Fixed a security issue in how AI Studio runs plugins (#1054)

app/MindWork AI Studio/Tools/PluginSystem/NoLuaFileSystem.cs

@@ -0,0 +1,35 @@
+using Lua.IO;
+
+namespace AIStudio.Tools.PluginSystem;
+
+/// <summary>
+/// The file system of the Lua runtime of plugins, in which no file exists.
+/// </summary>
+/// <remarks>
+/// The Lua runtime reaches files through its file system: dofile and loadfile do, and so does require
+/// for every module the module loader does not know, which it then looks for along package.path,
+/// relative to the working directory of the app. Plugins are shared between users, and the assistant
+/// builder runs code a model wrote, so none of them may reach a file this way.<br/><br/>
+/// A plugin still loads the files of its own directory with require: the module loader, see
+/// PluginLoader, reads them without this file system.
+/// </remarks>
+public sealed class NoLuaFileSystem : ILuaFileSystem
+{
+    private const string NO_FILES = "Plugins cannot reach files through the Lua runtime.";
+
+    #region Implementation of ILuaFileSystem
+
+    public bool IsReadable(string path) => false;
+
+    public ValueTask<ILuaStream> Open(string path, LuaFileOpenMode mode, CancellationToken cancellationToken) => throw new NotSupportedException(NO_FILES);
+
+    public ValueTask Rename(string oldName, string newName, CancellationToken cancellationToken) => throw new NotSupportedException(NO_FILES);
+
+    public ValueTask Remove(string path, CancellationToken cancellationToken) => throw new NotSupportedException(NO_FILES);
+
+    public string GetTempFileName() => throw new NotSupportedException(NO_FILES);
+
+    public ValueTask<ILuaStream> OpenTempFileStream(CancellationToken cancellationToken) => throw new NotSupportedException(NO_FILES);
+
+    #endregion
+}