RFR: 8043306 - Provide a replacement for the API that allowed to listen for LogManager configuration changes

[Daniel Fuchs]

Hi Peter,

On 9/12/14 9:14 AM, Peter Levart wrote:
 > Wouldn't it be cleaner to evaluate SM presence in the lambda wrapper
 > which would always be constructed, like that:
 >

Well - then we would always be storing the ACC, so
maybe we could just always call
AccessController.doPrivileged, whether there's
a security manager or not.

Do you think it would be cleaner?

best regards,

-- daniel


On 9/12/14 9:14 AM, Peter Levart wrote:
> On 09/11/2014 06:17 PM, Daniel Fuchs wrote:
>> On 9/10/14 1:25 PM, Alan Bateman wrote:
>>> On 10/09/2014 10:49, Daniel Fuchs wrote:
>>>> Hi,
>>>>
>>>> Please find below a proposed patch for
>>>>
>>>> 8043306 - Provide a replacement for the API that allowed to listen
>>>>           for LogManager configuration changes
>>>> https://bugs.openjdk.java.net/browse/JDK-8043306
>>>>
>>>> Proposed Patch:
>>>> http://cr.openjdk.java.net/~dfuchs/webrev_8043306/webrev.00/
>>>>
>>> It would be nice if ConfigurationListener could be an interface. I
>>> realize this might mean looking again at the security concerns in this
>>> area again to see if we could get away without requiring a construction
>>> time permission check. Clearly if it could be an interface then it begs
>>> the question as to why it's just not a Runnable but that probably means
>>> yet more effort to figure out the right security and whether the access
>>> control context should be recorded when registering.
>>
>> Given that both Paul & Alan have indicated that they would prefer
>> to use interfaces for listeners, I have been working on a
>> version that uses 'Runnable'.
>>
>> Thanks to Paul & Alan for all the suggestions that went into
>> this new patch (especially for refining the spec and suggesting
>> a nice way to rewrite addConfigurationListener() using lambdas)!
>>
>> http://cr.openjdk.java.net/~dfuchs/webrev_8043306/webrev.03/
>>
>> best regards,
>>
>> -- daniel
>
> Hi Daniel,
>
> Just a question about security and delayed execution...
>
> If at the time the configuration listener is added to the LogManager,
> SecurityManager is not set, the listener will be invoked directly even
> if at time the listener is invoked, SM has been set. For example:
>
>
>          LogManager.getLogManager().addConfigurationListener(...);
>          ...
>          System.setSecurityManager(...);
>          ...
>          // then somewhere in privileged context...
>          LogManager.getLogManager().readConfiguration(...);
>
>
> Wouldn't it be cleaner to evaluate SM presence in the lambda wrapper
> which would always be constructed, like that:
>
>
>      public LogManager addConfigurationListener(Runnable listener) {
>          final Runnable r = Objects.requireNonNull(listener);
>          checkPermission();
>          final AccessControlContext acc = AccessController.getContext();
>          final Runnable pr = () -> {
>              if (System.getSecurityManager() == null) {
>                  r.run();
>              } else {
> AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
>                      r.run();
>                      return null;
>                  }, acc);
>              }
>          };
>          // Will do nothing if already registered.
>          listeners.putIfAbsent(r, pr);
>          return this;
>      }
>
>
> Regards, Peter
>