Access Violation Problem

My only thought, is your program multi-threaded? You might have orphaned a thread and it decided to run amok.

In most cases this happens because you reserve memory and forget to free it.

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GA

I''ve had 0xc0000005: Access Violation a couple of time before when I have run a program that tries to access the contence of an object pointer.

I''m sorry if this is no help.

0xC0000005 Access violation is usually when the program is trying to access the contents of a NULL pointer.
>>>
and I don't think there's a problem with my destroy causing this, because then the AV would occur when I called Destroy...
>>>
Not necessarily. Objects are automatically deleted when they go out of scope.


ZoomBoy
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Edited by - ZoomBoy on 4/18/00 6:35:19 AM

The debugger tells me that I get about 3 First Chance exceptions before my program even runs! I have no idea how to find out more about this, but since it doesn''t seem to affect my program''s execution, I''m doing nothing for now.

Qoy: Your access violation is probably the result of an invalid pointer being accessed in a class destructor. I''ve also encountered this problem when I forgot to release a DirectDraw surface. Without being able to view your code, all we can do here is speculate.

Kylotan: If they occur before WinMain (or main) is called, then they are probably occuring in the constructor of a global variable. You might want to look into that. To prevent things like this, I always use pointers when I need globals and then I dynamically allocate them when the program starts.


Josh
http://www.jh-software.com

OK, I seem to have found the origin of the problem.. First of all, as it turns out, the AV wasn''t being thrown after WinMain returned, it was just displaying it on the debug window after.. It turns out it''s being thrown when I release the DirectDraw object (very weird).

Here''s the code:

void ShutdownDirectDraw()
{
	if(backBuffer)
		backBuffer->Release();
	if(primaryBuffer)
		primaryBuffer->Release();
	if(dDraw)
		dDraw->Release();
} // end ShutdownDirectDraw
 

The AV is being shown on the line dDraw->Release();

dDraw is an LPDIRECTDRAW, and primaryBuffer and backBuffer are LPDIRECTDRAWSURFACEs.

Is there any other code I need to show for this? I can''t think of what could be the problem...

OK, some more information..

I turned DDraw debugging up to the HIGHEST debug level I could, and this is what came out around the Access Violation:

DDraw:INFO:Resetting primary surface
DDraw:DeleteOneAttachment: 840ca664,840cb71c
DDraw:Leaving AddRef early to prevent recursion
DDraw:DeleteOneLink: 840cb71c,840ca664
DDraw:DeleteOneLink: 840ca664,840cb71c
DDraw:Leaving Release early to prevent recursion
DDraw:Unsubclassing window 000000c0
DDraw: ProcessSurfaceCleanup
DDraw:Leaving ProcessSurfaceCleanup
DDraw: ProcessPaletteCleanup, ppal=00000000
DDraw: ProcessClipperCleanup
DDraw:Not cleaning up clippers not owned by a driver object
DDraw: ProcessVideoPortCleanup
DDraw:Leaving ProcessVideoPortCleanup
DDraw: ProcessMotionCompCleanup
DDraw:Leaving ProcessMotionCompCleanup
DDraw:In RestoreDisplayMode
DDraw:Redrawing all windows
DDraw:DoneExclusiveMode
DDraw:Enabling error mode, hotkeys
DDraw:FREEING DRIVER OBJECT
DDraw:Calling HEL DestroyDriver
DDraw:0 surfaces allocated - 0 bytes total
DDraw:*********** DDHEL TIMING INFO ************
DDraw:******************************************
DDraw:Calling DestroyDriver
DDraw:Heap aliases reference count is zero: discarding aliases
DDraw:Driver is now FREE
First-chance exception in Invasion2.exe (KERNEL32.DLL): 0xC0000005: Access Violation.
-WinMain: Returning...
DDraw:====> ENTER: DLLMAIN(bab004c7): Process Detach fffa8269, tid=fffa52b5
DDraw:====> EXIT: DLLMAIN(bab004c7): Process Detach fffa8269


I hope that wasn't too much Anyway, just thought that might be of some help..

Thanks!

Edited by - Qoy on 4/18/00 3:54:44 PM

Hmmm, this is a longshot, but it''s possible that if you didn''t initialize your buffers to NULL when you started they might not be NULL when you check them if you never did anything with them and it would try to release something that isn''t there.
Also I''ve gotten into trouble doing if (backbuffer) rather than if (backbuffer != NULL) type things though not with DDraw, you might want to do the second type just in case.

-fel

If the primary is a complex chain, then you shouldn''t be releasing the backbuffer unless you added it to the flipping chain yourself. Otherwise you just want to release the primary, which will take care of all the attached surfaces for you (although I''ve never seen this actually crash a system).

And you don''t have any palettes or anything else that your not releasing? If not, I''d say you need to invoke the classic method of commenting stuff out until the ddraw object closes with no problems, and then add stuff back in to see what causes the problem.

Rock

Well, I got the backbuffer with primaryBuffer->GetAttachedSurface...

Anyway, I tried if (backBuffer != NULL) and I also tried not releasing the backbuffer explicitely, but the AV is still coming up. I'm starting to think I should just ignore it...

I guess I could try just commenting out stuff, but everything's so dependant on everything else with DDraw, that I wouldn't know where to start.

I'm running in a 16 bit mode, so I don't have any pallettes, and I don't have any clippers or anything, the only other DirectDraw object I have at all is a DDSURFACEDESC I think, and I used a DDPIXELFORMAT and DDSCAPS structs when I was initializing, but I don't think those should do anything...

Edited by - Qoy on 4/18/00 10:18:04 PM

Nope, it''s not that easy I guess I''m using VC++ 6.

How would I go about getting that massive amount of debug information? As far as I know, I have the debug sliders set to full in the DirectX control panel, but I still don''t get much more than the 3 first-chance exceptions info.

And as for errors in constructors of globals... I never have more than 3 or 4 globals, and they don''t have anything in them which could really go wrong... just stuff like someMember = someValue... not even memory allocation. I''m hoping that being able to see more debug info may shed some light on the situation.

I''ve had the same problem countless times. I have NO idea how to fix it! If anybody posts it up or knows what ''kind'' of error it is, PLEASE, for the love of god, mail me!

"Remember, I'm the monkey, and you're the cheese grater. So no messing around."
-Grand Theft Auto, London

"It's not whether I win or lose, as long as I piss you off"
-Morrigan, Super Puzzle Fighter II Turbo

The only thing that I can think of is this: did you declare dDraw as LPDIRECTDRAW dDraw or LPDIRECTDRAW *dDraw? if it''s the first case, change it to LPDIRECTDRAW *dDraw( don''t ask me why though, when I had the same problem, that''s what I did and it worked... )



Cyberdrek
Headhunter Soft
DLC Multimedia
Two Guys Soft

I don''t have much more to offer ...

Its definitely a problem, I know that sometimes in the release build the access violation won''t show up, but its still a symptom of a problem somewhere...it can just be a real pain to track down.

Follow fels advice and check all of your pointers:

if ( 0L != backbuffer ) ...


Once you have released your interfaces, set their pointers to 0L (NULL). Be sure that ShutdownDirectDraw() isn''t being called more than once..

Good luck!

I''m getting the same Access Violation too, only in GDI32.DLL. Sometimes it appears, and sometimes it doesn''t. If DirectDraw was in the middle of a Blt or Flip or something when the program shuts down, could that cause an Access Violation like this? If so, how do you wait for DirectDraw to finish its current operation before shutting it down?

*Sparkle*

I''ve never got KERNEL32.DLL AV. I used to get GDI32.DLL AV quite often last time. It just happen... and I don''t know where it came from.

Try commenting out your code.... comment out all DirectX code, leaving only Windows code, then slowly add them back.

You said that the pointer is LPDIRECTDRAW. Are you sure that''s the one you''re using? That is DDraw3, or some old version. Make sure your pointers match whatever interfaces you''re really using. If you get a IDirectDraw4 interface, you have to save it off into a LPDIRECTDRAW4 pointer.

Rock