FutureTask.cancel(true) should run thread.interrupt within doPrivileged

[Peter Levart]

Hi Martin,

If you want to optimize for without-security-manager case, then it would 
be better this way:

     private static void privilegedInterrupt(Thread t) {
         if (System.getSecurityManager() == null) {
             t.interrupt();
  	} else {
             PrivilegedAction<Void> doInterrupt =
                 () -> { t.interrupt(); return null; };
            AccessController.doPrivileged(doInterrupt);
         }
     }


...and no security exception catching. This way you don't trigger double 
security checks for case with-security-manager and not enough permission...

Regards, Peter

On 10/02/2013 06:29 PM, Martin Buchholz wrote:
> FutureTask.cancel(true) invokes thread.interrupt on the thread (if any)
> currently running the task.
> This should succeed even if modifyThread permission is denied by the
> security manager.
>
> Here's a proposed fix for jdk8+:
>
> --- src/main/java/util/concurrent/FutureTask.java 15 May 2013 02:39:59 -0000
> 1.103
> +++ src/main/java/util/concurrent/FutureTask.java 2 Oct 2013 16:25:23 -0000
> @@ -132,6 +132,12 @@
>           return state != NEW;
>       }
>
> +    private static void privilegedInterrupt(Thread t) {
> +        java.security.PrivilegedAction<Void> doInterrupt =
> +            () -> { t.interrupt(); return null; };
> +        java.security.AccessController.doPrivileged(doInterrupt);
> +    }
> +
>       public boolean cancel(boolean mayInterruptIfRunning) {
>           if (!(state == NEW &&
>                 UNSAFE.compareAndSwapInt(this, stateOffset, NEW,
> @@ -142,7 +148,11 @@
>                   try {
>                       Thread t = runner;
>                       if (t != null)
> -                        t.interrupt();
> +                        try {
> +                            t.interrupt();
> +                        } catch (SecurityException e) {
> +                            privilegedInterrupt(t);
> +                        }
>                   } finally { // final state
>                       UNSAFE.putOrderedInt(this, stateOffset, INTERRUPTED);
>                   }