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Android NDK/JNI: Building a shared library that depends on other shared libraries

I am writing an android app that wants to make JNI calls into a shared library built in using the NDK. The trick is this shared library calls functions provided by OTHER shared libraries. The other shared libraries are C libraries that have been compiled elsewhere.
Here's what I've tried:
My Environment:
I'm working in Eclipse. I've added native support and have a jni library. In that library I have my code and a \lib directory where I have copied my other .so files.
Attempt #1 Android.mk: Just telling it where the libs are
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := native_lib
LOCAL_SRC_FILES := native_lib.cpp
LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib -llog
LOCAL_LDLIBS += -L$(LOCAL_PATH)/lib/support_lib1
LOCAL_LDLIBS += -L$(LOCAL_PATH)/lib/support_lib2
include $(BUILD_SHARED_LIBRARY)
This builds just fine, but when I try to run I get errors indicating that dlopen(libnative_lib) failed because it couldn't load libsupport_lib1.
Coming here I found this:
Can shared library call another shared library?
which said that I needed to call load library on all necessary libraries. Great!
Attempt #2 Opening each library first
static {
System.loadLibrary("support_lib1");
System.loadLibrary("support_lib2");
System.loadLibrary("native_lib");
}
Again, this builds just fine, however when I run I get a new error:
couldn't load libsupport_lib1. findLibrary returned null.
Now we're getting somewhere. It must not be loading the libraries over to the target.
Attempt #3 Copying .so files into project/libs/armeabi
Didn't work. When Eclipse builds it deleted the files I dropped in there.
Attempt #4 Creating a new module for each library
So then I found this:
Android NDK: Link using a pre-compiled static library
It's about static libraries, but maybe I am having a similar problem. The gist is that I need to declare a module for each library. So my new Android.mk looks like this:
LOCAL_PATH := $(call my-dir)
#get support_lib1
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib1
LOCAL_SRC_FILES := $(LOCAL_PATH)/lib/support_lib1.so
include $(BUILD_SHARED_LIBRARY)
#get support_lib2
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib2
LOCAL_SRC_FILES := $(LOCAL_PATH)/lib/support_lib2.so
include $(BUILD_SHARED_LIBRARY)
#build native lib
include $(CLEAR_VARS)
LOCAL_MODULE := native_lib
LOCAL_SRC_FILES := native_lib.cpp
LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib -llog
LOCAL_LDLIBS += -L$(LOCAL_PATH)/lib/support_lib1
LOCAL_LDLIBS += -L$(LOCAL_PATH)/lib/support_lib2
include $(BUILD_SHARED_LIBRARY)
This builds! Even better, armeabi has the sos now! Even BETTER I get the following messages when I try to run it (telling me that support_lib1 and 2 were opened by LoadLibrary:
Trying to load lib /data/app-lib/com.example.tst/libsupport_lib1.so
added shared lib /data/app-lib/com.example.tst/libsupport_lib1.so
no JNI_OnLoad found in /data/app-lib/com.example.tst/libsupport_lib1.so, skipping init
but then...
dlopen failed: Could not locate symbol func_that_exists_in_libsupport_lib.so referenced by libnative_lib.so
Edit: Attempt 5: Use PREBUILT_SHARED_LIBRARY
So I found this:
How can i Link prebuilt shared Library to Android NDK project?
which seems to be exactly what I'm asking. Their answer seems to be 'don't use 'build_shared_library' but instead 'use PREBUILT_SHARED_LIBRARY
Okay, let's try.
LOCAL_PATH := $(call my-dir)
#get support_lib1
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib1
LOCAL_SRC_FILES := $(LOCAL_PATH)/lib/support_lib1.so
include $(PREBUILT_SHARED_LIBRARY)
#get support_lib2
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib2
LOCAL_SRC_FILES := $(LOCAL_PATH)/lib/support_lib2.so
include $(PREBUILT_SHARED_LIBRARY)
#build native lib
include $(CLEAR_VARS)
LOCAL_MODULE := native_lib
LOCAL_SRC_FILES := native_lib.cpp
LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib -llog
LOCAL_SHARED_LIBRARIES := support_lib1 support_lib2
include $(BUILD_SHARED_LIBRARY)
Build... fails! The build complains about missing symbols now.
Edit: Attempt 6: Flatten everything
So I went back to the prebuilts documentation in the NDK. It says:
Each prebuilt library must be declared as a single independent module to the build system. Here is a trivial example where we assume that the file "libfoo.so" is located in the same directory than the Android.mk below:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := foo-prebuilt
LOCAL_SRC_FILES := libfoo.so
include $(PREBUILT_SHARED_LIBRARY)
Notice that, to declare such a module, you really only need the following:
Give the module a name (here 'foo-prebuilt'). This does not need to correspond to the name of the prebuilt library itself.
Assign to LOCAL_SRC_FILES the path to the prebuilt library you are providing. As usual, the path is relative to your LOCAL_PATH.
Include PREBUILT_SHARED_LIBRARY, instead of BUILD_SHARED_LIBRARY, if you are providing a shared, library. For static ones, use PREBUILT_STATIC_LIBRARY.
A prebuilt module does not build anything. However, a copy of your prebuilt shared library will be copied into $PROJECT/obj/local, and another will be copied and stripped into $PROJECT/libs/.
So let's try flattening everything out to match the trivial example. I copied my libraries out of their cozy /lib folder and put them in the jni root. I then did this:
LOCAL_PATH := $(call my-dir)
#get support_lib1
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib1
LOCAL_SRC_FILES := support_lib1.so
include $(PREBUILT_SHARED_LIBRARY)
#get support_lib2
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib2
LOCAL_SRC_FILES := support_lib2.so
include $(PREBUILT_SHARED_LIBRARY)
#build native lib
include $(CLEAR_VARS)
LOCAL_MODULE := native_lib
LOCAL_SRC_FILES := native_lib.cpp
LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib -llog
LOCAL_SHARED_LIBRARIES := support_lib1 support_lib2
include $(BUILD_SHARED_LIBRARY)
and... same error. Moreover I'm most definitely NOT seeing library files getting copied to $PROJECT/obj/local.
sooooo.... now what?

Your problem is with the naming convention. NDK and Android insist on the shared library names to always begin with lib. Otherwise, the libraries will not be linked properly, and not copied to the libs/armeabi folder properly, and not installed on the device (copied to /data/data/package/lib directory properly.
If you rename support_lib1.so to libsupport_1.so and support_lib2.so to libsupport_2.so, and put these two files in jni/lib directory, then your Attempt #5 will work with minor change:
LOCAL_PATH := $(call my-dir)
#get support_lib1
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib1
LOCAL_SRC_FILES := lib/libsupport_1.so
include $(PREBUILT_SHARED_LIBRARY)
#get support_lib2
include $(CLEAR_VARS)
LOCAL_MODULE := support_lib2
LOCAL_SRC_FILES := lib/libsupport_2.so
include $(PREBUILT_SHARED_LIBRARY)
#build native lib
include $(CLEAR_VARS)
LOCAL_MODULE := native_lib
LOCAL_SRC_FILES := native_lib.cpp
LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib -llog
LOCAL_SHARED_LIBRARIES := support_lib1 support_lib2
include $(BUILD_SHARED_LIBRARY)
BTW, I don't think you need this -L$(SYSROOT)/../usr/lib.
PS Don't forget to update the Java side, too:
static {
System.loadLibrary("support_lib1");
System.loadLibrary("support_lib2");
System.loadLibrary("native_lib");
}

Not sure if this is exactly where you are at, but here's what I know about these sorts of things.
Make each prebuilt libary its own separate Makefile. Multiple targets in Android.mk tends to get wonky. Sad.
Include each make file using $(call import-add-path) and $(call import-module)
Export as much as you can from the prebuilt's make files, using the LOCAL_EXPORT_ family of variables.
Prebuilt Shared Library Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := my_module_name
MY_LIBRARY_NAME := shared_library_name
### export include path
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
### path to library
LOCAL_SRC_FILES := libs/$(TARGET_ARCH_ABI)/lib$(MY_LIBRARY_NAME).so
### export dependency on the library
LOCAL_EXPORT_LDLIBS := -L$(LOCAL_PATH)/libs/$(TARGET_ARCH_ABI)/
LOCAL_EXPORT_LDLIBS += -l$(MY_LIBRARY_NAME)
include $(PREBUILT_SHARED_LIBRARY)
This is assuming that the prebuilt libaries live in a dir structure like this
+ SharedProjectFolderName
+--- Android.mk
+--- include/
+-+- libs/$(TARGET_ARCH_ABI)/
|- libshared_library_name.so
If you are not building for multiple ABI, I guess you can leave that bit out
The Project's Android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := my_jni_module
## source files here, etc...
### define dependency on the other library
LOCAL_SHARED_LIBRARIES := my_module_name
include $(BUILD_SHARED_LIBRARY)
$(call import-add-path,$(LOCAL_PATH)/path/to/myLibraries/)
$(call import-module,SharedProjectFolderName)
$(call import-module,AnotherSharedProject)
I recommend you put all shared libraries in one folder. When you say $(call import-module,SharedProjectFolderName) it looks for a folder containing an Android.mk along the search path you told it (import-add-path)
By the way, you probably shouldn't specify LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib. It should be finding the proper libs from NDK by itself. Adding more linker paths will probably confuse it. The proper way is to export the linker paths as flags from the sub-modules.
ALSO, you can use ndk-build V=1 to get a ton of info on why it can't find paths, etc

The -L option gives the linker a directory path in which to look for libraries. The -l option gives the linker a library file name to link in. Library file names must begin with "lib". Your libraries should be named libsupport_lib1.so and libsupport_lib2.so. If you do that, then this is probably what you should do (replacing attempt #1):
LOCAL_LDLIBS := -L$(SYSROOT)/../usr/lib -llog -lsupport_lib1 -lsupport_lib2
LOCAL_LDLIBS += -L$(LOCAL_PATH)/lib
The linker will prefix the library name you specify using -l with "lib" and suffix it with ".so". (Why do you have -L$(SYSROOT)/../usr/lib?)
I believe that attempts #1 and #2 failed because you did not link your libraries into your executable - they are not mentioned in a -l option. By the way, you can verify this yourself. Unzip the .apk file and look in the lib directory and subdirectories. Are your .so files in there?
Looking at the error:
but then... dlopen failed: Could not locate symbol func_that_exists_in_libsupport_lib.so referenced by libnative_lib.so
Can you supply the entire message? dlopen() loads and links libraries into the running process.

Include prebuilt static library

I created a static C++ library for testing. It only defines a class, MyLibrary, and the constructor MyLibrary::MyLibrary(). I built it in qtcreator, and got a libMyLibrary.a file, which is a prebuilt static library.
I would like to use this library in an Android project (using the NDK). In a working NDK test project, I therefore added a folder called inc at the same level as jni, in which I put libMyLibrary.a and its corresponding header mylibrary.h.
My Android.mk is as follows:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := MyLibrary
LOCAL_SRC_FILES := ../inc/libMyLibrary.a
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := helloJNI
LOCAL_SRC_FILES := mainActivity.cpp
LOCAL_C_INCLUDES += inc
LOCAL_STATIC_LIBRARIES := MyLibrary
LOCAL_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)
The ndk-build command compiles without any error. But my static library is apparently not linked (i.e. it does not appear in obj/local/armeabi/objs).
I have tried to include it in my mainActivity.cpp file, but even though the header (mylibrary.h) is found, the library is not and I cannot create an object as in:
MyLibrary test = MyLibrary();
What am I doing wrong? I have read tens of similar questions on StackOverflow, but I still don't get it.

try to use this:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := helloJNI
LOCAL_SRC_FILES := mainActivity.cpp
LOCAL_C_INCLUDES := $(LOCAL_PATH)/inc/
LOCAL_LDLIBS := -llog -L$(LOCAL_PATH)/inc/ -lMyLibrary
include $(BUILD_SHARED_LIBRARY)
move libMyLibrary.a & mylibrary.h to jni/inc/libMyLibrary.a

Linking dependent .so files with ndk-build for Android

I have created a .so file that exposes a native C call to Java via JNI. This works well and I can deploy the app onto my Android system if I just use system libraries in my C code. However, if I want to make calls to functions in other .so files, I cannot get my project to link correctly.
For example, say I have the "libotherso.so" file which contains APIs defined in C that I can call from the "MyJNILibrary.c" code I'm using to generate "libMyJNILibrary.so".
I tried to change my Android.mk file as follows:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := MyJNILibrary
LOCAL_SRC_FILES := MyJNILibrary.c
LOCAL_LDLIBS += -lotherso
include $(BUILD_SHARED_LIBRARY)
But when I call ndk-build on this, I get errors finding -lotherso. Where do I put the "libotherso.so" file so that ndk-build can pick it up?
Thanks for any help you can provide.

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := otherso
LOCAL_SRC_FILES := ../lib/libotherso.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := MyJNILibrary
LOCAL_SRC_FILES := MyJNILibrary.c
LOCAL_SHARED_LIBRARIES := otherso
include $(BUILD_SHARED_LIBRARY)
Note that LOCAL_SRC_FILES is relative to your LOCAL_PATH.
Don't forget to load your dependency before your own JNI library:
static {
System.loadLibrary("otherso");
System.loadLibrary("MyJNILibrary");
}

Error in linking C++ static library with android ndk(Error: file format not recognized)

I am trying to include static cpp library in android. This library is already compiled(on mac os) and i have its include files.
Here is my Android.mk file
LOCAL_PATH := $(call my-dir)
include $(call all-subdir-makefiles)
include $(CLEAR_VARS)
LOCAL_MODULE:= utils
LOCAL_SRC_FILES:= libUtils.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/utils
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := sample
LOCAL_SRC_FILES := sample_cpp.cpp
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
LOCAL_STATIC_LIBRARIES := utils
LOCAL_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)
and here is Application.mk file
APP_STL := stlport_static
APP_CPPFLAGS = -fexceptions
but whenever it try to compile it using NDK i get the error
(Path of file)/libUtils.a: file not recognized: File format not recognized
collect2: ld returned 1 exit status

From the comments and so on it sounds like you trying to use a non arm version of the library. You should build the library with the ndk. The documentation has even documentation on how to do that.
For example building sigc++ could be like (from a project of mine, where sigc++ resides in the sigc++ subdirectory)
# SIGC++ Library built as static library
LOCAL_MODULE := sigc
LOCAL_PATH = $(CURRENT_DIR)
LOCAL_CPP_EXTENSION := .cc
LOCAL_SRC_FILES := sigc++/signal.cc sigc++/signal_base.cc sigc++/trackable.cc
LOCAL_SRC_FILES += sigc++/functors/slot_base.cc sigc++/adaptors/lambda/lambda.cc
LOCAL_SRC_FILES += sigc++/connection.cc sigc++/functors/slot.cc
LOCAL_C_INCLUDES := sigc++
include $(BUILD_STATIC_LIBRARY)
But you should really read how the compiling linking works. I am afraid building for android with ndk is more low level than using Xcode or Msvc.

Unsatisfied Link Error - Could not find Library

I'm attempting to load the libjnigraphics.so prebuilt library to my project, however when I deploy the application, I am receiving this error:
06-17 22:35:28.741: INFO/dalvikvm(298): Unable to dlopen(/data/data/com.foo/lib/libndkfoo.so): Cannot load library: link_image[1721]: 29 could not load needed library 'libjnigraphics.so' for 'libndkfoo.so' (load_library[1051]: Library 'libjnigraphics.so' not found)
It compiles perfectly, fine.
Here's my Android.mk as well:
LOCAL_PATH := $(call my-dir)
# Add prebuilt libjnigraphics
include $(CLEAR_VARS)
LOCAL_MODULE := libjnigraphics
LOCAL_SRC_FILES := libjnigraphics.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
# Here we give our module name and source file(s)
LOCAL_MODULE := ndkfoo
LOCAL_SRC_FILES := ndkfoo.c
LOCAL_SHARED_LIBRARY := libjnigraphics
#LOCAL_LDLIBS += -libjnigraphics
LOCAL_LDLIBS += -llog
include $(BUILD_SHARED_LIBRARY)
Is there a special place I need to put the libjnigraphics.so? Right now I have it in the jni folder, however I've tried it in multiple other places and it still fails. Any help?

The device has to be running Foyo (Android 2.2, target platform android-8) to be able to use libjnigraphics.so. It doesn't matter what is in your SDK or project directories, this library is part of the device's system libraries.
You can compile your code using the NDK with android-8, but then it will give link-time errors when you side-load the apk and your device happens to be running 2.1 or earlier.
There's this SO question with a workaround, but it shouldn't be relied upon and will crash on some devices. Here's a post on the android-ndk group explaining the issues.

just try these changes:
LOCAL_PATH := $(call my-dir)
# Add prebuilt libjnigraphics
include $(CLEAR_VARS)
LOCAL_MODULE := graphics-prebuilt
LOCAL_SRC_FILES := libjnigraphics.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
# Here we give our module name and source file(s)
LOCAL_MODULE := ndkfoo
LOCAL_SRC_FILES := ndkfoo.c
LOCAL_SHARED_LIBRARY := graphics-prebuilt
LOCAL_LDLIBS += -llog
include $(BUILD_SHARED_LIBRARY)