Invalid Handle (Using the Application Verifier)

Question

I have a problem I just can't find information for. The following code is causing the issue (I have left out a lot of code for brevity, but as I will explain, this code seems to work fine):

mHDC = GetDC(mHWnd);
int format = ChoosePixelFormat(mHDC, &pixelFormat);
SetPixelFormat(mHDC, format, &pixelFormat);
mHGLRC = wglCreateContext(mHDC);
wglMakeCurrent(mHDC, mHGLRC);

mHWnd is obtained through CreateWindow()

const HINSTANCE hInstance(static_cast<HINSTANCE>(::GetModuleHandle(NULL)));

mHWnd = CreateWindow(wndClass.lpszClassName, L"Test Application", style, CW_USEDEFAULT, CW_USEDEFAULT, clientRect.right, clientRect.bottom, NULL, NULL, hInstance, NULL);

ChoosePixelFormat() is causing an invalid handle first-chance exception in the debugger when I am using the Application Verifier with only Handles and Cuzz enabled. These two together cause the exception to trigger. Without both of these enabled (even if I just do one or the other), the exception isn't thrown and everything works okay. When I run the application without attaching to the debugger, the application crashes instead.

Even though the exception is raised, once I hit wglMakeCurrent() (by continuing debugging after and ignoring the exception), all the variables seem to end up with valid values anyway:

mHWnd == 0x1a1064e
mHDC == 0x440119c0
format == 7
mHGLRC == 0x10000

The stack trace looks like this:

ntdll.dll!00000000772012f7()
vfbasics.dll!000007feedaa81b4()
KernelBase.dll!000007fefd1610dc()
vfbasics.dll!000007feedaa7ce9()
vfcuzz.dll!000007fee5075179()
nvoglv64.dll!000000006979b732()
vfbasics.dll!000007feedaac1d5()
kernel32.dll!0000000076fa652d()
ntdll.dll!00000000771dc521()

And the active thread is a vfcuzz.dll thread, which is obviously allowing Cuzz to do it's business. vfbasics.dll in the stack trace is where the handle checker is, and as I said, only the handle checker is enabled.

For completion sake, here is the actual exception message:

First-chance exception at 0x00000000772012F7 (ntdll.dll) in Tests.exe: 0xC0000008: An invalid handle was specified.

I am assuming it isn't a bug in the Application Verifier that is causing it to throw an exception that shouldn't exist and crashing the program. I am just confused as to why it is throwing the exception when clearly I am getting valid values back from the function calls. I don't really want to ignore it until I understand what is going on.

Answer 1

It doesn't look like a problem with your code. The only handle ChoosePixelFormat takes is an HDC and the one you're giving it is presumably valid (although in the code you're showing there's no checking that GetDC succeeded, I assume you just left that out for brevity).

A first-chance exception isn't necessarily a problem. It simply means an exception occurred, and this is the first chance to handle it. My guess is the exception is most likely happening within the ChoosePixelFormat function itself (or within a function that ChoosePixelFormat calls) and being handled there - it's only because you are debugging that you actually find out about it. In every day usage the exception would be handled quietly and you'd never even know it had happened.