Cargo.toml

[package]
authors = ["Mika Attila <radiantstatue@gmail.com>"]
name = "plugintest"
version = "0.1.0"

[dependencies]
dylib = "0.0.2"

[lib]
name = "guest"
crate-type = ["dylib"]

src_bin_host.rs

extern crate dylib;

use dylib::DynamicLibrary;
use std::path::Path;

#[inline(never)]
pub fn drop_it_host(_: Box<u8>) {}

// Change this to switch between host and plugin drops.
const DROP_IN_HOST: bool = true;

fn main() {
    let dl = DynamicLibrary::open(Some(&Path::new("target/debug/libguest.so"))).unwrap();
    unsafe {
        let gimme: fn() -> Box<u8> = std::mem::transmute(dl.symbol::<()>("gimme").unwrap());
        let drop_it: fn(Box<u8>) -> String = std::mem::transmute(dl.symbol::<()>("drop_it").unwrap());
        loop {
            let x = gimme();
            println!("{}", x);
            if DROP_IN_HOST {
                drop_it_host(x);
            } else {
                drop_it(x);
            }
        }
    }
}

src_lib.rs

#[no_mangle]
pub fn gimme() -> Box<u8> {
    Box::new(42)
}
#[inline(never)]
#[no_mangle]
pub fn drop_it(_: Box<u8>) {}