From 5c88451f6fe8d1ab5f7ac97b7c341eb505cbe911 Mon Sep 17 00:00:00 2001
From: tterrag <tterrag1098@gmail.com>
Date: Thu, 5 Dec 2019 21:50:33 -0500
Subject: [PATCH] Allow classpath locator to discover jars via FMLModType
 attribute

---
 .../fml/loading/moddiscovery/ModFile.java     |  2 +-
 .../userdev/ClasspathLocator.java             | 40 ++++++++++++-------
 2 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFile.java b/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFile.java
index defe1005e..122c4c75a 100644
--- a/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFile.java
+++ b/src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModFile.java
@@ -92,7 +92,7 @@ public class ModFile implements IModFile {
     private List<CoreModFile> coreMods;
     private Path accessTransformer;
 
-    private static final Attributes.Name TYPE = new Attributes.Name("FMLModType");
+    public static final Attributes.Name TYPE = new Attributes.Name("FMLModType");
 
     public ModFile(final Path file, final IModLocator locator) {
         this.locator = locator;
diff --git a/src/userdev/java/net/minecraftforge/userdev/ClasspathLocator.java b/src/userdev/java/net/minecraftforge/userdev/ClasspathLocator.java
index 2c7f2e74c..824ab8a3c 100644
--- a/src/userdev/java/net/minecraftforge/userdev/ClasspathLocator.java
+++ b/src/userdev/java/net/minecraftforge/userdev/ClasspathLocator.java
@@ -25,24 +25,29 @@ import java.io.IOException;
 import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.ArrayList;
 import java.util.Enumeration;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
-import net.minecraftforge.forgespi.locating.IModFile;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import com.google.common.base.Predicates;
+
 import net.minecraftforge.fml.loading.LibraryFinder;
 import net.minecraftforge.fml.loading.moddiscovery.AbstractJarFileLocator;
 import net.minecraftforge.fml.loading.moddiscovery.ModFile;
+import net.minecraftforge.forgespi.locating.IModFile;
 
 public class ClasspathLocator extends AbstractJarFileLocator {
     private static final Logger LOGGER = LogManager.getLogger();
     private static final String MODS_TOML = "META-INF/mods.toml";
-    private List<Path> modCoords;
+    private static final String MANIFEST = "META-INF/MANIFEST.MF";
+    private Set<Path> modCoords;
 
     @Override
     public List<IModFile> scanMods() {
@@ -60,20 +65,27 @@ public class ClasspathLocator extends AbstractJarFileLocator {
     @Override
     public void initArguments(Map<String, ?> arguments) {
         try {
-            modCoords = new ArrayList<>();
-            final Enumeration<URL> resources = ClassLoader.getSystemClassLoader().getResources(MODS_TOML);
-            while (resources.hasMoreElements()) {
-                URL url = resources.nextElement();
-                Path path = LibraryFinder.findJarPathFor(MODS_TOML, "classpath_mod", url);
-                if (Files.isDirectory(path))
-                    continue;
-
-                LOGGER.debug(CORE, "Found classpath mod: {}", path);
-                this.modCoords.add(path);
-            }
+            modCoords = new LinkedHashSet<>();
+            locateMods(MODS_TOML, "classpath_mod", Predicates.alwaysTrue());
+            locateMods(MANIFEST, "manifest_jar", path -> findManifest(path).map(m -> m.getMainAttributes().getValue(ModFile.TYPE)).isPresent());
         } catch (IOException e) {
             LOGGER.fatal(CORE,"Error trying to find resources", e);
             throw new RuntimeException("wha?", e);
         }
     }
+    
+    private void locateMods(String resource, String name, Predicate<Path> filter) throws IOException {
+        final Enumeration<URL> modsTomls = ClassLoader.getSystemClassLoader().getResources(resource);
+        while (modsTomls.hasMoreElements()) {
+            URL url = modsTomls.nextElement();
+            Path path = LibraryFinder.findJarPathFor(resource, name, url);
+            if (Files.isDirectory(path))
+                continue;
+
+            if (filter.test(path)) {
+                LOGGER.debug(CORE, "Found classpath mod: {}", path);
+                this.modCoords.add(path);
+            }
+        }
+    }
 }