apkenv

A compatibility layer for applications packaged as .apk.

Support website: http://thp.io/2012/apkenv/

Example module and .apk

An example module is provided in modules/trg2.c - you can use this module as a basis to create your own modules. You can download the .apk that works with this example module from:

http://thp.io/2011/trg2/

"Installing" applications

apkenv now includes a very rudimentary facility to "install" an .apk as an application. What it really does is extract the icon from the .apk (this might not work for all .apks - we'd need to read the manifest to get the real file name and application name in all cases) and create a launcher icon that starts apkenv with the apk file as its argument. To use it, type:

apkenv --install /path/to/your.apk

please note that installing is not supported on the pandora port yet.

softfp vs. hardfp

Android is softfp. Maemo 5 is softfp. MeeGo 1.2 Harmattan is hardfp. Pandora is softfp.

softfp and hardfp differ in the way functions with floating point arguments get called. Trying to call a hardfp function with the softfp calling convention will not work and likely result in a crash or worse. To avoid this, you can add an attribute to function declarations to make sure that the function accepts its parameters using the softfp calling convention, like this:

__attribute__((pcs("aapcs")))

There's a convenience #define in apkenv.h called "SOFTFP" with which you can decorate all functions that are either in a native library (i.e. in modules/) or that will be called from the native library (i.e. in compat/). Please note that in theory this attribute is only required on functions that pass float values in the arguments, but do it always to save you some headaches.

Debugging crashes

First of all, enable debugging in the makefile (set DEBUG=1). Then rebuild to get a debug build with lots of debug output. You can then check which symbols get mapped from where at the linker phase (e.g. apkenv x.apk | grep 'from libc') - in general, most libc functions must be mapped in order to avoid problems (e.g. stdio functions don't work in Bionic libc, so we have to hack around these issues - the same is true for memory (de-)allocation, etc..).

When you have all relevant functions mapped, ltrace'ing apkenv can help you find the library function in which it crashes - this will not list functions from Bionic libs, but only from your system libraries (another reason why it is usually a good idea to map system-level functions).

apkenv now also has some more in depth debugging options (see --help), for example tracing calls to bionic libraries (-ta -u), while running an app this will show you which bionic functions are called from the app and if the crash happens soon after one of the bionic functions is called try adding this function to the hooks, in some cases this has helped us to fix crashes.

Documentation

JNI Invocation API http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/invocation.html

JNI Functions http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/functions.html

JNI Types and Data Structures http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/types.html

GCC Function Attributes http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html

ARM Hard Float Point: VFP Comparison http://wiki.debian.org/ArmHardFloatPort/VfpComparison

Android MotionEvent http://developer.android.com/reference/android/view/MotionEvent.html

Third Party Code

All code written by me (thp) for apkenv is licensed under a simplified BSD license (see LICENSE.apkenv). However, code from third parties might be licensed under a different license, and have different copyright holders:

apklib/unzip.{c,h}, apklib/ioapi.{c,h}: The MiniZip project - http://www.winimage.com/zLibDll/minizip.html Copyright (C) 1998-2010 Gilles Vollant (minizip) Copyright (C) 2007-2008 Even Rouault Copyright (C) 2009-2010 Mathias Svensson ( http://result42.com )

apklib/ioapi_mem.c: ioapi implementation for accessing .zip files in memory Copyright (C) 1998-2003 Gilles Vollant Copyright (C) 2003 Justin Fletcher

linker/*: The Android Bionic Linker + The Android Bionic C Library Copyright (c) 2005-2008, The Android Open Source Project

jni/jni.h: libnativehelper: Support functions for Android's class libraries Copyright (C) 2006 The Android Open Source Project

compat/hooks.c, compat/pthread_wrapper.c: pthread wrapper implementation based on code from libhybris Copyright (C) 2012 Carsten Munk

Pandora Port

All code written by me (crowriot) for apkenv's pandora port is licensed under same conditions as the apkenv itself.