SetupDiGetClassDevs returns an empty list even when configured not to filter by GUID, is there an alternative way to get the info list?

Question

I tried configuring the function not to filter by GUID like this:

SetupDiGetClassDevs(NULL, NULL, NULL, DIGCF_ALLCLASSES)

but still the dev info list is empty.

Is this a known issue? is there an alternative way to get the info list?

Answer 1

SetupDiGetClassDevs(NULL, NULL, NULL, DIGCF_ALLCLASSES)

The posted question asked about the above SetupApi function call. I could not reproduce the Questioner's issue when I used the following:

#include <Windows.h>
#include <SetupAPI.h>
#pragma comment(lib, "setupapi")
#define INITGUID
#include <guiddef.h>
#include <devpkey.h>

#include <stdio.h>
#include <tchar.h>

int wmain()
{
    auto hSet = SetupDiGetClassDevsW(NULL, NULL, NULL, DIGCF_ALLCLASSES);
    if (hSet != INVALID_HANDLE_VALUE)
    {
        SP_DEVINFO_DATA spdd{ sizeof spdd};
        DWORD ndx{ 0 };
        DWORD err{ ERROR_SUCCESS };

        while(err != ERROR_NO_MORE_ITEMS)
        {
            if (SetupDiEnumDeviceInfo(hSet, ndx, &spdd))
            {
                WCHAR szGuid[39]{};
                WCHAR szName[512]{};
                DEVPROPTYPE proptype{};

                StringFromGUID2(spdd.ClassGuid, szGuid, ARRAYSIZE(szGuid));
                if (SetupDiGetDevicePropertyW(hSet, &spdd, &DEVPKEY_NAME, &proptype, (PBYTE)szName, sizeof szName, NULL, 0))
                    wprintf_s(L"%u. Class GUID is %s, name is %s\n", ndx, szGuid, szName);
                else
                    wprintf_s(L"SetupDiGetDevicePropertyW for index %u failed with %u\n", ndx, GetLastError());

                ++ndx;
            }
            else
            {
                err = GetLastError();
                if (err != ERROR_NO_MORE_ITEMS)
                {
                    wprintf_s(L"Device enumeration for index %u failed with %u\n", ndx, err);
                    ++ndx;
                }
            }
        }

        wprintf_s(L"Enumerated %u devices\n", ndx);

        SetupDiDestroyDeviceInfoList(hSet);
    }

    return 0;
}

The code snippet that the Questioner posted was incomplete and diverged from the posted question and so it was ignored.