How to use 32-bit native libraries on 64-bit Android device

Question

I use a native library in my application that is only compiled for armeabi, armeabi-v7a and x86.

When this library is loaded on a 64-bit device like the Samsung S6, the application crashes with an UnsatisfiedLinkError

java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader[DexPathList[[zip file "/data/app/com.myapp-2/base.apk"],nativeLibraryDirectories=[/data/app/com.myapp-2/lib/arm64, /vendor/lib64, /system/lib64]]] couldn't find "libfoo.so"
    at java.lang.Runtime.loadLibrary(Runtime.java:366)
    at java.lang.System.loadLibrary(System.java:989)

The library is closed source unfortunately. Is there any way to fix this without recompiling the library with 64-bit targets?

Answer 1

When you install an APK on Android, the system will look for native libraries directories (armeabi, armeabi-v7a, arm64-v8a, x86, x86_64, mips64, mips) inside the lib folder of the APK, in the order determined by Build.SUPPORTED_ABIS.

If your app happen to have an arm64-v8a directory with missing libs, the missing libs will not be installed from another directory, the libs aren't mixed. That means you have to provide the full set of your libraries for each architecture.

So, to solve your issue, you can remove your 64-bit libs from your build, or set abiFilters to package only 32-bit architectures:

android {
    ....
    defaultConfig {
        ....
        ndk {
            abiFilters "armeabi", "armeabi-v7a", "x86", "mips"
        }
    }
}