Package Android apk with additional executables

Question

As a follow up to an earlier question (Android ioctl - root permissions and usage), is it possible to create a separate native executable and package it in an APK?

The app needs root access and isn't going into the Android marketplace, but I'd like to be able to install it without using a script that pushes an extra executable onto the device.

Answer 1

There is an easy way to package an executable into an APK, and let the system installer take care of unpacking this executable, see How to package native commandline application in apk?.

The trick (tested up to Jelly Bean 4.3) is to name the file "libmyexecutable.so" and put it into libs/armeabi of your Android project (I assume an ADT or ant build). The Package Manager will unpack the file to /data/data/your.package.full.name/lib (it's a symbolic link, for backwards compatibility reasons, so maybe in some future version of Android this will not work anymore) on the device, with executable permissions.

Note that the file has all read-and-execute permissions, so you can use Runtime.getRuntime().exec() or system() from other apps, too.

Update: These days, you should use libs/armeabi-v7a for 32 -bit ARM executables, and you probably need to prepare 64-bit ARM version of the same executables, too.

Answer 2

You can put it into assets and copy it to the app's private directory on first run. After you set the executable bit, you should be able to run it.