Fix exit code trapping across classloaders

A SecurityManager is once installed globally and stays the same across
all classloaders. TrapSecurityManager was installed this way, but it
looked up the `trapExitCode` in it's own classloader, while
classes in other classloaders (when cbt was using another version of
cbt) were writing it to their own classloader. This flag needs to be in
a global place instead to fix this, so we'll put it straight into the
TrapSecurityManager itself.

1 files changed, 48 insertions, 4 deletions

diff --git a/nailgun_launcher/TrapSecurityManager.java b/nailgun_launcher/TrapSecurityManager.java
index fada878..1626787 100644
--- a/nailgun_launcher/TrapSecurityManager.java
+++ b/nailgun_launcher/TrapSecurityManager.java
@@ -9,6 +9,33 @@ would be Nailgun's if running on Nailgun. If we do not delegate to Nailgun, it s
 could in some cases kill the server process
 */
 public class TrapSecurityManager extends ProxySecurityManager{
+  public static ThreadLocal<Boolean> trapExitCode(){
+    // storing the flag in the installed security manager
+    // instead of e.g. a static member is necessary because
+    // we run multiple versions of CBT with multiple TrapSecurityManager classes
+    // but we need to affect the installed one
+    SecurityManager sm = System.getSecurityManager();
+    if(sm instanceof TrapSecurityManager){
+      return ((TrapSecurityManager) sm)._trapExitCode;
+    } else {
+      try{
+        @SuppressWarnings("unchecked")
+        ThreadLocal<Boolean> res =
+          (ThreadLocal<Boolean>) sm.getClass().getMethod("trapExitCode").invoke(null);
+        return res;
+      } catch(Exception e) {
+        throw new RuntimeException(e);
+      }
+    }
+  }
+
+  private final ThreadLocal<Boolean> _trapExitCode =
+    new ThreadLocal<Boolean>() {
+      @Override protected Boolean initialValue() {
+        return false;
+      }
+    };
+
   public TrapSecurityManager(){
     super(NailgunLauncher.initialSecurityManager);
   }
@@ -19,21 +46,38 @@ public class TrapSecurityManager extends ProxySecurityManager{
     Calling .super leads to ClassNotFound exteption for a lambda.
     Calling to the previous SecurityManager leads to a stack overflow
     */
-    if(!NailgunLauncher.trapExitCode.get()){
+    if(!TrapSecurityManager.trapExitCode().get()){
       super.checkPermission(permission);
     }
   }
   public void checkPermission( Permission permission, Object context ){
     /* Does this methods need to be overidden? */
-    if(!NailgunLauncher.trapExitCode.get()){
+    if(!TrapSecurityManager.trapExitCode().get()){
       super.checkPermission(permission, context);
     }
   }
+
+  private static final String prefix = "[TrappedExit] ";
+
   @Override
   public void checkExit( int status ){
-    if(NailgunLauncher.trapExitCode.get()){
-      throw new TrappedExitCode(status);
+    if(TrapSecurityManager.trapExitCode().get()){
+      // using a RuntimeException and a prefix here instead of a custom
+      // exception type because this is thrown by the installed TrapSecurityManager
+      // but other versions of cbt need to be able to catch it, that do not have access
+      // to that version of the TrapSecurityManager class
+      throw new RuntimeException(prefix+status);
     }
     super.checkExit(status);
   }
+
+  public static boolean isTrappedExit( Throwable t ){
+    return t instanceof RuntimeException && t.getMessage().startsWith(prefix);
+  }
+
+  public static int exitCode( Throwable t ){
+    assert(isTrappedExit(t));
+    return Integer.parseInt( t.getMessage().substring(prefix.length()) );
+  }
+
 }