1 files changed, 250 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/process/unix/mod.rs b/third_party/rust/tokio/src/process/unix/mod.rs
new file mode 100644
index 0000000000..576fe6cb47
--- /dev/null
+++ b/third_party/rust/tokio/src/process/unix/mod.rs
@@ -0,0 +1,250 @@
+//! Unix handling of child processes.
+//!
+//! Right now the only "fancy" thing about this is how we implement the
+//! `Future` implementation on `Child` to get the exit status. Unix offers
+//! no way to register a child with epoll, and the only real way to get a
+//! notification when a process exits is the SIGCHLD signal.
+//!
+//! Signal handling in general is *super* hairy and complicated, and it's even
+//! more complicated here with the fact that signals are coalesced, so we may
+//! not get a SIGCHLD-per-child.
+//!
+//! Our best approximation here is to check *all spawned processes* for all
+//! SIGCHLD signals received. To do that we create a `Signal`, implemented in
+//! the `tokio-net` crate, which is a stream over signals being received.
+//!
+//! Later when we poll the process's exit status we simply check to see if a
+//! SIGCHLD has happened since we last checked, and while that returns "yes" we
+//! keep trying.
+//!
+//! Note that this means that this isn't really scalable, but then again
+//! processes in general aren't scalable (e.g. millions) so it shouldn't be that
+//! bad in theory...
+
+pub(crate) mod driver;
+
+pub(crate) mod orphan;
+use orphan::{OrphanQueue, OrphanQueueImpl, Wait};
+
+mod reap;
+use reap::Reaper;
+
+use crate::io::PollEvented;
+use crate::process::kill::Kill;
+use crate::process::SpawnedChild;
+use crate::signal::unix::driver::Handle as SignalHandle;
+use crate::signal::unix::{signal, Signal, SignalKind};
+
+use mio::event::Source;
+use mio::unix::SourceFd;
+use once_cell::sync::Lazy;
+use std::fmt;
+use std::fs::File;
+use std::future::Future;
+use std::io;
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::pin::Pin;
+use std::process::{Child as StdChild, ExitStatus, Stdio};
+use std::task::Context;
+use std::task::Poll;
+
+impl Wait for StdChild {
+    fn id(&self) -> u32 {
+        self.id()
+    }
+
+    fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
+        self.try_wait()
+    }
+}
+
+impl Kill for StdChild {
+    fn kill(&mut self) -> io::Result<()> {
+        self.kill()
+    }
+}
+
+static ORPHAN_QUEUE: Lazy<OrphanQueueImpl<StdChild>> = Lazy::new(OrphanQueueImpl::new);
+
+pub(crate) struct GlobalOrphanQueue;
+
+impl fmt::Debug for GlobalOrphanQueue {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ORPHAN_QUEUE.fmt(fmt)
+    }
+}
+
+impl GlobalOrphanQueue {
+    fn reap_orphans(handle: &SignalHandle) {
+        ORPHAN_QUEUE.reap_orphans(handle)
+    }
+}
+
+impl OrphanQueue<StdChild> for GlobalOrphanQueue {
+    fn push_orphan(&self, orphan: StdChild) {
+        ORPHAN_QUEUE.push_orphan(orphan)
+    }
+}
+
+#[must_use = "futures do nothing unless polled"]
+pub(crate) struct Child {
+    inner: Reaper<StdChild, GlobalOrphanQueue, Signal>,
+}
+
+impl fmt::Debug for Child {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("Child")
+            .field("pid", &self.inner.id())
+            .finish()
+    }
+}
+
+pub(crate) fn spawn_child(cmd: &mut std::process::Command) -> io::Result<SpawnedChild> {
+    let mut child = cmd.spawn()?;
+    let stdin = child.stdin.take().map(stdio).transpose()?;
+    let stdout = child.stdout.take().map(stdio).transpose()?;
+    let stderr = child.stderr.take().map(stdio).transpose()?;
+
+    let signal = signal(SignalKind::child())?;
+
+    Ok(SpawnedChild {
+        child: Child {
+            inner: Reaper::new(child, GlobalOrphanQueue, signal),
+        },
+        stdin,
+        stdout,
+        stderr,
+    })
+}
+
+impl Child {
+    pub(crate) fn id(&self) -> u32 {
+        self.inner.id()
+    }
+
+    pub(crate) fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
+        self.inner.inner_mut().try_wait()
+    }
+}
+
+impl Kill for Child {
+    fn kill(&mut self) -> io::Result<()> {
+        self.inner.kill()
+    }
+}
+
+impl Future for Child {
+    type Output = io::Result<ExitStatus>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        Pin::new(&mut self.inner).poll(cx)
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct Pipe {
+    // Actually a pipe and not a File. However, we are reusing `File` to get
+    // close on drop. This is a similar trick as `mio`.
+    fd: File,
+}
+
+impl<T: IntoRawFd> From<T> for Pipe {
+    fn from(fd: T) -> Self {
+        let fd = unsafe { File::from_raw_fd(fd.into_raw_fd()) };
+        Self { fd }
+    }
+}
+
+impl<'a> io::Read for &'a Pipe {
+    fn read(&mut self, bytes: &mut [u8]) -> io::Result<usize> {
+        (&self.fd).read(bytes)
+    }
+}
+
+impl<'a> io::Write for &'a Pipe {
+    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
+        (&self.fd).write(bytes)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        (&self.fd).flush()
+    }
+}
+
+impl AsRawFd for Pipe {
+    fn as_raw_fd(&self) -> RawFd {
+        self.fd.as_raw_fd()
+    }
+}
+
+pub(crate) fn convert_to_stdio(io: PollEvented<Pipe>) -> io::Result<Stdio> {
+    let mut fd = io.into_inner()?.fd;
+
+    // Ensure that the fd to be inherited is set to *blocking* mode, as this
+    // is the default that virtually all programs expect to have. Those
+    // programs that know how to work with nonblocking stdio will know how to
+    // change it to nonblocking mode.
+    set_nonblocking(&mut fd, false)?;
+
+    Ok(Stdio::from(fd))
+}
+
+impl Source for Pipe {
+    fn register(
+        &mut self,
+        registry: &mio::Registry,
+        token: mio::Token,
+        interest: mio::Interest,
+    ) -> io::Result<()> {
+        SourceFd(&self.as_raw_fd()).register(registry, token, interest)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &mio::Registry,
+        token: mio::Token,
+        interest: mio::Interest,
+    ) -> io::Result<()> {
+        SourceFd(&self.as_raw_fd()).reregister(registry, token, interest)
+    }
+
+    fn deregister(&mut self, registry: &mio::Registry) -> io::Result<()> {
+        SourceFd(&self.as_raw_fd()).deregister(registry)
+    }
+}
+
+pub(crate) type ChildStdio = PollEvented<Pipe>;
+
+fn set_nonblocking<T: AsRawFd>(fd: &mut T, nonblocking: bool) -> io::Result<()> {
+    unsafe {
+        let fd = fd.as_raw_fd();
+        let previous = libc::fcntl(fd, libc::F_GETFL);
+        if previous == -1 {
+            return Err(io::Error::last_os_error());
+        }
+
+        let new = if nonblocking {
+            previous | libc::O_NONBLOCK
+        } else {
+            previous & !libc::O_NONBLOCK
+        };
+
+        let r = libc::fcntl(fd, libc::F_SETFL, new);
+        if r == -1 {
+            return Err(io::Error::last_os_error());
+        }
+    }
+
+    Ok(())
+}
+
+pub(super) fn stdio<T>(io: T) -> io::Result<PollEvented<Pipe>>
+where
+    T: IntoRawFd,
+{
+    // Set the fd to nonblocking before we pass it to the event loop
+    let mut pipe = Pipe::from(io);
+    set_nonblocking(&mut pipe, true)?;
+
+    PollEvented::new(pipe)
+}