Strange behaviour after querying a friendly device name

Question

Hi,
I have observed some very strange behaviour after querying the friendly name of an audio capturing device. This is my code:
#include "stdafx.h"
#include <mmdeviceapi.h>
#include <Functiondiscoverykeys_devpkey.h>
int main(int argc, char *argv[]) {
    HRESULT hr = CoInitializeEx(0, COINIT_APARTMENTTHREADED);
    if(FAILED(hr)) throw;
    IMMDeviceEnumerator *pIMMDeviceEnumerator = 0;
    hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), 0, CLSCTX_INPROC_SERVER, __uuidof(IMMDeviceEnumerator), (LPVOID *) &pIMMDeviceEnumerator);
    if(FAILED(hr)) throw;
    IMMDeviceCollection *pIDeviceCollection = 0;
    hr = pIMMDeviceEnumerator->EnumAudioEndpoints(eCapture, DEVICE_STATE_ACTIVE, &pIDeviceCollection);
    if(FAILED(hr)) throw;
    IMMDevice *pIMMDevice = 0;
    hr = pIDeviceCollection->Item(0, &pIMMDevice);
    if(FAILED(hr)) throw;
    IPropertyStore *pIPropertyStore = 0;
    hr = pIMMDevice->OpenPropertyStore(STGM_READ, &pIPropertyStore);
    if(FAILED(hr)) throw;
    PROPVARIANT propVariant;
    PropVariantInit(&propVariant);
    pIPropertyStore->GetValue(PKEY_Device_FriendlyName, &propVariant);
    PropVariantClear(&propVariant);
    pIPropertyStore->Release();
    pIMMDevice->Release();
    pIDeviceCollection->Release();
    pIMMDeviceEnumerator->Release();
    CoUninitialize();
    return -1;
Please ignore the strange error handling, it's just to make the example code short.
The problem is the return value (as can be seen in the output window of Visual Studio after running the program or using "echo %errorlevel%" in cmd.exe). Certainly, one would expect to get -1. However, I get 0 instead of -1. What makes this
really strange is that -1 is properly returned when the line "pIPropertyStore->GetValue..." is commented out. Why does this have any effect on the return value of the process? I have observed this on two different Window 7 machines with different
soundcard configurations. However, I did another test on a Windows 8.1 machine, where everything worked correctly.
Can anyone explain what's going on here?
Thanks,
Holger

Answer 1

OK, here's what's going on.
Everything goes fine until main() exits.
At that point, mmdevapi.dll's DllMain is called with lpReserved set to a non-NULL value, which is to say, "don't bother to clean up."
mmdevapi.dll decides to clean up anyway (for shame) and calls into some SetupAPI.dll functions.
SetupAPI.dll is waiting on a critical section, but at that point ntdll.dll kicks in and says "you know what, the process is shutting down, and this is the last thread, so I can guarantee you this critical section will never be set." ntdll.dll then
terminates the process, and main()'s exit code is lost.
Matthew van Eerde