ServerExe/HookDll/hookdll.c

/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   Seamless windows - Remote server hook DLL

   Based on code copyright (C) 2004-2005 Martin Wickett

   Copyright (C) Peter Åstrand <astrand@cendio.se> 2005-2006
   Copyright (C) Pierre Ossman <ossman@cendio.se> 2006

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <stdio.h>
#include <stdarg.h>

#include <windows.h>
#include <winuser.h>

#include "../vchannel.h"

#define DLL_EXPORT __declspec(dllexport)

#ifdef __GNUC__
#define SHARED __attribute__((section ("SHAREDDATA"), shared))
#else
#define SHARED
#endif

// Shared DATA
#pragma data_seg ( "SHAREDDATA" )

// this is the total number of processes this dll is currently attached to
int g_instance_count SHARED = 0;

// blocks for locally generated events
RECT g_block_move SHARED = { 0, 0, 0, 0 };
HWND g_blocked_zchange[2] SHARED = { NULL, NULL };
HWND g_blocked_focus SHARED = NULL;

#pragma data_seg ()

#pragma comment(linker, "/section:SHAREDDATA,rws")

#define FOCUS_MSG_NAME "WM_SEAMLESS_FOCUS"
static UINT g_wm_seamless_focus;

static HHOOK g_cbt_hook = NULL;
static HHOOK g_wndproc_hook = NULL;
static HHOOK g_wndprocret_hook = NULL;

static HINSTANCE g_instance = NULL;

static HANDLE g_mutex = NULL;

static void
update_position(HWND hwnd)
{
        RECT rect, blocked;

        if (!GetWindowRect(hwnd, &rect))
        {
                debug("GetWindowRect failed!\n");
                return;
        }

        WaitForSingleObject(g_mutex, INFINITE);
        memcpy(&blocked, &g_block_move, sizeof(RECT));
        ReleaseMutex(g_mutex);

        if ((rect.left == blocked.left) && (rect.top == blocked.top)
            && (rect.right == blocked.right) && (rect.bottom == blocked.bottom))
                return;

        vchannel_write("POSITION,0x%p,%d,%d,%d,%d,0x%x",
                       hwnd,
                       rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, 0);
}

static LRESULT CALLBACK
wndproc_hook_proc(int code, WPARAM cur_thread, LPARAM details)
{
        HWND hwnd, parent;
        UINT msg;
        WPARAM wparam;
        LPARAM lparam;

        LONG style;

        if (code < 0)
                goto end;

        hwnd = ((CWPSTRUCT *) details)->hwnd;
        msg = ((CWPSTRUCT *) details)->message;
        wparam = ((CWPSTRUCT *) details)->wParam;
        lparam = ((CWPSTRUCT *) details)->lParam;

        style = GetWindowLong(hwnd, GWL_STYLE);

        /* Docs say that WS_CHILD and WS_POPUP is an illegal combination,
           but they exist nonetheless. */
        if ((style & WS_CHILD) && !(style & WS_POPUP))
                goto end;

        if (style & WS_POPUP)
        {
                parent = (HWND) GetWindowLong(hwnd, GWL_HWNDPARENT);
                if (!parent)
                        parent = (HWND) - 1;
        }
        else
                parent = NULL;

        switch (msg)
        {

                case WM_WINDOWPOSCHANGED:
                        {
                                WINDOWPOS *wp = (WINDOWPOS *) lparam;

                                if (wp->flags & SWP_SHOWWINDOW)
                                {
                                        unsigned short title[150];
                                        int state;

                                        vchannel_write("CREATE,0x%p,0x%p,0x%x", hwnd, parent, 0);

                                        GetWindowTextW(hwnd, title, sizeof(title) / sizeof(*title));

                                        vchannel_write("TITLE,0x%x,%s,0x%x", hwnd,
                                                       vchannel_strfilter_unicode(title), 0);

                                        if (style & WS_MAXIMIZE)
                                                state = 2;
                                        else if (style & WS_MINIMIZE)
                                                state = 1;
                                        else
                                                state = 0;

                                        update_position(hwnd);

                                        vchannel_write("STATE,0x%p,0x%x,0x%x", hwnd, state, 0);
                                }

                                if (wp->flags & SWP_HIDEWINDOW)
                                        vchannel_write("DESTROY,0x%p,0x%x", hwnd, 0);

                                if (!(style & WS_VISIBLE) || (style & WS_MINIMIZE))
                                        break;

                                if (!(wp->flags & SWP_NOMOVE && wp->flags & SWP_NOSIZE))
                                        update_position(hwnd);

                                if (!(wp->flags & SWP_NOZORDER))
                                {
                                        HWND block_hwnd, block_behind;
                                        WaitForSingleObject(g_mutex, INFINITE);
                                        block_hwnd = g_blocked_zchange[0];
                                        block_behind = g_blocked_zchange[1];
                                        ReleaseMutex(g_mutex);

                                        if ((hwnd != block_hwnd)
                                            || (wp->hwndInsertAfter != block_behind))
                                        {
                                                vchannel_write("ZCHANGE,0x%p,0x%p,0x%x",
                                                               hwnd,
                                                               wp->flags & SWP_NOACTIVATE ? wp->
                                                               hwndInsertAfter : 0, 0);
                                        }
                                }

                                break;
                        }

                case WM_SIZE:
                        if (!(style & WS_VISIBLE) || (style & WS_MINIMIZE))
                                break;
                        update_position(hwnd);
                        break;

                case WM_MOVE:
                        if (!(style & WS_VISIBLE) || (style & WS_MINIMIZE))
                                break;
                        update_position(hwnd);
                        break;

                case WM_DESTROY:
                        if (!(style & WS_VISIBLE))
                                break;
                        vchannel_write("DESTROY,0x%p,0x%x", hwnd, 0);
                        break;

                default:
                        break;
        }

      end:
        return CallNextHookEx(g_wndproc_hook, code, cur_thread, details);
}

static LRESULT CALLBACK
wndprocret_hook_proc(int code, WPARAM cur_thread, LPARAM details)
{
        HWND hwnd, parent;
        UINT msg;
        WPARAM wparam;
        LPARAM lparam;

        LONG style;

        if (code < 0)
                goto end;

        hwnd = ((CWPRETSTRUCT *) details)->hwnd;
        msg = ((CWPRETSTRUCT *) details)->message;
        wparam = ((CWPRETSTRUCT *) details)->wParam;
        lparam = ((CWPRETSTRUCT *) details)->lParam;

        style = GetWindowLong(hwnd, GWL_STYLE);

        /* Docs say that WS_CHILD and WS_POPUP is an illegal combination,
           but they exist nonetheless. */
        if ((style & WS_CHILD) && !(style & WS_POPUP))
                goto end;

        if (style & WS_POPUP)
        {
                parent = (HWND) GetWindowLong(hwnd, GWL_HWNDPARENT);
                if (!parent)
                        parent = (HWND) - 1;
        }
        else
                parent = NULL;

        switch (msg)
        {
                case WM_SETTEXT:
                        {
                                unsigned short title[150];
                                if (!(style & WS_VISIBLE))
                                        break;
                                /* We cannot use the string in lparam because
                                   we need unicode. */
                                GetWindowTextW(hwnd, title, sizeof(title) / sizeof(*title));
                                vchannel_write("TITLE,0x%p,%s,0x%x", hwnd,
                                               vchannel_strfilter_unicode(title), 0);
                                break;
                        }

                default:
                        break;
        }

        if (msg == g_wm_seamless_focus)
        {
                /* FIXME: SetActiveWindow() kills menus. Need to find a clean
                   way to solve this. */
                if ((GetActiveWindow() != hwnd) && !parent)
                        SetActiveWindow(hwnd);
        }

      end:
        return CallNextHookEx(g_wndprocret_hook, code, cur_thread, details);
}

static LRESULT CALLBACK
cbt_hook_proc(int code, WPARAM wparam, LPARAM lparam)
{
        if (code < 0)
                goto end;

        switch (code)
        {
                case HCBT_MINMAX:
                        {
                                int show, state;

                                show = LOWORD(lparam);

                                if ((show == SW_NORMAL) || (show == SW_SHOWNORMAL)
                                    || (show == SW_RESTORE))
                                        state = 0;
                                else if ((show == SW_MINIMIZE) || (show == SW_SHOWMINIMIZED))
                                        state = 1;
                                else if ((show == SW_MAXIMIZE) || (show == SW_SHOWMAXIMIZED))
                                        state = 2;
                                else
                                {
                                        debug("Unexpected show: %d", show);
                                        break;
                                }
                                vchannel_write("STATE,0x%p,0x%x,0x%x", (HWND) wparam, state, 0);
                                break;
                        }

                default:
                        break;
        }

      end:
        return CallNextHookEx(g_cbt_hook, code, wparam, lparam);
}

DLL_EXPORT void
SetHooks(void)
{
        if (!g_cbt_hook)
                g_cbt_hook = SetWindowsHookEx(WH_CBT, cbt_hook_proc, g_instance, 0);

        if (!g_wndproc_hook)
                g_wndproc_hook = SetWindowsHookEx(WH_CALLWNDPROC, wndproc_hook_proc, g_instance, 0);

        if (!g_wndprocret_hook)
                g_wndprocret_hook =
                        SetWindowsHookEx(WH_CALLWNDPROCRET, wndprocret_hook_proc, g_instance, 0);
}

DLL_EXPORT void
RemoveHooks(void)
{
        if (g_cbt_hook)
                UnhookWindowsHookEx(g_cbt_hook);

        if (g_wndproc_hook)
                UnhookWindowsHookEx(g_wndproc_hook);

        if (g_wndprocret_hook)
                UnhookWindowsHookEx(g_wndprocret_hook);
}

DLL_EXPORT void
SafeMoveWindow(HWND hwnd, int x, int y, int width, int height)
{
        WaitForSingleObject(g_mutex, INFINITE);
        g_block_move.left = x;
        g_block_move.top = y;
        g_block_move.right = x + width;
        g_block_move.bottom = y + height;
        ReleaseMutex(g_mutex);

        SetWindowPos(hwnd, NULL, x, y, width, height, SWP_NOACTIVATE | SWP_NOZORDER);

        WaitForSingleObject(g_mutex, INFINITE);
        memset(&g_block_move, 0, sizeof(RECT));
        ReleaseMutex(g_mutex);
}

DLL_EXPORT void
SafeZChange(HWND hwnd, HWND behind)
{
        if (behind == NULL)
                behind = HWND_TOP;

        WaitForSingleObject(g_mutex, INFINITE);
        g_blocked_zchange[0] = hwnd;
        g_blocked_zchange[1] = behind;
        ReleaseMutex(g_mutex);

        SetWindowPos(hwnd, behind, 0, 0, 0, 0, SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE);

        WaitForSingleObject(g_mutex, INFINITE);
        g_blocked_zchange[0] = NULL;
        g_blocked_zchange[1] = NULL;
        ReleaseMutex(g_mutex);
}

DLL_EXPORT void
SafeFocus(HWND hwnd)
{
        WaitForSingleObject(g_mutex, INFINITE);
        g_blocked_focus = hwnd;
        ReleaseMutex(g_mutex);

        SendMessage(hwnd, g_wm_seamless_focus, 0, 0);

        WaitForSingleObject(g_mutex, INFINITE);
        g_blocked_focus = NULL;
        ReleaseMutex(g_mutex);
}

DLL_EXPORT int
GetInstanceCount()
{
        return g_instance_count;
}

BOOL APIENTRY
DllMain(HINSTANCE hinstDLL, DWORD ul_reason_for_call, LPVOID lpReserved)
{
        switch (ul_reason_for_call)
        {
                case DLL_PROCESS_ATTACH:
                        // remember our instance handle
                        g_instance = hinstDLL;

                        g_mutex = CreateMutex(NULL, FALSE, "Local\\SeamlessDLL");
                        if (!g_mutex)
                                return FALSE;

                        WaitForSingleObject(g_mutex, INFINITE);
                        ++g_instance_count;
                        ReleaseMutex(g_mutex);

                        g_wm_seamless_focus = RegisterWindowMessage(FOCUS_MSG_NAME);

                        vchannel_open();

                        break;

                case DLL_THREAD_ATTACH:
                        break;

                case DLL_THREAD_DETACH:
                        break;

                case DLL_PROCESS_DETACH:
                        WaitForSingleObject(g_mutex, INFINITE);
                        --g_instance_count;
                        ReleaseMutex(g_mutex);

                        vchannel_close();

                        CloseHandle(g_mutex);

                        break;
        }

        return TRUE;
}
1	/* -- c-basic-offset: 8 --
2	rdesktop: A Remote Desktop Protocol client.
3	Seamless windows - Remote server hook DLL
4
5	Based on code copyright (C) 2004-2005 Martin Wickett
6
7	Copyright (C) Peter Åstrand <astrand@cendio.se> 2005-2006
8	Copyright (C) Pierre Ossman <ossman@cendio.se> 2006
9
10	This program is free software; you can redistribute it and/or modify
11	it under the terms of the GNU General Public License as published by
12	the Free Software Foundation; either version 2 of the License, or
13	(at your option) any later version.
14
15	This program is distributed in the hope that it will be useful,
16	but WITHOUT ANY WARRANTY; without even the implied warranty of
17	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18	GNU General Public License for more details.
19
20	You should have received a copy of the GNU General Public License
21	along with this program; if not, write to the Free Software
22	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23	*/
24
25	#include <stdio.h>
26	#include <stdarg.h>
27
28	#include <windows.h>
29	#include <winuser.h>
30
31	#include "../vchannel.h"
32
33	#define DLL_EXPORT __declspec(dllexport)
34
35	#ifdef __GNUC__
36	#define SHARED __attribute__((section ("SHAREDDATA"), shared))
37	#else
38	#define SHARED
39	#endif
40
41	// Shared DATA
42	#pragma data_seg ( "SHAREDDATA" )
43
44	// this is the total number of processes this dll is currently attached to
45	int g_instance_count SHARED = 0;
46
47	// blocks for locally generated events
48	RECT g_block_move SHARED = { 0, 0, 0, 0 };
49	HWND g_blocked_zchange[2] SHARED = { NULL, NULL };
50	HWND g_blocked_focus SHARED = NULL;
51
52	#pragma data_seg ()
53
54	#pragma comment(linker, "/section:SHAREDDATA,rws")
55
56	#define FOCUS_MSG_NAME "WM_SEAMLESS_FOCUS"
57	static UINT g_wm_seamless_focus;
58
59	static HHOOK g_cbt_hook = NULL;
60	static HHOOK g_wndproc_hook = NULL;
61	static HHOOK g_wndprocret_hook = NULL;
62
63	static HINSTANCE g_instance = NULL;
64
65	static HANDLE g_mutex = NULL;
66
67	static void
68	update_position(HWND hwnd)
69	{
70	RECT rect, blocked;
71
72	if (!GetWindowRect(hwnd, &rect))
73	{
74	debug("GetWindowRect failed!\n");
75	return;
76	}
77
78	WaitForSingleObject(g_mutex, INFINITE);
79	memcpy(&blocked, &g_block_move, sizeof(RECT));
80	ReleaseMutex(g_mutex);
81
82	if ((rect.left == blocked.left) && (rect.top == blocked.top)
83	&& (rect.right == blocked.right) && (rect.bottom == blocked.bottom))
84	return;
85
86	vchannel_write("POSITION,0x%p,%d,%d,%d,%d,0x%x",
87	hwnd,
88	rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, 0);
89	}
90
91	static LRESULT CALLBACK
92	wndproc_hook_proc(int code, WPARAM cur_thread, LPARAM details)
93	{
94	HWND hwnd, parent;
95	UINT msg;
96	WPARAM wparam;
97	LPARAM lparam;
98
99	LONG style;
100
101	if (code < 0)
102	goto end;
103
104	hwnd = ((CWPSTRUCT *) details)->hwnd;
105	msg = ((CWPSTRUCT *) details)->message;
106	wparam = ((CWPSTRUCT *) details)->wParam;
107	lparam = ((CWPSTRUCT *) details)->lParam;
108
109	style = GetWindowLong(hwnd, GWL_STYLE);
110
111	/* Docs say that WS_CHILD and WS_POPUP is an illegal combination,
112	but they exist nonetheless. */
113	if ((style & WS_CHILD) && !(style & WS_POPUP))
114	goto end;
115
116	if (style & WS_POPUP)
117	{
118	parent = (HWND) GetWindowLong(hwnd, GWL_HWNDPARENT);
119	if (!parent)
120	parent = (HWND) - 1;
121	}
122	else
123	parent = NULL;
124
125	switch (msg)
126	{
127
128	case WM_WINDOWPOSCHANGED:
129	{
130	WINDOWPOS wp = (WINDOWPOS ) lparam;
131
132	if (wp->flags & SWP_SHOWWINDOW)
133	{
134	unsigned short title[150];
135	int state;
136
137	vchannel_write("CREATE,0x%p,0x%p,0x%x", hwnd, parent, 0);
138
139	GetWindowTextW(hwnd, title, sizeof(title) / sizeof(*title));
140
141	vchannel_write("TITLE,0x%x,%s,0x%x", hwnd,
142	vchannel_strfilter_unicode(title), 0);
143
144	if (style & WS_MAXIMIZE)
145	state = 2;
146	else if (style & WS_MINIMIZE)
147	state = 1;
148	else
149	state = 0;
150
151	update_position(hwnd);
152
153	vchannel_write("STATE,0x%p,0x%x,0x%x", hwnd, state, 0);
154	}
155
156	if (wp->flags & SWP_HIDEWINDOW)
157	vchannel_write("DESTROY,0x%p,0x%x", hwnd, 0);
158
159	if (!(style & WS_VISIBLE) \|\| (style & WS_MINIMIZE))
160	break;
161
162	if (!(wp->flags & SWP_NOMOVE && wp->flags & SWP_NOSIZE))
163	update_position(hwnd);
164
165	if (!(wp->flags & SWP_NOZORDER))
166	{
167	HWND block_hwnd, block_behind;
168	WaitForSingleObject(g_mutex, INFINITE);
169	block_hwnd = g_blocked_zchange[0];
170	block_behind = g_blocked_zchange[1];
171	ReleaseMutex(g_mutex);
172
173	if ((hwnd != block_hwnd)
174	\|\| (wp->hwndInsertAfter != block_behind))
175	{
176	vchannel_write("ZCHANGE,0x%p,0x%p,0x%x",
177	hwnd,
178	wp->flags & SWP_NOACTIVATE ? wp->
179	hwndInsertAfter : 0, 0);
180	}
181	}
182
183	break;
184	}
185
186	case WM_SIZE:
187	if (!(style & WS_VISIBLE) \|\| (style & WS_MINIMIZE))
188	break;
189	update_position(hwnd);
190	break;
191
192	case WM_MOVE:
193	if (!(style & WS_VISIBLE) \|\| (style & WS_MINIMIZE))
194	break;
195	update_position(hwnd);
196	break;
197
198	case WM_DESTROY:
199	if (!(style & WS_VISIBLE))
200	break;
201	vchannel_write("DESTROY,0x%p,0x%x", hwnd, 0);
202	break;
203
204	default:
205	break;
206	}
207
208	end:
209	return CallNextHookEx(g_wndproc_hook, code, cur_thread, details);
210	}
211
212	static LRESULT CALLBACK
213	wndprocret_hook_proc(int code, WPARAM cur_thread, LPARAM details)
214	{
215	HWND hwnd, parent;
216	UINT msg;
217	WPARAM wparam;
218	LPARAM lparam;
219
220	LONG style;
221
222	if (code < 0)
223	goto end;
224
225	hwnd = ((CWPRETSTRUCT *) details)->hwnd;
226	msg = ((CWPRETSTRUCT *) details)->message;
227	wparam = ((CWPRETSTRUCT *) details)->wParam;
228	lparam = ((CWPRETSTRUCT *) details)->lParam;
229
230	style = GetWindowLong(hwnd, GWL_STYLE);
231
232	/* Docs say that WS_CHILD and WS_POPUP is an illegal combination,
233	but they exist nonetheless. */
234	if ((style & WS_CHILD) && !(style & WS_POPUP))
235	goto end;
236
237	if (style & WS_POPUP)
238	{
239	parent = (HWND) GetWindowLong(hwnd, GWL_HWNDPARENT);
240	if (!parent)
241	parent = (HWND) - 1;
242	}
243	else
244	parent = NULL;
245
246	switch (msg)
247	{
248	case WM_SETTEXT:
249	{
250	unsigned short title[150];
251	if (!(style & WS_VISIBLE))
252	break;
253	/* We cannot use the string in lparam because
254	we need unicode. */
255	GetWindowTextW(hwnd, title, sizeof(title) / sizeof(*title));
256	vchannel_write("TITLE,0x%p,%s,0x%x", hwnd,
257	vchannel_strfilter_unicode(title), 0);
258	break;
259	}
260
261	default:
262	break;
263	}
264
265	if (msg == g_wm_seamless_focus)
266	{
267	/* FIXME: SetActiveWindow() kills menus. Need to find a clean
268	way to solve this. */
269	if ((GetActiveWindow() != hwnd) && !parent)
270	SetActiveWindow(hwnd);
271	}
272
273	end:
274	return CallNextHookEx(g_wndprocret_hook, code, cur_thread, details);
275	}
276
277	static LRESULT CALLBACK
278	cbt_hook_proc(int code, WPARAM wparam, LPARAM lparam)
279	{
280	if (code < 0)
281	goto end;
282
283	switch (code)
284	{
285	case HCBT_MINMAX:
286	{
287	int show, state;
288
289	show = LOWORD(lparam);
290
291	if ((show == SW_NORMAL) \|\| (show == SW_SHOWNORMAL)
292	\|\| (show == SW_RESTORE))
293	state = 0;
294	else if ((show == SW_MINIMIZE) \|\| (show == SW_SHOWMINIMIZED))
295	state = 1;
296	else if ((show == SW_MAXIMIZE) \|\| (show == SW_SHOWMAXIMIZED))
297	state = 2;
298	else
299	{
300	debug("Unexpected show: %d", show);
301	break;
302	}
303	vchannel_write("STATE,0x%p,0x%x,0x%x", (HWND) wparam, state, 0);
304	break;
305	}
306
307	default:
308	break;
309	}
310
311	end:
312	return CallNextHookEx(g_cbt_hook, code, wparam, lparam);
313	}
314
315	DLL_EXPORT void
316	SetHooks(void)
317	{
318	if (!g_cbt_hook)
319	g_cbt_hook = SetWindowsHookEx(WH_CBT, cbt_hook_proc, g_instance, 0);
320
321	if (!g_wndproc_hook)
322	g_wndproc_hook = SetWindowsHookEx(WH_CALLWNDPROC, wndproc_hook_proc, g_instance, 0);
323
324	if (!g_wndprocret_hook)
325	g_wndprocret_hook =
326	SetWindowsHookEx(WH_CALLWNDPROCRET, wndprocret_hook_proc, g_instance, 0);
327	}
328
329	DLL_EXPORT void
330	RemoveHooks(void)
331	{
332	if (g_cbt_hook)
333	UnhookWindowsHookEx(g_cbt_hook);
334
335	if (g_wndproc_hook)
336	UnhookWindowsHookEx(g_wndproc_hook);
337
338	if (g_wndprocret_hook)
339	UnhookWindowsHookEx(g_wndprocret_hook);
340	}
341
342	DLL_EXPORT void
343	SafeMoveWindow(HWND hwnd, int x, int y, int width, int height)
344	{
345	WaitForSingleObject(g_mutex, INFINITE);
346	g_block_move.left = x;
347	g_block_move.top = y;
348	g_block_move.right = x + width;
349	g_block_move.bottom = y + height;
350	ReleaseMutex(g_mutex);
351
352	SetWindowPos(hwnd, NULL, x, y, width, height, SWP_NOACTIVATE \| SWP_NOZORDER);
353
354	WaitForSingleObject(g_mutex, INFINITE);
355	memset(&g_block_move, 0, sizeof(RECT));
356	ReleaseMutex(g_mutex);
357	}
358
359	DLL_EXPORT void
360	SafeZChange(HWND hwnd, HWND behind)
361	{
362	if (behind == NULL)
363	behind = HWND_TOP;
364
365	WaitForSingleObject(g_mutex, INFINITE);
366	g_blocked_zchange[0] = hwnd;
367	g_blocked_zchange[1] = behind;
368	ReleaseMutex(g_mutex);
369
370	SetWindowPos(hwnd, behind, 0, 0, 0, 0, SWP_NOACTIVATE \| SWP_NOMOVE \| SWP_NOSIZE);
371
372	WaitForSingleObject(g_mutex, INFINITE);
373	g_blocked_zchange[0] = NULL;
374	g_blocked_zchange[1] = NULL;
375	ReleaseMutex(g_mutex);
376	}
377
378	DLL_EXPORT void
379	SafeFocus(HWND hwnd)
380	{
381	WaitForSingleObject(g_mutex, INFINITE);
382	g_blocked_focus = hwnd;
383	ReleaseMutex(g_mutex);
384
385	SendMessage(hwnd, g_wm_seamless_focus, 0, 0);
386
387	WaitForSingleObject(g_mutex, INFINITE);
388	g_blocked_focus = NULL;
389	ReleaseMutex(g_mutex);
390	}
391
392	DLL_EXPORT int
393	GetInstanceCount()
394	{
395	return g_instance_count;
396	}
397
398	BOOL APIENTRY
399	DllMain(HINSTANCE hinstDLL, DWORD ul_reason_for_call, LPVOID lpReserved)
400	{
401	switch (ul_reason_for_call)
402	{
403	case DLL_PROCESS_ATTACH:
404	// remember our instance handle
405	g_instance = hinstDLL;
406
407	g_mutex = CreateMutex(NULL, FALSE, "Local\\SeamlessDLL");
408	if (!g_mutex)
409	return FALSE;
410
411	WaitForSingleObject(g_mutex, INFINITE);
412	++g_instance_count;
413	ReleaseMutex(g_mutex);
414
415	g_wm_seamless_focus = RegisterWindowMessage(FOCUS_MSG_NAME);
416
417	vchannel_open();
418
419	break;
420
421	case DLL_THREAD_ATTACH:
422	break;
423
424	case DLL_THREAD_DETACH:
425	break;
426
427	case DLL_PROCESS_DETACH:
428	WaitForSingleObject(g_mutex, INFINITE);
429	--g_instance_count;
430	ReleaseMutex(g_mutex);
431
432	vchannel_close();
433
434	CloseHandle(g_mutex);
435
436	break;
437	}
438
439	return TRUE;
440	}