preprocess mods through Mono.Cecil to allow rewriting later (#166)

5 files changed, 133 insertions, 29 deletions

diff --git a/src/StardewModdingAPI.Installer/StardewModdingAPI.Installer.csproj b/src/StardewModdingAPI.Installer/StardewModdingAPI.Installer.csproj
index 6f9ed2eb..23e2d278 100644
--- a/src/StardewModdingAPI.Installer/StardewModdingAPI.Installer.csproj
+++ b/src/StardewModdingAPI.Installer/StardewModdingAPI.Installer.csproj
@@ -67,6 +67,7 @@
     <Copy SourceFiles="$(TargetDir)\readme.txt" DestinationFiles="$(CompiledInstallerPath)\readme.txt" />
     <!-- copy SMAPI files for Mono -->
     <Copy Condition="$(OS) != 'Windows_NT'" SourceFiles="$(CompiledSmapiPath)\Newtonsoft.Json.dll" DestinationFolder="$(CompiledInstallerPath)\Mono" />
+    <Copy Condition="$(OS) != 'Windows_NT'" SourceFiles="$(CompiledSmapiPath)\Mono.Cecil.dll" DestinationFolder="$(CompiledInstallerPath)\Mono" />
     <Copy Condition="$(OS) != 'Windows_NT'" SourceFiles="$(CompiledSmapiPath)\StardewModdingAPI.exe" DestinationFolder="$(CompiledInstallerPath)\Mono" />
     <Copy Condition="$(OS) != 'Windows_NT'" SourceFiles="$(CompiledSmapiPath)\StardewModdingAPI.exe.mdb" DestinationFolder="$(CompiledInstallerPath)\Mono" />
     <Copy Condition="$(OS) != 'Windows_NT'" SourceFiles="$(CompiledSmapiPath)\StardewModdingAPI-settings.json" DestinationFolder="$(CompiledInstallerPath)\Mono" />
diff --git a/src/StardewModdingAPI/Framework/ModAssemblyLoader.cs b/src/StardewModdingAPI/Framework/ModAssemblyLoader.cs
new file mode 100644
index 00000000..2615e1f7
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/ModAssemblyLoader.cs
@@ -0,0 +1,65 @@
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Security.Cryptography;
+using Mono.Cecil;
+
+namespace StardewModdingAPI.Framework
+{
+    /// <summary>Loads mod assemblies.</summary>
+    internal class ModAssemblyLoader
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The directory in which to cache data.</summary>
+        private readonly string CacheDirPath;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="cacheDirPath">The cache directory.</param>
+        public ModAssemblyLoader(string cacheDirPath)
+        {
+            this.CacheDirPath = cacheDirPath;
+        }
+
+        /// <summary>Read an assembly from the given path.</summary>
+        /// <param name="assemblyPath">The assembly file path.</param>
+        public Assembly ProcessAssembly(string assemblyPath)
+        {
+            // read assembly data
+            byte[] assemblyBytes = File.ReadAllBytes(assemblyPath);
+            byte[] hash = MD5.Create().ComputeHash(assemblyBytes);
+
+            // get cache data
+            string key = Path.GetFileNameWithoutExtension(assemblyPath);
+            string cachePath = Path.Combine(this.CacheDirPath, $"{key}.dll");
+            string cacheHashPath = Path.Combine(this.CacheDirPath, $"{key}-hash.txt");
+            bool canUseCache = File.Exists(cachePath) && File.Exists(cacheHashPath) && hash.SequenceEqual(File.ReadAllBytes(cacheHashPath));
+
+            // process assembly if not cached
+            if (!canUseCache)
+            {
+                // read assembly definition
+                AssemblyDefinition definition;
+                using (Stream readStream = new MemoryStream(assemblyBytes))
+                    definition = AssemblyDefinition.ReadAssembly(readStream);
+
+                // write cache
+                using (MemoryStream outStream = new MemoryStream())
+                {
+                    definition.Write(outStream);
+                    byte[] outBytes = outStream.ToArray();
+                    File.WriteAllBytes(cachePath, outBytes);
+                    File.WriteAllBytes(cacheHashPath, hash);
+                }
+            }
+
+            // load assembly
+            return Assembly.UnsafeLoadFrom(cachePath);
+        }
+    }
+}
diff --git a/src/StardewModdingAPI/Program.cs b/src/StardewModdingAPI/Program.cs
index d31a1d39..12b6cad4 100644
--- a/src/StardewModdingAPI/Program.cs
+++ b/src/StardewModdingAPI/Program.cs
@@ -33,6 +33,9 @@ namespace StardewModdingAPI
         /// <summary>The full path to the folder containing mods.</summary>
         private static readonly string ModPath = Path.Combine(Constants.ExecutionPath, "Mods");
 
+        /// <summary>The full path to the folder containing cached SMAPI data.</summary>
+        private static readonly string CachePath = Path.Combine(Program.ModPath, ".cache");
+
         /// <summary>The log file to which to write messages.</summary>
         private static readonly LogFileManager LogFile = new LogFileManager(Constants.LogPath);
 
@@ -126,6 +129,7 @@ namespace StardewModdingAPI
                 Program.Monitor.Log("Loading SMAPI...");
                 Console.Title = Constants.ConsoleTitle;
                 Program.VerifyPath(Program.ModPath);
+                Program.VerifyPath(Program.CachePath);
                 Program.VerifyPath(Constants.LogDir);
                 if (!File.Exists(Program.GameExecutablePath))
                 {
@@ -293,6 +297,8 @@ namespace StardewModdingAPI
         private static void LoadMods()
         {
             Program.Monitor.Log("Loading mods...");
+
+            ModAssemblyLoader modAssemblyLoader = new ModAssemblyLoader(Program.CachePath);
             foreach (string directory in Directory.GetDirectories(Program.ModPath))
             {
                 foreach (string manifestPath in Directory.GetFiles(directory, "manifest.json"))
@@ -382,9 +388,11 @@ namespace StardewModdingAPI
                         }
                     }
 
-                    // load DLL & hook up mod
+                    // load assembly
+                    Assembly modAssembly;
                     try
                     {
+                        // get assembly path
                         string assemblyPath = Path.Combine(directory, manifest.EntryDll);
                         if (!File.Exists(assemblyPath))
                         {
@@ -392,36 +400,47 @@ namespace StardewModdingAPI
                             continue;
                         }
 
-                        Assembly modAssembly = Assembly.UnsafeLoadFrom(assemblyPath);
-                        if (modAssembly.DefinedTypes.Count(x => x.BaseType == typeof(Mod)) > 0)
+                        // read assembly
+                        modAssembly = modAssemblyLoader.ProcessAssembly(assemblyPath);
+                        if (modAssembly.DefinedTypes.Count(x => x.BaseType == typeof(Mod)) == 0)
                         {
-                            TypeInfo modEntryType = modAssembly.DefinedTypes.First(x => x.BaseType == typeof(Mod));
-                            Mod modEntry = (Mod)modAssembly.CreateInstance(modEntryType.ToString());
-                            if (modEntry != null)
-                            {
-                                // track mod
-                                Program.ModRegistry.Add(manifest, modAssembly);
-
-                                // hook up mod
-                                modEntry.Manifest = manifest;
-                                modEntry.Helper = helper;
-                                modEntry.Monitor = new Monitor(manifest.Name, Program.LogFile) { ShowTraceInConsole = Program.DeveloperMode };
-                                modEntry.PathOnDisk = directory;
-                                Program.Monitor.Log($"Loaded mod: {modEntry.Manifest.Name} by {modEntry.Manifest.Author}, v{modEntry.Manifest.Version} | {modEntry.Manifest.Description}", LogLevel.Info);
-                                Program.ModsLoaded += 1;
-                                modEntry.Entry(); // deprecated since 1.0
-                                modEntry.Entry((ModHelper)modEntry.Helper); // deprecated since 1.1
-                                modEntry.Entry(modEntry.Helper); // deprecated since 1.1
-
-                                // raise deprecation warning for old Entry() method
-                                if (Program.DeprecationManager.IsVirtualMethodImplemented(modEntryType, typeof(Mod), nameof(Mod.Entry), new[] { typeof(object[]) }))
-                                    Program.DeprecationManager.Warn(manifest.Name, $"an old version of {nameof(Mod)}.{nameof(Mod.Entry)}", "1.0", DeprecationLevel.Notice);
-                                if (Program.DeprecationManager.IsVirtualMethodImplemented(modEntryType, typeof(Mod), nameof(Mod.Entry), new[] { typeof(ModHelper) }))
-                                    Program.DeprecationManager.Warn(manifest.Name, $"an old version of {nameof(Mod)}.{nameof(Mod.Entry)}", "1.1", DeprecationLevel.Notice);
-                            }
-                        }
-                        else
                             Program.Monitor.Log($"{errorPrefix}: the mod DLL does not contain an implementation of the 'Mod' class.", LogLevel.Error);
+                            continue;
+                        }
+                    }
+                    catch (Exception ex)
+                    {
+                        Program.Monitor.Log($"{errorPrefix}: an error occurred while optimising the target DLL.\n{ex}", LogLevel.Error);
+                        continue;
+                    }
+
+                    // hook up mod
+                    try
+                    {
+                        TypeInfo modEntryType = modAssembly.DefinedTypes.First(x => x.BaseType == typeof(Mod));
+                        Mod modEntry = (Mod)modAssembly.CreateInstance(modEntryType.ToString());
+                        if (modEntry != null)
+                        {
+                            // track mod
+                            Program.ModRegistry.Add(manifest, modAssembly);
+
+                            // hook up mod
+                            modEntry.Manifest = manifest;
+                            modEntry.Helper = helper;
+                            modEntry.Monitor = new Monitor(manifest.Name, Program.LogFile) { ShowTraceInConsole = Program.DeveloperMode };
+                            modEntry.PathOnDisk = directory;
+                            Program.Monitor.Log($"Loaded mod: {modEntry.Manifest.Name} by {modEntry.Manifest.Author}, v{modEntry.Manifest.Version} | {modEntry.Manifest.Description}", LogLevel.Info);
+                            Program.ModsLoaded += 1;
+                            modEntry.Entry(); // deprecated since 1.0
+                            modEntry.Entry((ModHelper)modEntry.Helper); // deprecated since 1.1
+                            modEntry.Entry(modEntry.Helper); // deprecated since 1.1
+
+                            // raise deprecation warning for old Entry() method
+                            if (Program.DeprecationManager.IsVirtualMethodImplemented(modEntryType, typeof(Mod), nameof(Mod.Entry), new[] { typeof(object[]) }))
+                                Program.DeprecationManager.Warn(manifest.Name, $"an old version of {nameof(Mod)}.{nameof(Mod.Entry)}", "1.0", DeprecationLevel.Notice);
+                            if (Program.DeprecationManager.IsVirtualMethodImplemented(modEntryType, typeof(Mod), nameof(Mod.Entry), new[] { typeof(ModHelper) }))
+                                Program.DeprecationManager.Warn(manifest.Name, $"an old version of {nameof(Mod)}.{nameof(Mod.Entry)}", "1.1", DeprecationLevel.Notice);
+                        }
                     }
                     catch (Exception ex)
                     {
diff --git a/src/StardewModdingAPI/StardewModdingAPI.csproj b/src/StardewModdingAPI/StardewModdingAPI.csproj
index 0b6a185e..f3dbc45a 100644
--- a/src/StardewModdingAPI/StardewModdingAPI.csproj
+++ b/src/StardewModdingAPI/StardewModdingAPI.csproj
@@ -140,6 +140,22 @@
     </Otherwise>
   </Choose>
   <ItemGroup>
+    <Reference Include="Mono.Cecil, Version=0.9.6.0, Culture=neutral, PublicKeyToken=0738eb9f132ed756, processorArchitecture=MSIL">
+      <HintPath>..\packages\Mono.Cecil.0.9.6.4\lib\net45\Mono.Cecil.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="Mono.Cecil.Mdb, Version=0.9.6.0, Culture=neutral, PublicKeyToken=0738eb9f132ed756, processorArchitecture=MSIL">
+      <HintPath>..\packages\Mono.Cecil.0.9.6.4\lib\net45\Mono.Cecil.Mdb.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="Mono.Cecil.Pdb, Version=0.9.6.0, Culture=neutral, PublicKeyToken=0738eb9f132ed756, processorArchitecture=MSIL">
+      <HintPath>..\packages\Mono.Cecil.0.9.6.4\lib\net45\Mono.Cecil.Pdb.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="Mono.Cecil.Rocks, Version=0.9.6.0, Culture=neutral, PublicKeyToken=0738eb9f132ed756, processorArchitecture=MSIL">
+      <HintPath>..\packages\Mono.Cecil.0.9.6.4\lib\net45\Mono.Cecil.Rocks.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
     <Reference Include="Newtonsoft.Json, Version=8.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
       <HintPath>..\packages\Newtonsoft.Json.8.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
       <Private>True</Private>
@@ -200,6 +216,7 @@
     <Compile Include="Framework\DeprecationLevel.cs" />
     <Compile Include="Framework\DeprecationManager.cs" />
     <Compile Include="Framework\InternalExtensions.cs" />
+    <Compile Include="Framework\ModAssemblyLoader.cs" />
     <Compile Include="IModHelper.cs" />
     <Compile Include="Framework\LogFileManager.cs" />
     <Compile Include="LogLevel.cs" />
@@ -284,5 +301,6 @@
     <Copy SourceFiles="$(TargetDir)\$(TargetName).pdb" DestinationFolder="$(GamePath)" />
     <Copy SourceFiles="$(TargetDir)\$(TargetName).xml" DestinationFolder="$(GamePath)" />
     <Copy SourceFiles="$(TargetDir)\Newtonsoft.Json.dll" DestinationFolder="$(GamePath)" />
+    <Copy SourceFiles="$(TargetDir)\Mono.Cecil.dll" DestinationFolder="$(GamePath)" />
   </Target>
 </Project>
\ No newline at end of file
diff --git a/src/StardewModdingAPI/packages.config b/src/StardewModdingAPI/packages.config
index 0aec11c6..dc07902b 100644
--- a/src/StardewModdingAPI/packages.config
+++ b/src/StardewModdingAPI/packages.config
@@ -2,5 +2,6 @@
 <packages>
   <package id="Costura.Fody" version="1.3.3.0" targetFramework="net461" developmentDependency="true" />
   <package id="Fody" version="1.29.4" targetFramework="net461" developmentDependency="true" />
+  <package id="Mono.Cecil" version="0.9.6.4" targetFramework="net45" />
   <package id="Newtonsoft.Json" version="8.0.3" targetFramework="net461" />
 </packages>
\ No newline at end of file