initial commit, 4.5 stable

modules/mono/glue/GodotSharp/GodotPlugins/PluginLoadContext.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Runtime.Loader;
+
+namespace GodotPlugins
+{
+    public class PluginLoadContext : AssemblyLoadContext
+    {
+        private readonly AssemblyDependencyResolver _resolver;
+        private readonly ICollection<string> _sharedAssemblies;
+        private readonly AssemblyLoadContext _mainLoadContext;
+
+        public string? AssemblyLoadedPath { get; private set; }
+
+        public PluginLoadContext(string pluginPath, ICollection<string> sharedAssemblies,
+            AssemblyLoadContext mainLoadContext, bool isCollectible)
+            : base(isCollectible)
+        {
+            _resolver = new AssemblyDependencyResolver(pluginPath);
+            _sharedAssemblies = sharedAssemblies;
+            _mainLoadContext = mainLoadContext;
+
+            if (string.IsNullOrEmpty(AppContext.BaseDirectory))
+            {
+                // See https://github.com/dotnet/runtime/blob/v6.0.0/src/libraries/System.Private.CoreLib/src/System/AppContext.AnyOS.cs#L17-L35
+                // but Assembly.Location is unavailable, because we load assemblies from memory.
+                string? baseDirectory = Path.GetDirectoryName(pluginPath);
+                if (baseDirectory != null)
+                {
+                    if (!Path.EndsInDirectorySeparator(baseDirectory))
+                        baseDirectory += Path.DirectorySeparatorChar;
+                    // This SetData call effectively sets AppContext.BaseDirectory
+                    // See https://github.com/dotnet/runtime/blob/v6.0.0/src/libraries/System.Private.CoreLib/src/System/AppContext.cs#L21-L25
+                    AppDomain.CurrentDomain.SetData("APP_CONTEXT_BASE_DIRECTORY", baseDirectory);
+                }
+                else
+                {
+                    // TODO: How to log from GodotPlugins? (delegate pointer?)
+                    Console.Error.WriteLine("Failed to set AppContext.BaseDirectory. Dynamic loading of libraries may fail.");
+                }
+            }
+        }
+
+        protected override Assembly? Load(AssemblyName assemblyName)
+        {
+            if (assemblyName.Name == null)
+                return null;
+
+            if (_sharedAssemblies.Contains(assemblyName.Name))
+                return _mainLoadContext.LoadFromAssemblyName(assemblyName);
+
+            string? assemblyPath = _resolver.ResolveAssemblyToPath(assemblyName);
+            if (assemblyPath != null)
+            {
+                AssemblyLoadedPath = assemblyPath;
+
+                // Load in memory to prevent locking the file
+                using var assemblyFile = File.Open(assemblyPath, FileMode.Open, FileAccess.Read, FileShare.Read);
+                string pdbPath = Path.ChangeExtension(assemblyPath, ".pdb");
+
+                if (File.Exists(pdbPath))
+                {
+                    using var pdbFile = File.Open(pdbPath, FileMode.Open, FileAccess.Read, FileShare.Read);
+                    return LoadFromStream(assemblyFile, pdbFile);
+                }
+
+                return LoadFromStream(assemblyFile);
+            }
+
+            return null;
+        }
+
+        protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
+        {
+            string? libraryPath = _resolver.ResolveUnmanagedDllToPath(unmanagedDllName);
+            if (libraryPath != null)
+                return LoadUnmanagedDllFromPath(libraryPath);
+
+            return IntPtr.Zero;
+        }
+    }
+}