denoland-deno/runtime/ops/process.rs

// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.

use deno_core::anyhow::Context;
use deno_core::error::type_error;
use deno_core::error::AnyError;
use deno_core::op2;
use deno_core::serde_json;
use deno_core::AsyncMutFuture;
use deno_core::AsyncRefCell;
use deno_core::OpState;
use deno_core::RcRef;
use deno_core::Resource;
use deno_core::ResourceId;
use deno_core::ToJsBuffer;
use deno_io::fs::FileResource;
use deno_io::ChildStderrResource;
use deno_io::ChildStdinResource;
use deno_io::ChildStdoutResource;
use deno_permissions::PermissionsContainer;
use serde::Deserialize;
use serde::Serialize;
use std::borrow::Cow;
use std::cell::RefCell;
use std::collections::HashMap;
use std::path::Path;
use std::path::PathBuf;
use std::process::ExitStatus;
use std::rc::Rc;
use tokio::process::Command;

#[cfg(windows)]
use std::os::windows::process::CommandExt;

#[cfg(unix)]
use std::os::unix::prelude::ExitStatusExt;
#[cfg(unix)]
use std::os::unix::process::CommandExt;

pub const UNSTABLE_FEATURE_NAME: &str = "process";

#[derive(Copy, Clone, Eq, PartialEq, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum Stdio {
  Inherit,
  Piped,
  Null,
  IpcForInternalUse,
}

impl Stdio {
  pub fn as_stdio(&self) -> std::process::Stdio {
    match &self {
      Stdio::Inherit => std::process::Stdio::inherit(),
      Stdio::Piped => std::process::Stdio::piped(),
      Stdio::Null => std::process::Stdio::null(),
      _ => unreachable!(),
    }
  }
}

#[derive(Copy, Clone, Eq, PartialEq)]
pub enum StdioOrRid {
  Stdio(Stdio),
  Rid(ResourceId),
}

impl<'de> Deserialize<'de> for StdioOrRid {
  fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
  where
    D: serde::Deserializer<'de>,
  {
    use serde_json::Value;
    let value = Value::deserialize(deserializer)?;
    match value {
      Value::String(val) => match val.as_str() {
        "inherit" => Ok(StdioOrRid::Stdio(Stdio::Inherit)),
        "piped" => Ok(StdioOrRid::Stdio(Stdio::Piped)),
        "null" => Ok(StdioOrRid::Stdio(Stdio::Null)),
        "ipc_for_internal_use" => {
          Ok(StdioOrRid::Stdio(Stdio::IpcForInternalUse))
        }
        val => Err(serde::de::Error::unknown_variant(
          val,
          &["inherit", "piped", "null"],
        )),
      },
      Value::Number(val) => match val.as_u64() {
        Some(val) if val <= ResourceId::MAX as u64 => {
          Ok(StdioOrRid::Rid(val as ResourceId))
        }
        _ => Err(serde::de::Error::custom("Expected a positive integer")),
      },
      _ => Err(serde::de::Error::custom(
        r#"Expected a resource id, "inherit", "piped", or "null""#,
      )),
    }
  }
}

impl StdioOrRid {
  pub fn as_stdio(
    &self,
    state: &mut OpState,
  ) -> Result<std::process::Stdio, AnyError> {
    match &self {
      StdioOrRid::Stdio(val) => Ok(val.as_stdio()),
      StdioOrRid::Rid(rid) => {
        FileResource::with_file(state, *rid, |file| Ok(file.as_stdio()?))
      }
    }
  }

  pub fn is_ipc(&self) -> bool {
    matches!(self, StdioOrRid::Stdio(Stdio::IpcForInternalUse))
  }
}

deno_core::extension!(
  deno_process,
  ops = [
    op_spawn_child,
    op_spawn_wait,
    op_spawn_sync,
    op_spawn_kill,
    deprecated::op_run,
    deprecated::op_run_status,
    deprecated::op_kill,
  ],
);

/// Second member stores the pid separately from the RefCell. It's needed for
/// `op_spawn_kill`, where the RefCell is borrowed mutably by `op_spawn_wait`.
struct ChildResource(RefCell<tokio::process::Child>, u32);

impl Resource for ChildResource {
  fn name(&self) -> Cow<str> {
    "child".into()
  }
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SpawnArgs {
  cmd: String,
  args: Vec<String>,
  cwd: Option<String>,
  clear_env: bool,
  env: Vec<(String, String)>,
  #[cfg(unix)]
  gid: Option<u32>,
  #[cfg(unix)]
  uid: Option<u32>,
  #[cfg(windows)]
  windows_raw_arguments: bool,
  ipc: Option<i32>,

  #[serde(flatten)]
  stdio: ChildStdio,

  extra_stdio: Vec<Stdio>,
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ChildStdio {
  stdin: StdioOrRid,
  stdout: StdioOrRid,
  stderr: StdioOrRid,
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct ChildStatus {
  success: bool,
  code: i32,
  signal: Option<String>,
}

impl TryFrom<ExitStatus> for ChildStatus {
  type Error = AnyError;

  fn try_from(status: ExitStatus) -> Result<Self, Self::Error> {
    let code = status.code();
    #[cfg(unix)]
    let signal = status.signal();
    #[cfg(not(unix))]
    let signal: Option<i32> = None;

    let status = if let Some(signal) = signal {
      ChildStatus {
        success: false,
        code: 128 + signal,
        #[cfg(unix)]
        signal: Some(
          crate::ops::signal::signal_int_to_str(signal)?.to_string(),
        ),
        #[cfg(not(unix))]
        signal: None,
      }
    } else {
      let code = code.expect("Should have either an exit code or a signal.");

      ChildStatus {
        success: code == 0,
        code,
        signal: None,
      }
    };

    Ok(status)
  }
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
pub struct SpawnOutput {
  status: ChildStatus,
  stdout: Option<ToJsBuffer>,
  stderr: Option<ToJsBuffer>,
}

type CreateCommand = (
  std::process::Command,
  Option<ResourceId>,
  Vec<Option<ResourceId>>,
  Vec<deno_io::RawBiPipeHandle>,
);

fn create_command(
  state: &mut OpState,
  mut args: SpawnArgs,
  api_name: &str,
) -> Result<CreateCommand, AnyError> {
  let (cmd, run_env) = compute_run_cmd_and_check_permissions(
    &args.cmd,
    args.cwd.as_deref(),
    &args.env,
    args.clear_env,
    state,
    api_name,
  )?;
  let mut command = std::process::Command::new(cmd);

  #[cfg(windows)]
  if args.windows_raw_arguments {
    for arg in args.args.iter() {
      command.raw_arg(arg);
    }
  } else {
    command.args(args.args);
  }

  #[cfg(not(windows))]
  command.args(args.args);

  command.current_dir(run_env.cwd);
  command.env_clear();
  command.envs(run_env.envs);

  #[cfg(unix)]
  if let Some(gid) = args.gid {
    command.gid(gid);
  }
  #[cfg(unix)]
  if let Some(uid) = args.uid {
    command.uid(uid);
  }

  if args.stdio.stdin.is_ipc() {
    args.ipc = Some(0);
  } else {
    command.stdin(args.stdio.stdin.as_stdio(state)?);
  }

  command.stdout(match args.stdio.stdout {
    StdioOrRid::Stdio(Stdio::Inherit) => StdioOrRid::Rid(1).as_stdio(state)?,
    value => value.as_stdio(state)?,
  });
  command.stderr(match args.stdio.stderr {
    StdioOrRid::Stdio(Stdio::Inherit) => StdioOrRid::Rid(2).as_stdio(state)?,
    value => value.as_stdio(state)?,
  });

  #[cfg(unix)]
  // TODO(bartlomieju):
  #[allow(clippy::undocumented_unsafe_blocks)]
  unsafe {
    let mut extra_pipe_rids = Vec::new();
    let mut fds_to_dup = Vec::new();
    let mut fds_to_close = Vec::new();
    let mut ipc_rid = None;
    if let Some(ipc) = args.ipc {
      if ipc >= 0 {
        let (ipc_fd1, ipc_fd2) = deno_io::bi_pipe_pair_raw()?;
        fds_to_dup.push((ipc_fd2, ipc));
        fds_to_close.push(ipc_fd2);
        /* One end returned to parent process (this) */
        let pipe_rid =
          state
            .resource_table
            .add(deno_node::IpcJsonStreamResource::new(
              ipc_fd1 as _,
              deno_node::IpcRefTracker::new(state.external_ops_tracker.clone()),
            )?);
        /* The other end passed to child process via NODE_CHANNEL_FD */
        command.env("NODE_CHANNEL_FD", format!("{}", ipc));
        ipc_rid = Some(pipe_rid);
      }
    }

    for (i, stdio) in args.extra_stdio.into_iter().enumerate() {
      // index 0 in `extra_stdio` actually refers to fd 3
      // because we handle stdin,stdout,stderr specially
      let fd = (i + 3) as i32;
      // TODO(nathanwhit): handle inherited, but this relies on the parent process having
      // fds open already. since we don't generally support dealing with raw fds,
      // we can't properly support this
      if matches!(stdio, Stdio::Piped) {
        let (fd1, fd2) = deno_io::bi_pipe_pair_raw()?;
        fds_to_dup.push((fd2, fd));
        fds_to_close.push(fd2);
        let rid = state.resource_table.add(
          match deno_io::BiPipeResource::from_raw_handle(fd1) {
            Ok(v) => v,
            Err(e) => {
              log::warn!("Failed to open bidirectional pipe for fd {fd}: {e}");
              extra_pipe_rids.push(None);
              continue;
            }
          },
        );
        extra_pipe_rids.push(Some(rid));
      } else {
        extra_pipe_rids.push(None);
      }
    }

    command.pre_exec(move || {
      for &(src, dst) in &fds_to_dup {
        if src >= 0 && dst >= 0 {
          let _fd = libc::dup2(src, dst);
          libc::close(src);
        }
      }
      libc::setgroups(0, std::ptr::null());
      Ok(())
    });

    Ok((command, ipc_rid, extra_pipe_rids, fds_to_close))
  }

  #[cfg(windows)]
  {
    let mut ipc_rid = None;
    let mut handles_to_close = Vec::with_capacity(1);
    if let Some(ipc) = args.ipc {
      if ipc >= 0 {
        let (hd1, hd2) = deno_io::bi_pipe_pair_raw()?;

        /* One end returned to parent process (this) */
        let pipe_rid = Some(state.resource_table.add(
          deno_node::IpcJsonStreamResource::new(
            hd1 as i64,
            deno_node::IpcRefTracker::new(state.external_ops_tracker.clone()),
          )?,
        ));

        /* The other end passed to child process via NODE_CHANNEL_FD */
        command.env("NODE_CHANNEL_FD", format!("{}", hd2 as i64));

        handles_to_close.push(hd2);

        ipc_rid = pipe_rid;
      }
    }

    if args.extra_stdio.iter().any(|s| matches!(s, Stdio::Piped)) {
      log::warn!(
        "Additional stdio pipes beyond stdin/stdout/stderr are not currently supported on windows"
      );
    }

    Ok((command, ipc_rid, vec![], handles_to_close))
  }
}

#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
struct Child {
  rid: ResourceId,
  pid: u32,
  stdin_rid: Option<ResourceId>,
  stdout_rid: Option<ResourceId>,
  stderr_rid: Option<ResourceId>,
  ipc_pipe_rid: Option<ResourceId>,
  extra_pipe_rids: Vec<Option<ResourceId>>,
}

fn spawn_child(
  state: &mut OpState,
  command: std::process::Command,
  ipc_pipe_rid: Option<ResourceId>,
  extra_pipe_rids: Vec<Option<ResourceId>>,
) -> Result<Child, AnyError> {
  let mut command = tokio::process::Command::from(command);
  // TODO(@crowlkats): allow detaching processes.
  //  currently deno will orphan a process when exiting with an error or Deno.exit()
  // We want to kill child when it's closed
  command.kill_on_drop(true);

  let mut child = match command.spawn() {
    Ok(child) => child,
    Err(err) => {
      let command = command.as_std();
      let command_name = command.get_program().to_string_lossy();

      if let Some(cwd) = command.get_current_dir() {
        // launching a sub process always depends on the real
        // file system so using these methods directly is ok
        #[allow(clippy::disallowed_methods)]
        if !cwd.exists() {
          return Err(
            std::io::Error::new(
              std::io::ErrorKind::NotFound,
              format!(
                "Failed to spawn '{}': No such cwd '{}'",
                command_name,
                cwd.to_string_lossy()
              ),
            )
            .into(),
          );
        }

        #[allow(clippy::disallowed_methods)]
        if !cwd.is_dir() {
          return Err(
            std::io::Error::new(
              std::io::ErrorKind::NotFound,
              format!(
                "Failed to spawn '{}': cwd is not a directory '{}'",
                command_name,
                cwd.to_string_lossy()
              ),
            )
            .into(),
          );
        }
      }

      return Err(AnyError::from(err).context(format!(
        "Failed to spawn '{}'",
        command.get_program().to_string_lossy()
      )));
    }
  };

  let pid = child.id().expect("Process ID should be set.");

  let stdin_rid = child
    .stdin
    .take()
    .map(|stdin| state.resource_table.add(ChildStdinResource::from(stdin)));

  let stdout_rid = child
    .stdout
    .take()
    .map(|stdout| state.resource_table.add(ChildStdoutResource::from(stdout)));

  let stderr_rid = child
    .stderr
    .take()
    .map(|stderr| state.resource_table.add(ChildStderrResource::from(stderr)));

  let child_rid = state
    .resource_table
    .add(ChildResource(RefCell::new(child), pid));

  Ok(Child {
    rid: child_rid,
    pid,
    stdin_rid,
    stdout_rid,
    stderr_rid,
    ipc_pipe_rid,
    extra_pipe_rids,
  })
}

fn close_raw_handle(handle: deno_io::RawBiPipeHandle) {
  #[cfg(unix)]
  {
    // SAFETY: libc call
    unsafe {
      libc::close(handle);
    }
  }
  #[cfg(windows)]
  {
    // SAFETY: win32 call
    unsafe {
      windows_sys::Win32::Foundation::CloseHandle(handle as _);
    }
  }
}

fn compute_run_cmd_and_check_permissions(
  arg_cmd: &str,
  arg_cwd: Option<&str>,
  arg_envs: &[(String, String)],
  arg_clear_env: bool,
  state: &mut OpState,
  api_name: &str,
) -> Result<(PathBuf, RunEnv), AnyError> {
  let run_env = compute_run_env(arg_cwd, arg_envs, arg_clear_env)
    .with_context(|| format!("Failed to spawn '{}'", arg_cmd))?;
  let cmd = resolve_cmd(arg_cmd, &run_env)
    .with_context(|| format!("Failed to spawn '{}'", arg_cmd))?;
  check_run_permission(state, &cmd, &run_env, api_name)?;
  Ok((cmd, run_env))
}

struct RunEnv {
  envs: HashMap<String, String>,
  cwd: PathBuf,
}

/// Computes the current environment, which will then be used to inform
/// permissions and finally spawning. This is very important to compute
/// ahead of time so that the environment used to verify permissions is
/// the same environment used to spawn the sub command. This protects against
/// someone doing timing attacks by changing the environment on a worker.
fn compute_run_env(
  arg_cwd: Option<&str>,
  arg_envs: &[(String, String)],
  arg_clear_env: bool,
) -> Result<RunEnv, AnyError> {
  #[allow(clippy::disallowed_methods)]
  let cwd = std::env::current_dir().context("failed resolving cwd")?;
  let cwd = arg_cwd
    .map(|cwd_arg| resolve_path(cwd_arg, &cwd))
    .unwrap_or(cwd);
  let envs = if arg_clear_env {
    arg_envs.iter().cloned().collect()
  } else {
    let mut envs = std::env::vars().collect::<HashMap<_, _>>();
    for (key, value) in arg_envs {
      envs.insert(key.clone(), value.clone());
    }
    envs
  };
  Ok(RunEnv { envs, cwd })
}

fn resolve_cmd(cmd: &str, env: &RunEnv) -> Result<PathBuf, AnyError> {
  let is_path = cmd.contains('/');
  #[cfg(windows)]
  let is_path = is_path || cmd.contains('\\') || Path::new(&cmd).is_absolute();
  if is_path {
    Ok(resolve_path(cmd, &env.cwd))
  } else {
    let path = env.envs.get("PATH").or_else(|| {
      if cfg!(windows) {
        env.envs.iter().find_map(|(k, v)| {
          if k.to_uppercase() == "PATH" {
            Some(v)
          } else {
            None
          }
        })
      } else {
        None
      }
    });
    match which::which_in(cmd, path, &env.cwd) {
      Ok(cmd) => Ok(cmd),
      Err(which::Error::CannotFindBinaryPath) => {
        Err(std::io::Error::from(std::io::ErrorKind::NotFound).into())
      }
      Err(err) => Err(err.into()),
    }
  }
}

fn resolve_path(path: &str, cwd: &Path) -> PathBuf {
  deno_core::normalize_path(cwd.join(path))
}

fn check_run_permission(
  state: &mut OpState,
  cmd: &Path,
  run_env: &RunEnv,
  api_name: &str,
) -> Result<(), AnyError> {
  let permissions = state.borrow_mut::<PermissionsContainer>();
  if !permissions.query_run_all(api_name) {
    // error the same on all platforms
    let env_var_names = get_requires_allow_all_env_vars(run_env);
    if !env_var_names.is_empty() {
      // we don't allow users to launch subprocesses with any LD_ or DYLD_*
      // env vars set because this allows executing code (ex. LD_PRELOAD)
      return Err(deno_core::error::custom_error(
        "PermissionDenied",
        format!(
          "Requires --allow-all permissions to spawn subprocess with {} environment variable{}.",
          env_var_names.join(", "),
          if env_var_names.len() != 1 { "s" } else { "" }
        )
      ));
    }
    permissions.check_run(cmd, api_name)?;
  }
  Ok(())
}

fn get_requires_allow_all_env_vars(env: &RunEnv) -> Vec<&str> {
  fn requires_allow_all(key: &str) -> bool {
    let key = key.trim();
    // we could be more targted here, but there are quite a lot of
    // LD_* and DYLD_* env variables
    key.starts_with("LD_") || key.starts_with("DYLD_")
  }

  let mut found_envs = env
    .envs
    .iter()
    .filter(|(k, v)| requires_allow_all(k) && !v.trim().is_empty())
    .map(|(k, _)| k.as_str())
    .collect::<Vec<_>>();
  found_envs.sort();
  found_envs
}

#[op2]
#[serde]
fn op_spawn_child(
  state: &mut OpState,
  #[serde] args: SpawnArgs,
  #[string] api_name: String,
) -> Result<Child, AnyError> {
  let (command, pipe_rid, extra_pipe_rids, handles_to_close) =
    create_command(state, args, &api_name)?;
  let child = spawn_child(state, command, pipe_rid, extra_pipe_rids);
  for handle in handles_to_close {
    close_raw_handle(handle);
  }
  child
}

#[op2(async)]
#[allow(clippy::await_holding_refcell_ref)]
#[serde]
async fn op_spawn_wait(
  state: Rc<RefCell<OpState>>,
  #[smi] rid: ResourceId,
) -> Result<ChildStatus, AnyError> {
  let resource = state
    .borrow_mut()
    .resource_table
    .get::<ChildResource>(rid)?;
  let result = resource.0.try_borrow_mut()?.wait().await?.try_into();
  if let Ok(resource) = state.borrow_mut().resource_table.take_any(rid) {
    resource.close();
  }
  result
}

#[op2]
#[serde]
fn op_spawn_sync(
  state: &mut OpState,
  #[serde] args: SpawnArgs,
) -> Result<SpawnOutput, AnyError> {
  let stdout = matches!(args.stdio.stdout, StdioOrRid::Stdio(Stdio::Piped));
  let stderr = matches!(args.stdio.stderr, StdioOrRid::Stdio(Stdio::Piped));
  let (mut command, _, _, _) =
    create_command(state, args, "Deno.Command().outputSync()")?;
  let output = command.output().with_context(|| {
    format!(
      "Failed to spawn '{}'",
      command.get_program().to_string_lossy()
    )
  })?;

  Ok(SpawnOutput {
    status: output.status.try_into()?,
    stdout: if stdout {
      Some(output.stdout.into())
    } else {
      None
    },
    stderr: if stderr {
      Some(output.stderr.into())
    } else {
      None
    },
  })
}

#[op2(fast)]
fn op_spawn_kill(
  state: &mut OpState,
  #[smi] rid: ResourceId,
  #[string] signal: String,
) -> Result<(), AnyError> {
  if let Ok(child_resource) = state.resource_table.get::<ChildResource>(rid) {
    deprecated::kill(child_resource.1 as i32, &signal)?;
    return Ok(());
  }
  Err(type_error("Child process has already terminated."))
}

mod deprecated {
  use deno_core::anyhow;

  use super::*;

  #[derive(Deserialize)]
  #[serde(rename_all = "camelCase")]
  pub struct RunArgs {
    cmd: Vec<String>,
    cwd: Option<String>,
    env: Vec<(String, String)>,
    stdin: StdioOrRid,
    stdout: StdioOrRid,
    stderr: StdioOrRid,
  }

  struct ChildResource {
    child: AsyncRefCell<tokio::process::Child>,
  }

  impl Resource for ChildResource {
    fn name(&self) -> Cow<str> {
      "child".into()
    }
  }

  impl ChildResource {
    fn borrow_mut(self: Rc<Self>) -> AsyncMutFuture<tokio::process::Child> {
      RcRef::map(self, |r| &r.child).borrow_mut()
    }
  }

  #[derive(Serialize)]
  #[serde(rename_all = "camelCase")]
  // TODO(@AaronO): maybe find a more descriptive name or a convention for return structs
  pub struct RunInfo {
    rid: ResourceId,
    pid: Option<u32>,
    stdin_rid: Option<ResourceId>,
    stdout_rid: Option<ResourceId>,
    stderr_rid: Option<ResourceId>,
  }

  #[op2]
  #[serde]
  pub fn op_run(
    state: &mut OpState,
    #[serde] run_args: RunArgs,
  ) -> Result<RunInfo, AnyError> {
    let args = run_args.cmd;
    let cmd = args.first().ok_or_else(|| anyhow::anyhow!("Missing cmd"))?;
    let (cmd, run_env) = compute_run_cmd_and_check_permissions(
      cmd,
      run_args.cwd.as_deref(),
      &run_args.env,
      /* clear env */ false,
      state,
      "Deno.run()",
    )?;

    let mut c = Command::new(cmd);
    for arg in args.iter().skip(1) {
      c.arg(arg);
    }
    c.current_dir(run_env.cwd);

    c.env_clear();
    for (key, value) in run_env.envs {
      c.env(key, value);
    }

    #[cfg(unix)]
    // TODO(bartlomieju):
    #[allow(clippy::undocumented_unsafe_blocks)]
    unsafe {
      c.pre_exec(|| {
        libc::setgroups(0, std::ptr::null());
        Ok(())
      });
    }

    // TODO: make this work with other resources, eg. sockets
    c.stdin(run_args.stdin.as_stdio(state)?);
    c.stdout(
      match run_args.stdout {
        StdioOrRid::Stdio(Stdio::Inherit) => StdioOrRid::Rid(1),
        value => value,
      }
      .as_stdio(state)?,
    );
    c.stderr(
      match run_args.stderr {
        StdioOrRid::Stdio(Stdio::Inherit) => StdioOrRid::Rid(2),
        value => value,
      }
      .as_stdio(state)?,
    );

    // We want to kill child when it's closed
    c.kill_on_drop(true);

    // Spawn the command.
    let mut child = c.spawn()?;
    let pid = child.id();

    let stdin_rid = match child.stdin.take() {
      Some(child_stdin) => {
        let rid = state
          .resource_table
          .add(ChildStdinResource::from(child_stdin));
        Some(rid)
      }
      None => None,
    };

    let stdout_rid = match child.stdout.take() {
      Some(child_stdout) => {
        let rid = state
          .resource_table
          .add(ChildStdoutResource::from(child_stdout));
        Some(rid)
      }
      None => None,
    };

    let stderr_rid = match child.stderr.take() {
      Some(child_stderr) => {
        let rid = state
          .resource_table
          .add(ChildStderrResource::from(child_stderr));
        Some(rid)
      }
      None => None,
    };

    let child_resource = ChildResource {
      child: AsyncRefCell::new(child),
    };
    let child_rid = state.resource_table.add(child_resource);

    Ok(RunInfo {
      rid: child_rid,
      pid,
      stdin_rid,
      stdout_rid,
      stderr_rid,
    })
  }

  #[derive(Serialize)]
  #[serde(rename_all = "camelCase")]
  pub struct ProcessStatus {
    got_signal: bool,
    exit_code: i32,
    exit_signal: i32,
  }

  #[op2(async)]
  #[serde]
  pub async fn op_run_status(
    state: Rc<RefCell<OpState>>,
    #[smi] rid: ResourceId,
  ) -> Result<ProcessStatus, AnyError> {
    let resource = state
      .borrow_mut()
      .resource_table
      .get::<ChildResource>(rid)?;
    let mut child = resource.borrow_mut().await;
    let run_status = child.wait().await?;
    let code = run_status.code();

    #[cfg(unix)]
    let signal = run_status.signal();
    #[cfg(not(unix))]
    let signal = Default::default();

    code
      .or(signal)
      .expect("Should have either an exit code or a signal.");
    let got_signal = signal.is_some();

    Ok(ProcessStatus {
      got_signal,
      exit_code: code.unwrap_or(-1),
      exit_signal: signal.unwrap_or(-1),
    })
  }

  #[cfg(unix)]
  pub fn kill(pid: i32, signal: &str) -> Result<(), AnyError> {
    let signo = super::super::signal::signal_str_to_int(signal)?;
    use nix::sys::signal::kill as unix_kill;
    use nix::sys::signal::Signal;
    use nix::unistd::Pid;
    let sig = Signal::try_from(signo)?;
    unix_kill(Pid::from_raw(pid), Option::Some(sig)).map_err(AnyError::from)
  }

  #[cfg(not(unix))]
  pub fn kill(pid: i32, signal: &str) -> Result<(), AnyError> {
    use std::io::Error;
    use std::io::ErrorKind::NotFound;
    use winapi::shared::minwindef::DWORD;
    use winapi::shared::minwindef::FALSE;
    use winapi::shared::minwindef::TRUE;
    use winapi::shared::winerror::ERROR_INVALID_PARAMETER;
    use winapi::um::errhandlingapi::GetLastError;
    use winapi::um::handleapi::CloseHandle;
    use winapi::um::processthreadsapi::OpenProcess;
    use winapi::um::processthreadsapi::TerminateProcess;
    use winapi::um::winnt::PROCESS_TERMINATE;

    if !matches!(signal, "SIGKILL" | "SIGTERM") {
      Err(type_error(format!("Invalid signal: {signal}")))
    } else if pid <= 0 {
      Err(type_error("Invalid pid"))
    } else {
      let handle =
        // SAFETY: winapi call
        unsafe { OpenProcess(PROCESS_TERMINATE, FALSE, pid as DWORD) };

      if handle.is_null() {
        // SAFETY: winapi call
        let err = match unsafe { GetLastError() } {
          ERROR_INVALID_PARAMETER => Error::from(NotFound), // Invalid `pid`.
          errno => Error::from_raw_os_error(errno as i32),
        };
        Err(err.into())
      } else {
        // SAFETY: winapi calls
        unsafe {
          let is_terminated = TerminateProcess(handle, 1);
          CloseHandle(handle);
          match is_terminated {
            FALSE => Err(Error::last_os_error().into()),
            TRUE => Ok(()),
            _ => unreachable!(),
          }
        }
      }
    }
  }

  #[op2(fast)]
  pub fn op_kill(
    state: &mut OpState,
    #[smi] pid: i32,
    #[string] signal: String,
    #[string] api_name: String,
  ) -> Result<(), AnyError> {
    state
      .borrow_mut::<PermissionsContainer>()
      .check_run_all(&api_name)?;
    kill(pid, &signal)?;
    Ok(())
  }
}