From bd6ba6774576ecf8044bc7f00e2a283e5127e939 Mon Sep 17 00:00:00 2001
From: Duy Tran Khanh <khanhduytran0@users.noreply.github.com>
Date: Mon, 7 Feb 2022 05:20:05 +0700
Subject: [PATCH] Bug fix: Arc DNS injector breaks on Java 16+

This is caused by a missing function in our class loader.

Error:
System class loader does not define the
appendToClassPathForInstrumentation method
Unable to add
/Applications/PojavLauncher.app/libs/arc_dns_injector.jar to system
class path - the system class loader does not define the
appendToClassPathForInstrumentation method or the method failed
FATAL ERROR in native method: processing of -javaagent failed,
appending to system class path failed
---
 .../net/kdt/pojavlaunch/PojavClassLoader.java | 29 ++++++++++++++++++-
 Natives/JavaLauncher.m                        |  4 +++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/JavaApp/src/main/java/net/kdt/pojavlaunch/PojavClassLoader.java b/JavaApp/src/main/java/net/kdt/pojavlaunch/PojavClassLoader.java
index 386b4356..c39679ab 100644
--- a/JavaApp/src/main/java/net/kdt/pojavlaunch/PojavClassLoader.java
+++ b/JavaApp/src/main/java/net/kdt/pojavlaunch/PojavClassLoader.java
@@ -1,6 +1,7 @@
 package net.kdt.pojavlaunch;
 
 import java.io.File;
+import java.io.IOException;
 import java.net.*;
 
 /**
@@ -13,7 +14,7 @@ public class PojavClassLoader extends URLClassLoader {
     public PojavClassLoader(ClassLoader parent) {
         super(new URL[0], parent);
     }
-    
+
     @Override
     public void addURL(URL url) {
         super.addURL(url);
@@ -23,4 +24,30 @@ public class PojavClassLoader extends URLClassLoader {
             e.printStackTrace();
         }
     }
+
+    static URL getFileURL(File file) {
+        try {
+            file = file.getCanonicalFile();
+        } catch (IOException e) {}
+
+        try {
+            return file.toURL();
+        } catch (MalformedURLException e) {
+            // Should never happen since we specify the protocol...
+            throw new InternalError(e);
+        }
+    }
+
+    /**
+     * This class loader supports dynamic additions to the class path
+     * at runtime.
+     *
+     * @see java.lang.instrument.Instrumentation#appendToSystemClassPathSearch
+     */
+    private void appendToClassPathForInstrumentation(String path) {
+        assert(Thread.holdsLock(this));
+
+        // addURL is a no-op if path already contains the URL
+        super.addURL(getFileURL(new File(path)));
+    }
 }
\ No newline at end of file
diff --git a/Natives/JavaLauncher.m b/Natives/JavaLauncher.m
index 474711a1..50a8ea1c 100644
--- a/Natives/JavaLauncher.m
+++ b/Natives/JavaLauncher.m
@@ -674,7 +674,11 @@ int launchJVM(int argc, char *argv[]) {
             }
             margv[margc++] = cacio_classpath;
         }
+    } else if (!started) {
+        // Opens to ARC DNS
+        margv[margc++] = "--add-opens=java.base/java.net=ALL-UNNAMED";
     }
+
     if (!started) {
         init_loadCustomJvmFlags();
     }