Re: 15 RFR(XS): 8165276: Spec states that invoke the premain method in an agent class if it's public but implementation differs

[serguei.spit...@oracle.com]

On 6/23/20 23:33, Alan Bateman wrote:


On 24/06/2020 07:24, serguei.spit...@oracle.com wrote:
:

One approach would be to continue using the setAccessible and add 
extra check for non-public premain method.
Something like should probably work:
        if (!(Modifier.isPublic(m.getModifiers())) {
            throw new IllegalAccessException("premain method is not 
public");
        }
The equivalent with the java launcher is:

$ java Foo.java
error: 'main' method is not declared 'public static'

$ javac Foo.java
$ java Foo
Error: Main method not found in class Foo, please define the main 
method as:
   public static void main(String[] args)

So have the exception message provide a helpful message will be useful 
in the event that someone tries to deploy that doesn't have a public 
premain method.

Thank you for the example.
Yes, I'm working on a helpful message and was thinking to use the 
Reflection method:
 IllegalAccessException newIllegalAccessException(Class<?> currentClass,
                                                  Class<?> memberClass,
                                                  Class<?> targetClass,
                                                  int modifiers);


BTW: Have you checked the agentmain case too?

The InstrumentationImpl::loadClassAndStartAgent() is common for both 
premain and agentmain.
I'll update the CSR and my new test to cover the agentmain as well.

Thanks,
Serguei


-Alan.