Add VFS

pkNX.Containers/VFS/FileSystems/ReadOnlyFileSystem.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace pkNX.Containers.VFS;
+
+public class ReadOnlyFileSystem : IFileSystem
+{
+    public bool IsReadOnly => true;
+
+    public IFileSystem FileSystem { get; }
+
+    public ReadOnlyFileSystem(IFileSystem fileSystem)
+    {
+        FileSystem = fileSystem;
+    }
+
+    public void Dispose()
+    {
+        FileSystem.Dispose();
+        GC.SuppressFinalize(this);
+    }
+
+    public IEnumerable<FileSystemPath> GetEntities(FileSystemPath path)
+    {
+        return FileSystem.GetEntities(path);
+    }
+
+    public bool Exists(FileSystemPath path)
+    {
+        return FileSystem.Exists(path);
+    }
+
+    public Stream OpenFile(FileSystemPath path, FileAccess access)
+    {
+        if (access != FileAccess.Read)
+            throw new InvalidOperationException("This is a read-only filesystem.");
+        return FileSystem.OpenFile(path, access);
+    }
+
+    public Stream CreateFile(FileSystemPath path)
+    {
+        throw new InvalidOperationException("This is a read-only filesystem.");
+    }
+
+    public void CreateDirectory(FileSystemPath path)
+    {
+        throw new InvalidOperationException("This is a read-only filesystem.");
+    }
+
+    public void Delete(FileSystemPath path)
+    {
+        throw new InvalidOperationException("This is a read-only filesystem.");
+    }
+}