I am having issues creating a Android prebuilt shared library. In hope of figuring out what I'm doing wrong, I followed Google's example where I found the source for this example in the android-8.1.0_r52 tree at development/ndk/tests/prebuilt-library/jni.
Here's how I configure the ASOP
$ . build/envsetup.sh
$ lunch (I selected 29 aosp_bullhead_userdebug)
Then in the above jni folder I issued "$ mm"
The error I get is (which is the same is my other project)
ninja: error: 'out/target/product/bullhead/obj/SHARED_LIBRARIES/foo-prebuilt_intermediates/export_includes', needed by 'out/target/product/bullhead/obj/SHARED_LIBRARIES/foo-user_intermediates/import_includes', missing and no known rule to make it
When I grep the out/target/products/bullhead folder for "foo" I get nothing.
I also tried replacing
include $(PREBUILT_SHARED_LIBRARY)
with
include $(BUILD_PREBUILT)
and get the same error, but "obj" is replaced with "obj_arm".
Below is the stock Android.mk that comes with the tree.
LOCAL_PATH := $(call my-dir)
# Define BUILD_FOO=1 to rebuild libfoo.so from scratch, then
# copy obj/local/armeabi/libfoo.so to jni/libfoo.so
#
ifneq ($(BUILD_FOO),)
include $(CLEAR_VARS)
LOCAL_MODULE := foo
LOCAL_SRC_FILES := foo/foo.c
LOCAL_C_INCLUDES := $(LOCAL_PATH)/foo
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/foo
include $(BUILD_SHARED_LIBRARY)
else # not build libfoo.so, trying to use PREBUILT_SHARED_LIBRARY instead.
# Note: the module is named foo-prebuilt, but the library is libfool.so !
#
include $(CLEAR_VARS)
LOCAL_MODULE := foo-prebuilt
LOCAL_SRC_FILES := libfoo.so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/foo
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := foo-user
LOCAL_SRC_FILES := foo-user.c
LOCAL_SHARED_LIBRARIES := foo-prebuilt
include $(BUILD_SHARED_LIBRARY)
endif
This is the jni/ directory structure
jni/
Android.mk
foo-user.c
libfoo.so
foo/
foo.c
foo.h
I got a problem in android.mk.It always show me that cannot find -lsubstrate-dvm and -lsubstrate. I don't know what it is? Could someone tell me how to solve this problem ? Here is the logcat:
Android NDK:non-system libraries in linker flags: -libsubstrate-dvm -libsubstrate
Android NDK: This is likely to result in incorrect builds. Try using LOCAL_STATIC_LIBRARIES
Android NDK: or LOCAL_SHARED_LIBRARIES instead to list the library dependencies of the
Android NDK: current module
cannot find -libsubstrate-dvm
cannot find -libsubstrate
Here is the android.mk
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := substrate
LOCAL_SRC_FILES := libsubstrate.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := substrate-dvm
LOCAL_SRC_FILES := libsubstrate-dvm.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := cydiasubstrate.cy
LOCAL_SRC_FILES := cydiasubstrate.cy.cpp
LOCAL_LDLIBS := -llog -L$(LOCAL_PATH) -lsubstrate-dvm -lsubstrate -lz
LOCAL_ARM_MODE := arm
APP_ALLOW_MISSING_DEPS=true
include $(BUILD_SHARED_LIBRARY)
please help me to fix this issue.
substrate-dvm is the name of the module being built, it relies on a prebuild library, not on sources, so you should look for libsubstrate-dvm.so
You could follow the following link for further help:
https://blog.gdssecurity.com/labs/2014/12/16/hooking-non-public-methods-with-the-ndk-using-mobile-substra.html
to include the Substrate libraries. The easiest way to
do this is to navigate to the ‘/sdk/extras/saurikit/cydia_substrate/’
directory and copy ‘substrate.h’ and navigate to the
‘/sdk/extras/saurikit/cydia_substrate/lib//’ directory and copy
‘libsubstrate-dvm.so’ file into the jni folder of the project.
I am testing facedetection program at Android with NDK. I followed all discussions here. I copied all OpenCV's library files inside armeabi and armeabi-v7a into my project libs folder. Then my Android.mk is updated as
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
OPENCV_INSTALL_MODULES := on
OPENCV_CAMERA_MODULES := off
OPENCV_LIB_TYPE := STATIC
include C:\adt-bundle-windows-x86\OpenCV-2.4.9-android-sdk\sdk\native\jni\OpenCV.mk
LOCAL_SRC_FILES := DetectionBasedTracker_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)
LOCAL_LDLIBS += -llog -ldl
LOCAL_MODULE := detection_based_tracker
include $(BUILD_SHARED_LIBRARY)
Then I go to command window and type
C:\facedetection\jni\include>javah -classpath ../../bin/classes;C:
\adt-bundle-windows-x86\sdk\platforms\android-18\android.jar -o DetectionBas
edTracker_jni.h org.opencv.samples.facedetect.FdActivity
Error: Class org.opencv.android.CameraBridgeViewBase could not be found.
Then the error is Class org.opencv.android.CameraBridgeViewBase could not be found.
What could be the reason for that error?
Thanks
You are providing wrong \ slash. You need to use this / slash instead.
Please change your below line
include C:\adt-bundle-windows-x86\OpenCV-2.4.9-android-sdk\sdk\native\jni\OpenCV.mk
to
include C:/adt-bundle-windows-x86/OpenCV-2.4.9-android-sdk/sdk/native/jni/OpenCV.mk
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.
I know that to build so file, I should put the source file in /jni/ folder.
But how can I build separate so in different folders.
For example, the structure of my project:
/jni/Android.mk
/jni/submodule1/Android.mk
/jni/submodule1/sub1.c
/jni/submodule2/Android.mk
/jni/submodule2/sub2.c
I have tried to write this in Android.mk in the top level:
$(LOCAL_PATH) :=$(call all-makefiles-under)
then wrote make info in Android.mk in submodule
the error is:
ndk-build
make: *** No rule to make target `/home/../workspace/jni/sub.c', needed b
y `/home/../workspace/obj/local/armeabi/objs/submodule/sub.o'. Stop.
Can someone give me a solution? Thank you!
Update 1:
The code of Android.mk in submoudle:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := sub.c
LOCAL_C_INCLUDES := $(LOCAL_PATH)
LOCAL_MODULE := sub
LOCAL_LDLIBS := -ldl -llog
LOCAL_STATIC_LIBRARIES := libc
LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
LOCAL_MODULE_TAGS := debug
include $(BUILD_EXECUTABLE)
SOLVED:
I should use ndk-build in the root directory, but not in jni directory. Thanks all of you!
You should try include $(call all-subdir-makefiles) rather then $(LOCAL_PATH) :=$(call all-makefiles-under) in main Android.mk and make folder under jni folder with there separate c files and Android.mk files
Have you tried something like:
LOCAL_PATH := $(call my-dir)
LOCAL_SRC_FILES := /submodule1/sub1.c