Files
codex/codex-rs/utils/pty
Free Wortley df3ecee6f0 Launch Linux pipe processes through a fresh setup helper (#47612)
## Why

Linux pipe launches need session, parent-death signal, and descriptor setup. Move this work into a fresh, single-threaded executable image to avoid forking the app-server for child setup.

## What changed

- Register an early setup helper and launch it through `posix_spawn` for Linux pipe processes.
- Start the helper with an empty environment, then transfer the target environment over a control socket so loader settings cannot interfere with helper startup.
- Await target execution asynchronously, propagate setup and execution errors, and kill incomplete launches on cancellation.
- Preserve direct spawning as a fallback when the helper is unavailable or fails before target execution.

## Testing

Add coverage for launch semantics, avoiding fork, loader environment isolation, early argument dispatch, closed standard descriptors, and fallback under bootstrap failure or descriptor pressure. Add an app-server regression test that reuses a process handle after an execution failure.

GitOrigin-RevId: 079c673f0f22ebd531f8c57e5338095cc98acfdc
2026-09-23 18:25:07 +00:00
..

codex-utils-pty

Lightweight helpers for spawning interactive processes either under a PTY (pseudo terminal) or regular pipes. The public API is minimal and mirrors both backends so callers can switch based on their needs (e.g., enabling or disabling TTY).

API surface

  • spawn_pty_process(program, args, cwd, env, arg0, size) → SpawnedProcess
  • spawn_pipe_process(program, args, cwd, env, arg0) → SpawnedProcess
  • spawn_pipe_process_no_stdin(program, args, cwd, env, arg0) → SpawnedProcess
  • combine_output_receivers(stdout_rx, stderr_rx) → broadcast::Receiver<Vec<u8>>
  • conpty_supported() → bool (Windows only; always true elsewhere)
  • TerminalSize { rows, cols } selects PTY dimensions in character cells.
  • ProcessHandle exposes:
    • writer_sender() → mpsc::Sender<Vec<u8>> (stdin)
    • resize(TerminalSize)
    • close_stdin()
    • has_exited(), exit_code(), terminate()
  • SpawnedProcess bundles session, stdout_rx, stderr_rx, and exit_rx (oneshot exit code).

Usage examples

use std::collections::HashMap;
use std::path::Path;
use codex_utils_pty::combine_output_receivers;
use codex_utils_pty::spawn_pty_process;
use codex_utils_pty::TerminalSize;

# tokio_test::block_on(async {
let env_map: HashMap<String, String> = std::env::vars().collect();
let spawned = spawn_pty_process(
    "bash",
    &["-lc".into(), "echo hello".into()],
    Path::new("."),
    &env_map,
    &None,
    TerminalSize::default(),
).await?;

let writer = spawned.session.writer_sender();
writer.send(b"exit\n".to_vec()).await?;

// Collect output until the process exits.
let mut output_rx = combine_output_receivers(spawned.stdout_rx, spawned.stderr_rx);
let mut collected = Vec::new();
while let Ok(chunk) = output_rx.try_recv() {
    collected.extend_from_slice(&chunk);
}
let exit_code = spawned.exit_rx.await.unwrap_or(-1);
# let _ = (collected, exit_code);
# anyhow::Ok(())
# });

Swap in spawn_pipe_process for a non-TTY subprocess; the rest of the API stays the same. Use spawn_pipe_process_no_stdin to force stdin closed (commands that read stdin will see EOF immediately).

Tests

Unit tests live in src/lib.rs and cover both backends (PTY Python REPL and pipe-based stdin roundtrip). Run with:

just test -p codex-utils-pty --no-capture