Android demo compile issues

[Jasonvdb]

Steps to reproduce:

• Used these instructions to build the artifacts on ubuntu using docker.
• Copied artifacts/android/library-debug.aar into demo/android/app/libs/
• Open /demo/android in Android Studio and build project

Build error:

/Users/jason/Documents/Repositories/rgb/rgb-sdk/demo/android/app/src/main/java/org/lnpbp/demoapp/DemoApp.java:6: error: package org.lnpbp.rgbnode does not exist
import org.lnpbp.rgbnode.Runtime;
                        ^

I noticed org.lnpbp.rgbnode.Runtime does not exist but org.lnpbp.rgb.Runtime does so I made these changes and I get the app to build but it then crashes on first open with this run error:

I/DemoApp: Loading 'rgb_node' library
E/DemoApp: Error loading 'rgb_node' library: java.lang.UnsatisfiedLinkError: dlopen failed: library "librgb_node.so" not found
E/g.lnpbp.demoap: No implementation found for long org.lnpbp.rgb_autogen.rgbJNI.rgb_node_run(java.lang.String, java.lang.String, java.lang.String, short) (tried Java_org_lnpbp_rgb_1autogen_rgbJNI_rgb_1node_1run and Java_org_lnpbp_rgb_1autogen_rgbJNI_rgb_1node_1run__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2S)
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: org.lnpbp.demoapp, PID: 7455
    java.lang.UnsatisfiedLinkError: No implementation found for long org.lnpbp.rgb_autogen.rgbJNI.rgb_node_run(java.lang.String, java.lang.String, java.lang.String, short) (tried Java_org_lnpbp_rgb_1autogen_rgbJNI_rgb_1node_1run and Java_org_lnpbp_rgb_1autogen_rgbJNI_rgb_1node_1run__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2S)
        at org.lnpbp.rgb_autogen.rgbJNI.rgb_node_run(Native Method)
        at org.lnpbp.rgb_autogen.rgb.rgb_node_run(rgb.java:57)
        at org.lnpbp.rgb.Runtime.<init>(Runtime.java:24)
        at org.lnpbp.demoapp.DemoApp.onCreate(DemoApp.java:32)
        at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1192)
        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6712)
        at android.app.ActivityThread.access$1300(ActivityThread.java:237)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1913)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

[dr-orlovsky]

The crash seems to be another naming-related issue. Will try to fix

[dr-orlovsky]

Ok, this is not the naming issue. It just can't find the library in runtime, i.e. it is not copied as a part of APK: E/DemoApp: Error loading 'rgb_node' library: java.lang.UnsatisfiedLinkError: dlopen failed: library "librgb_node.so" not found

[dr-orlovsky]

Working on replicating all the steps. BTW, you get this error on device or in simulator? And are you using Java or already React Native?

[Jasonvdb]

Have managed to get the same error on a device and simulator.

For this error I'm using the Java Android demo in this repo. I do have a react-native wrapper that is working for iOS so far. If I can get this demo working then it should be simple enough to fix for react-native as well.

[dr-orlovsky]

From what I see by looking inside .aar package is that the binary library called librgb.so and not librgb_node.so (while Android is looking for librgb_node.so as error message says). Don't know how to change that part, I assume this is something gradle-related. Any ideas?

[dr-orlovsky]

... considering of renaming librgb.so back into librgb_node.so. This renaming was mostly accidential and I see has broken many things

[Jasonvdb]

I thought maybe just changing this line final String libName = "rgb_node"; to use rgb instead of rgb_node would work but I then get the this error:

E/DemoApp: Error loading 'rgb' library: java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZNSt12length_errorD1Ev" referenced by "/data/app/~~LN6GpR4dsQOH6xN0_cqfNA==/org.lnpbp.demoapp-1eB-I4WLe5-ims5tw7RtTA==/lib/x86/librgb.so"...
E/g.lnpbp.demoap: No implementation found for long org.lnpbp.rgb_autogen.rgbJNI.rgb_node_run(java.lang.String, java.lang.String, java.lang.String, short) (tried Java_org_lnpbp_rgb_1autogen_rgbJNI_rgb_1node_1run and Java_org_lnpbp_rgb_1autogen_rgbJNI_rgb_1node_1run__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2S)

I can't see where else to fix the name, there's nothing in the gradle file it seems.

[dr-orlovsky]

Ok, figured out the reason of the second error. Now actually it finds the library, however swig (after update?) generates incorrect binding linking uchar/byte to short (which is two bytes). Figuring out how to fix.

[dr-orlovsky]

E/DemoApp: Error loading 'rgb' library: java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZNSt12length_errorD1Ev" referenced by "/data/app/~~LN6GpR4dsQOH6xN0_cqfNA==/org.lnpbp.demoapp-1eB-I4WLe5-ims5tw7RtTA==/lib/x86/librgb.so"...

Spent a day investigating & trying to fix. No success so far; however what I have found out:

1. Error is a library linking error: it happens before any function inside the app or inside the library is called and before the app has actually started.
2. Error is independent from library name: I tried both librgb and librgb_node. Error and happens only when library named in the correct way (if the library named incorrectly we have the other, originally reported issue).
3. Changing function name and it's arguments does not fix the issue; it continues to happen for the new function
4. The symbol mentioned in the error text (length_error) is absent from the code and I have no idea why it is required and how it should be used.
5. Improving/changing swig.i does not affect error.

[dr-orlovsky]

Ok, this seems to be an Android NDK issue: android/ndk#833

Strange we had not it before. Will try to fix by switching to c++_static library.

[dr-orlovsky]

Other links relevant in the context:

• Static library may be used only when there is a single NDK library in the app, so this will probably not work alongside LNP Node (and I assume React Native uses other libs): https://developer.android.com/ndk/guides/cpp-support#static_runtimes
• Alternative is to use https://github.com/KeepSafe/ReLinker instead of System.loadLibrary which is more robust (and Android loadLibrary is infamously inrobust)

[dr-orlovsky]

ReLink does not help; the error persists.

With static lib now it can't find a function from libc++_shared.
The library is included into the .aar file, so DemoApp gradle due to some reason does not include it into the resulting apk, causing the original error.

I.e. the reason of the error is that libc++_shared is not part of the APK (while present in the aar produced from bindings). This is the problem of the demo app; unfortunately I have not found how to fix it yet.

[KotlinGeekDev]

Hello @dr-orlovsky . I am a volunteer for solving this bug. I just had a discussion with an NDK dev about it here . It seems that one of the problems is a dependency(actually, a set of dependencies), cc, and cmake, that first need to be updated, for better interop with the current version of the NDK(or newer) used in the build script.
Thanks.

[dr-orlovsky]

Hi @AnonymousGeekDev! Thank you for proposing volunteering! Right now this demo is outdated and we are preparing compatibility-breaking release of RGB which will require update of the demo and will reduce the number of downstream C dependencies, so the issue may be resolved at that point (but we may have other new issues of course, so we may still need your help then)

[KotlinGeekDev]

OK @dr-orlovsky thanks for the feedback! I am also interested in building an Android client for MyCitadel, and I have the impression that the future changes will probably be of relevance there :)

[dr-orlovsky]

@AnonymousGeekDev we will ship so-called CitadelRuntime Android build as a library that you will be able to use in your wallet on Android

[zoedberg]

as @DanAlbert pointed out here, the clang++ output is clobbered by the cargo build output (by a cp that overrides the output of the previous command).

you can find here the PR solving this issue, making the android library work again and the java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol [...] error disappear.

for future records, here the contents of a working library:

$ unzip -l artifacts/android/library-release.aar 

Archive:  artifacts/android/library-release.aar
  Length      Date    Time    Name
---------  ---------- -----   ----
    88185  1980-02-01 00:00   R.txt
      299  1980-02-01 00:00   AndroidManifest.xml
    11108  1980-02-01 00:00   classes.jar
        0  1980-02-01 00:00   jni/
        0  1980-02-01 00:00   jni/arm64-v8a/
   936368  1980-02-01 00:00   jni/arm64-v8a/libc++_shared.so
  9633752  1980-02-01 00:00   jni/arm64-v8a/librgb.so
    22360  1980-02-01 00:00   jni/arm64-v8a/librgb_node.so
        0  1980-02-01 00:00   jni/armeabi-v7a/
   558988  1980-02-01 00:00   jni/armeabi-v7a/libc++_shared.so
  6871928  1980-02-01 00:00   jni/armeabi-v7a/librgb.so
    30324  1980-02-01 00:00   jni/armeabi-v7a/librgb_node.so
        0  1980-02-01 00:00   jni/x86/
   939924  1980-02-01 00:00   jni/x86/libc++_shared.so
 13204352  1980-02-01 00:00   jni/x86/librgb.so
    26120  1980-02-01 00:00   jni/x86/librgb_node.so
        0  1980-02-01 00:00   jni/x86_64/
  1002168  1980-02-01 00:00   jni/x86_64/libc++_shared.so
 12435664  1980-02-01 00:00   jni/x86_64/librgb.so
    22632  1980-02-01 00:00   jni/x86_64/librgb_node.so
        0  1980-02-01 00:00   arm64-v8a/
        0  1980-02-01 00:00   armeabi-v7a/
        0  1980-02-01 00:00   x86/
        0  1980-02-01 00:00   x86_64/
---------                     -------
 45784172                     24 files

please note that in each ABI directory there are 3 files, the libc++_shared.so for standard library definitions, the librgb.so outputted by the cargo build and the librgb_node.so that glues all together