C / C++ / MFC

Re: SetWindowsHookEx function fails in VISTA

31-Jul-08 21:51

from MSDN [^]:

Return Value
If the function succeeds, the return value is the handle to the hook procedure.
If the function fails, the return value is NULL. To get extended error information, call GetLastError.

Anyway one may guess that elevation is needed there.
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Xing Chen31-Jul-08 21:58

Xing Chen

31-Jul-08 21:58

there are other guys discuss same case in MSDN Forums:

Journaling hooks on Vista? [^]

Hope it can help you.

Re: SetWindowsHookEx function fails in VISTA

ShilpiP2-Aug-08 1:26

ShilpiP

2-Aug-08 1:26

Thanks Xing Chen,
I read this but not find any suitable solution but now my problem is solved by disabling UAC in Vista.

Yes U Can ...If U Can ,Dream it , U can do it ...ICAN

FreeLibrary problem [modified]

Rahul Vaishnav31-Jul-08 20:51

31-Jul-08 20:51

Hi all,

Please help me...

I am have written below function in which I am calling repeated as per my requirement..

typedef HRESULT (*PROCHICON)(HICON*); 
typedef CString (*PROCCSTRNAME)(); 
typedef CString (*PROCCSTRCONT)(CString); 

LoadButtonPluginDLL(CString DLLPath,CString &ButtonText,HICON &ImageHandle,CString &ButtonContent)
{
PROCHICON ProcButtonHicon;
PROCCSTRNAME ProcButtonName;
PROCCSTRCONT ProcButtonContent;
HINSTANCE hLib = ::LoadLibrary(DLLPath); //load the plugin libarary dll//    
if(hLib==NULL)
{
 MessageBox(_T("Fails To Load Dll"));
return;
}

ProcButtonHicon =(PROCHICON)::GetProcAddress(hLib,"GetButtonImage"); 
if(ProcButtonHicon == NULL) //if dll is not loaded
{
  ::FreeLibrary(hLib);
  CoUninitialize();
 return;
} 
ProcButtonName =(PROCCSTRNAME)::GetProcAddress(hLib,"GetButtonText");  
if(ProcButtonName == NULL) 
{
 ::FreeLibrary(hLib);
 CoUninitialize();
 return;
}  
ProcButtonContent= (PROCCSTRCONT)::GetProcAddress(hLib,"GetPluginContent");
if(ProcButtonContent == NULL) //if dll is not loaded
{
::FreeLibrary(hLib);
CoUninitialize();
return;
}            
 ((PROCHICON)ProcButtonHicon)(&ImageHandle);
ButtonText =((PROCCSTRNAME)ProcButtonName)();  
ButtonContent =((PROCCSTRCONT)ProcButtonContent)("1");  

if(hLib)
 FreeLibrary(hLib); //free the libaray    
}

When I callabove function first time it works fine I get proper values in ImageHandle,ButtonText,ButtonContent from dll. but when I call this function second time and after calling FreeLibrary(hLib);variables ButtonText & ButtonContent become BadPtr and I can't use these values out side the function.

Frown | :(

modified on Friday, August 1, 2008 4:47 AM

CPallini31-Jul-08 21:26

31-Jul-08 21:26

1. Please use code block button to surround code snippets with <pre> tags.
2. Why do you need to initialise COM library?
3. Why do you load the DLL and unload it inside your function body (overhead)?
Smile | :)

Rahul Vaishnav31-Jul-08 22:01

31-Jul-08 22:01

Thanks for reply

Actually this thing is some what new for me
so while doing some R&D to overcome this problem I have initialize Com library, I think it is not necessary ..

>3. Why do you load the DLL and unload it inside your function body (overhead)?

- At runtime Dynamically my dll names & path will also be varying thats why I am Loading & Unloading DLL inside my function only.

this bug I am facing when I am calling this function for same dll, second time. I think my dlls are not getting freed properly in first call of this function.

Please help me...

CPallini31-Jul-08 22:08

31-Jul-08 22:08

Could you please edit the OP and reformat your code as requested?
Is the DLL's code yours (Are you properly doing cleanup inside it?)?
Smile | :)

Rahul Vaishnav31-Jul-08 23:02

31-Jul-08 23:02

thanks you for reply..

Code is reformatted please check..

the DLL's code is written by my team member,I need to check with him..
but it is working properly for ImageHandle which is passed by reference in this function. It is causing problem with ButtonText & ButtonContent only...

CPallini31-Jul-08 23:08

31-Jul-08 23:08

Rahul Vaishnav wrote:
Code is reformatted please check..

the DLL's code is written by my team member,I need to check with him..
but it is working properly for ImageHandle which is passed by reference in this function. It is causing problem with ButtonText & ButtonContent only...

Well, since the DLL's source code is available you may debug the whole thing.
Smile | :)

Rahul Vaishnav1-Aug-08 0:17

1-Aug-08 0:17

Ok I will debug it
Thank you very much for reply..

bye

Smile | :)

Re: FreeLibrary problem caused by different heaps of the dll and exe

David Crow1-Aug-08 3:35

David Crow

1-Aug-08 3:35

Rahul Vaishnav wrote:
((PROCHICON)ProcButtonHicon)(&ImageHandle);
ButtonText =((PROCCSTRNAME)ProcButtonName)();
ButtonContent =((PROCCSTRCONT)ProcButtonContent)("1");

This is a very odd way of calling functions. Why not:

ProcButtonHicon(&ImageHandle);
ButtonText = ProcButtonName();  
ButtonContent = ProcButtonContent("1");

Rahul Vaishnav wrote:
if(hLib)

Redundant check.

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

Hartwin Stuewe10-Aug-08 2:49

Hartwin Stuewe

10-Aug-08 2:49

I had a similar problem: Access violations caused by bad pointers after having freed a dll with FreeLibrary. Your problem sounds just the same.
The problem was, the dll and the exe each had its own copy of the c-runtime-library and each c-runtime-library had its own heap. Freeing the dll also freed its heap and all dynamically allocated memory.

To overcome this problem: Free memory where it had been allocated

Her is the link about the 'FreeLibrary problem' where i found the answer to the problem:

http://java.codeproject.com/Feature/SubtleBugs.aspx?fid=1647&msg=2660410

Re: FreeLibrary problem caused by different heaps of the dll and exe

Rahul Vaishnav24-Aug-08 18:14

Error specify the lpszIcon in the MSGBOXPARAM using ::LoadIcon

24-Aug-08 18:14

Thanks you for your reply..
I was on leave thats why I couldnt reply..?
I will go through this link..

Thanks you.

fantasy121531-Jul-08 20:15

fantasy1215

31-Jul-08 20:15

In the MSDN, it says below:
lpszIcon
Identifies an icon resource. This parameter can be either a null-terminated string or an integer resource identifier passed to the MAKEINTRESOURCE macro.
To load one of the standard system-defined icons, set the hInstance member to NULL and set lpszIcon to one of the values listed with the LoadIcon function.

This member is ignored if the dwStyle member does not specify the MB_USERICON flag.

        MSGBOXPARAMS msgparam = {0};
	msgparam.cbSize = sizeof(MSGBOXPARAMS);
	msgparam.hwndOwner = NULL;
	msgparam.lpszText = _T("text");
	msgparam.lpszCaption = _T("caption");
	msgparam.dwStyle = MB_USERICON | MB_OK;
	msgparam.hInstance = NULL;
	msgparam.lpszIcon = ::LoadIcon(NULL, IDI_WINLOGO); <font color="blue">I want to use as the MSDN says.Actually I know it will compile error.</font>
	::MessageBoxIndirect(&msgparam);
<pre>

Re: Error specify the lpszIcon in the MSGBOXPARAM using ::LoadIcon

Cedric Moonen31-Jul-08 20:43

Cedric Moonen

31-Jul-08 20:43

What is the problem ? What is your question in fact ?
Di you have a compilation error ? If yes, why don't you simply put the exact error message so we can try to help you ?

Cédric Moonen
Software developer

Charting control [v1.4]
OpenGL game tutorial in C++

Re: Error specify the lpszIcon in the MSGBOXPARAM using ::LoadIcon

fantasy121531-Jul-08 21:23

fantasy1215

31-Jul-08 21:23

//msgparam.lpszIcon = ::LoadIcon(NULL, IDI_WINLOGO);
msgparam.lpszIcon = MAKEINTRESOURCE(IDI_WINLOGO);

The MSDN has fooled me, or I misunderstand the MSDN words, I should just use MAKEINTRESOURCE, not using ::LoadIcon.

Re: Error specify the lpszIcon in the MSGBOXPARAM using ::LoadIcon [modified]

CPallini31-Jul-08 21:20