Native Android library in Unity throws DllNotFound exception

Question

I have written a chess library in C++ and I have compiled it for Windows (32-bit and 64-bit) and Android (x86 and armebi-v7).

My Windows build works completely correct, But when I build it for Android and when I run the game, I receive the following exception on my adb logcat -s Unity :

11-23 16:39:37.278 22335 22352 I Unity   : DllNotFoundException: MatinChess
11-23 16:39:37.278 22335 22352 I Unity   :   at (wrapper managed-to-native) MatinChess.Net.ExternMethods:Initialize ()
11-23 16:39:37.278 22335 22352 I Unity   :   at MatinChess.Net.MatinChess..ctor () [0x00000] in <filename unknown>:0
11-23 16:39:37.278 22335 22352 I Unity   :   at Model.Awake () [0x00000] in <filename unknown>:0

And when I unzip my apk file I have:

lib
|_ armeabi-v7a
|  |_ libmain.so
|  |_ libMatinChess.so
|  |_ libmono.so
|  |_ libunity.so
|_ x86
   |_ libmain.so
   |_ libMatinChess.so
   |_ libmono.so
   |_ libunity.so

Here are my settings and scripts:

Based on here and here, I have created Plugins folder in my Assets and placed my libraries like this:

Plugins
|_ Android
|  |_ libs
|     |_ armeabi-v7a
|     |  |_ libMatinChess.so
|     |_ x86
|        |_ libMatinChess.so
|_ x64
|  |_ MatinChess.dll
|_ x86
   |_ MatinChess.dll

And I got sure that the Platform Settings in my Inspector is configured correctly.

I have used my library in my scripts and based on here and here, instead of using libMatinChess.so for Android, I have not used lib at the beggining and .so at the end. So it is like this:

class ExternMethods
{
#if UNITY_ANDROID
    const string dll = "MatinChess";
#else
    const string dll = "MatinChess.dll";
#endif

    [DllImport(dll, CallingConvention = CallingConvention.Cdecl)]
    public extern static PlayState CheckState();

    [DllImport(dll, CallingConvention = CallingConvention.Cdecl)]
    public extern static void Initialize();

    //
    // other extern methods
    //
}

So when I build my Unity game for Windows, it works correctly. In order to make it work in Editor, I have followed this link and I have written the folowing script:

public class Model : MonoBehaviour
{    
    void Awake()
    {
#if UNITY_EDITOR_32
        var dllPath = Application.dataPath + Path.DirectorySeparatorChar + "Plugins" + Path.DirectorySeparatorChar + "x32";
#elif UNITY_EDITOR_64
        var dllPath = Application.dataPath + Path.DirectorySeparatorChar + "Plugins" + Path.DirectorySeparatorChar + "x64";
#else // Player
        var dllPath = Application.dataPath + Path.DirectorySeparatorChar + "Plugins";
#endif
        var currentPath = Environment.GetEnvironmentVariable("PATH", EnvironmentVariableTarget.Process);
        if (currentPath != null && currentPath.Contains(dllPath) == false)
            Environment.SetEnvironmentVariable("PATH", currentPath + Path.PathSeparator + dllPath, EnvironmentVariableTarget.Process);
    }
}

So it works on Unity Editor as well.

Why you are configuring .dll file for Android as you already have .so file? — Pravin Divraniya, Nov 26 '16 at 19:59
@PravinD I want to say that my Windows build which uses .dll configuration works ok but Android which has .so configuration does not. And inform you about the differences of my configurations. — Matin Lotfaliee, Nov 26 '16 at 20:04

score 0 · Answer 1 · edited May 23 '17 at 11:52

0

The method MatinChess.Net.ExternMethods.Initialize may be called before Environment.SetEnvironmentVariable("PATH",...), which leads to a DllNotFoundException.

Try printing a log message before you call MatinChess.Net.ExternMethods.Initialize and Environment.SetEnvironmentVariable. Then you can inspect the calling order of these methods.

Add if that's the cause, moving Environment.SetEnvironmentVariable("PATH",...) to the static initializer of MatinChess.Net.ExternMethods can possibly solve your problem.

Edit:
Try printing the PATH after you setting it, the method may failed to set it.

Edit:
Just a guess.. the android shared lib searching path should be LD_LIBRARY_PATH instead of PATH. Try setting that instead. I'm not sure if Unity3D has handled this.

Edit:
Not including all the library dependencies aside your libMatinChess.so is a possible cause. Some infomation here.

The above are all I can think of now.

edited May 23 '17 at 11:52

Community

1
1

answered Nov 27 '16 at 15:15

zwcloud

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Nope. I call Initialize after that. – Matin Lotfaliee Nov 27 '16 at 15:16
Have you checked the logs on the android platform? Is it in the correct order? – zwcloud Nov 27 '16 at 15:19
I have tested all you two edits. I also found my .so inside my adb shell but still dllnotfound exception. – Matin Lotfaliee Nov 27 '16 at 21:10
That's all I can think of now, sorry. – zwcloud Nov 28 '16 at 01:49

score 0 · Accepted Answer · answered Nov 28 '16 at 15:59

Check that you are actually exporting a valid .so file with the proper symbols.

Also check that you have included all library dependencies of your libMatinChess.so which may include your C runtime at times. Try linking statically with the standard library.

Native Android library in Unity throws DllNotFound exception

Here are my settings and scripts:

2 Answers2