PermissionDenied Error when using with j4rs

[wangxiaoying]

I'm using j4rs to run java code by invoking a jar file. The code works fine when I run the code using rust. However, it will throw the following error when I invoke the same function from python:

pyo3_runtime.PanicException: called `Result::unwrap()` on an `Err` value: GeneralError("Error { kind: PermissionDenied, message: \"Operation not permitted (os error 1)\" }")

The code panicked at the line of code for adding the jar file to class path.

Here is the permission of the jar file:

ll my.jar
-rwxrwxrwx  1 username  everyone    24M 14 Apr 23:16 my.jar

Any idea what's going on and how to fix it? Please let me know if you need more information!

Here is a repo that could reproduce the error: https://github.com/wangxiaoying/pyo3-j4rs-example

Both cargo run --example test and maturin develop && python test.py will invoke the run_java function, while the first successes and the later throws the error.

[birkenfeld]

I think we can't say much about this without a reproducing example, or at least the full code you're running. For example, in the link you gave there is no unwrap.

[wangxiaoying]

Thanks for the quick response! Here is a repo with minimum code that could reproduce the result: https://github.com/wangxiaoying/pyo3-j4rs-example

[wangxiaoying]

Here is a repo with minimum code that could reproduce the result: https://github.com/wangxiaoying/pyo3-j4rs-example.

Both cargo run --example test and maturin develop && python test.py will invoke the run_java function, while the first successes and the later throws the error.

[birkenfeld]

Thank you! I'm getting a different error

pyo3_runtime.PanicException: called `Result::unwrap()` on an `Err` value: GeneralError("Error { kind: NotFound, message: \"No such file or directory (os error 2)\" }")

but the cause is probably the same:

j4rs tries to find the jassets path which is under target/debug/jassets. It tries to find that in the same directory (or up) of the current executable. For Rust-only, this is under target/debug/... which works. For Python, it is /usr/bin/python, and there is no "jassets" there.

You need to set the proper path with https://docs.rs/j4rs/latest/j4rs/struct.JvmBuilder.html#method.with_base_path - this worked for me:

    let base = fs::canonicalize("./target/debug").unwrap();
    let jvm: Jvm = JvmBuilder::new().classpath_entry(entry).with_base_path(base.to_str().unwrap()).build().unwrap();

but of course the path will be different for different targets, and after deployment, so you probably need to add another env. var for it.

[wangxiaoying]

Thank you so much for such a quick response. Setting the base path solves the problem perfectly!