Question

我正在使用P / Invoke从C＃进行原始驱动器访问。我遇到了一个问题，其中ReadFile因错误87而失败，但我无法弄清楚哪个参数不正确：我的缓冲区和我访问的驱动器都有很好的句柄，并且整数参数的类型是正确的。

我已将相关代码Here放入
另外，这里：
来自Drive.cs

public Boolean TryOpen(){
 .
 .
 .
 _hDrive = FileIO.Methods.CreateFile(
                    Info.PhysicalPath,
                    FileIO.FileAccess.GenericRead | FileIO.FileAccess.GenericWrite,
                    FileIO.FileShare.Read | FileIO.FileShare.Write,
                    IntPtr.Zero,
                    FileIO.CreationDisposition.OpenExisting,
                    FileIO.FileAttributes.NoBuffering | FileIO.FileAttributes.Write_Through | FileIO.FileAttributes.RandomAccess,
                    IntPtr.Zero);
                    .
                    .
                    .
}
private const Int32 DRIVE_PAGEBUFFER_SIZE = 0x0000FFFF;
private unsafe Boolean _bufferFrom(UInt32 pageIdx)
        {
            bool success = false;
            long retPtr;
            uint retBytes;
            if (FileIO.Methods.SeekFile(_hDrive, pageIdx * DRIVE_PAGEBUFFER_SIZE, out retPtr, FileIO.FileSeekMethod.FileBegin))
            {
                _curPageIdx = pageIdx;

                if (FileIO.Methods.ReadFile(_hDrive,_pageBuffer, 65535, out retBytes, null))
                {
                    success = true;
                }
                else
                {
                    Console.WriteLine(System.Runtime.InteropServices.Marshal.GetLastWin32Error());

                    //read failed.
                }
            }
            else
            {
                //seek failed.
            }
            return success;
        }

来自FileIO.cs：

public static class Methods
    {
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern SafeFileHandle CreateFile(
             string lpFileName,
            [MarshalAs(UnmanagedType.U4)] FileAccess access,
            [MarshalAs(UnmanagedType.U4)] FileShare share,
            [Optional] IntPtr security,
            [MarshalAs(UnmanagedType.U4)] CreationDisposition disposition,
            [MarshalAs(UnmanagedType.U4)] FileAttributes attributes,
             IntPtr template
            );
        [DllImport("kernel32.dll", SetLastError = true)]
        public static unsafe extern Boolean WriteFile(
            SafeFileHandle hFile,
            SafeBuffer lpBuffer,
            UInt32 nNumberOfBytesToWrite,
            out UInt32 lpNumberOfBytesToWrite,
             NativeOverlapped* lpOverlapped
            );
        [DllImport("kernel32.dll", SetLastError = true)]
        public static unsafe extern Boolean ReadFile(
             SafeFileHandle hFile,
             SafeBuffer lpBuffer,
             UInt32 nNumberOfBytesToRead,
             out UInt32 lpNumberOfBytesRead,
             NativeOverlapped* lpOverlapped
            );
        [DllImport("kernel32.dll", EntryPoint = "SetFilePointerEx", SetLastError = true)]
        public static extern Boolean SeekFile(
            [In] SafeFileHandle hFile,
            [In] Int64 liDistanceToMove,
            [Out] out Int64 lpNewFilePointer,
            [In][MarshalAs(UnmanagedType.U4)] FileSeekMethod seekMethod
            );
    }

来自MemBuffer.cs：

class MemBuffer:SafeBuffer
    {
        public MemBuffer(Int32 size):base(true)
        {
            this.SetHandle(Marshal.AllocHGlobal(size));
            this.Initialize((ulong)size);
        }
        protected override bool ReleaseHandle()
        {
            Marshal.FreeHGlobal(this.handle);
            return true;
        }
    }

我尝试重新定义ReadFile和WriteFile以使用标准IntPtrs（而不是SafeFileHandle和SafeBuffer），但它并没有产生任何影响。

我做错了什么？

Answer 1

原始驱动器访问和对使用FILE_FLAG_NO_BUFFERING（FileIO.FileAttributes.NoBuffering）打开的文件的访问要求寻求转移为基础设备扇区大小（通常为512字节或4096字节）的倍数的偏移量，并且读取和写入的数量是扇区大小的倍数。

您的代码正在尝试寻找偏移量为0xFFFF的倍数并尝试读取65535字节。这些不是512或4096的倍数，因此“无效参数”错误。

更改您的代码以使用对齐的大小（即0x10000 / 65536），它应该可以工作。很可能，您尝试读取的结构实际上是65536字节，而不是65535。

P / Invoke ReadFile不工作（错误87：无效参数）

1 个答案: