How to build custom system privilege app in aosp

Question

I am trying to implement custom system app which has system privilege. I searched about it and I learned to make system app built in system image build result needs to be placed in system/app

First I put my custom app's java file, resource file, cpp file as in this below directory(packages/apps).

And I made Android.mk file like this below.

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

$(info Ojt System Module)

#LOCAL_MODULE_CLASS := APPS
#LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)

LOCAL_PACKAGE_NAME := OjtTestApp
LOCAL_CERTIFICATE := platform
LOCAL_PRIVILEGED_MODULE := true
LOCAL_UNINSTALLABLE_MODULE := true

LOCAL_SRC_FILES := $(call all-java-files-under,src)

LOCAL_STATIC_ANDROID_LIBRARIES := \
android-support-v13 \
android-support-v4 \
android-support-compat \
    android-support-v7-appcompat \
    android-support-v7-gridlayout

LOCAL_JNI_SHARED_LIBRARIES := libojt

LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res
LOCAL_SDK_VERSION := current

LOCAL_PROGUARD_ENABLED := disabled

LOCAL_MODULE_TAGS := optional
LOCAL_MODULE_PATH := $(TARGET_OUT_APPS)

include $(BUILD_PACKAGE)

#include $(BUILD_PREBUILT)
include $(call all-makefiles-under,$(LOCAL_PATH))

I also putted package name in aosp_sailfish.mk(device/google/marlin/aosp_sailfish.mk) file like this below.

PRODUCT_PACKAGE += OjtTestApp

After that I build my app by make OjtTestApp and build was completed without error. I tried to make apk file as in this post to system/app so that my custom app can built in system image but It keeps gave me following output(obj/APPS).

[100% 8/8] target Package: OjtTestApp (out/target/product/sailfish/obj/APPS/OjtTestApp_intermediates/package.apk)

Please help me I can't find error in my Android.mk file.

Answer 1

You don't need to go to that length. Build your apk normally don't sign it or sign it with system certificate. Now include the apk by writing a rule in as below in platform specific device.mk file PRODUCT_PACKAGES += \\ AppName

Sample mk file

LOCAL_PATH := $(call my-dir)


####################################
$(warning dont't include $(call my-dir)/Android.mk )

include $(CLEAR_VARS)
LOCAL_MODULE := <your app name>
LOCAL_MODULE_TAGS := optional
LOCAL_CERTIFICATE := PRESIGNED #If you have signed already using system key
LOCAL_PRIVILEGED_MODULE := true
LOCAL_MODULE_CLASS := APPS
LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
LOCAL_SRC_FILES := $(LOCAL_MODULE).apk
#LOCAL_REQUIRED_MODULES := libnative-lib
include $(BUILD_PREBUILT)

For full privilege use android:sharedUserId="android.uid.system" in Manifest