Debugging noob..

Is there a way to find memory leaks and other memory related issues using debug?

Like special software that can detect what vars don't get deleted or if a memmove is used on a non-allocated memory area?

It's a DLL by the way, unmanaged (duh!).

I tried using the built in debugger in VS but it doesn't seem to set the path for the binary file used to execute the *.dll so it crashes due to that alone.

Hey Manip

Do you own the dll source and can rebuild etc. If so, then maybe the easiest way is to rebuild with the appropriate crt debug switches on. If this is a vc built dll then you can follow the guidelines at

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vsdebug/html/vxconenablingmemoryleakdetection.asp


Other than that there are resource kit tools such as vadump and memsnap that will show you that leaks are occuring - pinpointing the actual variables may be more tricky.

memsnap info can be found here...
http://www.microsoft.com/resources/documentation/WindowsServ/2003/all/techref/en-us/Default.asp?url=/Resources/Documentation/windowsserv/2003/all/techref/en-us/memsnap.asp


things like memmove to an unallocated area should throw access violations and be easyish to detect. memmoves to incorrect but owned areas of memory are more tricky obviously...

Thanks for your suggestions, it looks like I can't try any of them, why? Well the program that is using my DLL doesn't like debug builds:



This is when the software in question is running in 'debug' mode by the way.. Software design at its best, I'm sure..

i hope your intentions are honourable in this manip

ah cool....

well you shouldn't need to attach a debugger. Rebuild your dll with the crt debug checking flags on and run a debug viewer. It should spew its output so that dbgview from www.sysinternals.com ( for example ) will show it up.

Get it to report leaks on exit and they'll probably show up.

memsnap and vadump dont need a debugger attached either so you might have some luck with them also.

oh...sorry, i'm not reading your mail correctly. That is a pain like you say - the half life server exe won't accept debug builds. hmmm....you could maybe ping the valve guys as if this is a legit server extension they maybe have a config for it?

Not sure what they are using to detect debug builds. maybe you can enable heap checking witrhout triggering the logic? unsure about this though...

memsnap and vadump will still work against release builds i believe and should be ok as they are external. you could do a release build with pdbs which would give you good symbols etc.

i'm assuming this is VC++ throughout so may be way off if this is gcc or some such btw.

I'm trying to use an unmanaged VC++ 6.0 DLL, but it's not my source, so I can't re-write it. I think it's a memory issue I'm having, but not sure how to debug.
You can check out my blog for more info.

It isn't cheap, but you can use Boundschecker/devpartner to look for leaks.  It will find them even in non-debug versions, but it will have very little useful info about who allocated them.  One method I've used is to look at the memory size of the allocated chunks and then try and determine when a chunk of that size was allocated.

Hope this helps.

I figured out how to get it to accept debug builds (there is an undocumented switch) ... I tried the Enabling Memory Leak Detection tutorial bit, which compiles fine .. only thing is when I'm running the app with the debugger attached and I execute the function to call _CrtDumpMemoryLeaks(); it simply does nothing.. nothing appears in the output window (other than the normal).

Hi manip.

Does a really simple program like the following show leaks ok for you?

#include <crtdbg.h>

int main()
{
   {
      int * x = new int;
   }
   _CrtDumpMemoryLeaks();
   return 0;
}

do external debug viewers show nothing also. sometimes they are better. i like dbgview from www.sysinternals.com for example.

One other thing to make sure is that you #included crtdebug early on in the process ( before your other headers )...

That example works fine for me.

When I do:

int * x = new int;

_CrtDumpMemoryLeaks();

In the main project, it prints nothing.

make sure you contain the x = new in another pair of braces so it goes out of scope b4 you do the _crtDumpxxx call. Might not report as a leak otherwise?

Also...make sure its just not the debugger being weird. if you do OutputDebugString("hello") in ur main project does it show up in the debugger ok?