Re: c4_Bytes destructor causes memory deallocation failure

Hi,

I have a followup to the c4_Bytes problem.

It seems that the destructor releases the wrong
memory.
In the debug build it gives an assertion at the
deallocation, but in a release build it gives no
error.
This just makes it worse though, since it may later
try to use the released memory, causing a crash.

Check this example program which on my machine fails
after the fourth iteration:

#include "mk4.h"
#include <string>
#include <iostream>
using namespace std;

void main() {
	c4_Storage storage("datafile.kit", true);
	c4_View v = storage.GetAs("v[b:B]");

	v.Add(c4_Row());
	c4_BytesProp pBytes("b");

	string teststring("Hello, this is a test!"); //
len=22
	c4_Bytes textbytes(teststring.data(),
teststring.length());

	for (int i=0;i < 100;++i) {
		cout << i << endl;
		c4_Bytes newbytes = pBytes(v[0]).Access(0, 17);
		pBytes(v[0]).Modify(textbytes, 0, textbytes.Size());
	}
}

I am using metakit 2.4.9.3 with the modify patch on
windows.

Best Regards,
  Arto Stimms


--- [email protected] wrote:
> I have another problem with c4_Bytes. It seems that
> the destructor in some cases deletes the wrong
> memory.
> 
> The following code works as release build, but as 
> debug build it fails in _CrtIsValidHeapPointer.
> 
> Curiously enough it works correctly as long as the
> length is <= 16?
> 
> #include "mk4.h"
> #include <string>
> #include <iostream>
> using namespace std;
> 
> void main() {
> 	c4_Storage storage("datafile.kit", true);
> 	c4_View v = storage.GetAs("v[b:B]");
> 
> 	v.Add(c4_Row());
> 	c4_BytesProp pBytes("b");
> 
> 	string teststring("Hello, this is a test!"); //
> len=22
> 	c4_Bytes textbytes(teststring.data(),
> teststring.length());
> 
> 	pBytes(v[0]).Modify(textbytes, 0,
> textbytes.Size());
> 
> 	// Works with up-to len=16
> 	c4_Bytes newbytes = pBytes(v[0]).Access(0, 16);
> 	//cout << string((const char *)newbytes.Contents(),
> newbytes.Size()) << endl;
> 
> 	newbytes = pBytes(v[0]).Access(0, 17);
> 	//cout << string((const char *)newbytes.Contents(),
> newbytes.Size()) << endl;
> }


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