CVI debugger reports dynamic memory corrupt

Question

Hi,
There is a problem most likely between debugger and CVIXML group of functions.
When I operate even one of CVI examples involving population of tree control out of XML the following function corrupting heap:
                CVIXMLGetElementValue (data,result);
It is important to recognize that even NI example "XMLTree" do not work correctly under debugger (breakpoints and single step).
However if release mode is selected then apparently no problems are noticeable.
Obviously I selected different debugger modes. But no cure found.
///// failing example
        char * result;      
        CVIXMLElement data = 0;
        assert(!CVIXMLGetChildElementByTag (column, "Data", &data));
        if (data) {
            int len;
            char * bs;
            CVIXMLGetElementValueLength (data, &len);
            if(len) {
                result=malloc(len+1);
                bs=malloc(1);
                free(bs);
                CVIXMLGetElementValue (data,result);
                bs=malloc(1);
                free(bs);                                 ///////////////// problem right here
                RemoveSurroundingWhiteSpace(result);
                bs=malloc(1);
                free(bs);
      printf("row=%i, column=%i >>>%s<<<\n",j,i,result);   
      free(result);      
        } else (result=""; //empty string (but printable ;-)
      CVIXMLDiscardElement(data);
/// But if variables are coming from stack then no problem occured.
        char result[100];      
        CVIXMLElement data = 0;
        assert(!CVIXMLGetChildElementByTag (column, "Data", &data));
        if (data) {
            int len;
            char * bs;
            CVIXMLGetElementValueLength (data, &len);
            if(len) {
                bs=malloc(1);
                free(bs);
                CVIXMLGetElementValue (data,result);
                bs=malloc(1);
                free(bs);
                RemoveSurroundingWhiteSpace(result);
                bs=malloc(1);
                free(bs);
        } else result[0]=0; //empty string (but printable ;-)
      printf("row=%i, column=%i >>>%s<<<\n",j,i,result);   
      CVIXMLDiscardElement(data);
Is there any remedy now other than giving up on debugger???
I am using brand new CVI 8.0.1 version and cannot use static data holders..
Otta

Answer 1

Mikie,
You should never attempt to write past the end of an array when programming in C. In fact you should be getting a fatal run-time error when you attempt to write past the end of an array. This is a feature of CVI that blocks the user from performing such actions which ANSI C does not prevent. What does your code look like that does this? Here is the code I have and as you can see in the comments, I receive the error before I get to freeing the memory.
#include <ansi_c.h>
int main (int argc, char *argv[])
int *myArray;
myArray = malloc(2*sizeof(int));
*(myArray) = 1;
*(myArray+1) = 2;
*(myArray+2) = 3; //FATAL RUN_TIME ERROR: Dereference of out-of-bounds pointer
free (myArray);
return 0;
National Instruments
Product Support Engineer