Using cpal in a library for android causes an error

[Flocksserver]

Hi all,
I have a Rust library and use it on Android via jni. I load my library into the JVM context as usual.

companion object {
        init {
            System.loadLibrary("myfancylib")
        }
    }

So far so good.
But as soon as I use cpal (e.g. cpal::default_host();) and cross compile it to android, the app crashes when loading my library with the error:
java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "__gxx_personality_v0" referenced by
Is this an indication that the oboe library is missing? Should I add this library separately? How?

---

Edit:
Found issue #563 - look similar. After adding c++_shared I get the error when calling cpal:

panicked at 'android context was not initialized': /Users/XXX/.cargo/registry/src/github.com-1ecc6299db9ec823/ndk-context-0.1.1/src/lib.rs:72

I am confused - there is a local path during runtime? 😅

[SuisChan]

Can you provide the output of readelf -d yourfancylib.so or llvm-readelf -d *.so ?

[Flocksserver]

Sure!

Dynamic section at offset 0x307aa8 contains 26 entries:
  Tag                Type           Name/Value
  0x0000000000000001 (NEEDED)       Shared library: [liblog.so]
  0x0000000000000001 (NEEDED)       Shared library: [libdl.so]
  0x0000000000000001 (NEEDED)       Shared library: [libc.so]
  0x000000000000001e (FLAGS)        BIND_NOW 
  0x000000006ffffffb (FLAGS_1)      NOW 
  0x0000000000000007 (RELA)         0x1310
  0x0000000000000008 (RELASZ)       223680 (bytes)
  0x0000000000000009 (RELAENT)      24 (bytes)
  0x000000006ffffff9 (RELACOUNT)    9318
  0x0000000000000017 (JMPREL)       0x37cd0
  0x0000000000000002 (PLTRELSZ)     1752 (bytes)
  0x0000000000000003 (PLTGOT)       0x30a638
  0x0000000000000014 (PLTREL)       RELA
  0x0000000000000006 (SYMTAB)       0x308
  0x000000000000000b (SYMENT)       24 (bytes)
  0x0000000000000005 (STRTAB)       0xcb8
  0x000000000000000a (STRSZ)        1624 (bytes)
  0x000000006ffffef5 (GNU_HASH)     0xc48
  0x0000000000000019 (INIT_ARRAY)   0x309aa0
  0x000000000000001b (INIT_ARRAYSZ) 8 (bytes)
  0x000000000000001a (FINI_ARRAY)   0x309a90
  0x000000000000001c (FINI_ARRAYSZ) 16 (bytes)
  0x000000006ffffff0 (VERSYM)       0xb48
  0x000000006ffffffe (VERNEED)      0xbf8
  0x000000006fffffff (VERNEEDNUM)   2
  0x0000000000000000 (NULL)         0x0

[Flocksserver]

i still don't understand the bug but since it has something to do with the oboe "java-interface" feature it is not a direct cpal problem

[trobanga]

I'm using this code to initialize the context. Just make it part of your fancy lib.

use jni::{JNIEnv, JavaVM};
use std::ffi::c_void;

#[no_mangle]
pub extern "C" fn JNI_OnLoad(vm: jni::JavaVM, res: *mut std::os::raw::c_void) -> jni::sys::jint {
    let env = vm.get_env().unwrap();
    let vm = vm.get_java_vm_pointer() as *mut c_void;
    unsafe {
        ndk_context::initialize_android_context(vm, res);
    }
    jni::JNIVersion::V6.into()
}

[Flocksserver]

Thanks @trobanga 🙏 that was the missing piece 🤩

[wujian752]

I'm using this code to initialize the context. Just make it part of your fancy lib.

use jni::{JNIEnv, JavaVM};
use std::ffi::c_void;

#[no_mangle]
pub extern "C" fn JNI_OnLoad(vm: jni::JavaVM, res: *mut std::os::raw::c_void) -> jni::sys::jint {
    let env = vm.get_env().unwrap();
    let vm = vm.get_java_vm_pointer() as *mut c_void;
    unsafe {
        ndk_context::initialize_android_context(vm, res);
    }
    jni::JNIVersion::V6.into()
}

It seems the argument res is always 0x0.

[MachineL102]

I'm using this code to initialize the context. Just make it part of your fancy lib.

use jni::{JNIEnv, JavaVM};
use std::ffi::c_void;

#[no_mangle]
pub extern "C" fn JNI_OnLoad(vm: jni::JavaVM, res: *mut std::os::raw::c_void) -> jni::sys::jint {
    let env = vm.get_env().unwrap();
    let vm = vm.get_java_vm_pointer() as *mut c_void;
    unsafe {
        ndk_context::initialize_android_context(vm, res);
    }
    jni::JNIVersion::V6.into()
}

It seems the argument res is always 0x0.

I have the same issue. Have you found the solution? very very thanks

[wujian752]

I'm using this code to initialize the context. Just make it part of your fancy lib.

use jni::{JNIEnv, JavaVM};
use std::ffi::c_void;

#[no_mangle]
pub extern "C" fn JNI_OnLoad(vm: jni::JavaVM, res: *mut std::os::raw::c_void) -> jni::sys::jint {
    let env = vm.get_env().unwrap();
    let vm = vm.get_java_vm_pointer() as *mut c_void;
    unsafe {
        ndk_context::initialize_android_context(vm, res);
    }
    jni::JNIVersion::V6.into()
}

It seems the argument res is always 0x0.

I have the same issue. Have you found the solution? very very thanks

Unfortunately, I haven't found a solution to the issue either.