Method calls on .class literal trigger invalid rule error

[jaikiran]

Consider this simple class:

public class Foo {
    public static void main(final String[] args) throws Exception {
        System.out.println("Hello world");
    }
}

and a trivial Byteman rule for it:

RULE simple test
CLASS Foo
METHOD main
AT ENTRY
IF TRUE
DO System.out.println("Hello from " + Foo.class);
   System.out.println("Loaded by " + Foo.class.getClassLoader());    
ENDRULE

When the Java command is invoked:

java -javaagent:byteman/byteman-4.0.7/lib/byteman.jar=script:/tmp/sample.btm,boot:byteman/byteman-4.0.7/lib/byteman.jar,prop:org.jboss.byteman.verbose=true,prop:org.jboss.byteman.transform.all=true Foo

It ends up with an invalid rule exception:

Setting org.jboss.byteman.verbose=true
Setting org.jboss.byteman.transform.all=true
AccessManager:init Initialising default AccessManager
org.jboss.byteman.agent.Transformer : error parsing rule simple test
org.jboss.byteman.rule.exception.ParseException: rule simple test
/tmp/sample.btm line 7 : invalid expression
org.jboss.byteman.rule.exception.ParseException: rule simple test
/tmp/sample.btm line 7 : invalid expression
    at org.jboss.byteman.rule.Rule.(Rule.java:233)
    at org.jboss.byteman.rule.Rule.create(Rule.java:389)
    at org.jboss.byteman.agent.TransformContext.parseRule(TransformContext.java:178)
    at org.jboss.byteman.agent.TransformContext.transform(TransformContext.java:88)
    at org.jboss.byteman.agent.Transformer.transform(Transformer.java:757)
    at org.jboss.byteman.agent.Transformer.tryTransform(Transformer.java:824)
    at org.jboss.byteman.agent.Transformer.tryTransform(Transformer.java:796)
    at org.jboss.byteman.agent.Transformer.transform(Transformer.java:264)
    at sun.instrument.TransformerManager.transform(TransformerManager.java:188)
    at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:428)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:495)

It looks like using any method invocations on a ".class" literal triggers this error. In this case the "Foo.class.getClassLoader()". Is this not allowed? I can't use $0 or even $this in this use case given that this is a static method. Neither can I use $CLASS here since it returns a string value.

[adinn]

Hi Jaikiran

Yes, this is a bug in the parser. The following does work:

RULE simple test 
CLASS Foo 
METHOD main 
AT ENTRY 
IF TRUE 
DO System.out.println("Hello from " + Foo.class); 
  System.out.println("Loaded by " + (Foo.class).getClassLoader());     
ENDRULE 

I'll have raised this JIRA and will patch it in the next release

Thanks for reporting this.

regards,

Andrew Dinn

[jaikiran]

Thank you Andrew. The workaround worked indeed.