Error 'use of invalid object' when any attempts ot interacting with activity instance using JNI

[katyo]

I don't sure, this problem actually related to android-ndk-sys nor jni crate but it looks very strange for me.
Also I don't quite familiar with JNI, so I may do wrong things here.

My rust code looks like a piece below:

    let app = unsafe { AndroidApp::from_ptr(android_glue::get_android_app()) };
    let activity = app.activity();

    let sdk_version = activity.sdk_version();
    println!("SDK VERSION: {}", sdk_version);

    let env = vm.attach_current_thread()?;
    println!("ENV: {:?}", env.get_version());

    println!("Activity: {:?}", activity);

    let class = env.find_class("android/app/NativeActivity")?;
    println!("Found NativeActivity class: {:?}", class);

    let class = env.get_object_class(activity)?;
    println!("Actual Activity class: {:?}", class);

But application failed on last line.

12-30 21:33:17.419 10414 10429 D RustStdoutStderr: SDK VERSION: 28
12-30 21:33:17.420 10414 10429 D RustStdoutStderr: ENV: Ok(V6)
12-30 21:33:17.420 10414 10429 D RustStdoutStderr: Activity: JObject { internal: 0x99f0a60c, lifetime: PhantomData }
12-30 21:33:17.420 10414 10429 D RustStdoutStderr: Found NativeActivity class: JClass(JObject { internal: 0x1, lifetime: PhantomData })
12-30 21:33:17.522 10414 10430 F .rust_oboe_dem: java_vm_ext.cc:542] JNI DETECTED ERROR IN APPLICATION: use of invalid jobject 0x99f0a60c

It seems, activity instance object is invalid.
But I understand that it may not be what it seems.

[katyo]

I found that I runs armv7 binary on aarch64 OS. Despite the fact that it works this may be one of possible source of problems.

When I runs my app on armv7 OS I gets the follow:

D/RustStdoutStderr(30168): SDK VERSION: 18
D/RustStdoutStderr(30168): ENV: Ok(V6)
D/RustStdoutStderr(30168): Activity: JObject { internal: 0x418d0edc, lifetime: PhantomData }
D/RustStdoutStderr(30168): Found NativeActivity class: JClass(JObject { internal: 0x1d200001, lifetime: PhantomData })
W/dalvikvm(30168): Invalid indirect reference 0x418d0edc in decodeIndirectRef

So the problem still has.

When I run aarch64 on aarch64 I cannot attach to current thread at all due to abort without any message somewhere in libc:

01-01 10:33:15.456 16090 16106 D RustStdoutStderr: SDK VERSION: 28
01-01 10:33:15.470 16090 16107 F libc    : Fatal signal 6 (SIGABRT), code -6 (SI_TKILL) in tid 16107 (.rust_oboe_demo), pid 16090 (.rust_oboe_demo)
...
01-01 10:33:15.653 16112 16112 F DEBUG   : signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
01-01 10:33:15.653 16112 16112 F DEBUG   :     x0  0000000000000000  x1  0000000000003eeb  x2  0000000000000006  x3  0000000000000008
01-01 10:33:15.653 16112 16112 F DEBUG   :     x4  0000007dfde11200  x5  0000007dfde11200  x6  0000007dfde11200  x7  0000007dfde11000
01-01 10:33:15.653 16112 16112 F DEBUG   :     x8  0000000000000083  x9  0000007ef69bbb38  x10 fffffff87ffffbdf  x11 0000000000000001
01-01 10:33:15.653 16112 16112 F DEBUG   :     x12 0000000000000000  x13 0000000000000000  x14 ffffffffffffffff  x15 0000000000000000
01-01 10:33:15.653 16112 16112 F DEBUG   :     x16 0000007ef69f32a8  x17 0000007ef69312c8  x18 0000007e5eb2b7d8  x19 0000000000003eda
01-01 10:33:15.653 16112 16112 F DEBUG   :     x20 0000000000003eeb  x21 0000000000000083  x22 0000007dfe038b1c  x23 0000007dfdf3b820
01-01 10:33:15.653 16112 16112 F DEBUG   :     x24 0000007dfdf57570  x25 0000007dfde5a000  x26 0000007ef76f95e0  x27 0000007dfe096c08
01-01 10:33:15.653 16112 16112 F DEBUG   :     x28 000000000000001c  x29 0000007dfdf3a660
01-01 10:33:15.653 16112 16112 F DEBUG   :     sp  0000007dfdf3a620  lr  0000007ef6925ad0  pc  0000007ef6925afc
01-01 10:33:15.654 16112 16112 F DEBUG   :
01-01 10:33:15.654 16112 16112 F DEBUG   : backtrace:
01-01 10:33:15.654 16112 16112 F DEBUG   :     #00 pc 0000000000021afc  /system/lib64/libc.so (abort+124)
...

[katyo]

android-ndk-rs/android-ndk/src/native_activity.rs

Lines 103 to 107 in 28afac8

	pub fn activity(&self) -> jni::objects::JObject<'_> {
	unsafe {
	jni::objects::JObject::from(&self.ptr.as_ref().clazz as *const _ as jni::sys::jobject)
	}
	}

It seems the unnecessary reference operator here because clazz already is a pointer.
I mean this fragment should looks like:

jni::objects::JObject::from(self.ptr.as_ref().clazz as *const _ as jni::sys::jobject)