We are students working on an academic software project.
Generally, our goal is to hook Android applications. We want to write a software that replaces C functions in Android applications.
We managed to use Xposed (https://github.com/rovo89/XposedBridge/wiki/Development-tutorial) in order to replace java methods in Android applications. In particular, we replaced java native methods. But the functions we want to replace are part of the Android implementation and not the application’s source code.
We tried to use LD_PRELOAD in order to replace the functions but we didn’t succeed. After updating LD_PRELOAD's content using setprop the applicaton crashed with the error message "Launcher3 isn't responding". We tried to fix the problem but we failed to do so.
We are using Genymotion's Android emulator and our device is rooted.
What is the best way to hook Android applications in order to replace C functions?