Automatically pausing/continuing a service when OS suspends

I made a Windows Service process that can be started/stopped/paused/continued.

The service is created with CreateService() and the service starts a service controller with RegisterServiceCtrlHandlerExA().

Even though the service can subscribe to power setting notifications using RegisterPowerSettingNotification() I find that these only represent events like battery/mains for laptops, and such. Not for suspend/sleep of the OS.

How can I tell the SCM to automatically pause my service before the OS suspends/sleeps? And continue my service after it wakes up again?

This requires calling the PowerRegisterSuspendResumeNotification() function.

For this, you need to #include <powrprof.h> and link against powrprof.lib.

The callback itself looks like:

static ULONG DeviceNotifyCallbackRoutine
(
    PVOID Context,
    ULONG Type,         // PBT_APMSUSPEND, PBT_APMRESUMESUSPEND, or PBT_APMRESUMEAUTOMATIC
    PVOID Setting       // Unused
)
{
    LOGI("DeviceNotifyCallbackRoutine");
    if (Type == PBT_APMSUSPEND)
    {
        turboledz_pause_all_devices();
        LOGI("Devices paused.");
    }
    if (Type == PBT_APMRESUMEAUTOMATIC)
    {
        turboledz_paused = 0;
        LOGI("Device unpaused.");
    }
    return 0;
}

static DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS notifycb =
{
    DeviceNotifyCallbackRoutine,
    NULL,
};

And then register it with:

    HPOWERNOTIFY registration;
    const DWORD registered = PowerRegisterSuspendResumeNotification
    (
        DEVICE_NOTIFY_CALLBACK,
        &notifycb,
        &registration
    );
    if (registered != ERROR_SUCCESS)
    {
        const DWORD err = GetLastError();
        LOGI("PowerRegisterSuspendResumeNotification failed with error 0x%lx", err);
    }