Build NDK exectuable with CMAKE : no dynamic library found error

Issue

What i want is to build a native binary with NDK. There are couples shared lib also been build. The APK structure look like this:

/data/data/mypackage/files/my_binary
/data/data/mypackage/lib/liba.so
/data/data/mypackage/lib/libb.so

When the binary is been executed,error like CANNOT LINK EXECUTABLE: could not load library "liba.so" needed by "./mybinay"; caused by library liba.so not found been throw out. It's working fine after setting LD_LIBRARY_PATH to /data/data/mypackage/lib.

My question is how to make it work without setting LD_LIBRARY_PATH in CMAKE file or Gradel?

Cmake file.

add_library(a, src/a.cc)
add_library(b, src/b.cc)
add_executable(mybinary src/mybinary.cc)
target_link_libraries(a log)
target_link_libraries(mybinary a android log b)

Gradle file.

externalNativeBuild {
    cmake {
        cppFlags "-std=c++14 -frtti -fexceptions"
        targets 'mybinary','a','b'
    }
}

Solution

The runtime scenario is not related to CMake or gradle. You don't need LD_LIBRARY_PATH to build the executable.

I prefer to pack the executable into libs/ of the APK, next to liba.so and libb.so. The trick is to rename my_binary to something Ike libmy_binary.so (see https://stackoverflow.com/a/15099666/192373).

So, this would mean that now CMakeLists.txt can look as follows:

add_library(a, src/a.cc)
add_library(b, src/b.cc)
add_executable(mybinary src/mybinary.cc)
target_link_libraries(a log)
target_link_libraries(lib.mybinary.so a android log b)

And setting LD_LIBRARY_PATH is trivial:

try {
    Runtime.getRuntime().exec(
        getApplicationInfo().nativeLibraryDir + "/lib.mybinary.so", 
        new String[]{"LD_LIBRARY_PATH="+ getApplicationInfo().nativeLibraryDir});
} catch (IOException e) {
    e.printStackTrace();
}

Answered By - Alex Cohn