Trouble with JNI integration in the build system
Maxime Ripard
I'm not quite sure what mailing list is the most appropriate for this
trouble. If I'm posting to the wrong one, sorry about that.
I'm trying to integrate an app to the build system, which uses JNI
bindings to the libusb.
I've put the libusb into the external folder, and it builds correctly.
My app is in package/apps, and the bindings are in the jni/ directory of
this app.
Everything builds fine, but when I try to call System.loadLibrary, I get
"java.lang.UnsatisfiedLinkError: Couldn't load ml: findLibrary returned
null" (libml being the bindings).
So, I've checked the content of the generated apk, and the lib is in it:
Archive: MissileControl.apk
Length Date Time Name
--------- ---------- ----- ----
918 2008-04-16 01:40 META-INF/MANIFEST.MF
960 2008-04-16 01:40 META-INF/CERT.SF
1714 2008-04-16 01:40 META-INF/CERT.RSA
1512 2008-04-16 01:40 AndroidManifest.xml
80992 2008-04-16 01:40 classes.dex
5328 2008-04-16 01:40 lib/armeabi/libml.so
821 2008-04-16 01:40 res/drawable-mdpi/arrows_down.png
757 2008-04-16 01:40 res/drawable-mdpi/arrows_left.png
800 2008-04-16 01:40 res/drawable-mdpi/arrows_right.png
762 2008-04-16 01:40 res/drawable-mdpi/arrows_up.png
2200 2008-04-16 01:40 res/drawable-mdpi/icon.png
3020 2008-04-16 01:40 res/layout-land/main.xml
2852 2008-04-16 01:40 res/layout/main.xml
1920 2008-04-16 01:40 resources.arsc
--------- -------
104556 14 files
So this part seems ok. Now, file tells me that :
lib/armeabi/libml.so: ELF 32-bit LSB shared object, ARM, version 1
(SYSV), dynamically linked, stripped
Which is ok too.
If I run strace on the process just before loadLibrary, here is the output :
access("/data/data/com.fe.android.ml/lib/libml.so", F_OK) = -1 ENOENT
(No such file or directory)
access("/vendor/lib/libml.so", F_OK) = -1 ENOENT (No such file or
directory)
access("/system/lib/libml.so", F_OK) = -1 ENOENT (No such file or
directory)
writev(3, [{"\5", 1}, {"dalvikvm\0", 9}, {"Exception
Ljava/lang/Unsatisfied"..., 109}], 3) = 119
And indeed, if I look into the /data/data/com.fe.android.ml/lib folder,
there is nothing in it. Which explains the loading problem, but raises
another one : Why the lib isn't copied at the apk installation ?
Reinstalling the apk doesn't seem to help. Do you have any idea on what
could be going on ?
Thanks,
--
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
Magnus Bäck
Maxime Ripard <maxime...@free-electrons.com> wrote:
> I'm trying to integrate an app to the build system, which uses JNI
> bindings to the libusb.
>
> I've put the libusb into the external folder, and it builds correctly.
>
> My app is in package/apps, and the bindings are in the jni/ directory
> of this app.
>
> Everything builds fine, but when I try to call System.loadLibrary, I
> get "java.lang.UnsatisfiedLinkError: Couldn't load ml: findLibrary
> returned null" (libml being the bindings).
[...]
> If I run strace on the process just before loadLibrary, here is the
> output :
>
> access("/data/data/com.fe.android.ml/lib/libml.so", F_OK) = -1 ENOENT
> (No such file or directory)
> access("/vendor/lib/libml.so", F_OK) = -1 ENOENT (No such file or
> directory)
> access("/system/lib/libml.so", F_OK) = -1 ENOENT (No such file or
> directory)
> writev(3, [{"\5", 1}, {"dalvikvm\0", 9}, {"Exception
> Ljava/lang/Unsatisfied"..., 109}], 3) = 119
>
> And indeed, if I look into the /data/data/com.fe.android.ml/lib
> folder, there is nothing in it. Which explains the loading problem,
> but raises another one : Why the lib isn't copied at the apk
> installation ?
Are you by any chance installing the APK into /system/app? Applications
installed there are assumed to have their libraries installed to
/system/lib and therefore won't be subject to the usual shared library
extraction.
--
Magnus B�ck Opinions are my own and do not necessarily
SW Configuration Manager represent the ones of my employer, etc.
Sony Ericsson
Ying Wang
--
Magnus Bäck Opinions are my own and do not necessarily
SW Configuration Manager represent the ones of my employer, etc.
Sony Ericsson
--
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Maxime Ripard
So, just to understand correctly.
Apps built in the build system are never installed in the system and
thus, libs in their apk are never copied to /data/data/<package>/lib.
I guess that it is the PackageManager that is responsible for this copy,
right ?
So, to ensure that the lib is present in the system, I need to use
LOCAL_REQUIRED_MODULES and add the module to PRODUCT_PACKAGES, right ?
But then, this lib won't be embedded in the apk, but will instead be in
/system/lib.
Is there anyway to have the lib embedded in the apk in my case ?
Maxime
On 27/07/2011 22:44, Ying Wang wrote:
> Magnus is right.
> You should not use LOCAL_JNI_SHARED_LIBRARIES for a preloaded apk, use
> LOCAL_REQUIRED_MODULES instead.
> In your app's Android.mk:
> LOCAL_REQUIRED_MODULES := libml
>
> On Wed, Jul 27, 2011 at 11:58 AM, Magnus B�ck
>> Magnus B�ck Opinions are my own and do not necessarily
>> SW Configuration Manager represent the ones of my employer, etc.
>> Sony Ericsson
>>
>> --
>> You received this message because you are subscribed to the "Android
>> Building" mailing list.
>> To post to this group, send email to android-...@googlegroups.com
>> To unsubscribe from this group, send email to
>> android-buildi...@googlegroups.com
>> For more options, visit this group at
>> http://groups.google.com/group/android-building?hl=en
>>
>
Ying Wang
Thanks for your answers,
So, just to understand correctly.
Apps built in the build system are never installed in the system and
thus, libs in their apk are never copied to /data/data/<package>/lib.
I guess that it is the PackageManager that is responsible for this copy,
right ?
So, to ensure that the lib is present in the system, I need to use
LOCAL_REQUIRED_MODULES and add the module to PRODUCT_PACKAGES, right ?
But then, this lib won't be embedded in the apk, but will instead be in
/system/lib.
Is there anyway to have the lib embedded in the apk in my case ?
Maxime
On 27/07/2011 22:44, Ying Wang wrote:
> Magnus is right.
> You should not use LOCAL_JNI_SHARED_LIBRARIES for a preloaded apk, use
> LOCAL_REQUIRED_MODULES instead.
> In your app's Android.mk:
> LOCAL_REQUIRED_MODULES := libml
>
> On Wed, Jul 27, 2011 at 11:58 AM, Magnus Bäck
>> Magnus Bäck Opinions are my own and do not necessarily
>> SW Configuration Manager represent the ones of my employer, etc.
>> Sony Ericsson
>>
>> --
>> You received this message because you are subscribed to the "Android
>> Building" mailing list.
>> To post to this group, send email to android-...@googlegroups.com
>> To unsubscribe from this group, send email to
>> android-buildi...@googlegroups.com
>> For more options, visit this group at
>> http://groups.google.com/group/android-building?hl=en
>>
>