Recupero dell'indirizzo Bluetooth del dispositivo HF

L'argomento Ottenere l'indirizzo Bluetooth del dispositivo HF illustra come il driver audio può ottenere l'indirizzo Bluetooth di un dispositivo HANDS-free (HF) associato.

La stringa di indirizzo può essere utile per identificare in modo univoco un particolare dispositivo HF associato. Ad esempio, la stringa di indirizzo può essere usata come parametro ReferenceString passato a IoRegisterDeviceInterface, il parametro RefString passato a KsCreateFilterFactory o il parametro Name passato a PcRegisterSubdevice.

Si noti che il collegamento simbolico dell'interfaccia del dispositivo GUID_DEVINTERFACE_BLUETOOTH_HFP_SCO_HCIBYPASS è univoco anche per ogni dispositivo HF associato, ma questa stringa può essere troppo lunga per alcuni scopi.

La routine IoHelperGetDevicePdo illustrata nell'esempio di codice seguente è una funzione di utilità usata da IoHelperGetDeviceBluetoothAddress. Tali funzioni possono essere chiamate mentre il driver audio gestisce una notifica di arrivo dell'interfaccia PnP. Il driver audio ottiene l'oggetto dispositivo da IoGetDeviceObjectPointer e lo passa a IoHelperGetDeviceBluetoothAddress.

_IRQL_requires_(PASSIVE_LEVEL)
NTSTATUS
IoHelperGetDevicePdo(
    _In_ PDEVICE_OBJECT DeviceObject,
    _Out_ PDEVICE_OBJECT *PhysicalDeviceObject
    )

/*++

Routine description:
    Returns a pointer to the physical device object in a driver stack and
    increments the reference count on that object.

Parameters:
    DeviceObject
        Pointer to the device object for which the physical device object is
        retrieved. 

    PhysicalDeviceObject
        Returns a pointer to the physical device object in a stack of device
        objects after incrementing the reference count on the object.

Return value:
    A status code.

Remarks:
    This routine uses IRP_MN_QUERY_DEVICE_RELATIONS TargetDeviceRelation to
    get the physical device object from the device stack.

Requirements:
    IRQL    = PASSIVE_LEVEL

--*/

{
    NTSTATUS status;
    PIRP irp = NULL;
    PDEVICE_RELATIONS deviceRelations = NULL;
    PIO_STACK_LOCATION ioStack;
    KEVENT completionEvent;

    PAGED_CODE();

    irp = IoAllocateIrp(DeviceObject->StackSize, FALSE);
    if (irp == NULL)
    {
        status = STATUS_INSUFFICIENT_RESOURCES;
        goto Exit;
    }

    irp->IoStatus.Status = STATUS_NOT_SUPPORTED;

    ioStack = IoGetNextIrpStackLocation(irp);
    ioStack->MajorFunction = IRP_MJ_PNP;
    ioStack->MinorFunction = IRP_MN_QUERY_DEVICE_RELATIONS;
    ioStack->Parameters.QueryDeviceRelations.Type = TargetDeviceRelation;

    KeInitializeEvent(&completionEvent, SynchronizationEvent, FALSE);

    IoSetCompletionRoutine(irp, OnRequestComplete, &completionEvent, TRUE, TRUE, TRUE);

    status = IoCallDriver(DeviceObject, irp);
    if (status == STATUS_PENDING) {
        // wait for irp to complete
        KeWaitForSingleObject(
            &completionEvent,
            Suspended,
            KernelMode,
            FALSE,
            NULL);
        status = irp->IoStatus.Status;
    }

    if (NT_SUCCESS(status))
    {
        deviceRelations = (PDEVICE_RELATIONS)irp->IoStatus.Information;
        *PhysicalDeviceObject = deviceRelations->Objects[0];
    }

Exit:
    if (deviceRelations != NULL)
    {
        ExFreePool(deviceRelations);
    }
    if (irp != NULL)
    {
        IoFreeIrp(irp);
    }
    return status;
}

_IRQL_requires_(PASSIVE_LEVEL)
NTSTATUS IoHelperGetDeviceBluetoothAddress(
    _In_ PDEVICE_OBJECT DeviceObject,
    _Outptr_ PWSTR *BluetoothAddress,
    _In_ ULONG Tag
    )

/*++

Routine description:
    Returns the Bluetooth address string for the physical device object in the
    device stack.

Parameters:
    DeviceObject
        Pointer to a device object in a device stack whose physical object has
        a Bluetooth address property.

    BluetoothAddress
        Returns a string allocated from NonPagedPoolNx pool. 

    Tag

Return value:
    A status code.

Remarks:
    This routine retrieves the DEVPKEY_Bluetooth_DeviceAddress property from
    the physical device object in the device stack containing the specified
    device object.

Requirements:
    IRQL    = PASSIVE_LEVEL

--*/

{
    NTSTATUS status;
    PDEVICE_OBJECT physicalDeviceObject = NULL;
    PWSTR bluetoothAddress = NULL;
    ULONG requiredSize;
    DEVPROPTYPE devPropType;

    PAGED_CODE();

    status = IoHelperGetDevicePdo(DeviceObject, &physicalDeviceObject);
    if (!NT_SUCCESS(status))
    {
        goto Exit;
    }

    status = IoGetDevicePropertyData(physicalDeviceObject, &DEVPKEY_Bluetooth_DeviceAddress, LOCALE_NEUTRAL, 0, 0, NULL, &requiredSize, &devPropType);
    if (NT_SUCCESS(status) || devPropType != DEVPROP_TYPE_STRING)
    {
        status = STATUS_UNSUCCESSFUL;
        goto Exit;
    }
    if (status != STATUS_BUFFER_TOO_SMALL)
    {
        goto Exit;
    }

    bluetoothAddress = (PWCH)ExAllocatePoolWithTag(NonPagedPoolNx, requiredSize, Tag);
    if (bluetoothAddress == NULL)
    {
        status = STATUS_INSUFFICIENT_RESOURCES;
        goto Exit;
    }

    status = IoGetDevicePropertyData(physicalDeviceObject, &DEVPKEY_Bluetooth_DeviceAddress, LOCALE_NEUTRAL, 0, requiredSize, bluetoothAddress, &requiredSize, &devPropType);
    if (!NT_SUCCESS(status))
    {
        goto Exit;
    }

    *BluetoothAddress = bluetoothAddress;
    bluetoothAddress = NULL;
    status = STATUS_SUCCESS;

Exit:
    if (bluetoothAddress != NULL)
    {
        ExFreePoolWithTag(bluetoothAddress, Tag);
    }
    if (physicalDeviceObject != NULL)
    {
        ObDereferenceObject(physicalDeviceObject);
    }
    return status;
}