From 6d2d90b7681e4e274e92742e98905ec4000486ca Mon Sep 17 00:00:00 2001
From: Jesse Plamondon-Willard <github@jplamondonw.com>
Date: Sun, 12 Mar 2017 01:31:15 -0500
Subject: [PATCH] add logic to detect incompatible mod instructions & reject
 mod load (#247)

---
 src/StardewModdingAPI/Constants.cs            |  8 ++++++
 .../Framework/AssemblyLoader.cs               | 18 +++++++++++++
 .../IncompatibleInstructionException.cs       | 27 +++++++++++++++++++
 src/StardewModdingAPI/Program.cs              |  5 ++++
 .../StardewModdingAPI.csproj                  |  1 +
 5 files changed, 59 insertions(+)
 create mode 100644 src/StardewModdingAPI/Framework/IncompatibleInstructionException.cs

diff --git a/src/StardewModdingAPI/Constants.cs b/src/StardewModdingAPI/Constants.cs
index 66bf5842..d8149766 100644
--- a/src/StardewModdingAPI/Constants.cs
+++ b/src/StardewModdingAPI/Constants.cs
@@ -135,6 +135,14 @@ namespace StardewModdingAPI
             return new PlatformAssemblyMap(targetPlatform, removeAssemblyReferences, targetAssemblies);
         }
 
+        /// <summary>Get finders which match incompatible CIL instructions in mod assemblies.</summary>
+        internal static IEnumerable<IInstructionFinder> GetIncompatibilityFinders()
+        {
+            return new IInstructionFinder[]
+            {
+            };
+        }
+
         /// <summary>Get rewriters which fix incompatible CIL instructions in mod assemblies.</summary>
         internal static IEnumerable<IInstructionRewriter> GetRewriters()
         {
diff --git a/src/StardewModdingAPI/Framework/AssemblyLoader.cs b/src/StardewModdingAPI/Framework/AssemblyLoader.cs
index 8af67772..dfe0d03f 100644
--- a/src/StardewModdingAPI/Framework/AssemblyLoader.cs
+++ b/src/StardewModdingAPI/Framework/AssemblyLoader.cs
@@ -55,6 +55,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>Preprocess and load an assembly.</summary>
         /// <param name="assemblyPath">The assembly file path.</param>
         /// <returns>Returns the rewrite metadata for the preprocessed assembly.</returns>
+        /// <exception cref="IncompatibleInstructionException">An incompatible CIL instruction was found while rewriting the assembly.</exception>
         public Assembly Load(string assemblyPath)
         {
             // get referenced local assemblies
@@ -159,6 +160,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>Rewrite the types referenced by an assembly.</summary>
         /// <param name="assembly">The assembly to rewrite.</param>
         /// <returns>Returns whether the assembly was modified.</returns>
+        /// <exception cref="IncompatibleInstructionException">An incompatible CIL instruction was found while rewriting the assembly.</exception>
         private bool RewriteAssembly(AssemblyDefinition assembly)
         {
             ModuleDefinition module = assembly.MainModule;
@@ -189,6 +191,22 @@ namespace StardewModdingAPI.Framework
                     this.ChangeTypeScope(type);
             }
 
+            // throw exception if assembly contains incompatible instructions can't be rewritten
+            {
+                IInstructionFinder[] finders = Constants.GetIncompatibilityFinders().ToArray();
+                foreach (MethodDefinition method in this.GetMethods(module))
+                {
+                    foreach (Instruction instruction in method.Body.Instructions)
+                    {
+                        foreach (IInstructionFinder finder in finders)
+                        {
+                            if (finder.IsMatch(instruction, platformChanged))
+                                throw new IncompatibleInstructionException(finder.NounPhrase, $"Found an incompatible CIL instruction ({finder.NounPhrase}) while loading assembly {assembly.Name.Name}.");
+                        }
+                    }
+                }
+            }
+
             // rewrite incompatible instructions
             bool anyRewritten = false;
             IInstructionRewriter[] rewriters = Constants.GetRewriters().ToArray();
diff --git a/src/StardewModdingAPI/Framework/IncompatibleInstructionException.cs b/src/StardewModdingAPI/Framework/IncompatibleInstructionException.cs
new file mode 100644
index 00000000..affe2cb3
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/IncompatibleInstructionException.cs
@@ -0,0 +1,27 @@
+using System;
+
+namespace StardewModdingAPI.Framework
+{
+    /// <summary>An exception raised when an incompatible instruction is found while loading a mod assembly.</summary>
+    internal class IncompatibleInstructionException : Exception
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A brief noun phrase which describes the incompatible instruction that was found.</summary>
+        public string NounPhrase { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="nounPhrase">A brief noun phrase which describes the incompatible instruction that was found.</param>
+        /// <param name="message">A message which describes the error.</param>
+        public IncompatibleInstructionException(string nounPhrase, string message)
+            : base(message)
+        {
+            this.NounPhrase = nounPhrase;
+        }
+    }
+}
diff --git a/src/StardewModdingAPI/Program.cs b/src/StardewModdingAPI/Program.cs
index bf3c86fb..cb8cc2e5 100644
--- a/src/StardewModdingAPI/Program.cs
+++ b/src/StardewModdingAPI/Program.cs
@@ -453,6 +453,11 @@ namespace StardewModdingAPI
                 {
                     modAssembly = modAssemblyLoader.Load(assemblyPath);
                 }
+                catch (IncompatibleInstructionException ex)
+                {
+                    this.Monitor.Log($"{skippedPrefix} because it's not compatible with the latest version of the game (detected {ex.NounPhrase}). Please check for a newer version of the mod (you have v{manifest.Version}).", LogLevel.Error);
+                    continue;
+                }
                 catch (Exception ex)
                 {
                     this.Monitor.Log($"{skippedPrefix} because its DLL '{manifest.EntryDll}' couldn't be loaded.\n{ex.GetLogSummary()}", LogLevel.Error);
diff --git a/src/StardewModdingAPI/StardewModdingAPI.csproj b/src/StardewModdingAPI/StardewModdingAPI.csproj
index ab808948..92726ca0 100644
--- a/src/StardewModdingAPI/StardewModdingAPI.csproj
+++ b/src/StardewModdingAPI/StardewModdingAPI.csproj
@@ -154,6 +154,7 @@
     <Compile Include="Framework\Content\ContentEventHelper.cs" />
     <Compile Include="Framework\Content\ContentEventHelperForDictionary.cs" />
     <Compile Include="Framework\Content\ContentEventHelperForImage.cs" />
+    <Compile Include="Framework\IncompatibleInstructionException.cs" />
     <Compile Include="Framework\Logging\ConsoleInterceptionManager.cs" />
     <Compile Include="Framework\Logging\InterceptingTextWriter.cs" />
     <Compile Include="Framework\CommandHelper.cs" />