Error adding prebuilt apk with shared libraries to AOSP

Question

I tried to add a prebuilt APK to my Android build. The APK contains several shared libraries (*.so files). It compiles without problem, but I still get an error from the app indicating that the libraries cannot be found.

Why could this be?

Here is the android.mk code:

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := apkwithso
LOCAL_SRC_FILES := $(LOCAL_MODULE).apk
LOCAL_REQUIRED_MODULES := libx liby libz
LOCAL_MODULE_CLASS := APPS
LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
LOCAL_CERTIFICATE := PRESIGNED
include $(BUILD_PREBUILT)

libx, y, z are my libx.so, liby.so, and libz.so

I also tried to copy the .so manually from the APK to the out lib directories but it didn't work.

I am compiling with Android 4.1.2 for Galaxy Nexus Maguro.

Answer 1

I've had this problem myself, the reason is that when APK files are included in a build they are essentially bypassing the installation process. This installation process is the point at which any shared libraries are extracted from the apk and put in the appropriate place, ergo if that never happens the libraries will not be available. This is because packages that are built from source during the AOSP build either have their prebuilt shared libraries included during that build process or their libraries are also built from source, and in either case those libraries are put in the appropriate place.

For this reason in addition to the apk module itself you should add the following in the same .mk file:

include $(CLEAR_VARS)
LOCAL_MODULE := libapkwithso
LOCAL_SRC_FILES := lib/libapkwithso.so # or wherever your so is
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE_SUFFIX := .so
LOCAL_MODULE_CLASS := SHARED_LIBRARIES
include $(BUILD_PREBUILT)

Then add:

LOCAL_REQUIRED_MODULES := libapkwithso

Answer 2

BUILD_PREBUILT calls prebuild.mk script. The description of this script is the following:

Standard rules for copying files that are prebuilt

It does not tell that the application will be installed. So I think that is why your application cannot find the libraries.

The solution is to extract libraries from the package and copy them separately from the application. The details how to do this you can find here.