ANDROID: Superuser + Shared JNI LIBs

If you need access to system libs (in my case, uinput), you will usually need to do one of 2 things:

1. create another unix executable (binary), which will call uinput, and invoke it with su (super user). Put this file in the /raw directory, and copy it to the device during run-time. This seems to be the easier method. The source is as such:

your_copy_binary(R.raw.your_binary, getFilesDir().getAbsolutePath()+"/your_binary");
Process sh = Runtime.getRuntime().exec("su");
OutputStream os = sh.getOutputStream();
os.write("chmod 777 " + getFilesDir().getAbsolutePath() + "/your_binary" + "\n", "ASCII");
os.write(getFilesDir().getAbsolutePath() _ "/your_binary", "ASCII");

2. create a unix shared library embedded within your android app, call open(...) to directly access the system lib, give the manifest SUPERUSER permissions, and finally set the lib to chmod 777.

Here's the JNI sourcecode:
int success = open("/dev/input", O_WRONLY | O_NONBLOCK);

Here's the Manifest added permission:
< uses-permission android:name="android.permission.ACCESS_SUPERUSER" />

Here's the final step to chmod
chmod 777 /dev/uinput


I prefer the second method, because it's closer to how the android NDK was intended to run.