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rkttu/script.cs

Created August 11, 2025 02:21
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  1. rkttu created this gist Aug 11, 2025.
    79 changes: 79 additions & 0 deletions script.cs
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,79 @@
    #!/usr/bin/env dotnet
    #:package ClosedXML@0.105.0
    #:property OutputType=Library
    #:property NativeLib=Shared
    #:property RuntimeIdentifier=win-x64
    #:property AllowUnsafeBlocks=true

    // dotnet publish .\script.cs -o bin
    // %windir%\system32\rundll32.exe bin\script.dll,EntryA "HelloWorld.xlsx"
    // start HelloWorld.xlsx

    using System.Runtime.CompilerServices;
    using System.Runtime.InteropServices;
    using ClosedXML.Excel;

    public static unsafe class Exports
    {
    // ANSI version: rundll32 "<...>\RundllXlsx.dll",EntryA "C:\path\HelloWorld.xlsx"
    [UnmanagedCallersOnly(EntryPoint = "EntryA", CallConvs = new[] { typeof(CallConvStdcall) })]
    public static void EntryA(nint hwnd, nint hinst, sbyte* cmdLine, int nCmdShow)
    => Run(hwnd, PtrToManagedAnsi(cmdLine));

    private static void Run(nint hwnd, string? rawArgs)
    {
    try
    {
    var path = ParseFirstToken(rawArgs);
    if (string.IsNullOrWhiteSpace(path))
    {
    Show(hwnd,
    "Usage:\nrundll32.exe \"<dll>\",EntryA \"C:\\out\\HelloWorld.xlsx\"",
    "RundllXlsx - Missing Path");
    return;
    }

    path = Path.GetFullPath(path.Trim());
    var dir = Path.GetDirectoryName(path);
    if (!string.IsNullOrEmpty(dir)) Directory.CreateDirectory(dir);

    CreateXlsx(path);

    Show(hwnd, $"XLSX written:\n{path}", "RundllXlsx - Success");
    }
    catch (Exception ex)
    {
    Show(hwnd, ex.ToString(), "RundllXlsx - Error");
    }
    }

    private static void CreateXlsx(string path)
    {
    using var wb = new XLWorkbook();
    var ws = wb.Worksheets.Add("Sample Sheet");
    ws.Cell("A1").Value = "Hello World!";
    ws.Cell("A2").FormulaA1 = "=MID(A1, 7, 5)";
    wb.SaveAs(path);
    }

    // ---- helpers ----
    private static string? PtrToManagedAnsi(sbyte* p)
    => p == null ? null : Marshal.PtrToStringAnsi((nint)p);
    private static string? PtrToManagedUni(char* p)
    => p == null ? null : Marshal.PtrToStringUni((nint)p);

    private static string? ParseFirstToken(string? s)
    {
    if (string.IsNullOrWhiteSpace(s)) return null;
    s = s.Trim();
    if (s.StartsWith("\"") && s.EndsWith("\"") && s.Length >= 2)
    return s.Substring(1, s.Length - 2);
    var idx = s.IndexOf(' ');
    return idx < 0 ? s : s.Substring(0, idx);
    }

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    private static extern int MessageBoxW(nint hWnd, string text, string caption, uint type);

    private static void Show(nint hwnd, string text, string caption) => MessageBoxW(hwnd, text, caption, 0);
    }