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Foreground process group management, again (#6584)

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* Revert "Revert "Try again: in unix like system, set foreground process while running external command (#6273)" (#6542)"

This reverts commit 2bb367f570.

* Make foreground job control hopefully work correctly

These changes are mostly inspired by the glibc manual.

* Fix typo in external command description

* Only restore tty control to shell when no fg procs are left; reuse pgrp

* Rework terminal acquirement code to be like fish

Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>
This commit is contained in:
unrelentingtech 2022-09-29 21:37:48 +03:00 committed by GitHub
parent 6486364610
commit 4af0a6a3fa
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GPG key ID: 4AEE18F83AFDEB23
8 changed files with 323 additions and 13 deletions
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5
Cargo.lock generated
View file

@ -2511,6 +2511,7 @@ dependencies = [
"bitflags",
"cfg-if 1.0.0",
"libc",
"memoffset",
]
[[package]]
@ -2580,6 +2581,7 @@ name = "nu"
version = "0.69.2"
dependencies = [
"assert_cmd",
"atty",
"chrono",
"crossterm 0.24.0",
"ctrlc",
@ -2588,6 +2590,7 @@ dependencies = [
"itertools",
"log",
"miette 5.1.1",
"nix",
"nu-ansi-term",
"nu-cli",
"nu-color-config",
@ -2873,11 +2876,13 @@ dependencies = [
name = "nu-system"
version = "0.69.2"
dependencies = [
"atty",
"chrono",
"errno",
"libc",
"libproc",
"mach2",
"nix",
"ntapi",
"once_cell",
"procfs",

5
Cargo.toml
View file

@ -122,3 +122,8 @@ debug = false
[[bin]]
name = "nu"
path = "src/main.rs"
[target.'cfg(target_family = "unix")'.dependencies]
nix = "0.24"
atty = "0.2"

33
crates/nu-command/src/system/run_external.rs
View file

@ -7,6 +7,7 @@ use nu_protocol::did_you_mean;
use nu_protocol::engine::{EngineState, Stack};
use nu_protocol::{ast::Call, engine::Command, ShellError, Signature, SyntaxShape, Value};
use nu_protocol::{Category, Example, ListStream, PipelineData, RawStream, Span, Spanned};
use nu_system::ForegroundProcess;
use pathdiff::diff_paths;
use std::collections::HashMap;
use std::io::{BufRead, BufReader, Write};
@ -34,7 +35,7 @@ impl Command for External {
Signature::build(self.name())
.switch("redirect-stdout", "redirect-stdout", None)
.switch("redirect-stderr", "redirect-stderr", None)
.required("command", SyntaxShape::Any, "external comamdn to run")
.required("command", SyntaxShape::Any, "external command to run")
.rest("args", SyntaxShape::Any, "arguments for external command")
.category(Category::System)
}
@ -141,7 +142,10 @@ impl ExternalCommand {
let ctrlc = engine_state.ctrlc.clone();
let mut process = self.create_process(&input, false, head)?;
let mut fg_process = ForegroundProcess::new(
self.create_process(&input, false, head)?,
engine_state.pipeline_externals_state.clone(),
);
// mut is used in the windows branch only, suppress warning on other platforms
#[allow(unused_mut)]
let mut child;
@ -156,8 +160,7 @@ impl ExternalCommand {
// fails to be run as a normal executable:
// 1. "shell out" to cmd.exe if the command is a known cmd.exe internal command
// 2. Otherwise, use `which-rs` to look for batch files etc. then run those in cmd.exe
match process.spawn() {
match fg_process.spawn() {
Err(err) => {
// set the default value, maybe we'll override it later
child = Err(err);
@ -174,7 +177,10 @@ impl ExternalCommand {
.any(|&cmd| command_name_upper == cmd);
if looks_like_cmd_internal {
let mut cmd_process = self.create_process(&input, true, head)?;
let mut cmd_process = ForegroundProcess::new(
self.create_process(&input, true, head)?,
engine_state.pipeline_externals_state.clone(),
);
child = cmd_process.spawn();
} else {
#[cfg(feature = "which-support")]
@ -202,8 +208,11 @@ impl ExternalCommand {
item: file_name.to_string_lossy().to_string(),
span: self.name.span,
};
let mut cmd_process = new_command
.create_process(&input, true, head)?;
let mut cmd_process = ForegroundProcess::new(
new_command
.create_process(&input, true, head)?,
engine_state.pipeline_externals_state.clone(),
);
child = cmd_process.spawn();
}
}
@ -221,7 +230,7 @@ impl ExternalCommand {
#[cfg(not(windows))]
{
child = process.spawn()
child = fg_process.spawn()
}
match child {
@ -273,7 +282,7 @@ impl ExternalCommand {
engine_state.config.use_ansi_coloring = false;
// if there is a string or a stream, that is sent to the pipe std
if let Some(mut stdin_write) = child.stdin.take() {
if let Some(mut stdin_write) = child.as_mut().stdin.take() {
std::thread::spawn(move || {
let input = crate::Table::run(
&crate::Table,
@ -314,7 +323,7 @@ impl ExternalCommand {
// and we create a ListStream that can be consumed
if redirect_stderr {
let stderr = child.stderr.take().ok_or_else(|| {
let stderr = child.as_mut().stderr.take().ok_or_else(|| {
ShellError::ExternalCommand(
"Error taking stderr from external".to_string(),
"Redirects need access to stderr of an external command"
@ -353,7 +362,7 @@ impl ExternalCommand {
}
if redirect_stdout {
let stdout = child.stdout.take().ok_or_else(|| {
let stdout = child.as_mut().stdout.take().ok_or_else(|| {
ShellError::ExternalCommand(
"Error taking stdout from external".to_string(),
"Redirects need access to stdout of an external command"
@ -391,7 +400,7 @@ impl ExternalCommand {
}
}
match child.wait() {
match child.as_mut().wait() {
Err(err) => Err(ShellError::ExternalCommand(
"External command exited with error".into(),
err.to_string(),

7
crates/nu-protocol/src/engine/engine_state.rs
View file

@ -10,7 +10,10 @@ use std::path::Path;
use std::path::PathBuf;
use std::{
collections::{HashMap, HashSet, VecDeque},
sync::{atomic::AtomicBool, Arc, Mutex},
sync::{
atomic::{AtomicBool, AtomicU32},
Arc, Mutex,
},
};
static PWD_ENV: &str = "PWD";
@ -80,6 +83,7 @@ pub struct EngineState {
pub env_vars: EnvVars,
pub previous_env_vars: HashMap<String, Value>,
pub config: Config,
pub pipeline_externals_state: Arc<(AtomicU32, AtomicU32)>,
pub repl_buffer_state: Arc<Mutex<Option<String>>>,
pub repl_operation_queue: Arc<Mutex<VecDeque<ReplOperation>>>,
#[cfg(feature = "plugin")]
@ -121,6 +125,7 @@ impl EngineState {
env_vars: EnvVars::from([(DEFAULT_OVERLAY_NAME.to_string(), HashMap::new())]),
previous_env_vars: HashMap::new(),
config: Config::default(),
pipeline_externals_state: Arc::new((AtomicU32::new(0), AtomicU32::new(0))),
repl_buffer_state: Arc::new(Mutex::new(None)),
repl_operation_queue: Arc::new(Mutex::new(VecDeque::new())),
#[cfg(feature = "plugin")]

4
crates/nu-system/Cargo.toml
View file

@ -16,6 +16,10 @@ path = "src/main.rs"
[dependencies]
libc = "0.2"
[target.'cfg(target_family = "unix")'.dependencies]
nix = "0.24"
atty = "0.2"
[target.'cfg(any(target_os = "linux", target_os = "android"))'.dependencies]
procfs = "0.14.0"

180
crates/nu-system/src/foreground.rs Normal file
View file

@ -0,0 +1,180 @@
use std::{
process::{Child, Command},
sync::{
atomic::{AtomicU32, Ordering},
Arc,
},
};
/// A simple wrapper for `std::process::Command`
///
/// ## Spawn behavior
/// ### Unix
///
/// The spawned child process will get its own process group id, and it's going to foreground (by making stdin belong's to child's process group).
///
/// On drop, the calling process's group will become the foreground process group once again.
///
/// ### Windows
/// It does nothing special on windows system, `spawn` is the same as [std::process::Command::spawn](std::process::Command::spawn)
pub struct ForegroundProcess {
inner: Command,
pipeline_state: Arc<(AtomicU32, AtomicU32)>,
}
/// A simple wrapper for `std::process::Child`
///
/// It can only be created by `ForegroundProcess::spawn`.
pub struct ForegroundChild {
inner: Child,
pipeline_state: Arc<(AtomicU32, AtomicU32)>,
}
impl ForegroundProcess {
pub fn new(cmd: Command, pipeline_state: Arc<(AtomicU32, AtomicU32)>) -> Self {
Self {
inner: cmd,
pipeline_state,
}
}
pub fn spawn(&mut self) -> std::io::Result<ForegroundChild> {
let (ref pgrp, ref pcnt) = *self.pipeline_state;
let existing_pgrp = pgrp.load(Ordering::SeqCst);
fg_process_setup::prepare_to_foreground(&mut self.inner, existing_pgrp);
self.inner
.spawn()
.map(|child| {
fg_process_setup::set_foreground(&child, existing_pgrp);
let _ = pcnt.fetch_add(1, Ordering::SeqCst);
if existing_pgrp == 0 {
pgrp.store(child.id(), Ordering::SeqCst);
}
ForegroundChild {
inner: child,
pipeline_state: self.pipeline_state.clone(),
}
})
.map_err(|e| {
fg_process_setup::reset_foreground_id();
e
})
}
}
impl AsMut<Child> for ForegroundChild {
fn as_mut(&mut self) -> &mut Child {
&mut self.inner
}
}
impl Drop for ForegroundChild {
fn drop(&mut self) {
let (ref pgrp, ref pcnt) = *self.pipeline_state;
if pcnt.fetch_sub(1, Ordering::SeqCst) == 1 {
pgrp.store(0, Ordering::SeqCst);
fg_process_setup::reset_foreground_id()
}
}
}
// It's a simpler version of fish shell's external process handling.
#[cfg(target_family = "unix")]
mod fg_process_setup {
use nix::{
sys::signal,
unistd::{self, Pid},
};
use std::os::unix::prelude::{CommandExt, RawFd};
// TODO: when raising MSRV past 1.63.0, switch to OwnedFd
struct TtyHandle(RawFd);
impl Drop for TtyHandle {
fn drop(&mut self) {
let _ = unistd::close(self.0);
}
}
pub(super) fn prepare_to_foreground(
external_command: &mut std::process::Command,
existing_pgrp: u32,
) {
let tty = TtyHandle(unistd::dup(nix::libc::STDIN_FILENO).expect("dup"));
unsafe {
// Safety:
// POSIX only allows async-signal-safe functions to be called.
// `sigprocmask`, `setpgid` and `tcsetpgrp` are async-signal-safe according to:
// https://manpages.ubuntu.com/manpages/bionic/man7/signal-safety.7.html
external_command.pre_exec(move || {
// When this callback is run, std::process has already done:
// - pthread_sigmask(SIG_SETMASK) with an empty sigset
// - signal(SIGPIPE, SIG_DFL)
// However, we do need TTOU/TTIN blocked again during this setup.
let mut sigset = signal::SigSet::empty();
sigset.add(signal::Signal::SIGTSTP);
sigset.add(signal::Signal::SIGTTOU);
sigset.add(signal::Signal::SIGTTIN);
sigset.add(signal::Signal::SIGCHLD);
signal::sigprocmask(signal::SigmaskHow::SIG_BLOCK, Some(&sigset), None)
.expect("signal mask");
// According to glibc's job control manual:
// https://www.gnu.org/software/libc/manual/html_node/Launching-Jobs.html
// This has to be done *both* in the parent and here in the child due to race conditions.
set_foreground_pid(unistd::getpid(), existing_pgrp, tty.0);
// Now let the child process have all the signals by resetting with SIG_SETMASK.
let mut sigset = signal::SigSet::empty();
sigset.add(signal::Signal::SIGTSTP); // for now not really all: we don't support background jobs, so keep this one blocked
signal::sigprocmask(signal::SigmaskHow::SIG_SETMASK, Some(&sigset), None)
.expect("signal mask");
Ok(())
});
}
}
pub(super) fn set_foreground(process: &std::process::Child, existing_pgrp: u32) {
// called from the parent shell process - do the stdin tty check here
if atty::is(atty::Stream::Stdin) {
set_foreground_pid(
Pid::from_raw(process.id() as i32),
existing_pgrp,
nix::libc::STDIN_FILENO,
);
}
}
// existing_pgrp is 0 when we don't have an existing foreground process in the pipeline.
// Conveniently, 0 means "current pid" to setpgid. But not to tcsetpgrp.
fn set_foreground_pid(pid: Pid, existing_pgrp: u32, tty: RawFd) {
let _ = unistd::setpgid(pid, Pid::from_raw(existing_pgrp as i32));
let _ = unistd::tcsetpgrp(
tty,
if existing_pgrp == 0 {
pid
} else {
Pid::from_raw(existing_pgrp as i32)
},
);
}
/// Reset the foreground process group to the shell
pub(super) fn reset_foreground_id() {
if atty::is(atty::Stream::Stdin) {
if let Err(e) = nix::unistd::tcsetpgrp(nix::libc::STDIN_FILENO, unistd::getpgrp()) {
println!("ERROR: reset foreground id failed, tcsetpgrp result: {e:?}");
}
}
}
}
#[cfg(not(target_family = "unix"))]
mod fg_process_setup {
pub(super) fn prepare_to_foreground(_: &mut std::process::Command, _: u32) {}
pub(super) fn set_foreground(_: &std::process::Child, _: u32) {}
pub(super) fn reset_foreground_id() {}
}

2
crates/nu-system/src/lib.rs
View file

@ -1,3 +1,4 @@
mod foreground;
#[cfg(any(target_os = "android", target_os = "linux"))]
mod linux;
#[cfg(target_os = "macos")]
@ -5,6 +6,7 @@ mod macos;
#[cfg(target_os = "windows")]
mod windows;
pub use self::foreground::{ForegroundChild, ForegroundProcess};
#[cfg(any(target_os = "android", target_os = "linux"))]
pub use self::linux::*;
#[cfg(target_os = "macos")]

100
src/main.rs
View file

@ -37,6 +37,100 @@ use std::{
thread_local! { static IS_PERF: RefCell<bool> = RefCell::new(false) }
// Inspired by fish's acquire_tty_or_exit
#[cfg(unix)]
fn take_control(interactive: bool) {
use nix::{
errno::Errno,
sys::signal::{self, SaFlags, SigAction, SigHandler, SigSet, Signal},
unistd::{self, Pid},
};
let shell_pgid = unistd::getpgrp();
let owner_pgid = unistd::tcgetpgrp(nix::libc::STDIN_FILENO).expect("tcgetpgrp");
// Common case, nothing to do
if owner_pgid == shell_pgid {
return;
}
// This can apparently happen with sudo: https://github.com/fish-shell/fish-shell/issues/7388
if owner_pgid == unistd::getpid() {
let _ = unistd::setpgid(owner_pgid, owner_pgid);
return;
}
// Reset all signal handlers to default
for sig in Signal::iterator() {
unsafe {
if let Ok(old_act) = signal::sigaction(
sig,
&SigAction::new(SigHandler::SigDfl, SaFlags::empty(), SigSet::empty()),
) {
// fish preserves ignored SIGHUP, presumably for nohup support, so let's do the same
if sig == Signal::SIGHUP && old_act.handler() == SigHandler::SigIgn {
let _ = signal::sigaction(sig, &old_act);
}
}
}
}
let mut success = false;
for _ in 0..4096 {
match unistd::tcgetpgrp(nix::libc::STDIN_FILENO) {
Ok(owner_pgid) if owner_pgid == shell_pgid => {
success = true;
break;
}
Ok(owner_pgid) if owner_pgid == Pid::from_raw(0) => {
// Zero basically means something like "not owned" and we can just take it
let _ = unistd::tcsetpgrp(nix::libc::STDIN_FILENO, shell_pgid);
}
Err(Errno::ENOTTY) => {
if !interactive {
// that's fine
return;
}
eprintln!("ERROR: no TTY for interactive shell");
std::process::exit(1);
}
_ => {
// fish also has other heuristics than "too many attempts" for the orphan check, but they're optional
if signal::killpg(Pid::from_raw(-shell_pgid.as_raw()), Signal::SIGTTIN).is_err() {
eprintln!("ERROR: failed to SIGTTIN ourselves");
std::process::exit(1);
}
}
}
}
if !success {
eprintln!("ERROR: failed take control of the terminal, we might be orphaned");
std::process::exit(1);
}
}
#[cfg(unix)]
fn acquire_terminal(interactive: bool) {
use nix::sys::signal::{signal, SigHandler, Signal};
if !atty::is(atty::Stream::Stdin) {
return;
}
take_control(interactive);
unsafe {
// SIGINT and SIGQUIT have special handling above
signal(Signal::SIGTSTP, SigHandler::SigIgn).expect("signal ignore");
signal(Signal::SIGTTIN, SigHandler::SigIgn).expect("signal ignore");
signal(Signal::SIGTTOU, SigHandler::SigIgn).expect("signal ignore");
// signal::signal(Signal::SIGCHLD, SigHandler::SigIgn).expect("signal ignore"); // needed for std::command's waitpid usage
}
}
#[cfg(not(unix))]
fn acquire_terminal(_: bool) {}
fn main() -> Result<()> {
// miette::set_panic_hook();
let miette_hook = std::panic::take_hook();
@ -155,6 +249,12 @@ fn main() -> Result<()> {
match parsed_nu_cli_args {
Ok(binary_args) => {
// keep this condition in sync with the branches below
acquire_terminal(
binary_args.commands.is_none()
&& (script_name.is_empty() || binary_args.interactive_shell.is_some()),
);
if let Some(t) = binary_args.threads {
// 0 means to let rayon decide how many threads to use
let threads = t.as_i64().unwrap_or(0);