Java JNI crashes on exit when called from Rust

Question

I want to launch a JVM and call a static Java method from Rust. Initially everything works fine, I see the expected output in the console. However, before the Java method ends, I get a segmentation fault.

This is the output:

Hello World!
Segmentation fault (core dumped)

Here is the Java class (packaged in a fat Jar):

public class HelloWorld {
    public static void greetings() {
        System.out.println("Hello World!");
    }
}

This is the Rust code that I execute:

extern crate rucaja;

use rucaja::{Jvm, jvalue};

fn main() {

    // The class path must contain the fat JAR.
    let class_path = "-Djava.class.path=./java/target/hello-0.1.0.jar";

    let jvm_options = [class_path];

    unsafe {
        // Instantiate the embedded JVM.
        let jvm = Jvm::new(&jvm_options);

        // Resolve the Java wrapper class from the fat JAR.
        let main_class = jvm.get_class("HelloWorld").expect("Could not find Java class");

        // Resolve Java methods in that wrapper class.
        let greetings_method = jvm.get_static_method(
            &main_class,
            "greetings",
            "()V"
        ).expect("Could not find Java method");

        // Prepare (no) arguments
        let args: Vec<jvalue> = vec![
        ];

        // Call the method
        jvm.call_static_object_method(
            &main_class,
            &greetings_method,
            args.as_ptr()
        );
    }

    println!("Done");
}

I tried running it with gdb, but the stack looks broken:

Program received signal SIGSEGV, Segmentation fault.
0x00007fffe575d2b4 in ?? ()
(gdb) bt
#0  0x00007fffe575d2b4 in ?? ()
#1  0x0000000000000246 in ?? ()
#2  0x00007fffe575d160 in ?? ()
#3  0x00007fffffffd530 in ?? ()
#4  0x00007fffffffd4e0 in ?? ()
#5  0x00007ffff790a6ad in ?? () from /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64/server/libjvm.so
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

What do you think is the cause of the segmentation fault?

Federico · Accepted Answer · 2017-11-01 16:06:31Z

2

The Java method does not return an object, so jvm.call_static_void_method(...) must be used instead of jvm.call_static_object_method(...).

Correct code:

// Call the method
jvm.call_static_void_method(
    &main_class,
    &greetings_method,
    args.as_ptr()
);

Then the programs runs fine:

Hello World!
Done

answered Nov 1, 2017 at 16:06

Federico

2,1932 gold badges17 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Java JNI crashes on exit when called from Rust

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related