "dll.h"
#pragma data_seg(".hook_data")
HHOOK g_hKeyboardHook = 0;
HWND  g_hAppWnd      = 0;
#pragma data_seg()
#pragma comment(linker, "/SECTION:.hook_data,RWS")
HINSTANCE g_hInstance = 0;

BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD,LPVOID){
        g_hInstance = hinstDLL;
        return TRUE;
}

HOOK_DECLSPEC BOOL InstallHook(HWND hAppWnd) {
        if (g_hKeyboardHook != 0){
                return FALSE;
        }
        g_hAppWnd = hAppWnd;
        g_hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)HookProc, g_hInstance, 0);
        if (g_hKeyboardHook == 0) {
                MessageBox(hAppWnd, "Failed to install hook!","Fatal Error", MB_ICONSTOP);
                return FALSE;
        }
        return TRUE;
}

HOOK_DECLSPEC void UninstallHook() {
        UnhookWindowsHookEx(g_hKeyboardHook);
        g_hAppWnd      = 0;
        g_hKeyboardHook = 0;
}

HOOK_DECLSPEC LRESULT CALLBACK HookProc(int nCode, WPARAM wParam,LPARAM lParam){
        if (nCode >= 0)  {
                if (!(lParam & 0x80000000)){
                        PostMessage(g_hAppWnd, KEYSTROKE_MSG, wParam, lParam);
                }
        }
        return CallNextHookEx(g_hKeyboardHook, nCode, wParam, lParam);
}

---

DLL header file:

Code:

---

#include <windows.h>
#define KEYSTROKE_MSG (WM_USER + 123)
#ifdef EXPORT_HOOK_FUNCS
  #define HOOK_DECLSPEC __declspec(dllexport)
#else
  #define HOOK_DECLSPEC __declspec(dllimport)
#endif

HOOK_DECLSPEC BOOL InstallHook(HWND hAppWnd);
HOOK_DECLSPEC void UninstallHook();
HOOK_DECLSPEC LRESULT CALLBACK HookProc(int nCode, WPARAM wParam, LPARAM lParam);

---

Program:

Code:

---

#include <windows.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
/*  Make the class name into a global variable  */
char szClassName[ ] = "WindowsApp";
#pragma comment(lib, "../hook/libProject1.a")
#include "../hook/dll.h"
int WINAPI WinMain (HINSTANCE hThisInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpszArgument,
                    int nFunsterStil)

{
    HWND hwnd;              /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
          0,                  /* Extended possibilites for variation */
          szClassName,        /* Classname */
          "Windows App",      /* Title Text */
          WS_OVERLAPPEDWINDOW, /* default window */
          CW_USEDEFAULT,      /* Windows decides the position */
          CW_USEDEFAULT,      /* where the window ends up on the screen */
          544,                /* The programs width */
          375,                /* and height in pixels */
          HWND_DESKTOP,        /* The window is a child-window to desktop */
          NULL,                /* No menu */
          hThisInstance,      /* Program Instance handler */
          NULL                /* No Window Creation data */
          );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nFunsterStil);
        InstallHook(hwnd);
    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {
        case WM_DESTROY:
            PostQuitMessage (0);      /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

---

It can't install the hook. SetWindowsHookEx fails.

I don't notice anything wrong with this code. Help?

GetLastError.

Please.

1428 ERROR_HOOK_NEEDS_HMOD
Cannot set nonlocal hook without a module handle.

What does it mean by that?

Ok, cracked the nut. Somehow g_hInstance wasn't set to the correct handle and I just used GetModuleHandle(NULL) instead of that. Thanks Tonto, that was very good advice.