vfs/rsh: better pipes, piped command execution in rsh

kernel/libk/src/vfs/file/mod.rs

@@ -17,8 +17,8 @@ use libk_util::sync::IrqSafeSpinlock;
 use yggdrasil_abi::{
     error::Error,
     io::{
-        DeviceRequest, DirectoryEntry, OpenOptions, RawFd, SeekFrom, TerminalOptions, TerminalSize,
+        DeviceRequest, DirectoryEntry, OpenOptions, PipeOptions, RawFd, SeekFrom, TerminalOptions,
-        TimerOptions,
+        TerminalSize, TimerOptions,
     },
 };
 
@@ -71,7 +71,7 @@ pub enum File {
     Block(BlockFile),
     Char(CharFile),
     Socket(SocketWrapper),
-    AnonymousPipe(PipeEnd),
+    AnonymousPipe(PipeEnd, AtomicBool),
     Poll(FdPoll),
     Timer(TimerFile),
     Channel(ChannelDescriptor),
@@ -103,11 +103,17 @@ pub struct FileSet {
 
 impl File {
     /// Constructs a pipe pair, returning its `(read, write)` ends
-    pub fn new_pipe_pair(capacity: usize) -> (Arc<Self>, Arc<Self>) {
+    pub fn new_pipe_pair(capacity: usize, options: PipeOptions) -> (Arc<Self>, Arc<Self>) {
         let (read, write) = PipeEnd::new_pair(capacity);
         (
-            Arc::new(Self::AnonymousPipe(read)),
+            Arc::new(Self::AnonymousPipe(
-            Arc::new(Self::AnonymousPipe(write)),
+                read,
+                AtomicBool::new(options.contains(PipeOptions::READ_NONBLOCKING)),
+            )),
+            Arc::new(Self::AnonymousPipe(
+                write,
+                AtomicBool::new(options.contains(PipeOptions::WRITE_NONBLOCKING)),
+            )),
         )
     }
 
@@ -289,6 +295,7 @@ impl File {
             Self::Socket(socket) => socket.poll_read(cx),
             Self::Timer(timer) => timer.poll_read(cx),
             Self::Pid(pid) => pid.poll_read(cx),
+            Self::AnonymousPipe(pipe, _) => pipe.poll_read(cx),
             // Polling not implemented, return ready immediately (XXX ?)
             _ => Poll::Ready(Err(Error::NotImplemented)),
         }
@@ -365,7 +372,9 @@ impl Read for File {
             Self::Regular(file) => file.read(buf),
             Self::Block(file) => file.read(buf),
             Self::Char(file) => file.read(buf),
-            Self::AnonymousPipe(pipe) => pipe.read(buf),
+            Self::AnonymousPipe(pipe, nonblocking) => {
+                pipe.read(buf, nonblocking.load(Ordering::Acquire))
+            }
             Self::PtySlave(half) => half.read(buf),
             Self::PtyMaster(half) => half.read(buf),
             Self::Timer(timer) => timer.read(buf),
@@ -388,7 +397,7 @@ impl Write for File {
             Self::Regular(file) => file.write(buf),
             Self::Block(file) => file.write(buf),
             Self::Char(file) => file.write(buf),
-            Self::AnonymousPipe(pipe) => pipe.write(buf),
+            Self::AnonymousPipe(pipe, _) => pipe.write(buf),
             Self::PtySlave(half) => half.write(buf),
             Self::PtyMaster(half) => half.write(buf),
             Self::Timer(timer) => timer.write(buf),
@@ -447,7 +456,7 @@ impl fmt::Debug for File {
                 .field("write", &file.write)
                 .finish_non_exhaustive(),
             Self::Directory(_) => f.debug_struct("DirectoryFile").finish_non_exhaustive(),
-            Self::AnonymousPipe(_) => f.debug_struct("AnonymousPipe").finish_non_exhaustive(),
+            Self::AnonymousPipe(_, _) => f.debug_struct("AnonymousPipe").finish_non_exhaustive(),
             Self::Poll(_) => f.debug_struct("Poll").finish_non_exhaustive(),
             Self::Channel(_) => f.debug_struct("Channel").finish_non_exhaustive(),
             Self::SharedMemory(_) => f.debug_struct("SharedMemory").finish_non_exhaustive(),

kernel/libk/src/vfs/file/pipe.rs

@@ -1,4 +1,5 @@
 use core::{
+    future::poll_fn,
     pin::Pin,
     sync::atomic::{AtomicBool, Ordering},
     task::{Context, Poll},
@@ -6,9 +7,14 @@ use core::{
 
 use alloc::{sync::Arc, vec, vec::Vec};
 use futures_util::{task::AtomicWaker, Future};
-use libk_util::sync::IrqSafeSpinlock;
+use libk_util::{
+    sync::{IrqSafeSpinlock, IrqSafeSpinlockGuard},
+    waker::QueueWaker,
+};
 use yggdrasil_abi::error::Error;
 
+use crate::vfs::FileReadiness;
+
 struct PipeInner {
     data: Vec<u8>,
     capacity: usize,
@@ -19,8 +25,8 @@ struct PipeInner {
 pub struct Pipe {
     inner: IrqSafeSpinlock<PipeInner>,
     shutdown: AtomicBool,
-    read_notify: AtomicWaker,
+    read_notify: QueueWaker,
-    write_notify: AtomicWaker,
+    write_notify: QueueWaker,
 }
 
 pub enum PipeEnd {
@@ -82,15 +88,15 @@ impl Pipe {
         Self {
             inner: IrqSafeSpinlock::new(PipeInner::new(capacity)),
             shutdown: AtomicBool::new(false),
-            read_notify: AtomicWaker::new(),
+            read_notify: QueueWaker::new(),
-            write_notify: AtomicWaker::new(),
+            write_notify: QueueWaker::new(),
         }
     }
 
     pub fn shutdown(&self) {
         self.shutdown.store(true, Ordering::Release);
-        self.read_notify.wake();
+        self.read_notify.wake_all();
-        self.write_notify.wake();
+        self.write_notify.wake_all();
     }
 
     pub fn blocking_write(&self, val: u8) -> impl Future<Output = Result<(), Error>> + '_ {
@@ -105,23 +111,15 @@ impl Pipe {
             fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
                 let mut lock = self.pipe.inner.lock();
 
-                // Try fast path before acquiring write notify to avoid unnecessary contention
-                if self.pipe.shutdown.load(Ordering::Acquire) {
-                    // TODO BrokenPipe
-                    return Poll::Ready(Err(Error::ReadOnly));
-                } else if lock.try_write(self.val) {
-                    self.pipe.read_notify.wake();
-                    return Poll::Ready(Ok(()));
-                }
-
-                self.pipe.write_notify.register(cx.waker());
-
                 if self.pipe.shutdown.load(Ordering::Acquire) {
+                    self.pipe.write_notify.remove(cx.waker());
                     Poll::Ready(Err(Error::ReadOnly))
                 } else if lock.try_write(self.val) {
-                    self.pipe.read_notify.wake();
+                    self.pipe.write_notify.remove(cx.waker());
+                    self.pipe.read_notify.wake_one();
                     Poll::Ready(Ok(()))
                 } else {
+                    self.pipe.write_notify.register(cx.waker());
                     Poll::Pending
                 }
             }
@@ -130,37 +128,54 @@ impl Pipe {
         F { pipe: self, val }
     }
 
-    pub fn blocking_read(&self) -> impl Future<Output = Option<u8>> + '_ {
+    fn poll_read_end(
-        struct F<'a> {
+        &self,
-            pipe: &'a Pipe,
+        cx: &mut Context<'_>,
-        }
+    ) -> Poll<Option<IrqSafeSpinlockGuard<'_, PipeInner>>> {
+        let lock = self.inner.lock();
 
-        impl<'a> Future for F<'a> {
+        if lock.can_read() {
-            type Output = Option<u8>;
+            self.read_notify.remove(cx.waker());
-
+            Poll::Ready(Some(lock))
-            fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        } else if self.shutdown.load(Ordering::Acquire) {
-                let mut lock = self.pipe.inner.lock();
+            self.read_notify.remove(cx.waker());
-
-                if let Some(val) = lock.try_read() {
-                    self.pipe.write_notify.wake();
-                    return Poll::Ready(Some(val));
-                } else if self.pipe.shutdown.load(Ordering::Acquire) {
-                    return Poll::Ready(None);
-                }
-
-                self.pipe.read_notify.register(cx.waker());
-
-                if let Some(val) = lock.try_read() {
-                    Poll::Ready(Some(val))
-                } else if self.pipe.shutdown.load(Ordering::Acquire) {
             Poll::Ready(None)
         } else {
+            self.read_notify.register(cx.waker());
             Poll::Pending
         }
     }
+
+    async fn read_async(&self, buf: &mut [u8]) -> Result<usize, Error> {
+        let mut pos = 0;
+        let lock = poll_fn(|cx| self.poll_read_end(cx)).await;
+        match lock {
+            Some(mut lock) => {
+                while pos < buf.len()
+                    && let Some(byte) = lock.try_read()
+                {
+                    buf[pos] = byte;
+                    pos += 1;
+                }
+                if pos != 0 {
+                    self.write_notify.wake_all();
+                }
+                Ok(pos)
+            }
+            None => Ok(0),
+        }
+    }
 }
 
-        F { pipe: self }
+impl FileReadiness for Pipe {
+    fn poll_read(&self, cx: &mut Context<'_>) -> Poll<Result<(), Error>> {
+        if self.shutdown.load(Ordering::Acquire) || self.inner.lock().can_read() {
+            self.read_notify.remove(cx.waker());
+            Poll::Ready(Ok(()))
+        } else {
+            self.read_notify.register(cx.waker());
+            Poll::Pending
+        }
     }
 }
 
@@ -173,27 +188,29 @@ impl PipeEnd {
         (read, write)
     }
 
-    pub fn read(&self, buf: &mut [u8]) -> Result<usize, Error> {
+    pub fn read(&self, buf: &mut [u8], nonblocking: bool) -> Result<usize, Error> {
         let PipeEnd::Read(read) = self else {
             return Err(Error::InvalidOperation);
         };
 
-        block! {
+        if nonblocking {
+            let mut lock = read.inner.lock();
             let mut pos = 0;
-            let mut rem = buf.len();
+            while pos < buf.len()
-
+                && let Some(ch) = lock.try_read()
-            while rem != 0 {
+            {
-                if let Some(val) = read.blocking_read().await {
+                buf[pos] = ch;
-                    buf[pos] = val;
                 pos += 1;
-                    rem -= 1;
+            }
+            read.write_notify.wake_all();
+            if pos == 0 && !read.shutdown.load(Ordering::Acquire) {
+                Err(Error::WouldBlock)
             } else {
-                    break;
-                }
-            }
-
                 Ok(pos)
-        }?
+            }
+        } else {
+            block!(read.read_async(buf).await)?
+        }
     }
 
     pub fn write(&self, buf: &[u8]) -> Result<usize, Error> {
@@ -216,6 +233,15 @@ impl PipeEnd {
     }
 }
 
+impl FileReadiness for PipeEnd {
+    fn poll_read(&self, cx: &mut Context<'_>) -> Poll<Result<(), Error>> {
+        match self {
+            Self::Read(pipe) => pipe.poll_read(cx),
+            Self::Write(_) => Poll::Ready(Err(Error::NotImplemented)),
+        }
+    }
+}
+
 impl Drop for PipeEnd {
     fn drop(&mut self) {
         match self {

kernel/src/syscall/imp/mod.rs

@@ -1,8 +1,8 @@
 pub(crate) use abi::{
     error::Error,
     io::{
-        DirectoryEntry, FileAttr, FileMode, MountOptions, OpenOptions, PollControl, RawFd,
+        DirectoryEntry, FileAttr, FileMode, MountOptions, OpenOptions, PipeOptions, PollControl,
-        TerminalOptions, TerminalSize, TimerOptions, UnmountOptions,
+        RawFd, TerminalOptions, TerminalSize, TimerOptions, UnmountOptions,
     },
     mem::MappingSource,
     net::SocketType,

kernel/src/syscall/imp/sys_io.rs

@@ -4,8 +4,8 @@ use abi::{
     error::Error,
     io::{
         ChannelPublisherId, DeviceRequest, DirectoryEntry, FileAttr, FileMetadataUpdate, FileMode,
-        MessageDestination, OpenOptions, PollControl, RawFd, ReceivedMessageMetadata, SeekFrom,
+        MessageDestination, OpenOptions, PipeOptions, PollControl, RawFd, ReceivedMessageMetadata,
-        SentMessage, TerminalOptions, TerminalSize, TimerOptions,
+        SeekFrom, SentMessage, TerminalOptions, TerminalSize, TimerOptions,
     },
     process::ProcessId,
 };
@@ -299,12 +299,15 @@ pub(crate) fn create_poll_channel() -> Result<RawFd, Error> {
     })
 }
 
-pub(crate) fn create_pipe(ends: &mut [MaybeUninit<RawFd>; 2]) -> Result<(), Error> {
+pub(crate) fn create_pipe(
+    ends: &mut [MaybeUninit<RawFd>; 2],
+    options: PipeOptions,
+) -> Result<(), Error> {
     let thread = Thread::current();
     let process = thread.process();
 
     run_with_io(&process, |mut io| {
-        let (read, write) = File::new_pipe_pair(256);
+        let (read, write) = File::new_pipe_pair(256, options);
 
         let read_fd = io.files.place_file(read, true)?;
         let write_fd = io.files.place_file(write, true)?;

lib/abi/def/io.abi

@@ -49,6 +49,13 @@ bitfield OpenOptions(u32) {
     CREATE_EXCL: 5,
 }
 
+bitfield PipeOptions(u32) {
+    /// If set, read end of the pipe will return WouldBlock if there's no data in the pipe
+    READ_NONBLOCKING: 0,
+    /// If set, write end of the pipe will return WouldBlock if the pipe is full
+    WRITE_NONBLOCKING: 1,
+}
+
 enum FileType(u32) {
     /// Regular file
     File = 1,

lib/abi/def/yggdrasil.abi

@@ -105,7 +105,7 @@ syscall create_pid(pid: ProcessId) -> Result<RawFd>;
 syscall create_pty(opts: &TerminalOptions, size: &TerminalSize, fds: &mut [MaybeUninit<RawFd>; 2]) -> Result<()>;
 syscall create_shared_memory(size: usize) -> Result<RawFd>;
 syscall create_poll_channel() -> Result<RawFd>;
-syscall create_pipe(fds: &mut [MaybeUninit<RawFd>; 2]) -> Result<()>;
+syscall create_pipe(fds: &mut [MaybeUninit<RawFd>; 2], options: PipeOptions) -> Result<()>;
 
 syscall poll_channel_wait(
     poll_fd: RawFd,

lib/abi/src/io/mod.rs

@@ -5,8 +5,8 @@ mod input;
 mod terminal;
 
 pub use crate::generated::{
-    DirectoryEntry, FileAttr, FileMode, FileType, GroupId, MountOptions, OpenOptions, PollControl,
+    DirectoryEntry, FileAttr, FileMode, FileType, GroupId, MountOptions, OpenOptions, PipeOptions,
-    RawFd, TimerOptions, UnmountOptions, UserId,
+    PollControl, RawFd, TimerOptions, UnmountOptions, UserId,
 };
 pub use channel::{ChannelPublisherId, MessageDestination, ReceivedMessageMetadata, SentMessage};
 pub use device::DeviceRequest;

lib/runtime/src/io.rs

@@ -23,5 +23,5 @@ pub mod poll {
 
 pub use abi::io::{
     DirectoryEntry, FileAttr, FileMetadataUpdate, FileMetadataUpdateMode, FileMode, FileType,
-    OpenOptions, RawFd, SeekFrom, TimerOptions,
+    OpenOptions, PipeOptions, RawFd, SeekFrom, TimerOptions,
 };

lib/runtime/src/sys/mod.rs

@@ -17,7 +17,8 @@ mod generated {
         error::Error,
         io::{
             ChannelPublisherId, DirectoryEntry, FileAttr, FileMode, MountOptions, OpenOptions,
-            PollControl, RawFd, TerminalOptions, TerminalSize, TimerOptions, UnmountOptions,
+            PipeOptions, PollControl, RawFd, TerminalOptions, TerminalSize, TimerOptions,
+            UnmountOptions,
         },
         mem::MappingSource,
         net::SocketType,

userspace/lib/cross/src/io.rs

@@ -1,10 +1,15 @@
 use std::{
-    io,
+    io::{self, Read, Write},
     os::fd::{AsRawFd, RawFd},
+    process::Stdio,
     time::Duration,
 };
 
-use crate::sys::{self, Poll as SysPoll, TimerFd as SysTimerFd, PidFd as SysPidFd};
+use crate::sys::{
+    self, PidFd as SysPidFd, Pipe as SysPipe, Poll as SysPoll, TimerFd as SysTimerFd,
+};
+
+use self::sys::PipeImpl;
 
 #[repr(transparent)]
 pub struct Poll(sys::PollImpl);
@@ -15,6 +20,9 @@ pub struct TimerFd(sys::TimerFdImpl);
 #[repr(transparent)]
 pub struct PidFd(sys::PidFdImpl);
 
+#[repr(transparent)]
+pub struct Pipe(sys::PipeImpl);
+
 impl Poll {
     pub fn new() -> io::Result<Self> {
         sys::PollImpl::new().map(Self)
@@ -74,3 +82,36 @@ impl AsRawFd for PidFd {
         self.0.as_raw_fd()
     }
 }
+
+impl Pipe {
+    pub fn new(read_nonblocking: bool, write_nonblocking: bool) -> io::Result<(Self, Self)> {
+        let (read, write) = PipeImpl::new(read_nonblocking, write_nonblocking)?;
+        Ok((Self(read), Self(write)))
+    }
+
+    pub fn to_child_stdio(&self) -> Stdio {
+        self.0.to_child_stdio()
+    }
+}
+
+impl Read for Pipe {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.read(buf)
+    }
+}
+
+impl Write for Pipe {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.0.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.0.flush()
+    }
+}
+
+impl AsRawFd for Pipe {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0.as_raw_fd()
+    }
+}

userspace/lib/cross/src/sys/mod.rs

@@ -9,8 +9,9 @@ mod unix;
 pub(crate) use unix::*;
 
 use std::{
-    io,
+    io::{self, Read, Write},
     os::fd::{AsRawFd, RawFd},
+    process::Stdio,
     time::Duration,
 };
 
@@ -31,3 +32,8 @@ pub(crate) trait PidFd: Sized + AsRawFd {
     fn new(pid: u32) -> io::Result<Self>;
     fn exit_status(&self) -> io::Result<i32>;
 }
+
+pub(crate) trait Pipe: Read + Write + AsRawFd + Sized {
+    fn new(read_nonblocking: bool, write_nonblocking: bool) -> io::Result<(Self, Self)>;
+    fn to_child_stdio(&self) -> Stdio;
+}

userspace/lib/cross/src/sys/unix/mod.rs

@@ -1,7 +1,9 @@
 pub mod poll;
 pub mod timer;
 pub mod pid;
+pub mod pipe;
 
 pub use poll::PollImpl;
 pub use timer::TimerFdImpl;
 pub use pid::PidFdImpl;
+pub use pipe::PipeImpl;

userspace/lib/cross/src/sys/unix/pid.rs

@@ -10,7 +10,7 @@ pub struct PidFdImpl {
 impl PidFd for PidFdImpl {
     fn new(pid: u32) -> io::Result<Self> {
         let pid = pid as i32;
-        let fd = unsafe { libc::pidfd_open(pid) };
+        let fd = unsafe { libc::syscall(libc::SYS_pidfd_open, pid, 0) } as i32;
         if fd < 0 {
             return Err(io::Error::last_os_error());
         }
@@ -19,7 +19,7 @@ impl PidFd for PidFdImpl {
     }
 
     fn exit_status(&self) -> io::Result<i32> {
-        let status = 0;
+        let mut status = 0;
         let res = unsafe { libc::waitpid(self.pid, &mut status, 0) };
         if res < 0 {
             return Err(io::Error::last_os_error());

userspace/lib/cross/src/sys/unix/pipe.rs

@@ -0,0 +1,47 @@
+use std::{io::{self, Read, Write}, os::fd::{AsRawFd, FromRawFd, OwnedFd, RawFd}};
+
+use crate::sys::Pipe;
+
+pub struct PipeImpl {
+    fd: OwnedFd,
+}
+
+impl Pipe for PipeImpl {
+    fn new(read_nonblocking: bool, write_nonblocking: bool) -> io::Result<(Self, Self)> {
+        let mut fds = [0; 2];
+        let res = unsafe { libc::pipe(fds.as_mut_ptr()) };
+        if res < 0 {
+            return Err(io::Error::last_os_error());
+        }
+        let read = unsafe { OwnedFd::from_raw_fd(fds[0]) };
+        let write = unsafe { OwnedFd::from_raw_fd(fds[1]) };
+
+        Ok((Self { fd: read }, Self { fd: write }))
+    }
+
+    fn to_child_stdio(&self) -> std::process::Stdio {
+        todo!()
+    }
+}
+
+impl Read for PipeImpl {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        todo!()
+    }
+}
+
+impl Write for PipeImpl {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        todo!()
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        todo!()
+    }
+}
+
+impl AsRawFd for PipeImpl {
+    fn as_raw_fd(&self) -> RawFd {
+        self.fd.as_raw_fd()
+    }
+}

userspace/lib/cross/src/sys/yggdrasil/mod.rs

@@ -1,7 +1,9 @@
 pub mod poll;
 pub mod timer;
 pub mod pid;
+pub mod pipe;
 
 pub use poll::PollImpl;
 pub use timer::TimerFdImpl;
 pub use pid::PidFdImpl;
+pub use pipe::PipeImpl;

userspace/lib/cross/src/sys/yggdrasil/pipe.rs

@@ -0,0 +1,50 @@
+use std::{
+    fs::File,
+    io::{self, Read, Write},
+    os::{
+        fd::{AsRawFd, FromRawFd, IntoRawFd, RawFd},
+        yggdrasil::io::pipe::create_pipe_pair,
+    },
+    process::Stdio,
+};
+
+use crate::sys::Pipe;
+
+pub struct PipeImpl {
+    file: File,
+}
+
+impl Pipe for PipeImpl {
+    fn new(read_nonblocking: bool, write_nonblocking: bool) -> io::Result<(Self, Self)> {
+        let (read, write) = create_pipe_pair(read_nonblocking, write_nonblocking)?;
+        let read = unsafe { File::from_raw_fd(read.into_raw_fd()) };
+        let write = unsafe { File::from_raw_fd(write.into_raw_fd()) };
+        Ok((Self { file: read }, Self { file: write }))
+    }
+
+    fn to_child_stdio(&self) -> Stdio {
+        unsafe { Stdio::from_raw_fd(self.as_raw_fd()) }
+    }
+}
+
+impl Write for PipeImpl {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.file.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.file.flush()
+    }
+}
+
+impl Read for PipeImpl {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.file.read(buf)
+    }
+}
+
+impl AsRawFd for PipeImpl {
+    fn as_raw_fd(&self) -> RawFd {
+        self.file.as_raw_fd()
+    }
+}

userspace/rsh/src/lib.rs

@@ -1,5 +1,5 @@
 #![cfg_attr(target_os = "yggdrasil", feature(yggdrasil_os))]
-#![feature(generic_const_exprs, portable_simd, if_let_guard)]
+#![feature(generic_const_exprs, portable_simd, if_let_guard, let_chains)]
 #![allow(incomplete_features)]
 
 pub mod socket;

userspace/rsh/src/main.rs

@@ -2,7 +2,7 @@
 #![feature(let_chains)]
 
 use std::{
-    io::{stdout, IsTerminal, Read, Write},
+    io::{stderr, stdout, IsTerminal, Read, Stderr, Write},
     ops::{Deref, DerefMut},
     os::fd::AsRawFd,
 };
@@ -11,11 +11,11 @@ use clap::Parser;
 use cross::io::Poll;
 use rsh::{
     crypt::{
-        client::{self, ClientSocket},
+        client::{self, ClientSocket, Message},
         config::{ClientConfig, SimpleClientKeyStore},
         signature::{SignEd25519, SignatureMethod},
     },
-    proto::ServerMessage,
+    proto::{ServerMessage, StreamIndex},
 };
 
 use std::{
@@ -70,8 +70,9 @@ enum Input {
 pub struct Client {
     poll: Poll,
     socket: ClientSocket,
-    input: Input,
+    stdin: RawStdin,
     stdout: Stdout,
+    stderr: Stderr,
     need_bye: bool,
     last0: u8,
     last1: u8,
@@ -124,30 +125,14 @@ impl Drop for RawStdin {
 }
 
 impl Client {
-    pub fn connect(
+    pub fn connect(remote: SocketAddr, crypto_config: ClientConfig) -> Result<Self, Error> {
-        remote: SocketAddr,
-        crypto_config: ClientConfig,
-        command: Vec<String>,
-    ) -> Result<Self, Error> {
         let mut poll = Poll::new()?;
         let mut socket = ClientSocket::connect(remote, crypto_config)?;
-        let input = match command.is_empty() {
-            true => {
         let stdin = RawStdin::open()?;
-                poll.add(&stdin)?;
-                Input::Stdin(stdin)
-            },
-            false => {
-                let mut bytes = vec![];
-                for command in command {
-                    bytes.extend_from_slice(command.as_bytes());
-                    bytes.push(b' ');
-                }
-                Input::Command(bytes)
-            },
-        };
         let stdout = stdout();
+        let stderr = stderr();
 
+        poll.add(&stdin)?;
         poll.add(&socket)?;
 
         let info = terminal_info(&stdout)?;
@@ -155,8 +140,9 @@ impl Client {
         Self::handshake(&mut socket, info)?;
 
         Ok(Self {
-            input,
+            stdin,
             stdout,
+            stderr,
             socket,
             poll,
             need_bye: false,
@@ -187,19 +173,20 @@ impl Client {
     pub fn run(mut self) -> Result<String, Error> {
         let mut recv_buf = [0; 512];
 
-        if let Input::Command(command) = &self.input {
-            self.socket.write_all(&ClientMessage::Input(&command[..]))?;
-        }
-
         loop {
             if let Some(message) = self.socket.read(&mut recv_buf)? {
                 match message {
                     ServerMessage::Bye(reason) => return Ok(reason.into()),
-                    ServerMessage::Output(data) => {
+                    ServerMessage::Output(StreamIndex::Stdout, data) => {
                         self.stdout.write_all(data).ok();
                         self.stdout.flush().ok();
                         continue;
                     }
+                    ServerMessage::Output(StreamIndex::Stderr, data) => {
+                        self.stderr.write_all(data).ok();
+                        self.stderr.flush().ok();
+                        continue;
+                    }
                     _ => continue,
                 }
             }
@@ -210,8 +197,8 @@ impl Client {
                 if self.socket.poll()? == 0 {
                     return Ok("".into());
                 }
-            } else if let Input::Stdin(stdin) = &mut self.input && stdin.as_raw_fd() == fd {
+            } else if self.stdin.as_raw_fd() == fd {
-                let len = stdin.read(&mut recv_buf)?;
+                let len = self.stdin.read(&mut recv_buf)?;
                 self.update_last(&recv_buf[..len])?;
                 self.socket
                     .write_all(&ClientMessage::Input(&recv_buf[..len]))?;
@@ -247,27 +234,101 @@ fn terminal_info(stdout: &Stdout) -> Result<TerminalInfo, Error> {
     })
 }
 
-fn run(args: Args) -> Result<(), Error> {
+fn run_terminal(remote: SocketAddr, config: ClientConfig) -> Result<(), Error> {
+    let reason = Client::connect(remote, config)?.run()?;
+    if !reason.is_empty() {
+        eprintln!("\nDisconnected: {reason}");
+    }
+    Ok(())
+}
+
+fn run_command(
+    remote: SocketAddr,
+    config: ClientConfig,
+    command: Vec<String>,
+) -> Result<ExitCode, Error> {
+    let mut poll = Poll::new()?;
+    let mut buffer = [0; 512];
+    let mut command_string = String::new();
+    for (i, word) in command.iter().enumerate() {
+        if i != 0 {
+            command_string.push(' ');
+        }
+        command_string.push_str(word);
+    }
+
+    let mut stdin = stdin();
+    let mut stdout = stdout();
+    let mut stderr = stderr();
+
+    let mut socket = ClientSocket::connect(remote, config)?;
+
+    poll.add(&socket)?;
+    poll.add(&stdin)?;
+
+    socket.write_all(&ClientMessage::RunCommand(command_string.as_str()))?;
+
+    loop {
+        let fd = poll.wait(None)?.unwrap();
+
+        match fd {
+            _ if fd == socket.as_raw_fd() => {
+                let message = match socket.poll_read(&mut buffer)? {
+                    Message::Data(data) => data,
+                    Message::Incomplete => continue,
+                    Message::Closed => break
+                };
+
+                match message {
+                    ServerMessage::Output(StreamIndex::Stdout, output) => {
+                        stdout.write_all(output).ok();
+                        stdout.flush().ok();
+                    }
+                    ServerMessage::Output(StreamIndex::Stderr, output) => {
+                        stderr.write_all(output).ok();
+                        stderr.flush().ok();
+                    }
+                    _ => todo!()
+                }
+            }
+            _ if fd == stdin.as_raw_fd() => {
+                let len = stdin.read(&mut buffer)?;
+                if len == 0 {
+                    poll.remove(&stdin)?;
+                    socket.write_all(&ClientMessage::CloseStdin)?;
+                } else {
+                    socket.write_all(&ClientMessage::Input(&buffer[..len]))?;
+                }
+            }
+            _ => unreachable!()
+        }
+
+    }
+
+    Ok(ExitCode::SUCCESS)
+}
+
+fn run(args: Args) -> Result<ExitCode, Error> {
     let remote = SocketAddr::new(args.remote, args.port);
     let ed25519 = SignEd25519::load_signing_key(args.key).unwrap();
     let key = SignatureMethod::Ed25519(ed25519);
     let config = ClientConfig::with_default_algorithms(SimpleClientKeyStore::new(key));
-    let reason = Client::connect(remote, config, args.command)?.run()?;
+    if args.command.is_empty() {
-    if !reason.is_empty() {
+        run_terminal(remote, config).map(|_| ExitCode::SUCCESS)
-        eprintln!("\nDisconnected: {reason}");
+    } else {
+        run_command(remote, config, args.command)
     }
-
-    Ok(())
 }
 
 fn main() -> ExitCode {
     env_logger::init();
     let args = Args::parse();
 
-    if let Err(error) = run(args) {
+    match run(args) {
+        Ok(status) => status,
+        Err(error) => {
             eprintln!("Error: {error}");
             ExitCode::FAILURE
-    } else {
+        }
-        ExitCode::SUCCESS
     }
 }

userspace/rsh/src/proto.rs

@@ -13,6 +13,13 @@ pub enum ClientMessage<'a> {
     RunCommand(&'a str),
     Bye(&'a str),
     Input(&'a [u8]),
+    CloseStdin,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum StreamIndex {
+    Stdout,
+    Stderr,
 }
 
 #[derive(Debug)]
@@ -20,7 +27,7 @@ pub enum ServerMessage<'a> {
     SessionOpen,
     CommandStatus(i32),
     Bye(&'a str),
-    Output(&'a [u8]),
+    Output(StreamIndex, &'a [u8]),
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -164,6 +171,32 @@ impl ClientMessage<'_> {
     const TAG_RUN_COMMAND: u8 = 0x81;
     const TAG_BYE: u8 = 0x82;
     const TAG_INPUT: u8 = 0x90;
+    const TAG_CLOSE_STDIN: u8 = 0x91;
+}
+
+impl StreamIndex {
+    const TAG_STDOUT: u8 = 0x01;
+    const TAG_STDERR: u8 = 0x02;
+}
+
+impl Encode for StreamIndex {
+    fn encode(&self, buffer: &mut Encoder) -> Result<(), EncodeError> {
+        match self {
+            Self::Stdout => buffer.write(&[Self::TAG_STDOUT]),
+            Self::Stderr => buffer.write(&[Self::TAG_STDERR]),
+        }
+    }
+}
+
+impl<'de> Decode<'de> for StreamIndex {
+    fn decode(buffer: &mut Decoder<'de>) -> Result<Self, DecodeError> {
+        let tag = buffer.read_u8()?;
+        match tag {
+            Self::TAG_STDOUT => Ok(Self::Stdout),
+            Self::TAG_STDERR => Ok(Self::Stderr),
+            _ => Err(DecodeError::InvalidMessage)
+        }
+    }
 }
 
 impl Encode for TerminalInfo {
@@ -201,6 +234,7 @@ impl<'a> Encode for ClientMessage<'a> {
                 buffer.write(&[Self::TAG_INPUT])?;
                 buffer.write_variable_bytes(data)
             }
+            Self::CloseStdin => buffer.write(&[Self::TAG_CLOSE_STDIN])
         }
     }
 }
@@ -221,6 +255,9 @@ impl<'de> Decode<'de> for ClientMessage<'de> {
             Self::TAG_INPUT => {
                 buffer.read_variable_bytes().map(Self::Input)
             }
+            Self::TAG_CLOSE_STDIN => {
+                Ok(Self::CloseStdin)
+            }
             _ => Err(DecodeError::InvalidMessage)
         }
     }
@@ -244,8 +281,9 @@ impl<'a> Encode for ServerMessage<'a> {
                 buffer.write(&[Self::TAG_BYE])?;
                 buffer.write_str(reason)
             }
-            Self::Output(data) => {
+            Self::Output(index, data) => {
                 buffer.write(&[Self::TAG_OUTPUT])?;
+                index.encode(buffer)?;
                 buffer.write_variable_bytes(data)
             }
         }
@@ -267,7 +305,9 @@ impl<'de> Decode<'de> for ServerMessage<'de> {
                 buffer.read_str().map(Self::Bye)
             }
             Self::TAG_OUTPUT => {
-                buffer.read_variable_bytes().map(Self::Output)
+                let index = StreamIndex::decode(buffer)?;
+                let data = buffer.read_variable_bytes()?;
+                Ok(Self::Output(index, data))
             },
             _ => Err(DecodeError::InvalidMessage),
         }

userspace/rsh/src/server.rs

@@ -1,12 +1,15 @@
 use std::{
     collections::{hash_map::Entry, HashMap},
-    fmt, io,
+    fmt,
+    hint::unreachable_unchecked,
+    io::{self, Read, Stdout, Write},
     net::SocketAddr,
     os::fd::{AsRawFd, RawFd},
+    process::{Child, Command, Stdio},
     time::Duration,
 };
 
-use cross::io::Poll;
+use cross::io::{PidFd, Pipe, Poll};
 
 use crate::{
     crypt::{
@@ -14,7 +17,7 @@ use crate::{
         config::ServerConfig,
         server::{self, ServerSocket},
     },
-    proto::{ClientMessage, ServerMessage, TerminalInfo},
+    proto::{ClientMessage, ServerMessage, StreamIndex, TerminalInfo},
 };
 
 pub const PING_INTERVAL: Duration = Duration::from_millis(500);
@@ -52,22 +55,28 @@ pub struct EchoSession {
     peer: SocketAddr,
 }
 
-struct ClientSession<T: Session> {
+struct PendingCommand {
-    stream: ClientSocket,
+    child: Child,
-    session: Option<T>,
+    child_pid: Option<PidFd>,
+    stdin: Option<Pipe>,
+    stdout: Option<Pipe>,
+    stderr: Option<Pipe>,
 }
 
-// enum Event<'b, T: Session> {
+enum ClientSession<T: Session> {
-//     NewSession(SocketAddr, TerminalInfo),
+    None,
-//     SessionInput(u64, SocketAddr, &'b [u8]),
+    Terminal(T),
-//     ClientBye(SocketAddr, &'b str),
+    Command(PendingCommand),
-//     SessionEvent(RawFd, SocketAddr, SessionEvent<'b, T>),
+}
-//     Tick,
-// }
 
-struct SessionSet<T: Session> {
+struct Client<T: Session> {
+    stream: ClientSocket,
+    session: ClientSession<T>,
+}
+
+struct ClientSet<T: Session> {
     last_session_key: u64,
-    sessions: HashMap<u64, ClientSession<T>>,
+    clients: HashMap<u64, Client<T>>,
     socket_fd_map: HashMap<RawFd, u64>,
     session_fd_map: HashMap<RawFd, u64>,
 }
@@ -76,29 +85,63 @@ pub struct Server<T: Session> {
     poll: Poll,
     socket: ServerSocket,
 
-    sessions: SessionSet<T>,
+    clients: ClientSet<T>,
 }
 
-impl<T: Session> SessionSet<T> {
+enum CommandEvent {
+    Output(StreamIndex, Result<usize, io::Error>),
+    Exited(Result<i32, io::Error>)
+}
+
+impl<T: Session> Client<T> {
+    fn make_command(text: &str) -> Result<PendingCommand, Error> {
+        let mut words = text.split(' ');
+        let program = words.next().unwrap();
+        let mut command = Command::new(program);
+
+        let (stdin_read, stdin_write) = Pipe::new(false, false)?;
+        let (stdout_read, stdout_write) = Pipe::new(true, false)?;
+        let (stderr_read, stderr_write) = Pipe::new(true, false)?;
+
+        command
+            .args(words)
+            .stdin(stdin_read.to_child_stdio())
+            .stdout(stdout_write.to_child_stdio())
+            .stderr(stderr_write.to_child_stdio());
+
+        let child = command.spawn()?;
+        let child_pid = PidFd::new(child.id())?;
+
+        Ok(PendingCommand {
+            child,
+            child_pid: Some(child_pid),
+            stdout: Some(stdout_read),
+            stderr: Some(stderr_read),
+            stdin: Some(stdin_write),
+        })
+    }
+}
+
+impl<T: Session> ClientSet<T> {
     pub fn new() -> Self {
         Self {
             last_session_key: 1,
-            sessions: HashMap::new(),
+            clients: HashMap::new(),
             socket_fd_map: HashMap::new(),
             session_fd_map: HashMap::new(),
         }
     }
 
     pub fn add_client(&mut self, stream: ClientSocket, poll: &mut Poll) -> Result<(), Error> {
-        let (key, session) = loop {
+        let (key, client) = loop {
             let key = self.last_session_key;
             self.last_session_key += 1;
 
-            match self.sessions.entry(key) {
+            match self.clients.entry(key) {
                 Entry::Vacant(entry) => {
-                    let session = entry.insert(ClientSession {
+                    let session = entry.insert(Client {
                         stream,
-                        session: None,
+                        session: ClientSession::None,
                     });
                     break (key, session);
                 }
@@ -106,23 +149,40 @@ impl<T: Session> SessionSet<T> {
             }
         };
 
-        poll.add(&session.stream)?;
+        poll.add(&client.stream)?;
-        self.socket_fd_map.insert(session.stream.as_raw_fd(), key);
+        self.socket_fd_map.insert(client.stream.as_raw_fd(), key);
 
         Ok(())
     }
 
     fn remove(&mut self, key: u64, poll: &mut Poll) -> Result<(), Error> {
-        if let Some(session) = self.sessions.remove(&key) {
+        if let Some(client) = self.clients.remove(&key) {
-            poll.remove(&session.stream)?;
+            poll.remove(&client.stream)?;
-            self.socket_fd_map.remove(&session.stream.as_raw_fd());
+            self.socket_fd_map.remove(&client.stream.as_raw_fd());
 
-            if let Some(session) = session.session {
+            match client.session {
-                for fd in session.event_fds() {
+                ClientSession::Terminal(terminal) => {
+                    for fd in terminal.event_fds() {
                         poll.remove(fd)?;
                         self.session_fd_map.remove(fd);
                     }
                 }
+                ClientSession::Command(mut command) => {
+                    if let Some(stdout) = command.stdout.take() {
+                        poll.remove(&stdout)?;
+                        self.session_fd_map.remove(&stdout.as_raw_fd());
+                    }
+                    if let Some(stderr) = command.stderr.take() {
+                        poll.remove(&stderr)?;
+                        self.session_fd_map.remove(&stderr.as_raw_fd());
+                    }
+                    if let Some(child_pid) = command.child_pid.take() {
+                        poll.remove(&child_pid)?;
+                        self.session_fd_map.remove(&child_pid.as_raw_fd());
+                    }
+                }
+                ClientSession::None => (),
+            }
         }
         Ok(())
     }
@@ -131,10 +191,10 @@ impl<T: Session> SessionSet<T> {
         let mut buffer = [0; 512];
 
         if let Some(&key) = self.socket_fd_map.get(&fd) {
-            let session = self.sessions.get_mut(&key).unwrap();
+            let client = self.clients.get_mut(&key).unwrap();
-            let peer = session.stream.remote_address();
+            let peer = client.stream.remote_address();
 
-            let mut closed = match session.stream.poll() {
+            let mut closed = match client.stream.poll() {
                 Ok(0) => true,
                 Ok(_) => false,
                 Err(error) => {
@@ -144,7 +204,7 @@ impl<T: Session> SessionSet<T> {
             };
 
             loop {
-                let message = match session.stream.read(&mut buffer) {
+                let message = match client.stream.read(&mut buffer) {
                     Ok(Some(message)) => message,
                     Ok(None) => break,
                     Err(error) => {
@@ -154,8 +214,33 @@ impl<T: Session> SessionSet<T> {
                     }
                 };
 
-                match (&message, &mut session.session) {
+                match (&message, &mut client.session) {
-                    (ClientMessage::OpenSession(terminal), None) => {
+                    (ClientMessage::RunCommand(command), ClientSession::None) => {
+                        log::info!("{peer}: cmd {command:?}");
+
+                        let command = match Client::<T>::make_command(command) {
+                            Ok(command) => command,
+                            Err(error) => {
+                                log::error!("{peer}: command error: {error}");
+                                return self.remove(key, poll);
+                            }
+                        };
+
+                        let stdout_fd = command.stdout.as_ref().unwrap().as_raw_fd();
+                        let stderr_fd = command.stderr.as_ref().unwrap().as_raw_fd();
+                        let child_pid_fd = command.child_pid.as_ref().unwrap().as_raw_fd();
+
+                        poll.add(&stdout_fd)?;
+                        poll.add(&stderr_fd)?;
+                        poll.add(&child_pid_fd)?;
+
+                        self.session_fd_map.insert(stdout_fd, key);
+                        self.session_fd_map.insert(stderr_fd, key);
+                        self.session_fd_map.insert(child_pid_fd, key);
+
+                        client.session = ClientSession::Command(command);
+                    }
+                    (ClientMessage::OpenSession(terminal), ClientSession::None) => {
                         log::info!("{peer}: new session");
                         let terminal = match T::open(&peer, &terminal) {
                             Ok(session) => session,
@@ -165,15 +250,33 @@ impl<T: Session> SessionSet<T> {
                                 return Ok(());
                             }
                         };
-                        let terminal = session.session.insert(terminal);
+                        let terminal = client.session.set_terminal(terminal);
                         for fd in terminal.event_fds() {
                             poll.add(fd)?;
                             self.session_fd_map.insert(*fd, key);
                         }
-                        session.stream.write_all(&ServerMessage::SessionOpen).ok();
+
+                        client.stream.write_all(&ServerMessage::SessionOpen).ok();
                     }
-                    (ClientMessage::Input(data), Some(terminal)) => {
+                    (ClientMessage::Input(data), ClientSession::Command(command)) => {
-                        let client = SessionClient { transport: &mut session.stream };
+                        if let Some(stdin) = command.stdin.as_mut() {
+                            match stdin.write_all(data) {
+                                Ok(()) => {
+                                    stdin.flush().ok();
+                                },
+                                Err(error) => {
+                                    log::error!("{peer}: stdin error: {error}");
+                                    return self.remove(key, poll);
+                                }
+                            }
+                        } else {
+                            log::warn!("{peer}: stdin already closed");
+                        }
+                    }
+                    (ClientMessage::Input(data), ClientSession::Terminal(terminal)) => {
+                        let client = SessionClient {
+                            transport: &mut client.stream,
+                        };
                         match terminal.handle_input(data, client) {
                             Ok(false) => (),
                             Ok(true) => {
@@ -186,6 +289,10 @@ impl<T: Session> SessionSet<T> {
                             }
                         }
                     }
+                    (ClientMessage::CloseStdin, ClientSession::Command(command)) => {
+                        // Drop stdin handle
+                        command.stdin.take();
+                    }
                     _ => {
                         log::warn!("{peer}: unhandled message");
                     }
@@ -199,25 +306,89 @@ impl<T: Session> SessionSet<T> {
 
             Ok(())
         } else if let Some(&key) = self.session_fd_map.get(&fd) {
-            let session = self.sessions.get_mut(&key).unwrap();
+            log::debug!("poll fd {:?}", fd);
-            let terminal = session.session.as_mut().unwrap();
+            let client = self.clients.get_mut(&key).unwrap();
-            let peer = session.stream.remote_address();
+            let peer = client.stream.remote_address();
 
-            match terminal.read_output(fd, &mut buffer) {
+            let (mut len, stream_index) = match &mut client.session {
-                Ok(0) => {
+                ClientSession::Command(command) => match command.read_output(fd, &mut buffer) {
-                    log::info!("{peer}: session closed");
+                    CommandEvent::Output(index, Ok(len)) => {
-                    self.remove(key, poll)
+                        if len == 0 {
+                            poll.remove(&fd)?;
+                            self.socket_fd_map.remove(&fd);
+
+                            match index {
+                                StreamIndex::Stdout => {
+                                    command.stdout = None;
                                 }
-                Ok(mut len) => {
+                                StreamIndex::Stderr => {
+                                    command.stderr = None;
+                                }
+                            }
+
+                            if command.is_dead() {
+                                log::info!("{peer}: command stdout/stderr closed");
+                                return self.remove(key, poll);
+                            }
+                        }
+                        (len, index)
+                    },
+                    CommandEvent::Output(index, Err(error)) => {
+                        if error.kind() == io::ErrorKind::WouldBlock {
+                            return Ok(());
+                        }
+                        log::error!("{peer}: {index:?} error: {error}");
+                        return self.remove(key, poll);
+                    }
+                    CommandEvent::Exited(status) => {
+                        log::info!("{peer}: command exited: {:?}", status);
+                        poll.remove(&fd)?;
+                        self.socket_fd_map.remove(&fd);
+                        command.child_pid = None;
+
+                        if command.is_dead() {
+                            log::info!("{peer}: command stdout/stderr closed");
+                            return self.remove(key, poll);
+                        }
+
+                        return Ok(());
+                    }
+                },
+                ClientSession::Terminal(terminal) => match terminal.read_output(fd, &mut buffer) {
+                    Ok(0) => {
+                        poll.remove(&fd)?;
+                        self.socket_fd_map.remove(&fd);
+
+                        // TODO check for process as well
+                        log::info!("{peer}: terminal closed");
+                        return self.remove(key, poll);
+                    }
+                    Ok(len) => {
+                        (len, StreamIndex::Stdout)
+                    },
+                    Err(error) => {
+                        log::error!("{peer}: terminal error: {error}");
+                        return self.remove(key, poll);
+                    }
+                },
+                ClientSession::None => unreachable!(),
+            };
+
+            if len == 0 {
+                log::info!("{peer}: {stream_index:?} closed");
+                return Ok(());
+                // return self.remove(key, poll);
+            }
+
             // Split output into 128-byte chunks
             let mut pos = 0;
             while len != 0 {
                 let amount = core::cmp::min(len, 128);
 
-                        if let Err(error) = session
+                if let Err(error) = client.stream.write_all(&ServerMessage::Output(
-                            .stream
+                    stream_index,
-                            .write_all(&ServerMessage::Output(&buffer[pos..pos + amount]))
+                    &buffer[pos..pos + amount],
-                        {
+                )) {
                     log::error!("{peer}: communication error: {error}");
                     return self.remove(key, poll);
                 }
@@ -225,19 +396,58 @@ impl<T: Session> SessionSet<T> {
                 pos += amount;
                 len -= amount;
             }
+
+            log::debug!("Done");
             Ok(())
-                }
-                Err(error) => {
-                    log::error!("{peer}: session read error: {error}");
-                    self.remove(key, poll)
-                }
-            }
         } else {
             unreachable!()
         }
     }
 }
 
+impl PendingCommand {
+    pub fn read_output(
+        &mut self,
+        fd: RawFd,
+        buffer: &mut [u8],
+    ) -> CommandEvent {
+        if let Some(stdout) = self.stdout.as_mut() && fd == stdout.as_raw_fd() {
+            log::debug!("poll stdout");
+            let res = stdout.read(buffer);
+            log::debug!(">> {:?}", res);
+            return CommandEvent::Output(StreamIndex::Stdout, res);
+        }
+        if let Some(stderr) = self.stderr.as_mut() && fd == stderr.as_raw_fd() {
+            return CommandEvent::Output(StreamIndex::Stderr, stderr.read(buffer));
+        }
+        if let Some(child_pid) = self.child_pid.as_mut() && fd == child_pid.as_raw_fd() {
+            let status = child_pid.exit_status();
+            return CommandEvent::Exited(status);
+        }
+        unreachable!()
+    }
+
+    pub fn is_dead(&self) -> bool {
+        self.child_pid.is_none() && self.stdout.is_none() && self.stderr.is_none()
+    }
+}
+
+impl Drop for PendingCommand {
+    fn drop(&mut self) {
+        self.child.wait().ok();
+    }
+}
+
+impl<T: Session> ClientSession<T> {
+    pub fn set_terminal(&mut self, terminal: T) -> &mut T {
+        *self = Self::Terminal(terminal);
+        match self {
+            Self::Terminal(terminal) => terminal,
+            _ => unsafe { unreachable_unchecked() },
+        }
+    }
+}
+
 impl<T: Session> Server<T> {
     pub fn listen(listen_addr: SocketAddr, crypto_config: ServerConfig) -> Result<Self, Error> {
         let mut poll = Poll::new()?;
@@ -246,7 +456,7 @@ impl<T: Session> Server<T> {
         Ok(Self {
             poll,
             socket,
-            sessions: SessionSet::new(),
+            clients: ClientSet::new(),
         })
     }
 
@@ -259,14 +469,14 @@ impl<T: Session> Server<T> {
                     // Poll server socket
                     match self.socket.poll()? {
                         Some(client) => {
-                            self.sessions.add_client(client, &mut self.poll)?;
+                            self.clients.add_client(client, &mut self.poll)?;
                         }
                         None => continue,
                     }
                 }
                 _ => {
                     // Client/Session-related activity
-                    self.sessions.handle_input(fd, &mut self.poll)?;
+                    self.clients.handle_input(fd, &mut self.poll)?;
                 }
             }
         }
@@ -275,7 +485,7 @@ impl<T: Session> Server<T> {
 
 impl<'s> SessionClient<'s> {
     pub fn send_data(&mut self, data: &[u8]) -> Result<(), Error> {
-        self.send_message(&ServerMessage::Output(data))
+        self.send_message(&ServerMessage::Output(StreamIndex::Stdout, data))
     }
 
     pub fn send_message(&mut self, message: &ServerMessage) -> Result<(), Error> {

userspace/shell/src/sys/yggdrasil.rs

@@ -74,7 +74,7 @@ pub fn wait_for_pipeline(
 }
 
 pub fn create_pipe() -> Result<Pipe, io::Error> {
-    let (read, write) = pipe::create_pipe_pair()?;
+    let (read, write) = pipe::create_pipe_pair(false, false)?;
     Ok(Pipe { read, write })
 }