win9xconhook.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef WIN32

/*
 * Win9xConHook.dll - a hook proc to clean up Win95/98 console behavior.
 *
 * It is well(?) documented by Microsoft that the Win9x HandlerRoutine
 * hooked by the SetConsoleCtrlHandler never receives the CTRL_CLOSE_EVENT,
 * CTRL_LOGOFF_EVENT or CTRL_SHUTDOWN_EVENT signals.  
 *
 * It is possible to have a second window to monitor the WM_ENDSESSION 
 * message, but the close button still fails..
 * 
 * There is a 16bit polling method for the close window option, but this
 * is CPU intensive and requires thunking.
 *
 * Attempts to subclass the 'tty' console fail, since that message thread
 * is actually owned by the 16 bit winoldap.mod process, although the 
 * window reports it is owned by the process/thread of the console app.
 *
 * Win9xConHook is thunks the WM_CLOSE and WM_ENDSESSION messages,
 * first through a window hook procedure in the winoldap context, into
 * a subclass WndProc, and on to a second hidden monitor window in the
 * console application's context that dispatches them to the console app's
 * registered HandlerRoutine.
 */

/* This debugging define turns on output to COM1, although you better init
 * the port first (even using hyperterm).  It's the only way to catch the
 * goings on within system logoff/shutdown.
 * #define DBG 1
 */

#include <windows.h>

/* Variables used within any process context:
 *  hookwndmsg is a shared message to send Win9xConHook signals
 *  origwndprop is a wndprop atom to store the orig wndproc of the tty
 *  hookwndprop is a wndprop atom to store the hwnd of the hidden child
 *  is_service reminds us to unmark this process on the way out
 */
static UINT hookwndmsg = 0;
static LPCTSTR origwndprop;
static LPCTSTR hookwndprop;
static BOOL is_service = 0;
//static HMODULE hmodThis = NULL;

/* Variables used within the tty processes' context:
 *  is_tty flags this process;  -1 == unknown, 1 == if tty, 0 == if not
 *  hw_tty is the handle of the top level tty in this process context
 *  is_subclassed is toggled to assure DllMain removes the subclass on unload
 *  hmodLock is there to try and prevent this dll from being unloaded if the
 *           hook is removed while we are subclassed
 */
static int is_tty = -1;
static HWND hwtty = NULL;
static BOOL is_subclassed = 0;

// This simply causes a gpfault the moment it tries to FreeLibrary within
// the subclass procedure ... not good.
//static HMODULE hmodLock = NULL;

/* Variables used within the service or console app's context:
 *  hmodHook is the instance handle of this module for registering the hooks
 *  hhkGetMessage is the hook handle for catching Posted messages
 *  hhkGetMessage is the hook handle for catching Sent messages
 *  monitor_hwnd is the invisible window that handles our tty messages
 *  the tty_info strucure is used to pass args into the hidden window's thread
 */
static HMODULE hmodHook = NULL;
static HHOOK hhkGetMessage;
//static HHOOK hhkCallWndProc;
static HWND monitor_hwnd = NULL;

typedef struct {
    PHANDLER_ROUTINE phandler;
    HINSTANCE instance;
    HWND parent;
    INT type;
    LPCSTR name;
} tty_info;

/* These are the GetWindowLong offsets for the hidden window's internal info
 *  gwltty_phandler is the address of the app's HandlerRoutine
 *  gwltty_ttywnd is the tty this hidden window will handle messages from
 */
#define gwltty_phandler 0
#define gwltty_ttywnd 4

/* Forward declaration prototypes for internal functions 
 */
static BOOL CALLBACK EnumttyWindow(HWND wnd, LPARAM retwnd);
static LRESULT WINAPI RegisterWindows9xService(BOOL set_service);
static LRESULT CALLBACK ttyConsoleCtrlWndProc(HWND hwnd, UINT msg, 
                                              WPARAM wParam, LPARAM lParam);
static DWORD WINAPI ttyConsoleCtrlThread(LPVOID tty);
static LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, 
                                WPARAM wParam, LPARAM lParam);
static int HookProc(int hc, HWND *hwnd, UINT *msg, 
                    WPARAM *wParam, LPARAM *lParam);
#ifdef DBG
static VOID DbgPrintf(LPTSTR fmt, ...);
#endif


/* DllMain is invoked by every process in the entire system that is hooked
 * by our window hooks, notably the tty processes' context, and by the user
 * who wants tty messages (the app).  Keep it light and simple.
 */
BOOL __declspec(dllexport) APIENTRY DllMain(HINSTANCE hModule, ULONG ulReason, 
                                            LPVOID pctx)
{
    if (ulReason == DLL_PROCESS_ATTACH) 
    {
        //hmodThis = hModule;
        if (!hookwndmsg) {
            origwndprop = MAKEINTATOM(GlobalAddAtom("Win9xConHookOrigProc"));
            hookwndprop = MAKEINTATOM(GlobalAddAtom("Win9xConHookThunkWnd"));
            hookwndmsg = RegisterWindowMessage("Win9xConHookMsg");
        }
#ifdef DBG
//        DbgPrintf("H ProcessAttach:%8.8x\r\n", 
//                  GetCurrentProcessId());
#endif
    }
    else if ( ulReason == DLL_PROCESS_DETACH ) 
    {
#ifdef DBG
//        DbgPrintf("H ProcessDetach:%8.8x\r\n", GetCurrentProcessId());                
#endif
        if (monitor_hwnd)
            SendMessage(monitor_hwnd, WM_DESTROY, 0, 0);
        if (is_subclassed) 
            SendMessage(hwtty, hookwndmsg, 0, (LPARAM)hwtty);
        if (hmodHook)
        {
            if (hhkGetMessage) {
                UnhookWindowsHookEx(hhkGetMessage);
                hhkGetMessage = NULL;
            }
            //if (hhkCallWndProc) {
            //    UnhookWindowsHookEx(hhkCallWndProc);
            //    hhkCallWndProc = NULL;
            //}
            FreeLibrary(hmodHook);
            hmodHook = NULL;
        }
        if (is_service)
            RegisterWindows9xService(FALSE);
        if (hookwndmsg) {
            GlobalDeleteAtom((ATOM)origwndprop);
            GlobalDeleteAtom((ATOM)hookwndprop);
            hookwndmsg = 0;
        }
    }
    return TRUE;
}


/*  This group of functions are provided for the service/console app
 *  to register itself a HandlerRoutine to accept tty or service messages
 */


/*  Exported function that creates a Win9x 'service' via a hidden window,
 *  that notifies the process via the HandlerRoutine messages.
 */
BOOL __declspec(dllexport) WINAPI Windows9xServiceCtrlHandler(
        PHANDLER_ROUTINE phandler,
        LPCSTR name)
{
    /* If we have not yet done so */
    FreeConsole();

    if (name)
    {
        DWORD tid;
        HANDLE hThread;
        /* NOTE: this is static so the module can continue to
         * access these args while we go on to other things
         */
        static tty_info tty;
        tty.instance = GetModuleHandle(NULL);
        tty.phandler = phandler;
        tty.parent = NULL;
        tty.name = name;
        tty.type = 2;
        RegisterWindows9xService(TRUE);
        hThread = CreateThread(NULL, 0, ttyConsoleCtrlThread,
                               (LPVOID)&tty, 0, &tid);
        if (hThread)
        {
            CloseHandle(hThread);
            return TRUE;
        }
    }
    else /* remove */
    {
        if (monitor_hwnd)
            SendMessage(monitor_hwnd, WM_DESTROY, 0, 0);
        RegisterWindows9xService(FALSE);
        return TRUE;
    }
    return FALSE;
}


/*  Exported function that registers a HandlerRoutine to accept missing
 *  Win9x CTRL_EVENTs from the tty window, as NT does without a hassle.
 *  If add is 1 or 2, register the handler, if 2 also mark it as a service.
 *  If add is 0 deregister the handler, and unmark if a service
 */
BOOL __declspec(dllexport) WINAPI FixConsoleCtrlHandler(
        PHANDLER_ROUTINE phandler,
        INT add)
{
    HWND parent;

    if (add)
    {
        HANDLE hThread;
        DWORD tid;
        /* NOTE: this is static so the module can continue to
         * access these args while we go on to other things
         */
        static tty_info tty;
        EnumWindows(EnumttyWindow, (LPARAM)&parent);
        if (!parent) {
#ifdef DBG
            DbgPrintf("A EnumttyWindow failed (%d)\r\n", GetLastError());
#endif
            return FALSE;
        }
        tty.instance = GetModuleHandle(NULL);
        tty.phandler = phandler;
        tty.parent = parent;
        tty.type = add;
        if (add == 2) {
            tty.name = "ttyService";
            RegisterWindows9xService(TRUE);
        }
        else 
            tty.name = "ttyMonitor";
        hThread = CreateThread(NULL, 0, ttyConsoleCtrlThread,
                               (LPVOID)&tty, 0, &tid);
        if (!hThread)
            return FALSE;        
        CloseHandle(hThread);
        hmodHook = LoadLibrary("Win9xConHook.dll");
        if (hmodHook)
        {
            hhkGetMessage = SetWindowsHookEx(WH_GETMESSAGE,
              (HOOKPROC)GetProcAddress(hmodHook, "GetMsgProc"), hmodHook, 0);
            //hhkCallWndProc = SetWindowsHookEx(WH_CALLWNDPROC,
            //  (HOOKPROC)GetProcAddress(hmodHook, "CallWndProc"), hmodHook, 0);
        }        
        return TRUE;
    }
    else /* remove */
    {
        if (monitor_hwnd) {
            SendMessage(monitor_hwnd, WM_DESTROY, 0, 0);
        }
        if (hmodHook)
        {
            if (hhkGetMessage) {
                UnhookWindowsHookEx(hhkGetMessage);
                hhkGetMessage = NULL;
            }
            //if (hhkCallWndProc) {
            //    UnhookWindowsHookEx(hhkCallWndProc);
            //    hhkCallWndProc = NULL;
            //}
            FreeLibrary(hmodHook);
            hmodHook = NULL;
        }
        if (is_service)
            RegisterWindows9xService(FALSE);
        return TRUE;
    }
    return FALSE;
}


/*  The following internal helpers are only used within the app's context
 */

/* ttyConsoleCreateThread is the process that runs within the user app's
 * context.  It creates and pumps the messages of a hidden monitor window,
 * watching for messages from the system, or the associated subclassed tty 
 * window.  Things can happen in our context that can't be done from the
 * tty's context, and visa versa, so the subclass procedure and this hidden
 * window work together to make it all happen.
 */
static DWORD WINAPI ttyConsoleCtrlThread(LPVOID tty)
{
    WNDCLASS wc;
    MSG msg;
    wc.style         = CS_GLOBALCLASS;
    wc.lpfnWndProc   = ttyConsoleCtrlWndProc; 
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 8; 
    wc.hInstance     = NULL;
    wc.hIcon         = NULL;
    wc.hCursor       = NULL;
    wc.hbrBackground = NULL;
    wc.lpszMenuName  = NULL;
    if (((tty_info*)tty)->parent)
        wc.lpszClassName = "ttyConHookChild";
    else
        wc.lpszClassName = "ApacheWin95ServiceMonitor";
        
    if (!RegisterClass(&wc)) { 
#ifdef DBG
        DbgPrintf("A proc %8.8x Error creating class %s (%d)\r\n", 
                  GetCurrentProcessId(), wc.lpszClassName, GetLastError());
#endif
        return 0;
    }

    /* Create an invisible window */
    monitor_hwnd = CreateWindow(wc.lpszClassName, ((tty_info*)tty)->name, 
                                WS_OVERLAPPED & ~WS_VISIBLE,
                                CW_USEDEFAULT, CW_USEDEFAULT, 
                                CW_USEDEFAULT, CW_USEDEFAULT, 
                                NULL, NULL, 
                                ((tty_info*)tty)->instance, tty);

    if (!monitor_hwnd) {
#ifdef DBG
        DbgPrintf("A proc %8.8x Error creating window %s %s (%d)\r\n", 
                  GetCurrentProcessId(), wc.lpszClassName, 
                  ((tty_info*)tty)->name, GetLastError());
#endif