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fix(wasi): enable all WasiFiles to be pollable (#3913)

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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>
This commit is contained in:
Nathaniel McCallum
2022-03-10 13:09:06 -05:00
committed by GitHub
parent 13b9396931
commit 0df4e961c0
10 changed files with 84 additions and 150 deletions
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70
crates/wasi-common/cap-std-sync/src/sched/windows.rs
View File

@@ -9,30 +9,21 @@
// taken the time to improve it. See bug #2880.
use anyhow::Context;
use io_extras::os::windows::{AsRawHandleOrSocket, RawHandleOrSocket};
use std::ops::Deref;
use std::sync::mpsc::{self, Receiver, RecvTimeoutError, Sender, TryRecvError};
use std::sync::Mutex;
use std::thread;
use std::time::Duration;
use wasi_common::{
file::WasiFile,
sched::{
subscription::{RwEventFlags, Subscription},
Poll,
},
Error, ErrorExt,
};
use wasi_common::sched::subscription::{RwEventFlags, Subscription};
use wasi_common::{file::WasiFile, sched::Poll, Error, ErrorExt};
pub async fn poll_oneoff<'a>(poll: &mut Poll<'a>) -> Result<(), Error> {
poll_oneoff_(poll, wasi_file_is_stdin, wasi_file_raw_handle).await
poll_oneoff_(poll, wasi_file_is_stdin).await
}
// For reuse by wasi-tokio, which has a different WasiFile -> RawHandle translator.
pub async fn poll_oneoff_<'a>(
poll: &mut Poll<'a>,
file_is_stdin: impl Fn(&dyn WasiFile) -> bool,
file_to_handle: impl Fn(&dyn WasiFile) -> Option<RawHandleOrSocket>,
) -> Result<(), Error> {
if poll.is_empty() {
return Ok(());
@@ -61,21 +52,17 @@ pub async fn poll_oneoff_<'a>(
Subscription::Read(r) => {
if file_is_stdin(r.file.deref()) {
stdin_read_subs.push(r);
} else if file_to_handle(r.file.deref()).is_some() {
} else if r.file.pollable().is_some() {
immediate_reads.push(r);
} else {
return Err(
Error::invalid_argument().context("read subscription fd downcast failed")
);
return Err(Error::invalid_argument().context("file is not pollable"));
}
}
Subscription::Write(w) => {
if file_to_handle(w.file.deref()).is_some() {
if w.file.pollable().is_some() {
immediate_writes.push(w);
} else {
return Err(
Error::invalid_argument().context("write subscription fd downcast failed")
);
return Err(Error::invalid_argument().context("file is not pollable"));
}
}
Subscription::MonotonicClock { .. } => unreachable!(),
@@ -139,49 +126,6 @@ pub fn wasi_file_is_stdin(f: &dyn WasiFile) -> bool {
f.as_any().is::<crate::stdio::Stdin>()
}
pub fn wasi_file_raw_handle(f: &dyn WasiFile) -> Option<RawHandleOrSocket> {
let a = f.as_any();
if a.is::<crate::file::File>() {
Some(
a.downcast_ref::<crate::file::File>()
.unwrap()
.as_raw_handle_or_socket(),
)
} else if a.is::<crate::net::TcpStream>() {
Some(
a.downcast_ref::<crate::net::TcpStream>()
.unwrap()
.as_raw_handle_or_socket(),
)
} else if a.is::<crate::net::TcpListener>() {
Some(
a.downcast_ref::<crate::net::TcpListener>()
.unwrap()
.as_raw_handle_or_socket(),
)
} else if a.is::<crate::stdio::Stdin>() {
Some(
a.downcast_ref::<crate::stdio::Stdin>()
.unwrap()
.as_raw_handle_or_socket(),
)
} else if a.is::<crate::stdio::Stdout>() {
Some(
a.downcast_ref::<crate::stdio::Stdout>()
.unwrap()
.as_raw_handle_or_socket(),
)
} else if a.is::<crate::stdio::Stderr>() {
Some(
a.downcast_ref::<crate::stdio::Stderr>()
.unwrap()
.as_raw_handle_or_socket(),
)
} else {
None
}
}
enum PollState {
Ready,
NotReady, // Not ready, but did not wait