getting unhandled exception error -- Access violation 
Author Message
 getting unhandled exception error -- Access violation

I have written a DLL in C++ that is accessed through a VB basic
program.  The DLL calls another C++ dll that is passed a typedef
structure,  if i set a certain typedef structure variable the program
crashes with the following error: "getting unhandled exception error --
Access violation"
,  also it nevers calls the callback function.  I am new at this
and need some help.  Below is a copy of the code.

// tcn2gen.cpp : Defines the initialization routines for the DLL.
//

#include "stdafx.h"
#include "tcn2gen.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

#define TRUE 1
#define FALSE 0
#define DLLEXPORT  __declspec( dllexport )

/////////////////////////////////////////////////////////////////////////////

// CTcn2genApp

BEGIN_MESSAGE_MAP(CTcn2genApp, CWinApp)
 //{{AFX_MSG_MAP(CTcn2genApp)
  // NOTE - the ClassWizard will add and remove mapping macros here.
  //    DO NOT EDIT what you see in these blocks of generated code!
 //}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////

// CTcn2genApp construction

CTcn2genApp::CTcn2genApp()
{
 AfxMessageBox("Starting DLL");
 // TODO: add construction code here,
 // Place all significant initialization in InitInstance

Quote:
}

/////////////////////////////////////////////////////////////////////////////

// The one and only CTcn2genApp object

CTcn2genApp theApp;

int DLLEXPORT WINAPI ReturnPosValue(int *iValue)
{
 // AFX_MANAGE_STATE(AfxGetStaticModuleState());
 //AfxMessageBox("ReturnPosValue Entered");
 if (iValue > 0 ) {
  return (*iValue);
 }
 else ( iValue <= 0 ); {
 // AfxMessageBox("Invalid Number - less than Zero!");
  return (0);
 }

Quote:
}

// THIS IS THE FUNCTION THAT IS BEING CALLED FROM
VB------------------------

int DLLEXPORT WINAPI CallGenCri()
{
 // UpdateData();
 GENCRI_CONTROL_BLOCK *GCB = new GENCRI_CONTROL_BLOCK;

 /*GCB->wCallNo  = m_CallNo;
 GCB->lpszDBFPath = m_DataPath.GetBuffer(0);
 GCB->lpszUserID  = m_UserID.GetBuffer(0) ;
 GCB->lpszRCXFile = m_MBAFile.GetBuffer(0);
 GCB->pCallBackFunc = Fn ;
 GCB->FileNM   = m_FileNM.GetBuffer(0) ;
 GCB->BorrowerNo  = m_BorNo.GetBuffer(0) ;*/

 GCB->wCallNo  = 0;        // When i set this var. the program crashes
 GCB->lpszDBFPath = "c:\\genesis\\data\\";
 GCB->lpszUserID  = "John" ;
 GCB->lpszRCXFile = "";
 GCB->pCallBackFunc = Fn ;
 GCB->FileNM   = "00000190" ;
 GCB->BorrowerNo  = "01" ;
 GenCRI(GCB);

 return(GCB->wStatus);

Quote:
}

void CALLBACK EXPORT Fn(WORD Status,
       LPSTR lpszRefNo
       )
{
 AfxMessageBox("CallBack");
 if (Status)
 {
  //AfxGetMainWnd()->PostMessage(GENCRIFAILED, (WPARAM)Status,0L);
  AfxMessageBox("GenCRIOK : Return From GenCRI Successfully NO");

 }
 else
 {

  //AfxGetMainWnd()->PostMessage(GENCRIOK, (WPARAM)Status,0L);
  AfxMessageBox("GenCRIOK : Return From GenCRI Successfully");

 };

Quote:
};

LRESULT GenCRIOK(WPARAM WParam, LPARAM LParam)
{
  AfxMessageBox("GenCRIOK : Return From GenCRI Successfully");
  return 0 ;

Quote:
};

LRESULT GenCRIFailed(WPARAM WParam, LPARAM LParam)
{

  switch (WParam)
  {
  case INVALID_CALL_NO:
   AfxMessageBox("GenCRIFailed : Invalid Call No Passed to GenCRI.");
   break;
  case F1003_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : GenCRI Can Not Open Database !");
   break;
  case GENCRI_RECORD_NOT_FOUND:
   AfxMessageBox("Record Not Found");
   break;
  case GENCRI_ERR_CREATING_CRI_FILE:
   AfxMessageBox("GenCRIFailed :  .CRI File Can't Be Created.");
   break;
  case TL_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : TrakLoan.DBF Can't be Opened");
   break;
  case VOE_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : VOE.DBF Can't be Opened");
   break;
  case LIAB_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : LIAB.DBF Can't be Opened");
   break;
  case PROP_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : VOM.DBF Can't be Opened");
   break;
  case PROPID_NOT_FOUND:
   AfxMessageBox("GenCRIFailed : PropId Can't be Located in PROP.DBF");
   break;
  case RCX_FILE_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : Received File Can't Be Opened");
   break;
  case  MBNA_SIGNATURE_NOT_FOUND:
   AfxMessageBox("GenCRIFailed : Start of MBNA format data not found
!");
   break;
  case  REPORT_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : REPORT.DBF can not be opened !");
   break;
  case  ERORR_WRITTING_REPORT:
   AfxMessageBox("GenCRIFailed : Error while writing REPORT.DBF !");
   break;
  case  SYSNUM_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : SYSNUM.DBF not found !");
   break;
  case  REQUEST_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : REQUEST.DBF not found !");
   break;
  case  ERORR_WRITTING_REQUEST:
   AfxMessageBox("GenCRIFailed : Error while writing REQUEST.DBF !");
   break;
  case  ERROR_INITILIZING_REQUEST:
   AfxMessageBox("GenCRIFailed : Error while writing REQUEST.DBF !");
   break;
  case REFNO_NOT_IN_REQUEST:
   AfxMessageBox("GenCRIFailed : Reference number not found in
REQUEST.DBF !");
   break;
  case REFNO_NOT_IN_REPORT:
   AfxMessageBox("GenCRIFailed : Reference number not found in
REPORT.DBF !");
   break;
  case MASTER_OPEN_ERROR:
   AfxMessageBox("GenCRIFailed : Can not open MASTER.DBF !");
   break;
  case FILENM_NOT_FOUND_IN_F1003:
   AfxMessageBox("GenCRIFailed : Record not found in F1003.DBF !");
   break;
  case INVALID_USER_ID:
   AfxMessageBox("GenCRIFailed : Genesis UserId is Blank !");
   break;
  case RECORD_NOT_FOUND_IN_TL:
   AfxMessageBox("GenCRIFailed : Record not found in TrakLoan.DBF !");
   break;
  case BLANK_FILENM:
   AfxMessageBox("GenCRIFailed : Genesis Filenm is Blank !");
   break;
  case INVALID_BORNO:
   AfxMessageBox("GenCRIFailed : Genesis BorrowerNo is Blank !");
   break;
  case INVALID_RECNO:
   AfxMessageBox("GenCRIFailed : Internal Error : Invalid Record No !");

   break;
  case GENCRI_ABORTED:
   AfxMessageBox("GenCRIFailed : GENCRI Aborted !");
    break;
  case REPOSITORY_CODE_NOT_VALID :
      AfxMessageBox("GenCRIFailed : Repository Code Not Valid While
Importing Score Information !");
   break;
  case MEMORY_ALLOCATION_ERROR :
          AfxMessageBox("GenCRIFailed : Memory Allocation Error While
Importing Credit Report !");
   break;
  default:
   AfxMessageBox("GenCRIFailed : Unknown Error !");
   break;
  };
  return 0 ;

Quote:
};

header file following

// tcn2gen.h : main header file for the TCN2GEN DLL
//

#ifndef __AFXWIN_H__
 #error include 'stdafx.h' before including this file for PCH
#endif

#include "resource.h"  // main symbols

/////////////////////////////////////////////////////////////////////////////

// CTcn2genApp
// See tcn2gen.cpp for the implementation of this class
//
#define GENCRI_SUCCESS     0
#define INVALID_CALL_NO     1
#define F1003_OPEN_ERROR    2
#define GENCRI_RECORD_NOT_FOUND   3
#define GENCRI_ERR_CREATING_CRI_FILE 4
#define TL_OPEN_ERROR     5
#define VOE_OPEN_ERROR     7
#define LIAB_OPEN_ERROR     8  // Either LIAB or AUTO open Error
#define PROP_OPEN_ERROR     9  // Either PROP or VOM  open Error
#define PROPID_NOT_FOUND    10 // PropertyID in VOM can not be found in
PROP
#define RCX_FILE_OPEN_ERROR    11 // Error Openning the file received
from Credit Company
#define MBNA_SIGNATURE_NOT_FOUND  12 // Chr(12)+Chr(19) in RCX File not
Found
#define REPORT_OPEN_ERROR    13 // Error Openning REPORT.DBF
#define ERORR_WRITTING_REPORT   14 // Error while attempting to append a

record to REPORT.DBF
#define SYSNUM_OPEN_ERROR    15 // Error Openning SysNum
#define REQUEST_OPEN_ERROR    16 // Error Openning REQUEST.DBF
#define ERORR_WRITTING_REQUEST   17 // Error while attempting to append
a record to REQUEST.DBF
#define ERROR_INITILIZING_REQUEST  18 // Error in either Openning or
writing request.dbf
#define REFNO_NOT_IN_REQUEST   19 // Seek failed finding RefNo in
REQUEST.DBF
#define REFNO_NOT_IN_REPORT    20 // Seek failed finding RefNo in
REPORT.DBF
#define MASTER_OPEN_ERROR    21 //
#define FILENM_NOT_FOUND_IN_F1003  22 // The filenm extracted from
MASTER.DBF was not found in F1003.DBF
#define INVALID_USER_ID     23 // User Id is Blank or empty
#define RECORD_NOT_FOUND_IN_TL   24 // FileNM can not be found in TL
#define INVALID_RECNO     25 // Record No is zero
#define BLANK_FILENM     26 // F1003 or MASTER FileNM is Blank
#define GENCRI_ABORTED     27 // User Pressed ESC while in the browser
#define INVALID_BORNO     28 // Genesis BorNo is Blank
#define REPOSITORY_CODE_NOT_VALID       29 // When checking SC fields
repository code was not valid
#define MEMORY_ALLOCATION_ERROR      30 // Memory Allocation Error in
Function call 4 ONLY
#define CREDIT_REPORT_TOO_LARGE      31 // Credit Report File Is Bigger
than 1MB
#define ERROR_READING_CREDIT_REPORT     32 // Number of bytes read is
less than Credit File Size (ONLY in 4)

#define GENCRIOK    WM_USER+1
#define GENCRIFAILED  WM_USER+2

typedef struct _GENCRI_CONTROL_BLOCK {

    WORD       wCallNo;       //IN  Function Call No
        //    1 :
        //    2 :
        //    3 :
        //    4 :
        //    5 :
    LPSTR     lpszDBFPath;   //IN  Path to Genesis Databases
    LPSTR     lpszUserID;    //IN  Genesis User ID
    LPSTR     FileNM;        //IN  FileNM
    LPSTR     BorrowerNo;    //IN  Borrower/CoBorrower
    LPSTR     lpszRCXFile;   //IN  Received File Name (from Credit
Company)
 LPSTR     lpszCrdtRptFile; //IN  Received Credit Report
    LPSTR     lpszRefNo;     //OUT Reference Number
    WORD      wStatus;        //OUT Status of operation
 void (CALLBACK *pCallBackFunc)(WORD Status, LPSTR lpszRefNo);

Quote:
} GENCRI_CONTROL_BLOCK;

void CALLBACK /*AFX_EXPORT*/ Fn(WORD Status, LPSTR lpszRefNo);
extern void WINAPI GenCRI(GENCRI_CONTROL_BLOCK* GCB);

class CTcn2genApp : public CWinApp
{
public:
 CTcn2genApp();

// Overrides
 // ClassWizard generated virtual function overrides
 //{{AFX_VIRTUAL(CTcn2genApp)
 //}}AFX_VIRTUAL

 //{{AFX_MSG(CTcn2genApp)
  // NOTE - the ClassWizard will add and remove member functions here.
  //    DO NOT EDIT what you see in these blocks of generated code !
 //}}AFX_MSG
 DECLARE_MESSAGE_MAP()

Quote:
};

...

read more »



Sun, 18 Feb 2001 03:00:00 GMT  
 getting unhandled exception error -- Access violation
Shawn,

I think the problem may be in the line below the one you have flagged.  You
write

GCB->lpszDBFPath = "c:\\genesis\\data\\";

yet you do not appear to have allocated any memory for lpszDBFPath and nor
can you assign string variables in this manner.

Try something like the following:

    GCB->lpszDBFPath = new char[30];
    strcpy(GCB->lpszDBFPath, "c:\\genesis\\data\\");

and see whether things improve.  BTW the reason your earlier assignments
(e.g. GCB->lpszDBFPath = m_DataPath.GetBuffer(0)) look to work is that you
are passing them an already existing pointer and that is legitimate).

HTH

Peter

Quote:

>I have written a DLL in C++ that is accessed through a VB basic
>program

<snip>

Quote:
>// THIS IS THE FUNCTION THAT IS BEING CALLED FROM
>VB------------------------

>int DLLEXPORT WINAPI CallGenCri()
>{
> // UpdateData();
> GENCRI_CONTROL_BLOCK *GCB = new GENCRI_CONTROL_BLOCK;

> /*GCB->wCallNo  = m_CallNo;
> GCB->lpszDBFPath = m_DataPath.GetBuffer(0);
> GCB->lpszUserID  = m_UserID.GetBuffer(0) ;
> GCB->lpszRCXFile = m_MBAFile.GetBuffer(0);
> GCB->pCallBackFunc = Fn ;
> GCB->FileNM   = m_FileNM.GetBuffer(0) ;
> GCB->BorrowerNo  = m_BorNo.GetBuffer(0) ;*/

> GCB->wCallNo  = 0;        // When i set this var. the program crashes
> GCB->lpszDBFPath = "c:\\genesis\\data\\";

<snip>


Sun, 18 Feb 2001 03:00:00 GMT  
 
 [ 2 post ] 

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