toString() overwrite can't call member functions

[nioncode]

Calling a member function of a Java Pojo inside its overridden toString() implementation raises an exception:

'TypeError: undefined not callable', 'stack': 'TypeError: undefined not callable\n    at [anon] (duk_js_call.c:842)\n    at script1.js:18\n    at call (native)\n    at toString (input:1)', 'fileName': 'script1.js', 'lineNumber': 18, 'columnNumber': 1}

Calling the same member function from a user defined method asString() works fine.

Java Pojo:

public class Pojo {

	private String str;
	private long num;

	public Pojo(String str, long num) {
		this.str = str;
		this.num = num;
	}

	public String getStr() {
		return str;
	}

	public long getNum() {
		return num;
	}

	public String asString() {
		return "Pojo[str=" + str + ", num=" + num + "]";
	}
}

Activity:

public class MainActivity extends Activity {

	static {
		System.loadLibrary("frida-gadget-10.5.14-android-x86");
	}

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		findViewById(R.id.btn).setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View view) {
				printPojo(new Pojo("demo", System.currentTimeMillis()));
			}
		});
	}

	public void printPojo(Pojo pojo) {
		Log.d("FRIDA-android", pojo.asString());
	}
}

excerpt of frida script:

	Java.perform(function() {
		log("    hooking java");
		var pojo = Java.use('com.example.myapplication.Pojo');
		pojo['toString'].implementation = function() {
			log("toString() called");
			var i = this.getNum();
			log('num=' + i);
		  	return 'Pojo[num=' + i + ']';
		};
		pojo['asString'].implementation = function() {
			log("asString() called");
			var i = this.getNum();
			log('num=' + i);
		  	return 'Pojo[num=' + i + ']';
		};

		var hook = Java.use('com.example.myapplication.MainActivity');
		hook['printPojo'].implementation = function() {
			var pojo = arguments[0];
			log('hook num=' + pojo.getNum());
			log('\ncalling asString');
			log('asString() result: ' + pojo.asString());
			log('\ncalling toString');
			log('toString() result: ' + pojo.toString());
		}
	});

stdout output:

java available: true
    hooking java
java done
hook num=1505470146320

calling asString
asString() called
num=1505470146320
asString() result: Pojo[num=1505470146320]

calling toString
toString() called
{'type': 'error', 'description': 'TypeError: undefined not callable', 'stack': 'TypeError: undefined not callable\n    at [anon] (duk_js_call.c:842)\n    at script1.js:18\n    at call (native)\n    at toString (input:1)', 'fileName': 'script1.js', 'lineNumber': 18, 'columnNumber': 1}
None
toString() result: null

[nioncode]

Might be related to #35

[oleavr]

Should be fixed in latest versions.