获取文件夹ID C#

发布时间：2020-12-15 05:39:23 所属栏目：百科来源：网络整理

导读：我试图在他们的生命周期中跟踪文件和文件夹(他们可能被移动或重命名).我已经完成了搜索,发现 FileSystemWatcher可能是最流行的跟踪文件和文件夹的方式,但是,这对我来说不起作用,因为应用程序可能会或可能不会一直运行.我选择尝试通过ID跟踪文件夹. 我找到了

我试图在他们的生命周期中跟踪文件和文件夹(他们可能被移动或重命名).我已经完成了搜索,发现 FileSystemWatcher可能是最流行的跟踪文件和文件夹的方式,但是,这对我来说不起作用,因为应用程序可能会或可能不会一直运行.我选择尝试通过ID跟踪文件夹.

我找到了一种方法来跟踪从答案到this stack post的ID中的文件.我可以在this answer中基于方法B成功获取文件ID.

在搜索时我发现this stack post说他找到了使用FSCTL_GET_OBJECT_ID的解决方案.我花了很多时间试图弄清楚如何使用这个功能,但我无法绕过它.我基本上没有从C#中调用本机Windows函数的经验.

任何人都可以为我推动正确的方向吗？我觉得我必须遗漏一些明显的东西.

有没有理由C#无法访问文件/文件夹ID？跟踪文件/文件夹是不常见的？

编辑,添加代码：

static uint returnVal;

    //Working example to get File ID
    public static string GetFileId(string path)
    {
        WinAPI.BY_HANDLE_FILE_INFORMATION objectFileInfo = new WinAPI.BY_HANDLE_FILE_INFORMATION();

        FileInfo fi = new FileInfo(path);
        FileStream fs = fi.Open(FileMode.Open,FileAccess.Read,FileShare.ReadWrite);

        WinAPI.GetFileInformationByHandle(fs.Handle,out objectFileInfo);

        fs.Close();

        ulong fileIndex = ((ulong)objectFileInfo.FileIndexHigh << 32) + (ulong)objectFileInfo.FileIndexLow;

        return fileIndex.ToString();
    }

    public static string GetFolderId(string path)
    {
        //Get a handle on the given folder
        IntPtr cFile = WinAPI.CreateFile(
            path,WinAPI.GENERIC_READ,FileShare.Read,IntPtr.Zero,(FileMode)WinAPI.OPEN_EXISTING,WinAPI.FILE_FLAG_BACKUP_SEMANTICS,IntPtr.Zero);

        Console.WriteLine(path);
        Console.WriteLine(cFile);

        if ((int)cFile != -1)
        {
            int cFileSize = Marshal.SizeOf(typeof(IntPtr));
            Console.WriteLine("cFile size = {0}",cFileSize);

            IntPtr cFileBlob = Marshal.AllocHGlobal(cFileSize);
            uint numBytesRead = 0;

            WinAPI.DeviceIoControl(cFile,WinAPI.FSCTL_GET_OBJECT_ID,cFileBlob,(uint)cFileSize,ref numBytesRead,IntPtr.Zero);

            if (returnVal == 0)
            {
                Console.WriteLine(Marshal.GetLastWin32Error()); // Returning error 87 here
            }
        }

        //Should be returning the ID from the folder.
        return String.Empty;
    }

    public static void Main(string[] args)
    {
    Console.WriteLine(GetFileId(@"C:UsersMattDesktopTestDocument.txt"));
    Console.WriteLine(GetFolderId(@"C:UsersMattDesktop"));
    }

}

class WinAPI
{
    // Win32 constants for accessing files.
    internal const int GENERIC_READ = unchecked((int)0x80000000);
    internal const int FILE_FLAG_BACKUP_SEMANTICS = unchecked((int)0x02000000);
    internal const int OPEN_EXISTING = unchecked((int)3);
    internal const int FSCTL_GET_OBJECT_ID = 0x0009009c;
    internal const int FSCTL_CREATE_OR_GET_OBJECT_ID = 0x000900c0;

    [DllImport("kernel32.dll",SetLastError = true)]
    public static extern bool DeviceIoControl(IntPtr hDevice,uint dwIoControlCode,IntPtr lpInBuffer,uint nInBufferSize,[Out] IntPtr lpOutBuffer,uint nOutBufferSize,ref uint lpBytesReturned,IntPtr lpOverlapped);

    [DllImport("kernel32.dll",SetLastError = true)]
    public static extern bool GetFileInformationByHandle(IntPtr hFile,out BY_HANDLE_FILE_INFORMATION lpFileInformation);

    [DllImport("kernel32.dll",SetLastError = true)]
    public static extern IntPtr CreateFile(
       String fileName,int dwDesiredAccess,System.IO.FileShare dwShareMode,IntPtr securityAttrs_MustBeZero,System.IO.FileMode dwCreationDisposition,int dwFlagsAndAttributes,IntPtr hTemplateFile_MustBeZero);

    public struct BY_HANDLE_FILE_INFORMATION
    {
        public uint FileAttributes;
        public FILETIME CreationTime;
        public FILETIME LastAccessTime;
        public FILETIME LastWriteTime;
        public uint VolumeSerialNumber;
        public uint FileSizeHigh;
        public uint FileSizeLow;
        public uint NumberOfLinks;
        public uint FileIndexHigh;
        public uint FileIndexLow;
    }
}

我从DeviceIoControl返回错误“87”,这是根据MSDN上的帖子无效参数(由于声誉限制,我无法发布更多链接.)

解决方法

似乎你对FileSystemWatcher没有任何问题.那么,对于如何在C#中使用DeviceIoControl,看看这个答案：

Physical disk size not correct (IoCtlDiskGetDriveGeometry)

对于这个问题,它使用以下代码完成：

class Program {
    const uint FSCTL_GET_OBJECT_ID=0x0009009c;

    public static String GetFileId(String path) {
        using(var fs=File.Open(
            path,FileMode.OpenOrCreate,FileAccess.ReadWrite,FileShare.ReadWrite)
            ) {
            WinAPI.BY_HANDLE_FILE_INFORMATION info;
            WinAPI.GetFileInformationByHandle(fs.Handle,out info);
            return String.Format(
                    "{0:x}",((info.FileIndexHigh<<32)|info.FileIndexLow));
        }
    }

    public static WinAPI.FILE_OBJECTID_BUFFER GetFolderIdBuffer(String path) {
        using(var hFile=WinAPI.CreateFile(
            path,IntPtr.Zero
            )) {
            if(null==hFile||hFile.IsInvalid)
                throw new Win32Exception(Marshal.GetLastWin32Error());

            var buffer=default(WinAPI.FILE_OBJECTID_BUFFER);
            var nOutBufferSize=Marshal.SizeOf(buffer);
            var lpOutBuffer=Marshal.AllocHGlobal(nOutBufferSize);
            var lpBytesReturned=default(uint);

            var result=
                WinAPI.DeviceIoControl(
                    hFile,FSCTL_GET_OBJECT_ID,lpOutBuffer,nOutBufferSize,ref lpBytesReturned,IntPtr.Zero
                    );

            if(!result)
                throw new Win32Exception(Marshal.GetLastWin32Error());

            var type=typeof(WinAPI.FILE_OBJECTID_BUFFER);

            buffer=(WinAPI.FILE_OBJECTID_BUFFER)
                Marshal.PtrToStructure(lpOutBuffer,type);

            Marshal.FreeHGlobal(lpOutBuffer);
            return buffer;
        }
    }

    public static void Main(String[] args) {
        Console.WriteLine(
            GetFileId(@"C:UsersMattDesktopTestDocument.txt"));

        var buffer=GetFolderIdBuffer(@"C:UsersMattDesktop");

        var objectId=buffer.ObjectId
                .Reverse()
                .Select(x => x.ToString("x2"))
                .Aggregate(String.Concat);

        Console.WriteLine("{0}",objectId);
    }
}

class WinAPI {
    internal const int
        GENERIC_READ=unchecked((int)0x80000000),FILE_FLAG_BACKUP_SEMANTICS=unchecked((int)0x02000000),OPEN_EXISTING=unchecked((int)3);

    [StructLayout(LayoutKind.Sequential)]
    public struct FILE_OBJECTID_BUFFER {
        public struct Union {
            [MarshalAs(UnmanagedType.ByValArray,SizeConst=16)]
            public byte[] BirthVolumeId;

            [MarshalAs(UnmanagedType.ByValArray,SizeConst=16)]
            public byte[] BirthObjectId;

            [MarshalAs(UnmanagedType.ByValArray,SizeConst=16)]
            public byte[] DomainId;
        }

        [MarshalAs(UnmanagedType.ByValArray,SizeConst=16)]
        public byte[] ObjectId;

        public Union BirthInfo;

        [MarshalAs(UnmanagedType.ByValArray,SizeConst=48)]
        public byte[] ExtendedInfo;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct BY_HANDLE_FILE_INFORMATION {
        public uint FileAttributes;
        public FILETIME CreationTime;
        public FILETIME LastAccessTime;
        public FILETIME LastWriteTime;
        public uint VolumeSerialNumber;
        public uint FileSizeHigh;
        public uint FileSizeLow;
        public uint NumberOfLinks;
        public uint FileIndexHigh;
        public uint FileIndexLow;
    }

    [DllImport("kernel32.dll",SetLastError=true)]
    public static extern bool DeviceIoControl(
        SafeFileHandle hDevice,int nOutBufferSize,IntPtr lpOverlapped
        );

    [DllImport("kernel32.dll",SetLastError=true)]
    public static extern SafeFileHandle CreateFile(
        String fileName,IntPtr hTemplateFile_MustBeZero
        );

    [DllImport("kernel32.dll",SetLastError=true)]
    public static extern bool GetFileInformationByHandle(
        IntPtr hFile,out BY_HANDLE_FILE_INFORMATION lpFileInformation);
}

名称空间需要使用：

using Microsoft.Win32.SafeHandles;

（编辑：李大同）

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