以编程方式检查 Windows 10 的区分大小写的目录属性

Question

自 2018 年 4 月以来，Windows 10 已经能够获取或设置使用 fsutil.exe 将目录标记为区分大小写。

有没有办法以编程方式查询目录的区分大小写，而无需运行 fsutil.exe 或不经意地创建具有不同大小写的文件以查看它们是否发生冲突？

我还没有真正找到任何方法来通过研究来测试这一点。我读过这是一个实际的 NTFS 属性，但在获取文件的属性时它没有显示出来。我还注意到，如果存在两个不同的大小写，FindFirstFile 将返回正确文件的大小写。除此之外，我不知道去哪里，因为这方面的信息真的不多。这东西还是很新的。

正如其他人所提到的，由于可比性问题，在 Windows 中区分大小写并不是一个好主意。我知道这一点，我的目标是扫描和使用文件系统中现有的区分大小写的目录。

进展：

我发现即使不使用FIND_FIRST_EX_CASE_SENSITIVE，Windows 的FindFirstFile 和朋友功能也会尊重目录的大小写敏感性。它不会返回大小写无效的文件。现在我想弄清楚是否有一个很好的方法来利用它。

Answer 1

感谢@eryksun 的评论，这是我的 P/Invoke 解决方案。

编辑2：添加SetDirectoryCaseSensitive()

编辑 3： 添加了IsDirectoryCaseSensitivitySupported()

我在使用FILE_INFORMATION_CLASS FileCaseSensitiveInformation 读取FILE_CASE_SENSITIVE_INFORMATION 结构时实现了本机方法NtQueryInformationFile。

public static partial class NativeMethods {
    public static readonly IntPtr INVALID_HANDLE = new IntPtr(-1);

    public const FileAttributes FILE_FLAG_BACKUP_SEMANTICS = (FileAttributes) 0x02000000;

    public enum NTSTATUS : uint {
        SUCCESS = 0x00000000,
        NOT_IMPLEMENTED = 0xC0000002,
        INVALID_INFO_CLASS = 0xC0000003,
        INVALID_PARAMETER = 0xC000000D,
        NOT_SUPPORTED = 0xC00000BB,
        DIRECTORY_NOT_EMPTY = 0xC0000101,
    }

    public enum FILE_INFORMATION_CLASS {
        None = 0,
        // Note: If you use the actual enum in here, remember to
        // start the first field at 1. There is nothing at zero.
        FileCaseSensitiveInformation = 71,
    }

    // It's called Flags in FileCaseSensitiveInformation so treat it as flags
    [Flags]
    public enum CASE_SENSITIVITY_FLAGS : uint {
        CaseInsensitiveDirectory = 0x00000000,
        CaseSensitiveDirectory = 0x00000001,
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct IO_STATUS_BLOCK {
        [MarshalAs(UnmanagedType.U4)]
        public NTSTATUS Status;
        public ulong Information;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct FILE_CASE_SENSITIVE_INFORMATION {
        [MarshalAs(UnmanagedType.U4)]
        public CASE_SENSITIVITY_FLAGS Flags;
    }

    // An override, specifically made for FileCaseSensitiveInformation, no IntPtr necessary.
    [DllImport("ntdll.dll")]
    [return: MarshalAs(UnmanagedType.U4)]
    public static extern NTSTATUS NtQueryInformationFile(
        IntPtr FileHandle,
        ref IO_STATUS_BLOCK IoStatusBlock,
        ref FILE_CASE_SENSITIVE_INFORMATION FileInformation,
        int Length,
        FILE_INFORMATION_CLASS FileInformationClass);

    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    public static extern IntPtr CreateFile(
            [MarshalAs(UnmanagedType.LPTStr)] string filename,
            [MarshalAs(UnmanagedType.U4)] FileAccess access,
            [MarshalAs(UnmanagedType.U4)] FileShare share,
            IntPtr securityAttributes, // optional SECURITY_ATTRIBUTES struct or IntPtr.Zero
            [MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
            [MarshalAs(UnmanagedType.U4)] FileAttributes flagsAndAttributes,
            IntPtr templateFile);

    [DllImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool CloseHandle(
        IntPtr hObject);

    public static bool IsDirectoryCaseSensitive(string directory, bool throwOnError = true) {
        // Read access is NOT required
        IntPtr hFile = CreateFile(directory, 0, FileShare.ReadWrite,
                                    IntPtr.Zero, FileMode.Open,
                                    FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero);
        if (hFile == INVALID_HANDLE)
            throw new Win32Exception();
        try {
            IO_STATUS_BLOCK iosb = new IO_STATUS_BLOCK();
            FILE_CASE_SENSITIVE_INFORMATION caseSensitive = new FILE_CASE_SENSITIVE_INFORMATION();
            NTSTATUS status = NtQueryInformationFile(hFile, ref iosb, ref caseSensitive,
                                                        Marshal.SizeOf<FILE_CASE_SENSITIVE_INFORMATION>(),
                                                        FILE_INFORMATION_CLASS.FileCaseSensitiveInformation);
            switch (status) {
            case NTSTATUS.SUCCESS:
                return caseSensitive.Flags.HasFlag(CASE_SENSITIVITY_FLAGS.CaseSensitiveDirectory);

            case NTSTATUS.NOT_IMPLEMENTED:
            case NTSTATUS.NOT_SUPPORTED:
            case NTSTATUS.INVALID_INFO_CLASS:
            case NTSTATUS.INVALID_PARAMETER:
                // Not supported, must be older version of windows.
                // Directory case sensitivity is impossible.
                return false;
            default:
                throw new Exception($"Unknown NTSTATUS: {(uint)status:X8}!");
            }
        }
        finally {
            CloseHandle(hFile);
        }
    }
}

这里是通过实现NTSetInformationFile来设置目录区分大小写的实现。 （它的参数列表与NTQueryInformationFile 相同。再次感谢@eryksun 的见解，问题得到了解决。

FILE_WRITE_ATTRIBUTES 是一个未在 C# 中实现的 FileAccess 标志，因此需要从值 0x100 定义和/或强制转换。

partial class NativeMethods {
    public const FileAccess FILE_WRITE_ATTRIBUTES = (FileAccess) 0x00000100;

    // An override, specifically made for FileCaseSensitiveInformation, no IntPtr necessary.
    [DllImport("ntdll.dll")]
    [return: MarshalAs(UnmanagedType.U4)]
    public static extern NTSTATUS NtSetInformationFile(
        IntPtr FileHandle,
        ref IO_STATUS_BLOCK IoStatusBlock,
        ref FILE_CASE_SENSITIVE_INFORMATION FileInformation,
        int Length,
        FILE_INFORMATION_CLASS FileInformationClass);

    // Require's elevated priviledges
    public static void SetDirectoryCaseSensitive(string directory, bool enable) {
        // FILE_WRITE_ATTRIBUTES access is the only requirement
        IntPtr hFile = CreateFile(directory, FILE_WRITE_ATTRIBUTES, FileShare.ReadWrite,
                                    IntPtr.Zero, FileMode.Open,
                                    FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero);
        if (hFile == INVALID_HANDLE)
            throw new Win32Exception();
        try {
            IO_STATUS_BLOCK iosb = new IO_STATUS_BLOCK();
            FILE_CASE_SENSITIVE_INFORMATION caseSensitive = new FILE_CASE_SENSITIVE_INFORMATION();
            if (enable)
                caseSensitive.Flags |= CASE_SENSITIVITY_FLAGS.CaseSensitiveDirectory;
            NTSTATUS status = NtSetInformationFile(hFile, ref iosb, ref caseSensitive,
                                                    Marshal.SizeOf<FILE_CASE_SENSITIVE_INFORMATION>(),
                                                    FILE_INFORMATION_CLASS.FileCaseSensitiveInformation);
            switch (status) {
            case NTSTATUS.SUCCESS:
                return;
            case NTSTATUS.DIRECTORY_NOT_EMPTY:
                throw new IOException($"Directory \"{directory}\" contains matching " +
                                      $"case-insensitive files!");

            case NTSTATUS.NOT_IMPLEMENTED:
            case NTSTATUS.NOT_SUPPORTED:
            case NTSTATUS.INVALID_INFO_CLASS:
            case NTSTATUS.INVALID_PARAMETER:
                // Not supported, must be older version of windows.
                // Directory case sensitivity is impossible.
                throw new NotSupportedException("This version of Windows does not support directory case sensitivity!");
            default:
                throw new Exception($"Unknown NTSTATUS: {(uint)status:X8}!");
            }
        }
        finally {
            CloseHandle(hFile);
        }
    }
}

最后，如果 Windows 版本支持区分大小写的目录，我添加了一种计算一次的方法。这只是在 Temp 中创建一个具有常量 GUID 名称的文件夹并检查 NTSTATUS 结果（因此它可以检查它知道它可以访问的文件夹）。

partial class NativeMethods {
    // Use the same directory so it does not need to be recreated when restarting the program
    private static readonly string TempDirectory =
        Path.Combine(Path.GetTempPath(), "88DEB13C-E516-46C3-97CA-46A8D0DDD8B2");

    private static bool? isSupported;
    public static bool IsDirectoryCaseSensitivitySupported() {
        if (isSupported.HasValue)
            return isSupported.Value;

        // Make sure the directory exists
        if (!Directory.Exists(TempDirectory))
            Directory.CreateDirectory(TempDirectory);

        IntPtr hFile = CreateFile(TempDirectory, 0, FileShare.ReadWrite,
                                IntPtr.Zero, FileMode.Open,
                                FILE_FLAG_BACKUP_SEMANTICS, IntPtr.Zero);
        if (hFile == INVALID_HANDLE)
            throw new Exception("Failed to open file while checking case sensitivity support!");
        try {
            IO_STATUS_BLOCK iosb = new IO_STATUS_BLOCK();
            FILE_CASE_SENSITIVE_INFORMATION caseSensitive = new FILE_CASE_SENSITIVE_INFORMATION();
            // Strangely enough, this doesn't fail on files
            NTSTATUS result = NtQueryInformationFile(hFile, ref iosb, ref caseSensitive,
                                                        Marshal.SizeOf<FILE_CASE_SENSITIVE_INFORMATION>(),
                                                        FILE_INFORMATION_CLASS.FileCaseSensitiveInformation);
            switch (result) {
            case NTSTATUS.SUCCESS:
                return (isSupported = true).Value;
            case NTSTATUS.NOT_IMPLEMENTED:
            case NTSTATUS.INVALID_INFO_CLASS:
            case NTSTATUS.INVALID_PARAMETER:
            case NTSTATUS.NOT_SUPPORTED:
                // Not supported, must be older version of windows.
                // Directory case sensitivity is impossible.
                return (isSupported = false).Value;
            default:
                throw new Exception($"Unknown NTSTATUS {(uint)result:X8} while checking case sensitivity support!");
            }
        }
        finally {
            CloseHandle(hFile);
            try {
                // CHOOSE: If you delete the folder, future calls to this will not be any faster
                // Directory.Delete(TempDirectory);
            }
            catch { }
        }
    }
}