MCUrlClassPath rogue classloading fix

Author: FalsePattern

src/main/java/com/falsepattern/lib/internal/impl/mixin/UCPImpl.java

@@ -21,20 +21,17 @@
 
 package com.falsepattern.lib.internal.impl.mixin;
 
-import com.falsepattern.lib.mixin.MinecraftURLClassPath;
 import lombok.val;
+import sun.misc.URLClassPath;
 
+import net.minecraft.launchwrapper.Launch;
 import net.minecraft.launchwrapper.LaunchClassLoader;
-import cpw.mods.fml.common.Loader;
-import cpw.mods.fml.common.ModClassLoader;
 
 import java.io.File;
-import java.lang.reflect.Method;
-import java.net.URL;
+import java.io.IOException;
 
 public final class UCPImpl {
-    private static final Object ucp;
-    private static final Method addURL;
+    private static final URLClassPath ucp;
     private static final boolean GRIMOIRE;
 
     static {
@@ -43,45 +40,33 @@ public final class UCPImpl {
                 new String[]{"io.github.crucible.grimoire.Grimoire", "io.github.crucible.grimoire.common.GrimoireCore"};
         for (val className : knownGrimoireClassNames) {
             try {
-                Class.forName(className, false, MinecraftURLClassPath.class.getClassLoader());
-                grimoire = true;
-                break;
-            } catch (ClassNotFoundException ignored) {
+                if (Launch.classLoader.getClassBytes(className) != null) {
+                    grimoire = true;
+                    break;
+                }
+            } catch (IOException e) {
+                throw new RuntimeException(e);
             }
         }
         GRIMOIRE = grimoire;
         if (!GRIMOIRE) {
             try {
-                val modClassLoaderField = Loader.class.getDeclaredField("modClassLoader");
-                modClassLoaderField.setAccessible(true);
-
-                val loaderInstanceField = Loader.class.getDeclaredField("instance");
-                loaderInstanceField.setAccessible(true);
-
-                val mainClassLoaderField = ModClassLoader.class.getDeclaredField("mainClassLoader");
-                mainClassLoaderField.setAccessible(true);
-
                 val ucpField = LaunchClassLoader.class.getSuperclass().getDeclaredField("ucp");
                 ucpField.setAccessible(true);
 
-                Object loader = loaderInstanceField.get(null);
-                val modClassLoader = (ModClassLoader) modClassLoaderField.get(loader);
-                val mainClassLoader = (LaunchClassLoader) mainClassLoaderField.get(modClassLoader);
-                ucp = ucpField.get(mainClassLoader);
-                addURL = ucp.getClass().getDeclaredMethod("addURL", URL.class);
-            } catch (NoSuchFieldException | IllegalAccessException | NoSuchMethodException e) {
+                ucp = (URLClassPath) ucpField.get(Launch.classLoader);
+            } catch (NoSuchFieldException | IllegalAccessException e) {
                 throw new RuntimeException(e.getMessage());
             }
         } else {
             ucp = null;
-            addURL = null;
             System.err.println("Grimoire detected, disabling jar loading utility");
         }
     }
 
     public static void addJar(File pathToJar) throws Exception {
         if (!GRIMOIRE) {
-            addURL.invoke(ucp, pathToJar.toURI().toURL());
+            ucp.addURL(pathToJar.toURI().toURL());
         }
     }
 }