Read Argument Values

[Ezriral]

What i would like to know is how can i read for example here the MemoryStream of the argument.
This code is just an example (and wrong) what i tried but cannot get it working.
Would be happy if someone could tell me how to hook a specific function

.filterClasses(clazz => clazz.name.toLowerCase().includes("player"))
          .filterMethods(method => method.name.toLowerCase().includes("position"))

and the function has one argument "m = System.IO.MemoryStream"
and i want to read the bytes of it.

Il2Cpp.perform(() => {
      console.log("Unity Version: " + Il2Cpp.unityVersion);

      // Trace all methods in Assembly-CSharp containing "serialize" in the name
      var trace = Il2Cpp.trace(true)
          .assemblies(Il2Cpp.domain.assembly("Assembly-CSharp"))
          .filterClasses(clazz => clazz.name.toLowerCase().includes("player"))
          .filterMethods(method => method.name.toLowerCase().includes("position"))
          .and()
          .attach();

      // Hook each serialize method
      trace.on('enter', function(args) {
          // Check if any of the arguments are an instance of MemoryStream
          for (let i = 0; i < this.method.parameterCount; i++) {
              const paramType = this.method.parameterType(i);
              if (paramType.name.includes("MemoryStream")) {
                  const memoryStream = new Il2Cpp.Object(args[i]);

                  console.log("MemoryStream passed to " + this.method.name);

                  // Read the internal buffer of MemoryStream (using internal fields/methods)
                  const buffer = memoryStream.field("internalBuffer").value;
                  const position = memoryStream.field("position").value;
                  const length = memoryStream.field("length").value;

                  console.log(`MemoryStream internal buffer at position ${position}, length ${length}`);

                  // Optionally, read the buffer data
                  const bufferContent = buffer.readByteArray(length);
                  console.log("Buffer Content (in bytes):");

                  // Print the buffer content as a hex string
                  let hexString = "";
                  for (let i = 0; i < bufferContent.length; i++) {
                      hexString += bufferContent[i].toString(16).padStart(2, '0') + " ";
                  }
                  console.log(hexString);

                  break; // Stop once MemoryStream is found
              }
          }
      });

      trace.on('leave', function(retval) {
          console.log("Method " + this.method.name + " finished.");
      });
  });

Thank you

[vfsfitvnm]

Il2Cpp.Tracer is designed to quickly trace the invocation of a bulk of methods. Currently, it's not possible to pass a custom printer for a certain Il2Cpp.Type (but this could be a nice to have feature!).

If know in advance the method you want to hook, you should override the implementation of the specific method you want to hook and supply the logic to dump the MemoryStream.

PS: trace.on doesn't exist