Question

我正在尝试从C＃调用DeviceIoControl来获取IOCTL_DVD_*个控制代码。在阅读了大量信息并尝试了一些例子后，我没有取得多大进展。

我最终要做的是获取有关当前DVD驱动器中的媒体的DVD_LAYER_DESCRIPTOR结构。我可以在DVD设备上成功呼叫CreateFile，但当我尝试使用控制代码DeviceIoControl呼叫IOCTL_DVD_START_SESSION时，它会返回成功代码，但我似乎没有得到sessionId值返回成功，总是返回0.（然后我尝试使用IOCTL_DVD_READ_STRUCTURE获取图层描述的任何尝试都失败，即函数失败或返回成功但是给出一个空白的输出结构。）

找到一些进行类似调用的C代码后，我能够编译这段代码（使用Visual C ++ 2008 Express Edition），它成功启动会话，阅读DVD_LAYER_DESCRIPTOR，并关闭会话问题所以我知道这有效。

C＃问题似乎与如何定义外部函数和编组参数有关。以及如何定义传递和返回的各种结构。

我已经查看了www.pinvoke.net他们如何定义它，并使用了一些给出的示例代码和定义，但仍然存在上述问题。部分问题似乎是每个IOCTL控制代码的参数都不同，主要是结构，但对于IOCTL_DVD_START_SESSION，输出值是32位整数。如何定义C＃中的extern方法来处理这些不同的情况？另外，使用正确大小的成员类型定义的各种结构显示它们在C和C＃代码之间的大小不同，但各个成员的大小相同???

如果我使用类似DeviceIOView的程序并观察C代码和C＃代码对IOCTL_DVD_START_SESSION的调用，则C版本返回3的sessionid，而DeviceIOView显示当发送回的数据时运行C＃代码也是3因此似乎存在某种返回参数的编组问题，因为我们在C＃代码中只看到0

有没有人有关于如何从C＃调用DeviceIoControl来访问DVD信息的任何想法或工作示例代码？（展示如何定义和使用结构和功能。）非常感谢任何有用网站或其他建议的链接。

（在Visual C＃2008 Express Edition，.NET 3.5中开发。）

N Johns

示例代码（已添加）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Win32.SafeHandles;
using System.Runtime.InteropServices;
using System.IO;
using System.Threading;

namespace Example
{
    class Program
    {
        static void Main(string[] args)
        {
            string driveLetter = args[0].Substring(0, 1).ToUpper() + ":";

            SafeFileHandle _hdev = CreateFileR(driveLetter);
            if (_hdev.IsClosed | _hdev.IsInvalid)
            {
                Console.WriteLine("Error opening device");
                return;
            }

            Console.WriteLine("DeviceIoControl - Version One");

            Console.WriteLine("IOCTL_DVD_START_SESSION");

            bool result = false;
            int bytesReturned = 0;
            int sessionId = 0;

            result = DeviceIoControl(_hdev, CTL_CODE(0x00000033, 0x0400, 0, 1), IntPtr.Zero, 0, (IntPtr)sessionId, Marshal.SizeOf(sessionId), out bytesReturned, IntPtr.Zero);

            if (result == false)
            {
                int error_code = Marshal.GetLastWin32Error();
                Console.WriteLine("Result: " + result);
                Console.WriteLine("error code: " + error_code);
            }
            else
            {
                Console.WriteLine("Result: " + result);
                Console.WriteLine("BytesReturned: " + bytesReturned);
                Console.WriteLine("SessionId: " + sessionId);
                Console.WriteLine("sizeof(SessionId): " + Marshal.SizeOf(sessionId));
            }

            Console.WriteLine("IOCTL_DVD_READ_STRUCTURE");
            Console.WriteLine("Skipping...");

            Console.WriteLine("IOCTL_DVD_END_SESSION");
            bytesReturned = 0;

            result = DeviceIoControl(_hdev, CTL_CODE(0x00000033, 0x0403, 0, 1), new IntPtr(sessionId), Marshal.SizeOf(sessionId), IntPtr.Zero, 0, out bytesReturned, IntPtr.Zero);

            if (result == false)
            {
                int error_code = Marshal.GetLastWin32Error();
                Console.WriteLine("error code: " + error_code);
                Console.WriteLine("Result: " + result);
            }
            else
            {
                Console.WriteLine("Result: " + result);
                Console.WriteLine("BytesReturned: " + bytesReturned);
            }

            Console.WriteLine("\nDeviceIoControl - Version Two");

            Console.WriteLine("IOCTL_DVD_START_SESSION");

            result = false;
            uint bytesReturned2 = 0;
            sessionId = -10;

            NativeOverlapped nativeOverlapped = new NativeOverlapped();

            result = DeviceIoControlAlt(_hdev, EIOControlCode.DvdStartSession, 0, 0, sessionId, (uint)Marshal.SizeOf(sessionId), ref bytesReturned2, ref nativeOverlapped);

            if (result == false)
            {
                int error_code = Marshal.GetLastWin32Error();
                Console.WriteLine("Result: " + result);
                Console.WriteLine("error code: " + error_code);
            }
            else
            {
                Console.WriteLine("Result: " + result);
                Console.WriteLine("BytesReturned: " + bytesReturned2);
                Console.WriteLine("SessionId: " + sessionId);
                Console.WriteLine("sizeof(SessionId): " + Marshal.SizeOf(sessionId));
            }

            Console.WriteLine("IOCTL_DVD_READ_STRUCTURE");
            Console.WriteLine("Skipping...");

            Console.WriteLine("IOCTL_DVD_END_SESSION");
            bytesReturned2 = 0;

            result = DeviceIoControlAlt(_hdev, EIOControlCode.DvdEndSession, sessionId, (uint)Marshal.SizeOf(sessionId), 0, 0, ref bytesReturned2, ref nativeOverlapped);

            if (result == false)
            {
                int error_code = Marshal.GetLastWin32Error();
                Console.WriteLine("Result: " + result);
                Console.WriteLine("error code: " + error_code);
            }
            else
            {
                Console.WriteLine("Result: " + result);
                Console.WriteLine("BytesReturned: " + bytesReturned2);
            }

            _hdev.Close();
        }

        public static int CTL_CODE(int DeviceType, int Function, int Method, int Access)
        {
            return (((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2)
              | (Method));
        } 

        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess, uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition, uint dwFlagsAndAttributes, IntPtr hTemplateFile);
        public static SafeFileHandle CreateFileR(string device)
        {
            string str = device.EndsWith(@"\") ? device.Substring(0, device.Length - 1) : device;
            return new SafeFileHandle(CreateFile(@"\\.\" + str, WinntConst.GENERIC_READ, WinntConst.FILE_SHARE_READ, IntPtr.Zero, WinntConst.OPEN_EXISTING, WinntConst.FILE_ATTRIBUTE_NORMAL, IntPtr.Zero), true);
        }

        [return: MarshalAs(UnmanagedType.Bool)]
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern bool DeviceIoControl([In] SafeFileHandle hDevice,
            [In] int dwIoControlCode, [In] IntPtr lpInBuffer,
            [In] int nInBufferSize, [Out] IntPtr lpOutBuffer,
            [In] int nOutBufferSize, out int lpBytesReturned,
            [In] IntPtr lpOverlapped);

        internal class WinntConst
        {
            // Fields
            internal static uint FILE_ATTRIBUTE_NORMAL = 0x80;
            internal static uint FILE_SHARE_READ = 1;
            internal static uint GENERIC_READ = 0x80000000;
            internal static uint OPEN_EXISTING = 3;
        }

        // Other code for DeviceIoControl from pinvoke.net
        [Flags]
        public enum EIOControlCode : uint
        {
            // DVD
            DvdReadStructure = (EFileDevice.Dvd << 16) | (0x0450 << 2) | EMethod.Buffered | (FileAccess.Read << 14),
            DvdStartSession = (EFileDevice.Dvd << 16) | (0x0400 << 2) | EMethod.Buffered | (FileAccess.Read << 14),
            DvdEndSession = (EFileDevice.Dvd << 16) | (0x0403 << 2) | EMethod.Buffered | (FileAccess.Read << 14)
        };

        [Flags]
        public enum EFileDevice : uint
        {
            Dvd = 0x00000033,
        }

        [Flags]
        public enum EMethod : uint
        {
            Buffered = 0,
            InDirect = 1,
            OutDirect = 2,
            Neither = 3
        }

        [DllImport("Kernel32.dll", EntryPoint="DeviceIoControl", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern bool DeviceIoControlAlt(
            Microsoft.Win32.SafeHandles.SafeFileHandle hDevice,
            EIOControlCode IoControlCode,
            [MarshalAs(UnmanagedType.AsAny)][In] object InBuffer,
            uint nInBufferSize,
            [MarshalAs(UnmanagedType.AsAny)][Out] object OutBuffer,
            uint nOutBufferSize,
            ref uint pBytesReturned,
            [In] ref System.Threading.NativeOverlapped Overlapped
        );
    }
}

要运行此代码，您需要在命令行上指定DVD驱动器的驱动器号。

输出

DeviceIoControl - Version One
IOCTL_DVD_START_SESSION
Result: False
error code: 122
IOCTL_DVD_READ_STRUCTURE
Skipping...
IOCTL_DVD_END_SESSION
error code: 87
Result: False

DeviceIoControl - Version Two
IOCTL_DVD_START_SESSION
Result: True
BytesReturned: 4
SessionId: -10
sizeof(SessionId): 4
IOCTL_DVD_READ_STRUCTURE
Skipping...
IOCTL_DVD_END_SESSION
Result: True
BytesReturned: 0

第一个版本在两次调用时都失败并带有给定的错误代码：

122 - ERROR_INSUFFICIENT_BUFFER

87 - ERROR_INVALID_PARAMETER

第二个版本似乎成功但是SessionId的值是初始化值-10。（从MSDN开始，此值应介于-1和3之间？）结束会话也会成功。

[注意：第二个版本的启动会话似乎只在其他所有调用上都成功，不知道为什么，但这似乎也是我所拥有的C代码中的一个问题，因为它的错误处理是再次重试。 ]

Answer 1

问题在于：

result = DeviceIoControl(_hdev, CTL_CODE(0x00000033, 0x0400, 0, 1),
   IntPtr.Zero, 0, (IntPtr)sessionId, Marshal.SizeOf(sessionId),
   out bytesReturned, IntPtr.Zero);

驱动程序需要在lpOutBuffer中指向缓冲区的指针，但是你提供了sessionId本身（它为零）。当然这不起作用。

您需要做什么：

IntPtr buffer = Marshal.AllocHGlobal(sizeof(int));
result = DeviceIoControl(_hdev, CTL_CODE(0x00000033, 0x0400, 0, 1),
    IntPtr.Zero, 0, buffer, sizeof(int), out bytesReturned, IntPtr.Zero);
int sessionId = Marshal.ReadInt32(buffer);
Marshal.FreeHGlobal(buffer);

BTW，同样适用于所有后续的DeviceIoControl调用，当你需要提供指向值的指针时，你再次提供值。您还需要检查您的CTL_CODE函数是否构建了有效的io代码。

同样，DeviceIoControl需要指向入口和出口结构的缓冲区。

使用IOCTL_DVD_ *控制代码从C＃调用DeviceIoControl

1 个答案: