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POSetWindowsHook stops working after some time
 

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    <p>I defined a global hook on WM_MOUSE that works perfectly for some time. It post a message to a specific window each time the mouse move.</p> <p>After some random time the hook stop sending messages. If I unregister and register the hook it works again. I suppose some specific thing happening in Windows cause the hook to stop, but I can't find what.</p> <p>Any ideas ?</p> <p><strong>Edit</strong>: I attached a debugger to other processes when the hook is not active anymore, and I observed that the dll is not loaded anymore.</p> <p>What could cause a hook dll to unload ?</p> <p><strong>Edit2</strong> : I find out that a crash in MouseHookProc the dll in any process unload the hook dll from every process it's loaded in. I can't find a cause to a crash in my code. Might be some race condition or something ? Here is the hook dll code :</p> <pre><code>#include "stdafx.h" // define a data segment #pragma data_seg(".SHARED") HWND hwnd=0; HHOOK hHook=0; #pragma data_seg() // tell the linker to share the segment #pragma comment(linker, "/section:.SHARED,RWS") #define WM_MOUSEHOOK WM_USER+0x100 HINSTANCE hInstance=0; // this allow to build a very small executable without any extra libraries // (probably not the problem, the bug still occurs without this ) #ifndef _DEBUG void *__cdecl operator new(unsigned int bytes) { return HeapAlloc(GetProcessHeap(), 0, bytes); } void __cdecl operator delete(void *ptr) { if(ptr) HeapFree(GetProcessHeap(), 0, ptr); } extern "C" int __cdecl __purecall(void) { return 0; } #endif BOOL APIENTRY DllMain( HINSTANCE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) { hInstance=hModule; return TRUE; } LRESULT CALLBACK MouseHookProc(int nCode, WORD wParam, DWORD lParam) { if(nCode==HC_ACTION &amp;&amp; (wParam==WM_MOUSEMOVE || wParam==WM_NCMOUSEMOVE)) { MSLLHOOKSTRUCT *mhs=(MSLLHOOKSTRUCT*)lParam; PostMessage(hwnd, WM_MOUSEHOOK, wParam, 0); } return CallNextHookEx(hHook,nCode,wParam,lParam); } extern "C" __declspec(dllexport) HHOOK InitializeWindowsHook(char *title) { hwnd=FindWindow(0, title); if(hwnd) hHook=SetWindowsHookEx(WH_MOUSE, (HOOKPROC)MouseHookProc, hInstance, 0); return hHook; } extern "C" __declspec(dllexport) BOOL DeinitializeWindowsHook() { if(hHook) { BOOL b=UnhookWindowsHookEx(hHook); hHook=0; return b; } return FALSE; } </code></pre>
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    1. USEmmanuel Caradec
    1. USEmmanuel Caradec
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      1. POSetWindowsHook stops working after some time
      1. USEmmanuel Caradec
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      1. USBrian R. Bondy
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    1. COAre you propagating the messages to other hooks in the chain?
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      1. USrpg
    2. COI noticed that while you have a `WH_MOUSE` hook you use `MSLLHOOKSTRUCT` instead of `MOUSEHOOKSTRUCT` structure.
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      1. USNick Dandoulakis
    3. COActually you declare `*mhs` but you don't use it.
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      1. USNick Dandoulakis
 

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