C#「NTFSのADSでファイルにコメントをつける」

using System.Runtime.InteropServices;
using System.Runtime.ConstrainedExecution;
using System.Security;
using System.Diagnostics;

namespace EditComment;

public partial class Form1 : Form
{
    // CreateFileW
    [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
    static extern IntPtr CreateFileW(
        [MarshalAs(UnmanagedType.LPWStr)] string filename,
        [MarshalAs(UnmanagedType.U4)] FileAccess access,
        [MarshalAs(UnmanagedType.U4)] FileShare share,
        IntPtr securityAttributes,
        [MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
        [MarshalAs(UnmanagedType.U4)] FileAttributes flagsAndAttributes,
        IntPtr templateFile);
    
    // CloseHandle
    [DllImport("kernel32.dll", SetLastError=true)]
    [SuppressUnmanagedCodeSecurity]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool CloseHandle(IntPtr hObject);

    // WriteFile
    [DllImport("kernel32.dll")]
    static extern bool WriteFile(IntPtr hFile, byte [] lpBuffer,
        uint nNumberOfBytesToWrite, out uint lpNumberOfBytesWritten,
        [In] ref System.Threading.NativeOverlapped lpOverlapped);

    // ReadFile
    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool ReadFile(IntPtr hFile, [Out] byte[] lpBuffer,
        uint nNumberOfBytesToRead, out uint lpNumberOfBytesRead, IntPtr lpOverlapped);
    
    // GetFileSizeEx
    [DllImport("kernel32.dll")]
    static extern bool GetFileSizeEx(IntPtr hFile, out long lpFileSize);

    public Form1()
    {
        InitializeComponent();
        
        string[] args = System.Environment.GetCommandLineArgs();

        if (2 > args.Length) return;

        string file = args[1];
        if (!File.Exists(file)) return;

        string msg = String.Format("「{0}」のコメント", file);
        string comment = "";

        System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);

        var handle = CreateFileW(file+":Comment", FileAccess.ReadWrite, FileShare.Read, IntPtr.Zero, FileMode.OpenOrCreate, FileAttributes.Normal, IntPtr.Zero);
        if (handle != IntPtr.Zero)
        {
            Debug.Print("Success");

            long len = 0;
            GetFileSizeEx(handle, out len);
            if (len > 0)
            {
                UInt32 sz = 0;
                UInt32 l = (UInt32)len;
                byte[] buf = new byte[len];
                ReadFile(handle, buf, l, out sz, IntPtr.Zero);
                comment = (System.Text.Encoding.GetEncoding("Shift_JIS")).GetString(buf);
            }
        }
        else
        {
            Debug.Print("Failed");
            return;
        }


        Size = new Size(640, 360);
        Text = "コメント";

        var panel = new TableLayoutPanel
        {
            Dock = DockStyle.Fill,
            Padding = new Padding(16),
        };

        var label = new Label
        {
            Dock = DockStyle.Fill,
            Margin = new Padding(16),
            Text = msg,
        };
        panel.Controls.Add(label, 0, 0);

        var tbox = new TextBox
        {
            Dock = DockStyle.Fill,
            Margin = new Padding(16),
            Text = comment,
        };
        panel.Controls.Add(tbox, 0, 1);

        var panel2 = new FlowLayoutPanel
        {
            Margin = new Padding(16),
            Anchor = AnchorStyles.None,
            Dock = DockStyle.Fill,
        };
        panel.Controls.Add(panel2, 0, 2);

        var okBtn = new Button
        {
            Margin = new Padding(16),
            Size = new Size(100, 40),
            Text = "OK",
        };
        panel2.Controls.Add(okBtn);

        var cancelBtn = new Button
        {
            Margin = new Padding(16),
            Size = new Size(100, 40),
            Text = "Cancel",
        };
        panel2.Controls.Add(cancelBtn);

        Controls.Add(panel);
        Action<Form> okAction = (Form form) =>
        {
            string str = tbox.Text;
            byte[] bytes = (System.Text.Encoding.GetEncoding("Shift_JIS")).GetBytes(str.ToCharArray());
            UInt32 length = (UInt32)bytes.Length;
            UInt32 sz = 0;
            System.Threading.NativeOverlapped lpOverlapped = new();
            WriteFile(handle, bytes, length, out sz, ref lpOverlapped);

            CloseHandle(handle);
            form.Close();
        };
        Action<Form> cancelAction = (Form form) =>
        {
            CloseHandle(handle);
            form.Close();
        };
        okBtn.Click += (s, e) => okAction(this);
        tbox.KeyDown += (s, e) =>
        {
            if (e.KeyCode == Keys.Return)
            {
                okAction(this);
            }
        };
        cancelBtn.Click += (s, e) => cancelAction(this);
    }
}