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Mutex doesn't removed after FreeLibrary
Hi
I have a DLL which creates like this:
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "Testing");
I have program which loads this DLL:
HMODULE test = LoadLibrary("MyDLL.dll");
do something
FreeLibrary(test);
Now I do this check AFTER! FreeLibrary:
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "c14");
if (hMutex != NULL)
{
if(GetLastError() == ERROR_ALREADY_EXISTS)
MessageBox(0, "Already Loaded!", "Loaded!", 64);
else
MessageBox(0, "NOT Loaded!", "NOT Loaded!", 64);
}
Always I get already loaded!
I don't want it, I want to lose Mutex when MyDLL is unloaded... How to accomplish this? FreeLibrary doesn't remove DLL from memory?
Please advice... Even if you better method for detection of loaded/unloaded DLL please advice... I don't want to use CreateWindow method, but if I have to use, I'll use...
Thanks
I have a DLL which creates like this:
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "Testing");
I have program which loads this DLL:
HMODULE test = LoadLibrary("MyDLL.dll");
do something
FreeLibrary(test);
Now I do this check AFTER! FreeLibrary:
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "c14");
if (hMutex != NULL)
{
if(GetLastError() == ERROR_ALREADY_EXISTS)
MessageBox(0, "Already Loaded!", "Loaded!", 64);
else
MessageBox(0, "NOT Loaded!", "NOT Loaded!", 64);
}
Always I get already loaded!
I don't want it, I want to lose Mutex when MyDLL is unloaded... How to accomplish this? FreeLibrary doesn't remove DLL from memory?
Please advice... Even if you better method for detection of loaded/unloaded DLL please advice... I don't want to use CreateWindow method, but if I have to use, I'll use...
Thanks
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THat's odd because the name of the other mutex is different.
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "Testing");
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "c14");
So there is no way the 2nd one (c14) already existing can have anything to do with the first(Testing).
Are you sure your analysis of this problem is correct?
Also, GetError is ONLY valid if the CreateMutex returns NULL, which it clearly doesn't for it to get into this code. This means the create has worked and the error response from GetError is most likely unrelated.
"If the function fails, the return value is NULL. To get extended error information, call GetLastError."
http://msdn.microsoft.com/en-us/library/ms682411(VS.85).aspx
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "Testing");
HANDLE hMutex = ::CreateMutex(NULL,FALSE, "c14");
So there is no way the 2nd one (c14) already existing can have anything to do with the first(Testing).
Are you sure your analysis of this problem is correct?
Also, GetError is ONLY valid if the CreateMutex returns NULL, which it clearly doesn't for it to get into this code. This means the create has worked and the error response from GetError is most likely unrelated.
"If the function fails, the return value is NULL. To get extended error information, call GetLastError."
http://msdn.microsoft.com/en-us/library/ms682411(VS.85).aspx
>>I want to lose Mutex when MyDLL is unloaded... How to accomplish this?
Since mutexes are designed to work across process boundaries, the behaviour you're observing is absolutely 'by design' (unless you forgot to call 'CloseHandle()' on your mutex). If you want to force the closing of the mutex in question, you could do that like
Since mutexes are designed to work across process boundaries, the behaviour you're observing is absolutely 'by design' (unless you forgot to call 'CloseHandle()' on your mutex). If you want to force the closing of the mutex in question, you could do that like
void ForceCloseMutex(LPCTSTR pName) {
HANDLE hMutex = OpenMutex(MUTEX_ALL_ACCESS,FALSE,pName);
while(CloseHandle(hMutex));
}
// ...
BOOL WINAPI DllMain(
HINSTANCE hinstDLL, // handle to DLL module
DWORD fdwReason, // reason for calling function
LPVOID lpvReserved // reserved
) {
switch(fdwReason) {
// ...
case DLL_PROCESS_DETACH: ForceCloseMutex(_T("MyMutex"));
};
}
evilrix, that was mistyping... sorry!
About jkr... Sometimes my DLL crashes and goes away, this is what I'm doing such thing... I want to see if my DLL is crashed or exited unexpectedly, so I can't run ForceCloseMutex, because it won't get fired
About jkr... Sometimes my DLL crashes and goes away, this is what I'm doing such thing... I want to see if my DLL is crashed or exited unexpectedly, so I can't run ForceCloseMutex, because it won't get fired
>> Sometimes my DLL crashes and goes away, this is what I'm doing such thing...
Maybe the correct thing to do is to fix the problem rather than adding an additional layer of complexity on to of it? :)
Maybe the correct thing to do is to fix the problem rather than adding an additional layer of complexity on to of it? :)
I must agree with evlirix, but, btw, calling Loadlibrary twice with the same dll isn't a problem since it checks if it has already been loaded. You cant load it twice.
When that process crashes, why don't you just open the already existing mutex? E.g.
HANDLE ConnectMutex ( LPCTSTR pszName)
{
HANDLE hMutex = CreateMutex ( NULL,
FALSE,
FALSE,
pszName
);
if ( INVALID_HANDLE_VALUE == hMutex)
{
if ( ERROR_ALREADY_EXISTS == GetLastError ())
{
hMutex = OpenMutex ( SYNCHRONIZE,
FALSE,
pszName
);
if ( INVALID_HANDLE_VALUE == hMutex)
{
return NULL;
}
}
}
return hMutex;
}
Some users detach my dll using some programs... That's my problem... I want to see when my DLL is unloaded and doesn't exists in memory, I should re-load my dll...
That's very good idea to enumerate loaded modules, but when I include dbghelp.h I get error:
unresolved external symbol __imp__EnumerateLoadedModu
unresolved external symbol __imp__EnumerateLoadedModu
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