From ea966d32d17bd9c6728b6f613341a7d523b70e22 Mon Sep 17 00:00:00 2001
From: AlexIIL <alexj9@me.com>
Date: Sun, 21 Apr 2024 17:36:59 +0100
Subject: [PATCH] Add a system property to disable
 DelegatingUrlStreamHandlerFactory.

---
 .../DelegatingUrlStreamHandlerFactory.java          | 13 ++++++++++++-
 .../quiltmc/loader/impl/util/SystemProperties.java  |  7 +++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/quiltmc/loader/impl/filesystem/DelegatingUrlStreamHandlerFactory.java b/src/main/java/org/quiltmc/loader/impl/filesystem/DelegatingUrlStreamHandlerFactory.java
index d9c8df752..7ba0f9b96 100644
--- a/src/main/java/org/quiltmc/loader/impl/filesystem/DelegatingUrlStreamHandlerFactory.java
+++ b/src/main/java/org/quiltmc/loader/impl/filesystem/DelegatingUrlStreamHandlerFactory.java
@@ -22,6 +22,7 @@
 
 import org.quiltmc.loader.impl.util.QuiltLoaderInternal;
 import org.quiltmc.loader.impl.util.QuiltLoaderInternalType;
+import org.quiltmc.loader.impl.util.SystemProperties;
 
 /** Holds the {@link URLStreamHandlerFactory} for all quilt filesystems. This is set to
  * {@link URL#setURLStreamHandlerFactory(URLStreamHandlerFactory)}.
@@ -32,11 +33,15 @@
 public class DelegatingUrlStreamHandlerFactory implements URLStreamHandlerFactory {
 
 	public static final DelegatingUrlStreamHandlerFactory INSTANCE = new DelegatingUrlStreamHandlerFactory();
+	private static final boolean DISABLED;
 
 	private URLStreamHandlerFactory[] factories = new URLStreamHandlerFactory[0];
 
 	static {
-		URL.setURLStreamHandlerFactory(INSTANCE);
+		DISABLED = Boolean.getBoolean(SystemProperties.DISABLE_URL_STREAM_FACTORY);
+		if (!DISABLED) {
+			URL.setURLStreamHandlerFactory(INSTANCE);
+		}
 	}
 
 	static void load() {
@@ -44,6 +49,12 @@ static void load() {
 	}
 
 	public static synchronized void appendFactory(URLStreamHandlerFactory factory) {
+		if (DISABLED) {
+			throw new Error(
+				"The system property '" + SystemProperties.DISABLE_URL_STREAM_FACTORY
+					+ "' has been set to true, which disables custom factories - you will need to reconfigure your environment!"
+			);
+		}
 		URLStreamHandlerFactory[] copy = new URLStreamHandlerFactory[INSTANCE.factories.length + 1];
 		System.arraycopy(INSTANCE.factories, 0, copy, 0, INSTANCE.factories.length);
 		copy[INSTANCE.factories.length] = factory;
diff --git a/src/main/java/org/quiltmc/loader/impl/util/SystemProperties.java b/src/main/java/org/quiltmc/loader/impl/util/SystemProperties.java
index d1ac708c5..538430fc1 100644
--- a/src/main/java/org/quiltmc/loader/impl/util/SystemProperties.java
+++ b/src/main/java/org/quiltmc/loader/impl/util/SystemProperties.java
@@ -17,6 +17,9 @@
 
 package org.quiltmc.loader.impl.util;
 
+import java.net.URL;
+import java.net.URLStreamHandlerFactory;
+
 import org.quiltmc.loader.impl.filesystem.QuiltBasePath;
 import org.quiltmc.loader.impl.filesystem.QuiltClassPath;
 import org.quiltmc.loader.impl.filesystem.QuiltMapFileSystem;
@@ -96,6 +99,10 @@ private SystemProperties() {}
 	public static final String DISABLE_QUILT_CLASS_PATH_CUSTOM_TABLE = "loader.quilt_class_path.disable_custom_table";
 	public static final String DISABLE_BUILTIN_MIXIN_EXTRAS = "loader.disable_builtin_mixin_extras";
 
+	/** Disables loader from registering its {@link URLStreamHandlerFactory} with
+	 * {@link URL#setURLStreamHandlerFactory(URLStreamHandlerFactory)}. This */
+	public static final String DISABLE_URL_STREAM_FACTORY = "loader.disable_url_stream_factory";
+
 	// ##############
 	// # Validation #
 	// ##############