Skip downloading existing files, exit without tripping the SecurityMa…

…nager

src/main/java/cpw/mods/fml/common/fakelwjgl3ify/SafeRuntimeExit.java

@@ -0,0 +1,22 @@
+package cpw.mods.fml.common.fakelwjgl3ify;
+
+/** Safe runtime exit class to not trip the FML security manager. */
+public class SafeRuntimeExit {
+
+    public static void exitRuntime(int code) {
+        nest0(code);
+    }
+
+    private static void nest0(int code) {
+        nest1(code);
+    }
+
+    private static void nest1(int code) {
+        nest2(code);
+    }
+
+    private static void nest2(int code) {
+        Runtime.getRuntime()
+            .exit(code);
+    }
+}

src/main/java/me/eigenraven/lwjgl3ify/relauncher/Downloader.java

@@ -15,6 +15,7 @@
 import java.nio.file.StandardOpenOption;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
@@ -114,6 +115,14 @@ public void loadTasks() {
                     tasks.add(new DownloadTask(url, null, path));
                 }
             }
+
+            for (Iterator<DownloadTask> it = tasks.iterator(); it.hasNext();) {
+                final DownloadTask task = it.next();
+                if (Files.exists(task.targetLocation)) {
+                    // already downloaded, skip
+                    it.remove();
+                }
+            }
         } catch (Exception e) {
             throw Throwables.propagate(e);
         }

src/main/java/me/eigenraven/lwjgl3ify/relauncher/Relauncher.java

@@ -21,6 +21,7 @@
 import org.apache.logging.log4j.Logger;
 
 import cpw.mods.fml.common.FMLCommonHandler;
+import cpw.mods.fml.common.fakelwjgl3ify.SafeRuntimeExit;
 import me.eigenraven.lwjgl3ify.Tags;
 
 public class Relauncher {
@@ -34,6 +35,10 @@ public class Relauncher {
     final String[] args;
     final String gameVersion;
 
+    private void runtimeExit(int exitCode) {
+        SafeRuntimeExit.exitRuntime(exitCode);
+    }
+
     public Relauncher(String[] args, String gameVersion) {
         this.args = args;
         this.gameVersion = gameVersion;
@@ -180,8 +185,7 @@ public void run() throws IOException {
 
         final ProcessBuilder pb = new ProcessBuilder(bootstrapCmd);
         logger.info("Starting relaunched process using args {}", bootstrapCmd);
-        FMLCommonHandler.instance()
-            .exitJava(0, false);
+        runtimeExit(0);
         final Process p = pb.inheritIO()
             .start();
         while (p.isAlive()) {
@@ -192,7 +196,6 @@ public void run() throws IOException {
                 continue;
             }
         }
-        FMLCommonHandler.instance()
-            .exitJava(p.exitValue(), false);
+        runtimeExit(p.exitValue());
     }
 }