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Diffstat (limited to 'src/process.rs')
| -rw-r--r-- | src/process.rs | 362 |
1 files changed, 362 insertions, 0 deletions
diff --git a/src/process.rs b/src/process.rs new file mode 100644 index 0000000..ed3344c --- /dev/null +++ b/src/process.rs @@ -0,0 +1,362 @@ +use futures::future::Future as _; +use snafu::ResultExt as _; +use std::os::unix::io::AsRawFd as _; +use tokio::io::{AsyncRead as _, AsyncWrite as _}; +use tokio_pty_process::{CommandExt as _, PtyMaster as _}; + +const READ_BUFFER_SIZE: usize = 4 * 1024; + +/// Represents events generated by the process. +#[derive(Debug, PartialEq, Eq)] +pub enum Event { + /// Emitted once the command has been successfully spawned. + CommandStart { cmd: String, args: Vec<String> }, + + /// Emitted every time the command produces output. Note that when a + /// process is running under a pty, both stdout and stderr are attached to + /// the single pty input - there is no way to differentiate them when + /// reading from the pty output. + Output { data: Vec<u8> }, + + /// Emitted when the command has exited. + CommandExit { status: std::process::ExitStatus }, +} + +struct State { + pty: Option<tokio_pty_process::AsyncPtyMaster>, + process: Option<tokio_pty_process::Child>, +} + +impl State { + fn new() -> Self { + Self { + pty: None, + process: None, + } + } + + fn pty(&self) -> &tokio_pty_process::AsyncPtyMaster { + self.pty.as_ref().unwrap() + } + + fn pty_mut(&mut self) -> &mut tokio_pty_process::AsyncPtyMaster { + self.pty.as_mut().unwrap() + } + + fn process(&mut self) -> &mut tokio_pty_process::Child { + self.process.as_mut().unwrap() + } +} + +/// A spawned process. +/// +/// Wraps `AsyncPtyMaster` and `Child` from `tokio-pty-process` to provide a +/// view of the process as a single stream which emits events. In particular, +/// the stream will return an event when the process starts, when it writes +/// output to the pty, and when it exits. See the `Event` type for more +/// details. +pub struct Process<R: tokio::io::AsyncRead> { + state: State, + input: R, + input_buf: std::collections::VecDeque<u8>, + cmd: String, + args: Vec<String>, + buf: [u8; READ_BUFFER_SIZE], + started: bool, + exited: bool, + needs_resize: Option<(u16, u16)>, + stdin_closed: bool, + stdout_closed: bool, +} + +impl<R: tokio::io::AsyncRead + 'static> Process<R> { + /// Creates a new process stream. + /// + /// The process is not spawned and the pty is not opened until `poll` is + /// called. + /// + /// Takes as input the command and arguments to run, as well as the + /// `AsyncRead` object to read input from. Typically you will pass in + /// something connected to stdin here, although other options may be more + /// useful for automation or testing. + pub fn new(cmd: &str, args: &[String], input: R) -> Self { + Self { + state: State::new(), + input, + input_buf: std::collections::VecDeque::new(), + cmd: cmd.to_string(), + args: args.to_vec(), + buf: [0; READ_BUFFER_SIZE], + started: false, + exited: false, + needs_resize: None, + stdin_closed: false, + stdout_closed: false, + } + } + + /// Requests a change to the pty's terminal size. + /// + /// This will only be applied on the next call to `poll`. + pub fn resize(&mut self, rows: u16, cols: u16) { + self.needs_resize = Some((rows, cols)); + } + + /// Returns a mutable reference to the input object provided in the + /// constructor. + /// + /// This can be useful if you are driving the input manually, rather than + /// just hooking it up directly to stdin. + pub fn input(&mut self) -> &mut R { + &mut self.input + } +} + +impl<R: tokio::io::AsyncRead + 'static> Process<R> { + const POLL_FNS: + &'static [&'static dyn for<'a> Fn( + &'a mut Self, + ) + -> component_future::Poll< + Option<Event>, + crate::error::Error, + >] = &[ + // order is important here - checking command_exit first so that we + // don't try to read from a process that has already exited, which + // causes an error. also, poll_resize needs to happen after + // poll_command_start, or else the pty might not be initialized. + &Self::poll_command_start, + &Self::poll_command_exit, + &Self::poll_resize, + &Self::poll_read_stdin, + &Self::poll_write_stdin, + &Self::poll_read_stdout, + ]; + + fn poll_resize( + &mut self, + ) -> component_future::Poll<Option<Event>, crate::error::Error> { + if let Some((rows, cols)) = &self.needs_resize { + component_future::try_ready!(self + .state + .pty() + .resize(*rows, *cols) + .context(crate::error::ResizePty)); + log::debug!("resize({}x{})", cols, rows); + self.needs_resize = None; + Ok(component_future::Async::DidWork) + } else { + Ok(component_future::Async::NothingToDo) + } + } + + fn poll_command_start( + &mut self, + ) -> component_future::Poll<Option<Event>, crate::error::Error> { + if self.started { + return Ok(component_future::Async::NothingToDo); + } + + if self.state.pty.is_none() { + self.state.pty = Some( + tokio_pty_process::AsyncPtyMaster::open() + .context(crate::error::OpenPty)?, + ); + log::debug!( + "openpty({})", + self.state.pty.as_ref().unwrap().as_raw_fd() + ); + } + + if self.state.process.is_none() { + self.state.process = Some( + std::process::Command::new(&self.cmd) + .args(&self.args) + .spawn_pty_async(self.state.pty()) + .context(crate::error::SpawnProcess { + cmd: self.cmd.clone(), + })?, + ); + log::debug!( + "spawn({})", + self.state.process.as_ref().unwrap().id() + ); + } + + self.started = true; + Ok(component_future::Async::Ready(Some(Event::CommandStart { + cmd: self.cmd.clone(), + args: self.args.clone(), + }))) + } + + fn poll_read_stdin( + &mut self, + ) -> component_future::Poll<Option<Event>, crate::error::Error> { + if self.exited || self.stdin_closed { + return Ok(component_future::Async::NothingToDo); + } + + let n = component_future::try_ready!(self + .input + .poll_read(&mut self.buf) + .context(crate::error::ReadTerminal)); + log::debug!("read_stdin({})", n); + if n > 0 { + self.input_buf.extend(self.buf[..n].iter()); + } else { + self.input_buf.push_back(b'\x04'); + self.stdin_closed = true; + } + Ok(component_future::Async::DidWork) + } + + fn poll_write_stdin( + &mut self, + ) -> component_future::Poll<Option<Event>, crate::error::Error> { + if self.exited || self.input_buf.is_empty() { + return Ok(component_future::Async::NothingToDo); + } + + let (a, b) = self.input_buf.as_slices(); + let buf = if a.is_empty() { b } else { a }; + let n = component_future::try_ready!(self + .state + .pty_mut() + .poll_write(buf) + .context(crate::error::WritePty)); + log::debug!("write_stdin({})", n); + for _ in 0..n { + self.input_buf.pop_front(); + } + Ok(component_future::Async::DidWork) + } + + fn poll_read_stdout( + &mut self, + ) -> component_future::Poll<Option<Event>, crate::error::Error> { + match self + .state + .pty_mut() + .poll_read(&mut self.buf) + .context(crate::error::ReadPty) + { + Ok(futures::Async::Ready(n)) => { + log::debug!("read_stdout({})", n); + let bytes = self.buf[..n].to_vec(); + Ok(component_future::Async::Ready(Some(Event::Output { + data: bytes, + }))) + } + Ok(futures::Async::NotReady) => { + Ok(component_future::Async::NotReady) + } + Err(e) => { + // XXX this seems to be how eof is returned, but this seems... + // wrong? i feel like there has to be a better way to do this + if let crate::error::Error::ReadPty { source } = &e { + if source.kind() == std::io::ErrorKind::Other { + log::debug!("read_stdout(eof)"); + self.stdout_closed = true; + return Ok(component_future::Async::DidWork); + } + } + Err(e) + } + } + } + + fn poll_command_exit( + &mut self, + ) -> component_future::Poll<Option<Event>, crate::error::Error> { + if self.exited { + return Ok(component_future::Async::Ready(None)); + } + if !self.stdout_closed { + return Ok(component_future::Async::NothingToDo); + } + + let status = component_future::try_ready!(self + .state + .process() + .poll() + .context(crate::error::ProcessExitPoll)); + log::debug!("exit({})", status); + self.exited = true; + Ok(component_future::Async::Ready(Some(Event::CommandExit { + status, + }))) + } +} + +#[must_use = "streams do nothing unless polled"] +impl<R: tokio::io::AsyncRead + 'static> futures::stream::Stream + for Process<R> +{ + type Item = Event; + type Error = crate::error::Error; + + fn poll(&mut self) -> futures::Poll<Option<Self::Item>, Self::Error> { + component_future::poll_stream(self, Self::POLL_FNS) + } +} + +#[cfg(test)] +mod test { + use super::*; + use futures::sink::Sink as _; + use futures::stream::Stream as _; + + #[test] + fn test_simple() { + let (wres, rres) = tokio::sync::mpsc::channel(100); + let wres2 = wres.clone(); + let mut wres = wres.wait(); + let buf = std::io::Cursor::new(b"hello world\n"); + let fut = Process::new("cat", &[], buf) + .for_each(move |e| { + wres.send(Ok(e)).unwrap(); + Ok(()) + }) + .map_err(|e| { + wres2.wait().send(Err(e)).unwrap(); + }); + tokio::run(fut); + + let mut rres = rres.wait(); + + let event = rres.next(); + let event = event.unwrap(); + let event = event.unwrap(); + let event = event.unwrap(); + assert_eq!( + event, + Event::CommandStart { + cmd: "cat".to_string(), + args: vec![] + } + ); + + let mut output: Vec<u8> = vec![]; + let mut exited = false; + for event in rres { + assert!(!exited); + let event = event.unwrap(); + let event = event.unwrap(); + match event { + Event::CommandStart { .. } => { + panic!("unexpected CommandStart") + } + Event::Output { data } => { + output.extend(data.iter()); + } + Event::CommandExit { status } => { + assert!(status.success()); + exited = true; + } + } + } + assert!(exited); + assert_eq!(output, b"hello world\r\nhello world\r\n"); + } +} |