Compiling for Android NDK: unable to find Android NDK function definitions - android

I am attempting to compile an Android-9 project that calls Android NDK functions (such as "AAsset_close") by running "ndk-build" via the Cygwin terminal, but the "ndk-build" command returns an error message, stating that it is unable to find the function definitions.
The error messages from "ndk-build" are as follows:
[Android NDK path]/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld.exe: [project folder]/static library: in function [function name]:[file name]:39: error: undefined reference to 'AAsset_close'
etc.
My "Android.mk" file is as follows:
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := <name of project>
LOCAL_C_INCLUDES := <folders where header files are located>
LOCAL_CFLAGS := $(LOCAL_C_INCLUDES:%=-I%) -O2 -Wall -D__ANDROID__ -DtyANDROID
LOCAL_CPPFLAGS := $(LOCAL_C_INCLUDES:%=-I%) -O2 -Wall -D__ANDROID__ -DtyANDROID
LOCAL_LDLIBS := -lm -lEGL -lGLESv2 -llog -lz -landroid
LOCAL_STATIC_LIBRARIES := android_native_app_glue
LOCAL_ARM_MODE := arm
LOCAL_SRC_FILES := <source files>
include $(BUILD_STATIC_LIBRARY)
...
My "Application.mk" makefile is as follows:
APP_ABI := armeabi armeabi-v7a x86
APP_PLATFORM := android-9
According to the "nm" Unix command, this function is defined within the Android NDK library "libandroid.so", which is present in the NDK path for all target platforms. As demonstrated above, I have included "-landroid" to the "LOCAL_LDLIBS" macro, which should allow me to link against that library. What else do I need to do to fix this compile error?

You show the Android.mk that builds a static library, at this step the linker is not called, threfore $(LOCAL_LDLIBS) is ignored. You probably have another Android.mk or a different section, where you have
include $(BUILD_SHARED_LIBRARY)
Please check, -landroid is probably missing in that section.

Related

ANDROID: How to properly link against static libraries while creating shared libraries with dependencies on the static ones

I have to use some c++ code in my android application. This code was used successfully in an iOS project.
The code depends on 2 external libraries: zero-mq and protocol buffers.
I compiled the zmq library as an static library like explained here. I added the static (.a) library and the .jar to my project.
I created the protobuf library with the following configurations:
./configure --host=arm-eabi --with-sysroot=x/android-ndk-r10d/platforms/android-21/arch-arm CC="x/android-ndk-r10d/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86/bin/arm-linux-androideabi-gcc --sysroot x/android-ndk-r10d/platforms/android-21/arch-arm" --enable-cross-compile --with-protoc=protoc LIBS=-lc
make
I changed the real directories to x to make them shorter.
In my Android Project(IDE: Android Studio) I prepared everything which is necessary. I created a JNI Folder and deactivated the auto-creation of the makefiles.
Application.mk:
APP_MODULE := proxy
APP_STL := gnustl_shared
APP_CPPFLAGS := -frtti -fexceptions --std=c++11
APP_ABI := armeabi-v7a ##all later
NDK_TOOLCHAIN_VERSION := 4.9
Android.mk:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := zmq_static
LOCAL_SRC_FILES := zmq/libzmq.a
include $(PREBUILD_STATIC_LIBRARY)
LOCAL_MODULE := protobuf_static1
LOCAL_SRC_FILES := protobuf/libprotobuf.a
LOCAL_EXPORT_C_INCLUDES := google/protobuf protobuf/
include $(PREBUILD_STATIC_LIBRARY)
LOCAL_MODULE := protobuf_static2
LOCAL_SRC_FILES := protobuf/libprotobuf-lite.a
LOCAL_EXPORT_C_INCLUDES := google/protobuf protobuf/
include $(PREBUILD_STATIC_LIBRARY)
LOCAL_MODULE := protobuf_static3
LOCAL_SRC_FILES := protobuf/libprotoc.a
LOCAL_EXPORT_C_INCLUDES := google/protobuf protobuf/
include $(PREBUILD_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := proxy
LOCAL_CFLAGS := -I/include -pthread -lpthread -D__GXX_EXPERIMENTAL_CXX0X__ - frtti
LOCAL_CPPFLAGS := -I/include -pthread -lpthread -D__GXX_EXPERIMENTAL_CXX0X__ -frtti
LOCAL_CPP_FEATURES += exceptions
LOCAL_LDLIBS := -llog
LOCAL_SRC_FILES := \
usersession.cpp\
## LOCAL_ALLOW_UNDEFINED_SYMBOLS := true will compile the code but shutdown on runtime
LOCAL_C_INCLUDES += C:\Users\M\Dropbox\Workspace\ndk_swig_test\app\src\main\jni
LOCAL_C_INCLUDES += C:\Users\M\Dropbox\Workspace\ndk_swig_test\app\src\arm\jni
LOCAL_C_INCLUDES += C:\Users\M\Dropbox\Workspace\ndk_swig_test\app\src\debug\jni
LOCAL_C_INCLUDES += C:\Users\M\Dropbox\Workspace\ndk_swig_test\app\src\armDebug\jni
LOCAL_C_INCLUDES += \zmq
LOCAL_C_INCLUDES += \protobuf
LOCAL_STATIC_LIBRARIES := zmq_static protobuf_static1 protobuf_static2 protobuf_static3
LOCAL_WHOLE_STATIC_LIBRARIES := zmq_static protobuf_static1 protobuf_static2 protobuf_static3
include $(BUILD_SHARED_LIBRARY)
The zmq library is in the subdirectory zmq and the protobuf library is in the subfolder protobuf.
Now the linking of the Objects still does not work. The Error Output when I execute ndk-build:
C:\Users\M\Dropbox\Workspace\ndk_swig_test\app\src\main\jni>ndk-build
[armeabi-v7a] SharedLibrary : libproxy.so
C:/Users/M/Documents/ndk/sources/cxx-stl/gnu- libstdc++/4.9/include/ext/new_allocator.h:127: error: undefined reference to 'ControlledInstance::ControlledInstan (std::shared_ptr<protogen::Application>, std:
:shared_ptr<protogen::Role>, std::shared_ptr<protogen::User>)'
C:/Users/M/Documents/ndk/sources/cxx-stl/gnu- libstdc++/4.9/include/bits/shared_ptr_base.h:511: error: undefined reference to 'protogen::User::User()'
C:/Users/M/Documents/ndk/sources/cxx-stl/gnu- libstdc++/4.9/include/bits/shared_ptr_base.h:914: error: undefined reference to 'google::protobuf::internal::empty tring_'
C:/Users/M/Dropbox/Workspace/ndk_swig_test/app/src/main//jni/controlledinstance.h :23: error: undefined reference to 'protogen::MetaGraph::~MetaGraph()'
collect2.exe: error: ld returned 1 exit status
make.exe: *** [C:/Users/M/Dropbox/Workspace/ndk_swig_test/app/src/main//obj/local/armeabi- v7a/libproxy.so] Error 1
I tried many versions of the Android.mk and recreated the library more than once with different options which I found all over the internet.
I also looked at dozens of threads on stackoverflow which did not help me.(I'm not allowed to link them because of low reputation)
Additionally i read most of the doc files from the ndk e.g. PREBUILTS.
I added some other directories to my JNI directory e.g. the directory with the original files and directories (compiler, io, stubs...). I think this directory should offer the export of the necessary methods if the prebuild library was successfully linked to my shared library - which is not the case.
I tried far more than I can explain in few minutes and I think it would be overkill if i added everything I've tried because nothing helped.
Because this is my first question I dont have the reputation to include more than 2 links. Sorry for that.
There may probably be other issues as well, but you at least have got a typo - it should be include $(PREBUILT_STATIC_LIBRARY), as in, BUILT, not BUILD.

WARNING: .../Android.mk: non-system libraries in linker flags

I'm getting this warning while running $ANDROID_NDK_ROOT/ndk-build. The Android.mk is below.
$ $ANDROID_NDK_ROOT/ndk-build
WARNING:/Users/jwalton/Android-CryptoPP/jni/Android.mk:prng:
non-system libraries in linker flags: -lcryptopp -lstlport_shared
This is likely to result in incorrect builds. Try using LOCAL_STATIC_LIBRARIES
or LOCAL_SHARED_LIBRARIES instead to list the library dependencies of the
current module
...
However, when I follow the instructions and remove -lcryptopp -lstlport_shared from LOCAL_LDLIBS, then I get link errors related to symbols from libstlport_shared.so. A sample of the errors are shown below after the Android.mk file.
How, exactly, does ndk-build want Android.mk set up?
Why do I have to add $(STLPORT_INCL) to LOCAL_C_INCLUDES, and $(STLPORT_LIB) to LOCAL_LDFLAGS? Why does APP_STL := stlport_shared not setup the STL correctly out of the box?
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
TARGET_ARCH_ABI := armeabi
TARGET_ABI := android-9-armeabi
CRYPTOPP_INCL := /usr/local/cryptopp-android-9/include
CRYPTOPP_LIB := /usr/local/cryptopp-android-9/lib
STLPORT_INCL := /opt/android-ndk-r9/sources/cxx-stl/stlport/stlport
STLPORT_LIB := /opt/android-ndk-r9/sources/cxx-stl/stlport/libs/armeabi
APP_STL := stlport_shared
APP_MODULES := stlport_shared cryptopp
LOCAL_CPP_FEATURES := rtti exceptions
LOCAL_C_INCLUDES := $(CRYPTOPP_INCL) $(CRYPTOPP_INCL)/cryptopp $(STLPORT_INCL)
LOCAL_LDFLAGS := -L $(CRYPTOPP_LIB) -L $(STLPORT_LIB)
LOCAL_LDLIBS := -lcryptopp -lstlport_shared -llog -landroid
# LOCAL_LDLIBS := -llog -landroid
# LOCAL_SHARED_LIBRARIES := -lcryptopp -lstlport_shared
LOCAL_MODULE := prng
LOCAL_SRC_FILES := libprng.cpp
include $(BUILD_SHARED_LIBRARY)
Here is a sample of the error when trying to follow the advice by removing my local libraries from LOCAL_LDLIBS:
$ $ANDROID_NDK_ROOT/ndk-build
Android NDK: WARNING: APP_PLATFORM android-14 is larger than android:minSdkVersion 9 in /Users/jwalton/Android-CryptoPP/AndroidManifest.xml
Gdbserver : [arm-linux-androideabi-4.6] libs/armeabi/gdbserver
Gdbsetup : libs/armeabi/gdb.setup
Compile++ thumb : prng <= libprng.cpp
SharedLibrary : libprng.so
/opt/android-ndk-r9/toolchains/arm-linux-androideabi-4.6/prebuilt/darwin-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: /Users/jwalton/Android-CryptoPP/obj/local/armeabi/objs-debug/prng/libprng.o: in function std::__node_alloc::allocate(unsigned int&):/opt/android-ndk-r9/sources/cxx-stl/stlport/stlport/stl/_alloc.h:158: error: undefined reference to 'std::__node_alloc::_M_allocate(unsigned int&)'
/opt/android-ndk-r9/toolchains/arm-linux-androideabi-4.6/prebuilt/darwin-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: /Users/jwalton/Android-CryptoPP/obj/local/armeabi/objs-debug/prng/libprng.o: in function std::__node_alloc::deallocate(void*, unsigned int):/opt/android-ndk-r9/sources/cxx-stl/stlport/stlport/stl/_alloc.h:161: error: undefined reference to 'std::__node_alloc::_M_deallocate(void*, unsigned int)'
/opt/android-ndk-r9/toolchains/arm-linux-androideabi-4.6/prebuilt/darwin-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: /Users/jwalton/Android-CryptoPP/obj/local/armeabi/objs-debug/prng/libprng.o: in function std::ios_base::_M_check_exception_mask():/opt/android-ndk-r9/sources/cxx-stl/stlport/stlport/stl/_ios_base.h:193: error: undefined reference to 'std::ios_base::_M_throw_failure()'
...
I interpret the "non-system libraries in linker flags" message as a warning that you're not using the default system libraries (in usr/lib) which may be perfectly fine, but which could also lead to errors (incompatibility between different libraries versions). Whether this warning bugs you is completely up to you.
Then, about the way you tried to solve it, I think you're using wrongly the LOCAL_SHARED_LIBRARIES variable of the NDK.
I paste here a sample from one of my Android.mk file which uses Assimp
#------------------------------------------------------------------ Assimp
include $(CLEAR_VARS)
LOCAL_MODULE := Assimp
LOCAL_EXPORT_C_INCLUDES := $(GENERATED_INCLUDE_PATH)/assimp/include
LOCAL_SRC_FILES := $(GENERATED_PATH)/assimp/lib/libassimp.a
include $(PREBUILT_STATIC_LIBRARY)
...
LOCAL_STATIC_LIBRARIES := \
Assimp \
<Your other libs here>
As you can see, I declare a LOCAL_MODULE with a custom name, set up a few variables and then include the PREBUILT_STATIC_LIBRARY script which tells the NDK to use this lib.
Then in LOCAL_STATIC_LIBRARIES I list the libraries I use with their module name, not as if this was a linker flag like you're doing here.
In your case, I believe you should do the following, for example for the stl
include $(CLEAR_VARS)
LOCAL_MODULE := STLPortShared
LOCAL_EXPORT_C_INCLUDES := <path to stlport includes>
LOCAL_SRC_FILES := <path to stlport library>
include $(PREBUILT_SHARED_LIBRARY)
...
#Notice the name, identical to the one specified for LOCAL_MODULE
LOCAL_SHARED_LIBRARIES = STLPortShared
I think this should do it. Of course, repeat the process for each libs that causes trouble, and don't forget the include(CLEAR_VARS) between each lib specification.

building android project produces make error 2

I have recently purchased a book to assist in my development of C++ for Android which contained some code samples. However, when I come to build some of the sample code, I receive the following error:
C:\ndk\android-ndk-r9\ndk-build.cmd all
"Compile++ : Chapter10 <= Chapter10.cpp
process_begin: CreateProcess(NULL, C:/ndk/android-ndk-r9/toolchains/arm-linux-androideabi-4.7/prebuilt/windows/bin/arm-linux-androideabi-g++ -MMD -MP -MF ./obj/local/armeabi/objs/Chapter10/Chapter10.o.d -fno-exceptions -fno-rtti -Ijni -IC:/ndk/android-ndk-r9/sources/android/native_app_glue -IC:/ndk/android-ndk-r9/sources/cxx-stl/stlport/stlport -IC:/ndk/android-ndk-r9/sources/cxx-stl//gabi++/include -Ijni -DANDROID -Wa,--noexecstack -Wformat -Werror=format-security -frtti -c jni/Chapter10.cpp -o ./obj/local/armeabi/objs/Chapter10/Chapter10.o, ...) failed.
make (e=2): The system cannot find the file specified.
make: *** [obj/local/armeabi/objs/Chapter10/Chapter10.o] Error 2
The make file is as shown below:
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_ARM_MODE := arm
LOCAL_C_INCLUDES := $(LOCAL_PATH)
LOCAL_MODULE := Chapter10
LOCAL_SRC_FILES := Chapter10.cpp \
(Other cpp Files . . . )
LOCAL_LDLIBS := -llog -landroid -lEGL -lGLESv2 -lOpenSLES
LOCAL_STATIC_LIBRARIES := android_native_app_glue
include $(BUILD_SHARED_LIBRARY)
$(call import-module,android/native_app_glue)
The Application.mk file is as below:
APP_PLATFORM := android-9
APP_STL := stlport_static
NDK_TOOLCHAIN_VERSION := 4.7
This was compiled using ADT v22.2.1 and Android NDK r9 on a Windows 7 Machine.
The NDK was installed to 'C:\ndk\android-ndk-r9\'.
Android NDK r9 contains the following toolchains:
arm-linux-androideabi-4.6
arm-linux-androideabi-4.8
arm-linux-androideabi-clang3.2
arm-linux-androideabi-clang3.3
llvm-3.2
llvm-3.3
mipsel-linux-android-4.6
mipsel-linux-android-4.8
mipsel-linux-android-clang3.2
mipsel-linux-android-clang3.3
x86-4.6
x86-4.8
x86-clang3.2
x86-clang3.3
There is no toolchain for gcc 4.7. However, your Application.mk contains the line:
NDK_TOOLCHAIN_VERSION := 4.7
Which tells the NDK to look for the 4.7 toolchain. And it fails.
So, the solution to your problem is changing the NDK_TOOLCHAIN_VERSION variable to 4.6, 4.8, clang3.2, clang3.3, or just clang (which will use the most recent version of Clang available in the NDK).
Check your project path if is contain spaces and non-english characters.
I moved my project into somewhere without spaces, re-build it and works.

Build android native application for many types of CPU

I want to use ffmpeg library in my application so I wrote an Android.mk file as follow:
LOCAL_PATH := $(call my-dir)
TOP_LOCAL_PATH := $(LOCAL_PATH)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES += $(LOCAL_PATH)/android-8/armv5te/include/
LOCAL_CPP_EXTENSION := .cpp
LOCAL_C_EXTENSION := .c
LOCAL_CFLAGS := -O3
LOCAL_MODULE := FilterEngine
LOCAL_SRC_FILES := \
decoding_encoding.c \
LOCAL_LDLIBS := -lm -llog -ljnigraphics -L$(LOCAL_PATH)/android-8/armv5te/lib/ -lavcodec -lavfilter -lavutil -lm -lz
LOCAL_STATIC_LIBRARIES := avcodec avfilter avutil
include $(BUILD_SHARED_LIBRARY)
This make file only builds the library for ARM v5 CPU, to create an ARM v7 build of the library I have to modify the Android.mk file (change from armv5te to armv7a). How can I specify 2 types of CPU in the make file so I can build the library for both CPUs at one.
Thanks in advance.
In your jni folder make "Application.mk" and add the desired target architectures, for example:
APP_ABI := armeabi armeabi-v7a x86
Next, change your Android.mk to use: $(TARGET_ARCH_ABI) where you have the architecture hardcoded.
I'm doing something similar with FFmpeg. Here is a link for further reference:
http://sourceforge.net/p/servestream/code/1217/tree/trunk/jni/
Let me know if you have any additional questions.

Android NDK linking

I am trying to build an android application that calls into a C++ backend. This backend uses ZeroMQ for messaging. Per the android build page on the ZeroMQ guide, I have built a native toolchain of ndk version 6 and used that to (successfully) build ZeroMQ.
However, when I build my own .so with the JNI implementations, I can't seem to make everything load properly. Specifically, if I call System.LoadLibrary("zmq"), this completes successfully, but if I then call *System.LoadLibrary("my_lib")* I always get an UnsatisfiedLinkError complaining that:
Cannot load library reloc_library[1244]: 29 cannot locate zmq_msg_init'...
The libmy_lib.so has been generated several different ways, each with no success. After generating it, I always copies libmy_lib.so (as well as libzmq.so) to my android project's folder: libs/armeabi/.
# Compile all object files - this part was done for all options
/opt/android-toolchain/bin/arm-linux-androideabi-g++ -fpic -c Client_Events.cpp \
Client Wrapper.cpp jni.cpp -I /opt/android-root/include/ -I /my/project/specific/stuff
# Option 1 - Don't link the lib in at all
/opt/android-toolchain/bin/arm-linux-androideabi-g++ -shared \
-Wl,-soname,libmy_lib.so -o libmy_lib.so jni.o Client_Events.o Client_Wrapper.o
# Option 2 - Link ZeroMQ in statically
/opt/android-toolchain/bin/arm-linux-androideabi-g++ -shared \
-Wl,-soname,libmy_lib.so -o libmy_lib.so jni.o Client_Events.o Client_Wrapper.o \
libzmq.a libstdc++.a -Wl,--whole-archive
# Option 3 - Explicitly link ZeroMQ in dynamically
/opt/android-toolchain/bin/arm-linux-androideabi-g++ -shared \
-Wl,-soname,libmy_lib.so -o libmy_lib.so jni.o Client_Events.o Client_Wrapper.o \
-L /opt/android-root/lib/ -lzmq
With each of these options I tried both explicitly calling System.LoadLibrary("zmq") before loading my own library and not. Nothing varied the results. Using nm confirms that, at least in the case of option #2, the missing symbol *zmq_msg_init* is indeed present in libmy_lib.so.
Any ideas as to why it cannot find the ZeroMQ symbols that are linked in?
I just learnt how to compile a 2nd library and link it to my main library in android ndk. Let me see if I am of any use to you.
The following is how I create my 2nd library (In my case, I build bullet physics library and the irrlicht rendering engine as 2 separate libraries for my game).
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES := HEADER FILES
LOCAL_MODULE := bullet
LOCAL_SRC_FILES := SRC FILES
LOCAL_ARM_MODE := arm
LOCAL_CFLAGS := $(LOCAL_C_INCLUDES:%=-I%) -O3 -DANDROID_NDK -DDISABLE_IMPORTGL
LOCAL_LDLIBS := -ldl -llog
include $(BUILD_SHARED_LIBRARY)
Then copy your libxxxx.so (In my case, libbullet.so and libirrlicht.so) to your jni folder. And in your main library .mk file add the following.
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES := (includes for bullet)
LOCAL_MODULE := bullet
LOCAL_SRC_FILES := libbullet.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES := (includes for irrlicht)
LOCAL_MODULE := irrlicht
LOCAL_SRC_FILES := libirrlicht.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_C_INCLUDES := (includes for bullet + includes for irrlicht + includes for main code)
LOCAL_SRC_FILES := main code src files
LOCAL_MODULE := gamescript
LOCAL_ARM_MODE := arm
LOCAL_CFLAGS := $(LOCAL_C_INCLUDES:%=-I%) -O3 -DANDROID_NDK -DDISABLE_IMPORTGL
LOCAL_LDLIBS := -lOpenSLES -landroid -ldl -llog
LOCAL_SHARED_LIBRARIES := bullet irrlicht
include $(BUILD_SHARED_LIBRARY)
And now, add all the libraries to your java code in right order.
System.loadLibrary("bullet");
System.loadLibrary("irrlicht");
System.loadLibrary("gamescript");

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