LabWindows/CVI 2013 SP2 crashes when I call a VB dll dynamically

[marcshan]

A customer using LabWindows/CVI 2013 to call a VB dll, it can call the function in the dll successfully, but leads the LabWindows/CVI Crashing when leaving the CVI.

 The CVI will crash after finish the last line of code. If I remove the 6th line "#define Test", the code runs ok since it will not call the function in dll. If I recover the 6th line, the code will get Error as below

The code is shown below.

#include <stdio.h>
#include <windows.h>
#include <ansi_c.h>
#include <cvirte.h>

#define TEST
 
typedef struct {
 unsigned int size; //0+4
 unsigned short vid; //4+2
 unsigned short pid; //6+2
 unsigned int friendlyNameSize; //8+4
 unsigned char friendlyName[512]; //12+512
 unsigned int serialNumberSize; //524+4
 unsigned char serialNumber[512]; //528+512
 unsigned int locked; //1040+4
 unsigned int usbPrintPathSize; //1044+4
 unsigned char usbPrintPath[256]; //1048+256
 unsigned int usbStackPathSize; //1304+4
 unsigned char usbStackPath[256]; //1308+256 
 unsigned int usbStackAddress; //1564+4 = 1568
}ZUsbPrinterInformation;


typedef unsigned int (* DLLFunction)(const unsigned int includeLocked,
 unsigned int *deviceCount,
 signed int *changedSinceLastEnumeration);

int main()
{
 HINSTANCE ZusbLib = NULL;
 const unsigned int index=1;
 int result;
 DLLFunction DLLFAddress;
 
 unsigned int *Count;
 signed int *Changed;
 
 ZusbLib=LoadLibrary("ZUSB.DLL");

 if (ZusbLib == NULL) 
 {
 printf(" ** Failed to invoke Dll ** \n");
 getchar();
 return -1;
 }
 
 printf(" ** Success to invoke Dll ZusbLibx=%x ** \n",ZusbLib); 
 DLLFAddress = (DLLFunction)GetProcAddress(ZusbLib, "ZUsbEnumerateUSBPrinters");

 if (DLLFAddress == NULL) 
 {
 FreeLibrary(ZusbLib);
 printf(" ** ZUsbEnumerateUSBPrinters is not existed ** \n");
 getchar();
 return -1;
 }
 
 printf(" ** Success to excute ZUsbEnumerateUSBPrinters ** \n");
#ifdef TEST
 result=(DLLFAddress) (0,&Count,&Changed);
 
 printf(" USB countu=%u\n",Count);
 printf(" Changed count=%d\n",Changed); 
#endif 
 if(ZusbLib)
 {
 FreeLibrary(ZusbLib);
 ZusbLib=NULL;
 printf("Free ZusbLib");
 }
 printf("End%d\n",index);
 getchar();

}

[carlox]

Hi

You've declared two pointers to integers:

 unsigned int *Count;
 signed int *Changed; 

 when you should have simply declared the two integers:

 unsigned int Count;
 signed int Changed; 

 They will be converted to pointers by the "address of" operator "&"  when you actually call the function:

 result= DLLFAddress (0, &Count, &Changed);

 With this correction your code does not crash anymore.