Handle invalid JAR files more gracefully. Don't crash.

Signed-off-by: cpw <cpw+github@weeksfamily.ca>

src/fmllauncher/java/net/minecraftforge/fml/loading/LoadingModList.java

@@ -47,6 +47,7 @@ public class LoadingModList
     private final Map<String, ModFileInfo> fileById;
     private BackgroundScanHandler scanner;
     private final List<EarlyLoadingException> preLoadErrors;
+    private List<ModFile> brokenFiles;
 
     private LoadingModList(final List<ModFile> modFiles, final List<ModInfo> sortedList)
     {
@@ -131,4 +132,8 @@ public class LoadingModList
     public List<EarlyLoadingException> getErrors() {
         return preLoadErrors;
     }
+
+    public void setBrokenFiles(final List<ModFile> brokenFiles) {
+        this.brokenFiles = brokenFiles;
+    }
 }

src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/AbstractJarFileLocator.java

@@ -39,7 +39,7 @@ import java.util.zip.ZipError;
 
 import static net.minecraftforge.fml.loading.LogMarkers.SCAN;
 
-public class AbstractJarFileLocator {
+public abstract class AbstractJarFileLocator implements IModLocator {
     private static final Logger LOGGER = LogManager.getLogger();
     protected final Map<ModFile, FileSystem> modJars;
 
@@ -51,7 +51,7 @@ public class AbstractJarFileLocator {
         try {
             return FileSystems.newFileSystem(modFile.getFilePath(), modFile.getClass().getClassLoader());
         } catch (ZipError | IOException e) {
-            LOGGER.debug(SCAN,"Ignoring invalid JAR file {}", modFile.getFilePath());
+            LOGGER.debug(SCAN,"Invalid JAR file {} - no filesystem created", modFile.getFilePath());
             return null;
         }
     }
@@ -87,4 +87,9 @@ public class AbstractJarFileLocator {
             return Optional.empty();
         }
     }
+
+    @Override
+    public boolean isValid(final ModFile modFile) {
+        return modJars.get(modFile) != null;
+    }
 }

src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ExplodedDirectoryLocator.java

@@ -117,4 +117,9 @@ public class ExplodedDirectoryLocator implements IModLocator {
             rootDirs.addAll(explodedTargets);
         }
     }
+
+    @Override
+    public boolean isValid(final ModFile modFile) {
+        return mods.get(modFile) != null;
+    }
 }

src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/IModLocator.java

@@ -42,4 +42,6 @@ public interface IModLocator {
     Optional<Manifest> findManifest(Path file);
 
     void initArguments(Map<String, ?> arguments);
+
+    boolean isValid(ModFile modFile);
 }

src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/MavenDirectoryLocator.java

@@ -28,7 +28,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
-public class MavenDirectoryLocator extends AbstractJarFileLocator implements IModLocator {
+public class MavenDirectoryLocator extends AbstractJarFileLocator {
     private List<Path> modCoords;
 
     @Override

src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModDiscoverer.java

@@ -27,6 +27,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
 import java.nio.file.Path;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
@@ -67,12 +68,14 @@ public class ModDiscoverer {
         FMLLoader.getLanguageLoadingProvider().addAdditionalLanguages(modFiles.get(ModFile.Type.LANGPROVIDER));
         BackgroundScanHandler backgroundScanHandler = new BackgroundScanHandler();
         final List<ModFile> mods = modFiles.getOrDefault(ModFile.Type.MOD, Collections.emptyList());
+        final List<ModFile> brokenFiles = new ArrayList<>();
         for (Iterator<ModFile> iterator = mods.iterator(); iterator.hasNext(); )
         {
             ModFile mod = iterator.next();
-            if (!mod.identifyMods()) {
-                LOGGER.debug(SCAN, "Removing file {} from further analysis - it is invalid", mod);
+            if (!mod.getLocator().isValid(mod) || !mod.identifyMods()) {
+                LOGGER.warn(SCAN, "File {} has been ignored - it is invalid", mod.getFilePath());
                 iterator.remove();
+                brokenFiles.add(mod);
             }
         }
         LOGGER.debug(SCAN,"Found {} mod files with {} mods", mods::size, ()->mods.stream().mapToInt(mf -> mf.getModInfos().size()).sum());
@@ -80,6 +83,7 @@ public class ModDiscoverer {
         loadingModList.addCoreMods();
         loadingModList.addAccessTransformers();
         loadingModList.addForScanning(backgroundScanHandler);
+        loadingModList.setBrokenFiles(brokenFiles);
         return backgroundScanHandler;
     }
 

src/fmllauncher/java/net/minecraftforge/fml/loading/moddiscovery/ModsFolderLocator.java

@@ -37,7 +37,7 @@ import static net.minecraftforge.fml.loading.LogMarkers.SCAN;
 /**
  * Support loading mods located in JAR files in the mods folder
  */
-public class ModsFolderLocator extends AbstractJarFileLocator implements IModLocator {
+public class ModsFolderLocator extends AbstractJarFileLocator {
     private static final String SUFFIX = ".jar";
     private static final Logger LOGGER = LogManager.getLogger();
     private final Path modFolder;