fix behavior of System.exit trapping

Installing one globally for the JVM live-time and make behavior dependent
on a thread local variable seems safer than globally switching it out
and having race conditions.

Also now all other calls are forwarded to a potential Nailgun
SecurityManager, which should fix some bugs.

1 files changed, 22 insertions, 2 deletions

diff --git a/nailgun_launcher/TrapSecurityManager.java b/nailgun_launcher/TrapSecurityManager.java
index ed00582..fada878 100644
--- a/nailgun_launcher/TrapSecurityManager.java
+++ b/nailgun_launcher/TrapSecurityManager.java
@@ -1,19 +1,39 @@
 package cbt;
 import java.security.*;
-public class TrapSecurityManager extends SecurityManager{
+/*
+When enabled, this SecurityManager turns System.exit(...) calls into exceptions that can be caught and handled.
+Installing a SecurityManager is a global side-effect and thus needs extra care in a persistent
+background process like CBT's. The current approach is install it once during JVM-startup.
+When disabled this delegates to the SecurityManager installed before if any, which
+would be Nailgun's if running on Nailgun. If we do not delegate to Nailgun, it seems we
+could in some cases kill the server process
+*/
+public class TrapSecurityManager extends ProxySecurityManager{
+  public TrapSecurityManager(){
+    super(NailgunLauncher.initialSecurityManager);
+  }
+  
   public void checkPermission( Permission permission ){
     /*
     NOTE: is it actually ok, to just make these empty?
     Calling .super leads to ClassNotFound exteption for a lambda.
     Calling to the previous SecurityManager leads to a stack overflow
     */
+    if(!NailgunLauncher.trapExitCode.get()){
+      super.checkPermission(permission);
+    }
   }
   public void checkPermission( Permission permission, Object context ){
     /* Does this methods need to be overidden? */
+    if(!NailgunLauncher.trapExitCode.get()){
+      super.checkPermission(permission, context);
+    }
   }
   @Override
   public void checkExit( int status ){
+    if(NailgunLauncher.trapExitCode.get()){
+      throw new TrappedExitCode(status);
+    }
     super.checkExit(status);
-    throw new TrappedExitCode(status);
   }
 }