Is "instanceof" supported in conditions?
Consider this trivial Java code:
public class Foo {
public static void main(final String[] args) throws Exception {
printMessage("Hello");
}
private static void printMessage(final String msg) {
System.out.println(msg);
}
}
and a simple Byteman rule:
RULE instanceof test
CLASS Foo
METHOD printMessage
AT ENTRY
IF $1 instanceof java.lang.String
DO System.out.println("Hello World from Byteman");
ENDRULE
Running Byteman against the code, results in:
/tmp/byteman.btm line 5 : 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)
(line 5 is the line where the IF instanceof check is there).
Is it intentional that instanceof isn't supported?
I have a workaround to get past it for now:
RULE instanceof test
CLASS Foo
METHOD printMessage
AT ENTRY
IF (java.lang.String.class).isInstance($1)
DO System.out.println("Hello World from Byteman");
ENDRULE
