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use cap_std::time::Duration;
use rustix::io::{PollFd, PollFlags};
use std::convert::TryInto;
use wasi_common::sched::subscription::{RwEventFlags, Subscription};
use wasi_common::{sched::Poll, Error, ErrorExt};
pub async fn poll_oneoff<'a>(poll: &mut Poll<'a>) -> Result<(), Error> {
if poll.is_empty() {
return Ok(());
}
let mut pollfds = Vec::new();
for s in poll.rw_subscriptions() {
match s {
Subscription::Read(f) => {
let fd = f
.file
.pollable()
.ok_or(Error::invalid_argument().context("file is not pollable"))?;
pollfds.push(PollFd::from_borrowed_fd(fd, PollFlags::IN));
}
Subscription::Write(f) => {
let fd = f
.file
.pollable()
.ok_or(Error::invalid_argument().context("file is not pollable"))?;
pollfds.push(PollFd::from_borrowed_fd(fd, PollFlags::OUT));
}
Subscription::MonotonicClock { .. } => unreachable!(),
}
}
let ready = loop {
let poll_timeout = if let Some(t) = poll.earliest_clock_deadline() {
let duration = t.duration_until().unwrap_or(Duration::from_secs(0));
(duration.as_millis() + 1)
.try_into()
.map_err(|_| Error::overflow().context("poll timeout"))?
} else {
std::os::raw::c_int::max_value()
};
tracing::debug!(
poll_timeout = tracing::field::debug(poll_timeout),
poll_fds = tracing::field::debug(&pollfds),
"poll"
);
match rustix::io::poll(&mut pollfds, poll_timeout) {
Ok(ready) => break ready,
Err(rustix::io::Errno::INTR) => continue,
Err(err) => return Err(err.into()),
}
};
if ready > 0 {
for (rwsub, pollfd) in poll.rw_subscriptions().zip(pollfds.into_iter()) {
let revents = pollfd.revents();
let (nbytes, rwsub) = match rwsub {
Subscription::Read(sub) => {
let ready = sub.file.num_ready_bytes().await?;
(std::cmp::max(ready, 1), sub)
}
Subscription::Write(sub) => (0, sub),
_ => unreachable!(),
};
if revents.contains(PollFlags::NVAL) {
rwsub.error(Error::badf());
} else if revents.contains(PollFlags::ERR) {
rwsub.error(Error::io());
} else if revents.contains(PollFlags::HUP) {
rwsub.complete(nbytes, RwEventFlags::HANGUP);
} else {
rwsub.complete(nbytes, RwEventFlags::empty());
};
}
} else {
poll.earliest_clock_deadline()
.expect("timed out")
.result()
.expect("timer deadline is past")
.unwrap()
}
Ok(())
}