async-usercalls 0.7.2

An interface for asynchronous usercalls in SGX enclaves. This is an SGX-only crate, you should compile it with the `x86_64-fortanix-unknown-sgx` target. 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

use crate::AsyncUsercallProvider;
use std::ops::Deref;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread;

pub(crate) struct AutoPollingProvider {
    provider: AsyncUsercallProvider,
    shutdown: Arc<AtomicBool>,
    join_handle: Option<thread::JoinHandle<()>>,
}

impl AutoPollingProvider {
    pub fn new() -> Self {
        let (provider, handler) = AsyncUsercallProvider::new();
        let shutdown = Arc::new(AtomicBool::new(false));
        let shutdown1 = shutdown.clone();
        let join_handle = Some(thread::spawn(move || loop {
            handler.poll(None);
            if shutdown1.load(Ordering::Relaxed) {
                break;
            }
        }));
        Self {
            provider,
            shutdown,
            join_handle,
        }
    }
}

impl Deref for AutoPollingProvider {
    type Target = AsyncUsercallProvider;

    fn deref(&self) -> &Self::Target {
        &self.provider
    }
}

impl Drop for AutoPollingProvider {
    fn drop(&mut self) {
        self.shutdown.store(true, Ordering::Relaxed);
        // send a usercall to ensure thread wakes up
        self.provider.insecure_time(|_, _| {});
        self.join_handle.take().unwrap().join().unwrap();
    }
}