Unmanaged C++ DLL with STL causes crash

[Kurt Smith]

We are in the process of creating a managed C++ library to wrap some
existing unmanaged code. The unmanaged code makes use of the STL. We
are seeing NULL pointer exceptions whenever we construct our unmanaged
object. If we remove the dependency on STL in the unmanaged code the
crash goes away. Also, we can always instantiate the unmanged object
the first time but it fails on subsequent attempts. The managed code
is pretty simple. has anyone else seen this behavior?
// SimpleManaged.h

#pragma once

#include "./import/simpleunmanaged .h"
#pragma comment(lib, "./import/simpleunmanaged .lib")
public __gc class CSimpleManaged
{
private:
CSimpleUnmanage d __nogc* m_pSimpleUnmana ged;

public:
CSimpleManaged( void)
: m_pSimpleUnmana ged(new CSimpleUnmanage d())
{
}

~CSimpleManaged (void)
{
//System::Console ::WriteLine(S"~ CSimpleManaged" );
if(NULL != m_pSimpleUnmana ged)
{
delete m_pSimpleUnmana ged;
m_pSimpleUnmana ged = NULL;
}
}

int Sum(int p_iData)
{
int rc = m_pSimpleUnmana ged->Sum(p_iData) ;
return(rc);
}

System::String* Concat(System:: String* p_strData)
{
System::IntPtr ipStrData =
System::Runtime ::InteropServic es::Marshal::St ringToHGlobalUn i(p_strData);
wchar_t* pszData = static_cast<wch ar_t*>(ipStrDat a.ToPointer());

wchar_t* pszResult = m_pSimpleUnmana ged->Concat(pszData );
System::String* strResult = new System::String( pszResult);

System::Runtime ::InteropServic es::Marshal::Fr eeHGlobal(ipStr Data);

return(strResul t);
}
};

[Nadav]

Well, mixed mode DLLs are linked without an entry point so _DLLmainCRTStar tup is not being called and CRT is not being initialized so static variables are not set, it is possible that the STL classes used by you use some static variables, if those variables are not initialized you would probably get errors during runtime, a detailed explanation of how to resolve this problem could be fond at the following URL: http://msdn.microsoft.com/library/de...omixedmode.asp

--
Nadav
Sofin l.t.d.

"Kurt Smith" wrote:

We are in the process of creating a managed C++ library to wrap some
existing unmanaged code. The unmanaged code makes use of the STL. We
are seeing NULL pointer exceptions whenever we construct our unmanaged
object. If we remove the dependency on STL in the unmanaged code the
crash goes away. Also, we can always instantiate the unmanged object
the first time but it fails on subsequent attempts. The managed code
is pretty simple. has anyone else seen this behavior?
// SimpleManaged.h

#pragma once

#include "./import/simpleunmanaged .h"
#pragma comment(lib, "./import/simpleunmanaged .lib")
public __gc class CSimpleManaged
{
private:
CSimpleUnmanage d __nogc* m_pSimpleUnmana ged;

public:
CSimpleManaged( void)
: m_pSimpleUnmana ged(new CSimpleUnmanage d())
{
}

~CSimpleManaged (void)
{
//System::Console ::WriteLine(S"~ CSimpleManaged" );
if(NULL != m_pSimpleUnmana ged)
{
delete m_pSimpleUnmana ged;
m_pSimpleUnmana ged = NULL;
}
}

int Sum(int p_iData)
{
int rc = m_pSimpleUnmana ged->Sum(p_iData) ;
return(rc);
}

System::String* Concat(System:: String* p_strData)
{
System::IntPtr ipStrData =
System::Runtime ::InteropServic es::Marshal::St ringToHGlobalUn i(p_strData);
wchar_t* pszData = static_cast<wch ar_t*>(ipStrDat a.ToPointer());

wchar_t* pszResult = m_pSimpleUnmana ged->Concat(pszData );
System::String* strResult = new System::String( pszResult);

System::Runtime ::InteropServic es::Marshal::Fr eeHGlobal(ipStr Data);

return(strResul t);
}
};