C / C++ / MFC

6-May-08 20:53

In my project i am using FormatMessage API which is returning the LPTSTR buffer pointer lpMsgBuf, if i use
CComBstr Message(lpMsgBuf); to copy the lpMsgBuf to BSTR.
But this conversion shows memory leak. I am using LocalFree(lpMsgBuf); to release the lpMsgBuf. I am using USES_CONVERSION macro also.

Is there anyway to resolve this? or what is the correct way to convert LPTSTR to BSTR?

Thanks in advance.

Regards,
Bala

Rajkumar R6-May-08 21:11

6-May-08 21:11

May be posting the code snippet helps,

one possible leak in using CComBSTR is
"Passing the address of an initialized CComBSTR to a function as an [out] parameter causes a memory leak." from msdn.

ThatsAlok6-May-08 21:17

6-May-08 21:17

try _bstr_t

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
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CPallini6-May-08 21:37

CPallini

6-May-08 21:37

Probably posting your code will help.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

balakrishnan vinchu6-May-08 21:55

Re: How to convert LPTSTR to BSTR? [modified]

6-May-08 21:55

Here is my code:

//Functions used to report the Error
STDMETHODIMP CVBErrAgent::ReportError(IErrMsg *pErrMsg, SAFEARRAY** args)
{
//CCOmBstr variables for unformatted and formatted message
CComBSTR formatstring, message;
pErrMsg->get_ErrMsg(&formatstring);
//Function to format the message. This function uses FormatMessage API to get formatted string.
FormatMessageFromString(formatstring, args, &message);
pErrMsg->put_ErrMsg(message);
tlErrorBehavior behav;
pErrMsg->get_Behavior(&behav);
if(behav != tlErrorIgnore)
return CErrSvcClientImpl<cvberragent>::tl_Error(pErrMsg);
return S_FALSE;
}

HRESULT CVBErrAgent::FormatMessageFromString(BSTR formatstring, SAFEARRAY **args, BSTR *outputstring)
{
std::vector<ccomvariant> vecargs;
VARIANT HUGEP * pvar;
long lbound, ubound, elcount;

//Codes to read SAFEARRAY and creates the argsarray vector, this will be passed to FormatMessage API.
if (FAILED (SafeArrayGetLBound(*args, 1, &lbound)) ||
FAILED (SafeArrayGetUBound(*args, 1, &ubound)))
return E_INVALIDARG;
elcount = ubound - lbound + 1;
if(elcount == 1)
{
SafeArrayAccessData(*args, (void HUGEP **)&pvar);

//If the SAFEARRAY consists of a single VARIANT that is of type VT_ARRAY then
//We want to call SafeArrayToVector using the embedded array.
if(pvar[0].vt & VT_ARRAY)
{
SafeArrayToVector(pvar->parray, vecargs);
}
else
SafeArrayToVector(*args, vecargs);
SafeArrayUnaccessData(*args);
}
else
SafeArrayToVector(*args, vecargs);
std::vector<variant>::iterator it;
int count = vecargs.size();
vector<pvoid> argsarray(count);
USES_CONVERSION;

for(it = vecargs.begin(), count = 0; it != vecargs.end(); it++, count++)
{
if((*it).vt & VT_BSTR)
{
if((*it).vt & VT_BYREF)
argsarray[count] = reinterpret_cast<void*>(OLE2T(*(*it).pbstrVal));
else
argsarray[count] = reinterpret_cast<void*>(OLE2T((*it).bstrVal));
}
else if((*it).vt & VT_I4 || (*it).vt & VT_I2)
{
if((*it).vt & VT_BYREF)
argsarray[count] = reinterpret_cast<void*>(*(*it).plVal);
else
argsarray[count] = reinterpret_cast<void*>((*it).lVal);
}
}

LPTSTR lpMsgBuf;
DWORD messageflags = FORMAT_MESSAGE_FROM_STRING | FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_ARGUMENT_ARRAY ;
DWORD retval;
//Format the message from the format string.
retval = FormatMessage(
messageflags,
OLE2T(formatstring),
NULL,
LANG_SYSTEM_DEFAULT,
(LPTSTR) &lpMsgBuf,
0,
(va_list*)&argsarray[0]
);
if (!retval)
return MAKE_HRESULT(SEVERITY_ERROR, FACILITY_WIN32, GetLastError());
CComBSTR message(lpMsgBuf); // Here is the leak... Why the memory allocated by this CComBSTR is not released? Atleast the when the caller CVBErrAgent::ReportError() function goes out of scope then it should be released. Am i correct? since we detached the CCOmBSTR to outputstring.
*outputstring = message.Detach();
LocalFree(lpMsgBuf);

return S_OK;
}

Where i did wrong? How CComBSTR message(lpMsgBuf); is leaking? Confused | :confused:

Regards,
Bala

CPallini6-May-08 22:08

CPallini

6-May-08 22:08

In your FormatMessage call

balakrishnan vinchu wrote:
retval = FormatMessage(
messageflags,
OLE2T(formatstring),
NULL,
LANG_SYSTEM_DEFAULT,
(LPTSTR) &lpMsgBuf,
0,
(va_list*)&argsarray[0]
);

The line

(LPTSTR) &lpMsgBuf,

is wrong. It should be simply

lpMsgBuf,

Forget it.

Smile | :)

modified on Wednesday, May 7, 2008 5:40 AM

balakrishnan vinchu6-May-08 23:04

6-May-08 23:04

I changed my code as you explained in previous mail.

LPTSTR lpMsgBuf = NULL;
DWORD messageflags = FORMAT_MESSAGE_FROM_STRING | FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_ARGUMENT_ARRAY ;
DWORD retval;
//Format the message from the format string.
retval = FormatMessage(
messageflags,
OLE2T(formatstring),
NULL,
LANG_SYSTEM_DEFAULT,
lpMsgBuf, // Suggested to pass simply lpMsgBug
0,
(va_list*)&argsarray[0]
);
if (!retval)
return MAKE_HRESULT(SEVERITY_ERROR, FACILITY_WIN32, GetLastError());

CComBSTR message(lpMsgBuf);
*outputstring = message.Detach();
LocalFree(lpMsgBuf);

Now i am not getting the Formatted message, since retval returned from FormatMessgae API is zero (i.e 0), Because of this CComBSTR message didn't created. Also if i wont initialize lpMsgBuf = NULL, then functions just gives exception.

Give me some suggestion.
Thanks

Regards,
Bala

Mukesh Kumar6-May-08 23:13

Mukesh Kumar

6-May-08 23:13

Once try this
initialize lpMsgBuf as:
LPVOID lpMsgBuf;
and inside FormatMessage write lpMsgBuf as:

(LPTSTR) &lpMsgBuf,<br />

Mukesh Kumar
Software Engineer

balakrishnan vinchu6-May-08 23:31

6-May-08 23:31

Is this the right way?

LPVOID lpMsgBuf;
DWORD messageflags = FORMAT_MESSAGE_FROM_STRING | FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_ARGUMENT_ARRAY ;
DWORD retval;
//Format the message from the format string.
retval = FormatMessage(
messageflags,
OLE2T(formatstring),
NULL,
LANG_SYSTEM_DEFAULT,
(LPTSTR) &lpMsgBuf,
0,
(va_list*)&argsarray[0]
);
if (!retval)
return MAKE_HRESULT(SEVERITY_ERROR, FACILITY_WIN32, GetLastError());

CComBSTR message;
message = T2OLE(LPTSTR(lpMsgBuf));
message.CopyTo(outputstring);

I modified LPTSTR lpMsgBuf; to LPVOID lpMsgBuf;
And converted LPTSTR to LPOLESTR.

Am i doing correct here? Smile | :)

Regards,
Bala

Mukesh Kumar6-May-08 23:37

Mukesh Kumar

6-May-08 23:37

Is this working correctly now?
Smile | :)

Mukesh Kumar
Software Engineer

CPallini6-May-08 23:33

CPallini

6-May-08 23:33

You're right (and I was wrong...). Whenever you use FORMAT_MESSAGE_ALLOCATE_BUFFER you have to pass the address of the variable, hence your code was correct.
Smile | :)

Rajkumar R6-May-08 23:16

6-May-08 23:16

balakrishnan vinchu wrote:
*outputstring = message.Detach();

you already taken the ownership of the BSTR, created and associated with the CComBSTR, by Detach method; hence CComBSTR is not expected to release the BSTR. If you are expecting so then you are not supposed to return that buffer as out parameter (outputstring). this outputstring is not released and i think, so the tool you used to detect memory leak points to the creator of it, CComBSTR message(lpMsgBuf);.

balakrishnan vinchu6-May-08 23:34

6-May-08 23:34

Regards,
Bala

Rajkumar R6-May-08 23:39

logging information and save as excel, How? [modified]

6-May-08 23:39

the question is not about "message" variable how you clean up "outputstring" variable.

general_era6-May-08 20:37

general_era

6-May-08 20:37

I wanna make a session logger program for different users working with my program(create a list buttons they click), this should be saved somewhere and later, it must be possible to read this info and create an excel report file from it.
How can I do it?

modified on Wednesday, May 7, 2008 2:49 AM

ThatsAlok6-May-08 21:19

6-May-08 21:19

Yes it is possible, you need to add Excel com object in your program!

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You/codeProject$$>

ThatsAlok6-May-08 21:21

6-May-08 21:21

try this canned search result as your programming input!

http://www.codeproject.com/info/search.aspx?artkw=excel[^]

cheers,
Alok Gupta
VC Forum Q&A :- I/IV
Support CRY- Child Relief and You/codeProject$$>

general_era6-May-08 21:48

general_era

6-May-08 21:48

there are 2 problems! The big problem is the first one, I don't have any idea how they log events and save them!

ThatsAlok7-May-08 5:01

7-May-08 5:01

look for Log class!

Game screenshot problem

redclover6-May-08 20:00

redclover

6-May-08 20:00

Hi,

I'm looking for a way to take a screen shot of a game from another process. I can get a screen shot of any normal application but the game uses DirectX and i have no idea how to do that Confused | :confused:

. I searched the internet for a solution but i couldn't find any clue. All my attempts resulted in a black screen taken as screen shot which is normal due to that fact that the game doesn't render its images on screen but directly to the graphic card memory.
Any help regarding my problem is be appreciated.

Thanks

dehseth6-May-08 20:08

dehseth

6-May-08 20:08

You can use
1. to hook DirectX
2. get address of graphics card and read bitmap in it

redclover7-May-08 0:48

redclover

7-May-08 0:48

Interesting, do you know a resource about how to hook to directx and gain access to its surface buffer?

Rajkumar R7-May-08 0:23

7-May-08 0:23

Have you tried printscreen when the game is running if so it would be possible in external application i think. probably you might have choosen wrong window handle to capture when in fullscreen. Have you tried to run the game in windowed mode.

Some Games have inbuilt feature for screen capture check that too.