hdf5 thread safety in rust

hdf5_mutex.rs

#[allow(unstable)]
extern crate libc;

#[allow(unstable)]
mod test {
    use libc::c_int;
    use std::sync::{StaticMutex, MUTEX_INIT};

    static LOCK: StaticMutex = MUTEX_INIT;

    #[link(name = "hdf5")]
    extern {
        static H5E_ERR_CLS_g: c_int;
        fn H5open() -> c_int;
    }

    fn get_err_cls() -> c_int {
        unsafe {
            let _ = LOCK.lock().unwrap();
            H5open();
        }
        H5E_ERR_CLS_g
    }

    #[test]
    fn test1() { println!("test1(): H5E_ERR_CLS_g = {}", get_err_cls()); }

    #[test]
    fn test2() { println!("test1(): H5E_ERR_CLS_g = {}", get_err_cls()); }

    #[test]
    fn test3() { println!("test1(): H5E_ERR_CLS_g = {}", get_err_cls()); }
}

running 3 tests
test2(): H5E_ERR_CLS_g = -1
test3(): H5E_ERR_CLS_g = -1
test test::test2 ... ok
test test::test3 ... ok
test1(): H5E_ERR_CLS_g = 184549376
test test::test1 ... ok

running 3 tests
test2(): H5E_ERR_CLS_g = 184549376
test3(): H5E_ERR_CLS_g = 184549376
test test::test2 ... ok
test test::test3 ... ok
test1(): H5E_ERR_CLS_g = 184549376
test test::test1 ... ok

running 3 tests
test2(): H5E_ERR_CLS_g = -1
test3(): H5E_ERR_CLS_g = 184549376
test test::test2 ... ok
test test::test3 ... ok
test1(): H5E_ERR_CLS_g = 184549376
test test::test1 ... ok