How to check that the current process is running as Windows Service using WinAPI functions?

Question

I have a program that can be run as a simple console application or can be registered as Windows Service. I want to detect in main() function the current running context:

#include <windows.h>

BOOL IsWindowsService()
{
    ???
}

int main(int argc, char** argv)
{
    if (IsWindowsService())
    {
        // Running as Windows Service...
        RunService();
        return;
    }

    // Running as console application...    
    return 0;
}

The main use-case is to have a single exe file that can be installed and run as a Windows Service with '--install' and '--start' arguments or executed without any parameters in console mode (e.g. from VS debugger).

Can you help me with a possible implementation of IsWindowsService() function?

Answer 1

int __stdcall wWinMain(HINSTANCE, HINSTANCE, LPWSTR, int)
    { 
    SERVICE_TABLE_ENTRY ServiceTable[] =
    {
        { SERVICE_NAME,(LPSERVICE_MAIN_FUNCTION)ServiceMain },
    { NULL,NULL }
    };
    if (StartServiceCtrlDispatcher(ServiceTable))
        //service
    else app; // last error ERROR_FAILED_SERVICE_CONTROLLER_CONNECT
}


VOID WINAPI ServiceMain(DWORD argc, LPTSTR *argv)
{...}

Documentation https://learn.microsoft.com/en-us/windows/desktop/api/winsvc/nf-winsvc-startservicectrldispatchera