wine/dlls/hidclass.sys/device.c

/*
 * HIDClass device functions
 *
 * Copyright (C) 2015 Aric Stewart
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include "config.h"

#include <stdarg.h>
#define NONAMELESSUNION
#include "hid.h"
#include "wine/unicode.h"
#include "winreg.h"
#include "winuser.h"
#include "setupapi.h"

#include "wine/debug.h"
#include "ddk/hidsdi.h"
#include "ddk/hidtypes.h"

#include "initguid.h"
#include "devguid.h"

WINE_DEFAULT_DEBUG_CHANNEL(hid);
WINE_DECLARE_DEBUG_CHANNEL(hid_report);

static const WCHAR device_name_fmtW[] = {'\\','D','e','v','i','c','e',
    '\\','H','I','D','#','%','p','&','%','p',0};
static const WCHAR device_regname_fmtW[] = {'H','I','D','\\',
    'v','i','d','_','%','0','4','x','&','p','i','d','_','%',
    '0','4','x','&','%','s','\\','%','i','&','%','s',0};
static const WCHAR device_link_fmtW[] = {'\\','?','?','\\','h','i','d','#',
    'v','i','d','_','%','0','4','x','&','p','i','d','_','%',
    '0','4','x','&','%','s','#','%','i','&','%','s','#','%','s',0};
/* GUID_DEVINTERFACE_HID */
static const WCHAR class_guid[] = {'{','4','D','1','E','5','5','B','2',
    '-','F','1','6','F','-','1','1','C','F','-','8','8','C','B','-','0','0',
    '1','1','1','1','0','0','0','0','3','0','}',0};


NTSTATUS HID_CreateDevice(DEVICE_OBJECT *native_device, HID_MINIDRIVER_REGISTRATION *driver, DEVICE_OBJECT **device)
{
    WCHAR dev_name[255];
    UNICODE_STRING nameW;
    NTSTATUS status;
    BASE_DEVICE_EXTENSION *ext;

    sprintfW(dev_name, device_name_fmtW, driver->DriverObject, native_device);
    RtlInitUnicodeString( &nameW, dev_name );

    TRACE("Create base hid device %s\n", debugstr_w(dev_name));

    status = IoCreateDevice(driver->DriverObject, driver->DeviceExtensionSize + sizeof(BASE_DEVICE_EXTENSION), &nameW, 0, 0, FALSE, device);
    if (status)
    {
        FIXME( "failed to create device error %x\n", status );
        return status;
    }

    ext = (*device)->DeviceExtension;

    ext->deviceExtension.MiniDeviceExtension = ext + 1;
    ext->deviceExtension.PhysicalDeviceObject = *device;
    ext->deviceExtension.NextDeviceObject = native_device;
    ext->device_name = HeapAlloc(GetProcessHeap(), 0, (lstrlenW(dev_name) + 1) * sizeof(WCHAR));
    lstrcpyW(ext->device_name, dev_name);
    ext->link_name = NULL;

    return S_OK;
}

NTSTATUS HID_LinkDevice(DEVICE_OBJECT *device, LPCWSTR serial, LPCWSTR index)
{
    WCHAR regname[255];
    WCHAR dev_link[255];
    SP_DEVINFO_DATA Data;
    UNICODE_STRING nameW, linkW;
    NTSTATUS status;
    HDEVINFO devinfo;
    GUID hidGuid;
    BASE_DEVICE_EXTENSION *ext;

    HidD_GetHidGuid(&hidGuid);
    ext = device->DeviceExtension;

    sprintfW(dev_link, device_link_fmtW, ext->information.VendorID,
        ext->information.ProductID, index, ext->information.VersionNumber, serial,
        class_guid);
    struprW(dev_link);

    RtlInitUnicodeString( &nameW, ext->device_name);
    RtlInitUnicodeString( &linkW, dev_link );

    TRACE("Create link %s\n", debugstr_w(dev_link));

    ext->link_name = HeapAlloc(GetProcessHeap(), 0, sizeof(WCHAR) * (lstrlenW(dev_link) + 1));
    lstrcpyW(ext->link_name, dev_link);

    status = IoCreateSymbolicLink( &linkW, &nameW );
    if (status)
    {
        FIXME( "failed to create link error %x\n", status );
        return status;
    }

    sprintfW(regname, device_regname_fmtW, ext->information.VendorID, ext->information.ProductID, index, ext->information.VersionNumber, serial);

    devinfo = SetupDiGetClassDevsW(&GUID_DEVCLASS_HIDCLASS, NULL, NULL, DIGCF_DEVICEINTERFACE);
    if (!devinfo)
    {
        FIXME( "failed to get ClassDevs %x\n", GetLastError());
        return GetLastError();
    }
    Data.cbSize = sizeof(Data);
    if (!SetupDiCreateDeviceInfoW(devinfo, regname, &GUID_DEVCLASS_HIDCLASS, NULL, NULL, DICD_INHERIT_CLASSDRVS, &Data))
    {
        if (GetLastError() == ERROR_DEVINST_ALREADY_EXISTS)
        {
            SetupDiDestroyDeviceInfoList(devinfo);
            return ERROR_SUCCESS;
        }
        FIXME( "failed to Create Device Info %x\n", GetLastError());
        return GetLastError();
    }
    if (!SetupDiRegisterDeviceInfo( devinfo, &Data, 0, NULL, NULL, NULL ))
    {
        FIXME( "failed to Register Device Info %x\n", GetLastError());
        return GetLastError();
    }
    if (!SetupDiCreateDeviceInterfaceW( devinfo, &Data,  &hidGuid, NULL, 0, NULL))
    {
        FIXME( "failed to Create Device Interface %x\n", GetLastError());
        return GetLastError();
    }
    SetupDiDestroyDeviceInfoList(devinfo);

    return S_OK;
}

void HID_DeleteDevice(HID_MINIDRIVER_REGISTRATION *driver, DEVICE_OBJECT *device)
{
    NTSTATUS status;
    BASE_DEVICE_EXTENSION *ext;
    UNICODE_STRING linkW;
    LIST_ENTRY *entry;
    IRP *irp;

    ext = device->DeviceExtension;

    if (ext->link_name)
    {
        TRACE("Delete link %s\n", debugstr_w(ext->link_name));
        RtlInitUnicodeString(&linkW, ext->link_name);

        status = IoDeleteSymbolicLink(&linkW);
        if (status != STATUS_SUCCESS)
            ERR("Delete Symbolic Link failed (%x)\n",status);
    }

    if (ext->thread)
    {
        SetEvent(ext->halt_event);
        WaitForSingleObject(ext->thread, INFINITE);
    }
    CloseHandle(ext->halt_event);

    HeapFree(GetProcessHeap(), 0, ext->preparseData);
    if (ext->ring_buffer)
        RingBuffer_Destroy(ext->ring_buffer);

    entry = RemoveHeadList(&ext->irp_queue);
    while(entry != &ext->irp_queue)
    {
        irp = CONTAINING_RECORD(entry, IRP, Tail.Overlay.ListEntry);
        irp->IoStatus.u.Status = STATUS_DEVICE_REMOVED;
        IoCompleteRequest(irp, IO_NO_INCREMENT);
        entry = RemoveHeadList(&ext->irp_queue);
    }

    TRACE("Delete device(%p) %s\n", device, debugstr_w(ext->device_name));
    HeapFree(GetProcessHeap(), 0, ext->device_name);
    HeapFree(GetProcessHeap(), 0, ext->link_name);

    IoDeleteDevice(device);
}

static void HID_Device_processQueue(DEVICE_OBJECT *device)
{
    LIST_ENTRY *entry;
    IRP *irp;
    BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;
    UINT buffer_size = RingBuffer_GetBufferSize(ext->ring_buffer);
    HID_XFER_PACKET *packet;

    packet = HeapAlloc(GetProcessHeap(), 0, buffer_size);

    entry = RemoveHeadList(&ext->irp_queue);
    while(entry != &ext->irp_queue)
    {
        int ptr;
        irp = CONTAINING_RECORD(entry, IRP, Tail.Overlay.ListEntry);
        ptr = PtrToUlong( irp->Tail.Overlay.OriginalFileObject->FsContext );

        RingBuffer_Read(ext->ring_buffer, ptr, packet, &buffer_size);
        if (buffer_size)
        {
            IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation(irp);
            TRACE_(hid_report)("Processing Request (%i)\n",ptr);
            if (irpsp->Parameters.Read.Length >= packet->reportBufferLen)
            {
                memcpy(irp->AssociatedIrp.SystemBuffer, packet->reportBuffer, packet->reportBufferLen);
                irp->IoStatus.Information = packet->reportBufferLen;
                irp->IoStatus.u.Status = STATUS_SUCCESS;
            }
            else
            {
                irp->IoStatus.Information = 0;
                irp->IoStatus.u.Status = STATUS_BUFFER_OVERFLOW;
            }
        }
        else
        {
            irp->IoStatus.Information = 0;
            irp->IoStatus.u.Status = STATUS_UNSUCCESSFUL;
        }
        IoCompleteRequest( irp, IO_NO_INCREMENT );
        entry = RemoveHeadList(&ext->irp_queue);
    }
    HeapFree(GetProcessHeap(), 0, packet);
}

static NTSTATUS WINAPI read_Completion(DEVICE_OBJECT *deviceObject, IRP *irp, void *context )
{
    SetEvent(irp->UserEvent);
    return STATUS_MORE_PROCESSING_REQUIRED;
}

static DWORD CALLBACK hid_device_thread(void *args)
{
    DEVICE_OBJECT *device = (DEVICE_OBJECT*)args;

    IRP *irp;
    IO_STATUS_BLOCK irp_status;
    IO_STACK_LOCATION *irpsp;
    DWORD rc;
    HANDLE events[2];
    NTSTATUS ntrc;

    BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;
    events[0] = CreateEventA(NULL, FALSE, FALSE, NULL);
    events[1] = ext->halt_event;

    if (ext->information.Polled)
    {
        while(1)
        {
            HID_XFER_PACKET *packet;
            ResetEvent(events[0]);

            packet = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*packet) + ext->preparseData->caps.InputReportByteLength);
            packet->reportBufferLen = ext->preparseData->caps.InputReportByteLength;
            packet->reportBuffer = ((BYTE*)packet) + sizeof(*packet);
            packet->reportId = 0;

            irp = IoBuildDeviceIoControlRequest(IOCTL_HID_GET_INPUT_REPORT,
                device, NULL, 0, packet, sizeof(packet), TRUE, events[0],
                &irp_status);

            irpsp = IoGetNextIrpStackLocation(irp);
            irpsp->CompletionRoutine = read_Completion;
            irpsp->Control = SL_INVOKE_ON_SUCCESS | SL_INVOKE_ON_ERROR;

            ntrc = IoCallDriver(device, irp);

            if (ntrc == STATUS_PENDING)
                rc = WaitForMultipleObjects(2, events, FALSE, INFINITE);

            if (irp->IoStatus.u.Status == STATUS_SUCCESS)
            {
                RingBuffer_Write(ext->ring_buffer, packet);
                HID_Device_processQueue(device);
            }

            IoCompleteRequest(irp, IO_NO_INCREMENT );

            rc = WaitForSingleObject(ext->halt_event, ext->poll_interval);

            if (rc == WAIT_OBJECT_0)
                break;
            else if (rc != WAIT_TIMEOUT)
                ERR("Wait returned unexpected value %x\n",rc);
        }
    }
    else
    {
        INT exit_now = FALSE;

        HID_XFER_PACKET *packet;
        packet = HeapAlloc(GetProcessHeap(), 0, sizeof(*packet) + ext->preparseData->caps.InputReportByteLength);
        packet->reportBufferLen = ext->preparseData->caps.InputReportByteLength;
        packet->reportBuffer = ((BYTE*)packet) + sizeof(*packet);
        packet->reportId = 0;

        while(1)
        {
            BYTE *buffer;

            buffer = HeapAlloc(GetProcessHeap(), 0, ext->preparseData->caps.InputReportByteLength);

            ResetEvent(events[0]);

            irp = IoBuildDeviceIoControlRequest(IOCTL_HID_READ_REPORT,
                device, NULL, 0, buffer,
                ext->preparseData->caps.InputReportByteLength, TRUE, events[0],
                &irp_status);

            irpsp = IoGetNextIrpStackLocation(irp);
            irpsp->CompletionRoutine = read_Completion;
            irpsp->Control = SL_INVOKE_ON_SUCCESS | SL_INVOKE_ON_ERROR;

            ntrc = IoCallDriver(device, irp);

            if (ntrc == STATUS_PENDING)
            {
                rc = WaitForMultipleObjects(2, events, FALSE, INFINITE);

                if (rc == WAIT_OBJECT_0 + 1)
                    exit_now = TRUE;
            }

            if (!exit_now && irp->IoStatus.u.Status == STATUS_SUCCESS)
            {
                packet->reportId = buffer[0];
                memcpy(packet->reportBuffer, buffer, ext->preparseData->caps.InputReportByteLength);
                RingBuffer_Write(ext->ring_buffer, packet);
                HID_Device_processQueue(device);
            }

            IoCompleteRequest(irp, IO_NO_INCREMENT );

            if (exit_now)
                break;
        }

        HeapFree(GetProcessHeap(), 0, packet);
    }

    CloseHandle(events[0]);

    TRACE("Device thread exiting\n");
    return 1;
}

void HID_StartDeviceThread(DEVICE_OBJECT *device)
{
    BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;
    ext->halt_event = CreateEventA(NULL, FALSE, FALSE, NULL);
    ext->thread = CreateThread(NULL, 0, hid_device_thread, device, 0, NULL);
}

static NTSTATUS handle_IOCTL_HID_GET_COLLECTION_INFORMATION(IRP *irp, BASE_DEVICE_EXTENSION *base)
{
    IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation( irp );
    if (irpsp->Parameters.DeviceIoControl.OutputBufferLength <  sizeof(HID_COLLECTION_INFORMATION))
    {
        irp->IoStatus.u.Status = STATUS_BUFFER_OVERFLOW;
        irp->IoStatus.Information = 0;
    }
    else
    {
        memcpy(irp->AssociatedIrp.SystemBuffer, &base->information, sizeof(HID_COLLECTION_INFORMATION));
        irp->IoStatus.Information = sizeof(HID_COLLECTION_INFORMATION);
        irp->IoStatus.u.Status = STATUS_SUCCESS;
    }
    return STATUS_SUCCESS;
}

static NTSTATUS handle_IOCTL_HID_GET_COLLECTION_DESCRIPTOR(IRP *irp, BASE_DEVICE_EXTENSION *base)
{
    IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation( irp );

    if (irpsp->Parameters.DeviceIoControl.OutputBufferLength <  base->preparseData->dwSize)
    {
        irp->IoStatus.u.Status = STATUS_INVALID_BUFFER_SIZE;
        irp->IoStatus.Information = 0;
    }
    else
    {
        memcpy(irp->UserBuffer, base->preparseData, base->preparseData->dwSize);
        irp->IoStatus.Information = base->preparseData->dwSize;
        irp->IoStatus.u.Status = STATUS_SUCCESS;
    }
    return STATUS_SUCCESS;
}

static NTSTATUS handle_minidriver_string(DEVICE_OBJECT *device, IRP *irp, SHORT index)
{
    IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation( irp );
    WCHAR buffer[127];
    NTSTATUS status;
    ULONG InputBuffer;

    InputBuffer = MAKELONG(index, 0);
    status = call_minidriver(IOCTL_HID_GET_STRING, device, ULongToPtr(InputBuffer), sizeof(InputBuffer), buffer, sizeof(buffer));

    if (status == STATUS_SUCCESS)
    {
        WCHAR *out_buffer = (WCHAR*)(((BYTE*)irp->MdlAddress->StartVa) + irp->MdlAddress->ByteOffset);
        int length = irpsp->Parameters.DeviceIoControl.OutputBufferLength/sizeof(WCHAR);
        TRACE("got string %s from minidriver\n",debugstr_w(buffer));
        lstrcpynW(out_buffer, buffer, length);
        irp->IoStatus.Information = (lstrlenW(buffer)+1) * sizeof(WCHAR);
    }
    irp->IoStatus.u.Status = status;

    return STATUS_SUCCESS;
}

NTSTATUS WINAPI HID_Device_ioctl(DEVICE_OBJECT *device, IRP *irp)
{
    NTSTATUS rc = STATUS_SUCCESS;
    IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation( irp );
    BASE_DEVICE_EXTENSION *extension = device->DeviceExtension;

    irp->IoStatus.Information = 0;

    TRACE("device %p ioctl(%x)\n", device, irpsp->Parameters.DeviceIoControl.IoControlCode);

    switch (irpsp->Parameters.DeviceIoControl.IoControlCode)
    {
        case IOCTL_HID_GET_POLL_FREQUENCY_MSEC:
            TRACE("IOCTL_HID_GET_POLL_FREQUENCY_MSEC\n");
            if (irpsp->Parameters.DeviceIoControl.OutputBufferLength < sizeof(ULONG))
            {
                irp->IoStatus.u.Status = STATUS_BUFFER_OVERFLOW;
                irp->IoStatus.Information = 0;
                break;
            }
            *((ULONG*)irp->AssociatedIrp.SystemBuffer) = extension->poll_interval;
            irp->IoStatus.Information = sizeof(ULONG);
            irp->IoStatus.u.Status = STATUS_SUCCESS;
            break;
        case IOCTL_HID_SET_POLL_FREQUENCY_MSEC:
        {
            ULONG poll_interval;
            TRACE("IOCTL_HID_SET_POLL_FREQUENCY_MSEC\n");
            if (irpsp->Parameters.DeviceIoControl.InputBufferLength < sizeof(ULONG))
            {
                irp->IoStatus.u.Status = STATUS_BUFFER_TOO_SMALL;
                break;
            }
            poll_interval = *(ULONG *)irp->AssociatedIrp.SystemBuffer;
            if (poll_interval == 0)
                FIXME("Handle opportunistic reads\n");
            else if (poll_interval <= MAX_POLL_INTERVAL_MSEC)
            {
                extension->poll_interval = poll_interval;
                irp->IoStatus.u.Status = STATUS_SUCCESS;
            }
            else
                irp->IoStatus.u.Status = STATUS_INVALID_PARAMETER;
            break;
        }
        case IOCTL_HID_GET_PRODUCT_STRING:
        {
            rc = handle_minidriver_string(device, irp, HID_STRING_ID_IPRODUCT);
            break;
        }
        case IOCTL_HID_GET_MANUFACTURER_STRING:
        {
            rc = handle_minidriver_string(device, irp, HID_STRING_ID_IMANUFACTURER);
            break;
        }
        case IOCTL_HID_GET_COLLECTION_INFORMATION:
        {
            rc = handle_IOCTL_HID_GET_COLLECTION_INFORMATION(irp, extension);
            break;
        }
        case IOCTL_HID_GET_COLLECTION_DESCRIPTOR:
        {
            rc = handle_IOCTL_HID_GET_COLLECTION_DESCRIPTOR(irp, extension);
            break;
        }
        case IOCTL_HID_GET_INPUT_REPORT:
        {
            HID_XFER_PACKET packet;
            BYTE* buffer = ((BYTE*)irp->MdlAddress->StartVa) + irp->MdlAddress->ByteOffset;

            if (extension->preparseData->InputReports[0].reportID)
                packet.reportId = buffer[0];
            else
                packet.reportId = 0;
            packet.reportBuffer = buffer;
            packet.reportBufferLen = irpsp->Parameters.DeviceIoControl.OutputBufferLength;

            call_minidriver(IOCTL_HID_GET_INPUT_REPORT, device, NULL, 0, &packet, sizeof(packet));
            irp->IoStatus.Information = packet.reportBufferLen;
            irp->IoStatus.u.Status = STATUS_SUCCESS;
            break;
        }
        default:
        {
            ULONG code = irpsp->Parameters.DeviceIoControl.IoControlCode;
            FIXME("Unsupported ioctl %x (device=%x access=%x func=%x method=%x)\n",
                  code, code >> 16, (code >> 14) & 3, (code >> 2) & 0xfff, code & 3);
            irp->IoStatus.u.Status = STATUS_NOT_SUPPORTED;
            rc = STATUS_UNSUCCESSFUL;
            break;
        }
    }

    if (rc != STATUS_PENDING)
        IoCompleteRequest( irp, IO_NO_INCREMENT );

    return rc;
}

NTSTATUS WINAPI HID_Device_read(DEVICE_OBJECT *device, IRP *irp)
{
    HID_XFER_PACKET *packet;
    BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;
    UINT buffer_size = RingBuffer_GetBufferSize(ext->ring_buffer);
    NTSTATUS rc = STATUS_SUCCESS;
    int ptr = -1;

    packet = HeapAlloc(GetProcessHeap(), 0, buffer_size);
    ptr = PtrToUlong( irp->Tail.Overlay.OriginalFileObject->FsContext );

    irp->IoStatus.Information = 0;
    RingBuffer_Read(ext->ring_buffer, ptr, packet, &buffer_size);

    if (buffer_size)
    {
        IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation( irp );
        TRACE_(hid_report)("Got Packet %p %i\n", packet->reportBuffer, packet->reportBufferLen);
        if (irpsp->Parameters.Read.Length >= packet->reportBufferLen)
        {
            memcpy(irp->AssociatedIrp.SystemBuffer, packet->reportBuffer, packet->reportBufferLen);
            irp->IoStatus.Information = packet->reportBufferLen;
            irp->IoStatus.u.Status = STATUS_SUCCESS;
        }
        else
        {
            irp->IoStatus.Information = 0;
            irp->IoStatus.u.Status = STATUS_BUFFER_OVERFLOW;
        }
        IoCompleteRequest( irp, IO_NO_INCREMENT );
    }
    else
    {
        TRACE_(hid_report)("Queue irp\n");
        InsertTailList(&ext->irp_queue, &irp->Tail.Overlay.ListEntry);
        rc = STATUS_PENDING;
    }
    HeapFree(GetProcessHeap(), 0, packet);

    return rc;
}

NTSTATUS WINAPI HID_Device_write(DEVICE_OBJECT *device, IRP *irp)
{
    IO_STACK_LOCATION *irpsp = IoGetCurrentIrpStackLocation( irp );

    irp->IoStatus.Information = 0;

    TRACE("Buffer length %i\n", irpsp->Parameters.Write.Length);

    FIXME("device %p\n", device);

    irp->IoStatus.u.Status = STATUS_SUCCESS;
    IoCompleteRequest( irp, IO_NO_INCREMENT );
    return STATUS_SUCCESS;
}

NTSTATUS WINAPI HID_Device_create(DEVICE_OBJECT *device, IRP *irp)
{
    BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;

    TRACE("Open handle on device %p\n", device);
    irp->Tail.Overlay.OriginalFileObject->FsContext = UlongToPtr(RingBuffer_AddPointer(ext->ring_buffer));
    irp->IoStatus.u.Status = STATUS_SUCCESS;
    IoCompleteRequest( irp, IO_NO_INCREMENT );
    return STATUS_SUCCESS;
}

NTSTATUS WINAPI HID_Device_close(DEVICE_OBJECT *device, IRP *irp)
{
    BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;
    int ptr = PtrToUlong(irp->Tail.Overlay.OriginalFileObject->FsContext);
    TRACE("Close handle on device %p\n", device);
    RingBuffer_RemovePointer(ext->ring_buffer, ptr);
    irp->IoStatus.u.Status = STATUS_SUCCESS;
    IoCompleteRequest( irp, IO_NO_INCREMENT );
    return STATUS_SUCCESS;
}