In btrace, how can I print a byte array in a readable format?

Question

I want to use btrace to inspect the byte[] value of a method return use the @Return annotation.

The byte array is actually a normal string encoded using utf8.

The class is like below:

Class A {
  byte[] method1() {
    ...
  }
}

I have tried printArray, but it only accepts type of Objetc[], not working for type of byte[]. For print, it just outputs the internal object id like '[B@4fbc7b65'.

Is there any other way can solve the problem?

as btrace has this limitation, maybe you can try byteman, which is also awesome — sel-fish, Mar 08 '18 at 14:39

score 1 · Answer 1 · edited Mar 20 '18 at 10:01

1

Yes, this is an omission in BTrace (https://github.com/btraceio/btrace/issues/322)

For now, use "trusted" mode where the safety checks will be turned off and you can do eg.

@BTrace(trusted = true)
public class TrustedTrace {
  @OnMethod(clazz = "MyClass", method = "m", location = Location(Kind.RETURN))
  public static void intercept(@Return byte[] data) {
    println(Arrays.toString(data));
  }
}

edited Mar 20 '18 at 10:01

sel-fish

4,308
2
20
39

answered Mar 20 '18 at 06:34

JB-

2,615
18
17

Does "trusted" mode means we can invoke any static method to the object? – cainanyang Mar 23 '18 at 00:19
It means that all the protections are turned off and you can do whatever is possible in JVM. If a field/method is visible you can read/modify/execute it. – JB- Mar 26 '18 at 19:01

In btrace, how can I print a byte array in a readable format?

1 Answers1