0df4e961c0
Currently, the use of the downcast method means that you have to use one of the hard-coded types. But Enarx needs to define its own `WasiFile` implementations. This works fine, except the resulting files cannot be used in poll because they aren't part of the hard-coded list. Replace this with an accessor method for the pollable type in `WasiFile`. Because we provide a default implementation of the method and manually implement it on all the hard-coded types, this is backwards compatible. Signed-off-by: Nathaniel McCallum <nathaniel@profian.com>
83 lines
3.0 KiB
Rust
83 lines
3.0 KiB
Rust
use cap_std::time::Duration;
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use rustix::io::{PollFd, PollFlags};
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use std::convert::TryInto;
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use wasi_common::sched::subscription::{RwEventFlags, Subscription};
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use wasi_common::{sched::Poll, Error, ErrorExt};
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pub async fn poll_oneoff<'a>(poll: &mut Poll<'a>) -> Result<(), Error> {
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if poll.is_empty() {
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return Ok(());
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}
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let mut pollfds = Vec::new();
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for s in poll.rw_subscriptions() {
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match s {
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Subscription::Read(f) => {
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let fd = f
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.file
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.pollable()
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.ok_or(Error::invalid_argument().context("file is not pollable"))?;
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pollfds.push(PollFd::from_borrowed_fd(fd, PollFlags::IN));
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}
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Subscription::Write(f) => {
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let fd = f
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.file
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.pollable()
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.ok_or(Error::invalid_argument().context("file is not pollable"))?;
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pollfds.push(PollFd::from_borrowed_fd(fd, PollFlags::OUT));
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}
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Subscription::MonotonicClock { .. } => unreachable!(),
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}
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}
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let ready = loop {
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let poll_timeout = if let Some(t) = poll.earliest_clock_deadline() {
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let duration = t.duration_until().unwrap_or(Duration::from_secs(0));
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(duration.as_millis() + 1) // XXX try always rounding up?
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.try_into()
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.map_err(|_| Error::overflow().context("poll timeout"))?
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} else {
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std::os::raw::c_int::max_value()
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};
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tracing::debug!(
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poll_timeout = tracing::field::debug(poll_timeout),
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poll_fds = tracing::field::debug(&pollfds),
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"poll"
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);
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match rustix::io::poll(&mut pollfds, poll_timeout) {
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Ok(ready) => break ready,
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Err(rustix::io::Error::INTR) => continue,
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Err(err) => return Err(err.into()),
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}
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};
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if ready > 0 {
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for (rwsub, pollfd) in poll.rw_subscriptions().zip(pollfds.into_iter()) {
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let revents = pollfd.revents();
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let (nbytes, rwsub) = match rwsub {
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Subscription::Read(sub) => {
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let ready = sub.file.num_ready_bytes().await?;
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(std::cmp::max(ready, 1), sub)
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}
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Subscription::Write(sub) => (0, sub),
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_ => unreachable!(),
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};
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if revents.contains(PollFlags::NVAL) {
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rwsub.error(Error::badf());
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} else if revents.contains(PollFlags::ERR) {
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rwsub.error(Error::io());
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} else if revents.contains(PollFlags::HUP) {
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rwsub.complete(nbytes, RwEventFlags::HANGUP);
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} else {
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rwsub.complete(nbytes, RwEventFlags::empty());
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};
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}
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} else {
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poll.earliest_clock_deadline()
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.expect("timed out")
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.result()
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.expect("timer deadline is past")
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.unwrap()
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}
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Ok(())
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}
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