RFR: 8330005: RandomGeneratorFactory.getDefault() throws exception when the runtime image only has java.base module [v6]

[Alan Bateman]

On Sun, 5 May 2024 12:05:48 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> src/java.base/share/classes/java/util/random/RandomGeneratorFactory.java line 147:
>> 
>>> 145:             FactoryMapHolder.class.getModule().addUses(RandomGenerator.class);
>>> 146:             return ServiceLoader
>>> 147:                 .load(RandomGenerator.class, ClassLoader.getPlatformClassLoader())
>> 
>> SecurityManager is still a supported execution mode so you'll need to get the platform class loader in a privileged block until the SM feature is removed.
>
> Yes, I considered the interactions with a security manager.
> 
> But here the call to `getPlatformClassLoader()` is done from a platform class, namely `FactoryMapHolder` itself. According to its documentation, the call succeeds in this case because the security manager is not even consulted.
> 
> When experimenting with the following code and the default manager, as with `-Djava.security.manager=default`, no exceptions are thrown, neither with the full JDK nor with the minimal image that just includes `java.base`. There's only a warning about future removal of `SecurityManager`, as expected from JEP 411.
> 
> 
> import java.util.random.*;
> 
> public class Foo {
>     public static void main(final String[] args) throws Exception {
>         RandomGeneratorFactory.all().forEach(g -> System.out.println(g.name()));
>         final RandomGeneratorFactory<RandomGenerator> rgf = RandomGeneratorFactory.getDefault();
>         System.out.println("Got " + rgf);
>     }
> }
> 
> 
> But if the call to `getPlatformClassLoader()` is done directly from an app loaded by the system class loader, then an exception is thrown when the default security manager is active.

Thanks, I'd forgotten the check in that method is caller sensitive.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18932#discussion_r1590318688