SetWaitableTimer fail

[Gavin-Williams]

I have the following code...

        // create a waitable timer object
        SafeHandle hTimer = CreateWaitableTimerEx(
            lpTimerAttributes: null,
            lpTimerName: "FrameTimer",
            dwFlags: CREATE_WAITABLE_TIMER_HIGH_RESOLUTION,
            dwDesiredAccess: (uint)FILE_ACCESS_RIGHTS.SYNCHRONIZE);
        if (hTimer == null)
        {
            Console.WriteLine("CreateWaitableTimerEx failed : " + Marshal.GetLastWin32Error());
            return;
        }

        // wait 5 seconds
        long lpDueTime = -100000000L;
        int lPeriod = 0;
        if (!SetWaitableTimer(hTimer, in lpDueTime, lPeriod, null, null, false))
        {
            Console.WriteLine("SetWaitableTimer failed : " + Marshal.GetLastWin32Error());
            return;
        }

But I'm getting an error 6 (invalid handle) on the SetWaitableTimer call. I notice that CreateWaitableTimerEx returns a SafeFileHandle. Is that an issue? Or what have I done wrong here?

[AArnott]

Your null check is incorrect. When you apply this change:

-if (hTimer == null)
+if (hTimer.IsInvalid)

You'll find you get error 87. If you throw Win32Exception you get the full error message, which indicates you have an invalid parameter in the first of your two calls.

I'm no expert on this API, but my guess is it's your dwDesiredAccess argument.