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

This reverts commit 1d18f6947e.

Cargo.lock

@@ -2509,7 +2509,6 @@ dependencies = [
  "bitflags",
  "cfg-if 1.0.0",
  "libc",
- "memoffset",
 ]
 
 [[package]]
@@ -2869,13 +2868,11 @@ dependencies = [
 name = "nu-system"
 version = "0.68.1"
 dependencies = [
- "atty",
  "chrono",
  "errno",
  "libc",
  "libproc",
  "mach2",
- "nix",
  "ntapi",
  "once_cell",
  "procfs",

crates/nu-command/src/system/run_external.rs

@@ -7,7 +7,6 @@ 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};
@@ -142,7 +141,7 @@ impl ExternalCommand {
 
         let ctrlc = engine_state.ctrlc.clone();
 
-        let mut fg_process = ForegroundProcess::new(self.create_process(&input, false, head)?);
+        let mut process = self.create_process(&input, false, head)?;
         // mut is used in the windows branch only, suppress warning on other platforms
         #[allow(unused_mut)]
         let mut child;
@@ -157,7 +156,8 @@ 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 fg_process.spawn() {
+
+            match process.spawn() {
                 Err(err) => {
                     // set the default value, maybe we'll override it later
                     child = Err(err);
@@ -174,8 +174,7 @@ impl ExternalCommand {
                         .any(|&cmd| command_name_upper == cmd);
 
                     if looks_like_cmd_internal {
-                        let mut cmd_process =
+                        let mut cmd_process = self.create_process(&input, true, head)?;
-                            ForegroundProcess::new(self.create_process(&input, true, head)?);
                         child = cmd_process.spawn();
                     } else {
                         #[cfg(feature = "which-support")]
@@ -203,10 +202,8 @@ impl ExternalCommand {
                                                     item: file_name.to_string_lossy().to_string(),
                                                     span: self.name.span,
                                                 };
-                                                let mut cmd_process = ForegroundProcess::new(
+                                                let mut cmd_process = new_command
-                                                    new_command
+                                                    .create_process(&input, true, head)?;
-                                                        .create_process(&input, true, head)?,
-                                                );
                                                 child = cmd_process.spawn();
                                             }
                                         }
@@ -224,7 +221,7 @@ impl ExternalCommand {
 
         #[cfg(not(windows))]
         {
-            child = fg_process.spawn()
+            child = process.spawn()
         }
 
         match child {
@@ -276,7 +273,7 @@ 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.as_mut().stdin.take() {
+                    if let Some(mut stdin_write) = child.stdin.take() {
                         std::thread::spawn(move || {
                             let input = crate::Table::run(
                                 &crate::Table,
@@ -317,7 +314,7 @@ impl ExternalCommand {
                     // and we create a ListStream that can be consumed
 
                     if redirect_stderr {
-                        let stderr = child.as_mut().stderr.take().ok_or_else(|| {
+                        let stderr = child.stderr.take().ok_or_else(|| {
                             ShellError::ExternalCommand(
                                 "Error taking stderr from external".to_string(),
                                 "Redirects need access to stderr of an external command"
@@ -356,7 +353,7 @@ impl ExternalCommand {
                     }
 
                     if redirect_stdout {
-                        let stdout = child.as_mut().stdout.take().ok_or_else(|| {
+                        let stdout = child.stdout.take().ok_or_else(|| {
                             ShellError::ExternalCommand(
                                 "Error taking stdout from external".to_string(),
                                 "Redirects need access to stdout of an external command"
@@ -394,7 +391,7 @@ impl ExternalCommand {
                         }
                     }
 
-                    match child.as_mut().wait() {
+                    match child.wait() {
                         Err(err) => Err(ShellError::ExternalCommand(
                             "External command exited with error".into(),
                             err.to_string(),

crates/nu-system/Cargo.toml

@@ -16,10 +16,6 @@ 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"
 

crates/nu-system/src/foreground.rs

@@ -1,117 +0,0 @@
-use std::process::{Child, Command};
-
-/// A simple wrapper for `std::process::Command`
-///
-/// ## spawn behavior
-/// ### Unix
-/// When invoke `spawn`, current process will block `SIGTSTP`, `SIGTTOU`, `SIGTTIN`, `SIGCHLD`
-///
-/// spawned child process will get it's own process group id, and it's going to foreground(by making stdin belong's to child's process group).
-///
-/// When child is to over, unblock `SIGTSTP`, `SIGTTOU`, `SIGTTIN`, `SIGCHLD`, foreground process is back to callers' process.
-/// It bahaves something like `SignalHandler` in ion(https://gitlab.redox-os.org/redox-os/ion/-/tree/master/).
-///
-/// ### 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,
-}
-
-/// A simple wrapper for `std::process::Child`
-///
-/// It can only be created by `ForegroundProcess::spawn`.
-pub struct ForegroundChild {
-    inner: Child,
-}
-
-impl ForegroundProcess {
-    pub fn new(cmd: Command) -> Self {
-        Self { inner: cmd }
-    }
-
-    pub fn spawn(&mut self) -> std::io::Result<ForegroundChild> {
-        fg_process_setup::prepare_to_foreground(&mut self.inner);
-        self.inner.spawn().map(|child| {
-            fg_process_setup::set_foreground(&child);
-            ForegroundChild { inner: child }
-        })
-    }
-}
-
-impl AsMut<Child> for ForegroundChild {
-    fn as_mut(&mut self) -> &mut Child {
-        &mut self.inner
-    }
-}
-
-impl Drop for ForegroundChild {
-    fn drop(&mut self) {
-        // It's ok to use here because we have called `set_foreground` during creation.
-        unsafe { 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 crate::signal::{block, unblock};
-    use nix::unistd::{self, Pid};
-    use std::os::unix::prelude::CommandExt;
-
-    pub(super) fn prepare_to_foreground(external_command: &mut std::process::Command) {
-        unsafe {
-            block();
-            // Safety:
-            // POSIX only allows async-signal-safe functions to be called.
-            // And `setpgid` is async-signal-safe function according to:
-            // https://manpages.ubuntu.com/manpages/bionic/man7/signal-safety.7.html
-            // So we're ok to invoke `libc::setpgid` inside `pre_exec`.
-            external_command.pre_exec(|| {
-                // make the command startup with new process group.
-                // The process group id must be the same as external commands' pid.
-                // Or else we'll failed to set it as foreground process.
-                // For more information, check `fork_child_for_process` function:
-                // https://github.com/fish-shell/fish-shell/blob/023042098396aa450d2c4ea1eb9341312de23126/src/exec.cpp#L398
-                if let Err(e) = unistd::setpgid(Pid::from_raw(0), Pid::from_raw(0)) {
-                    println!("ERROR: setpgid for external failed, result: {e:?}");
-                }
-                Ok(())
-            });
-        }
-    }
-
-    // If `prepare_to_foreground` function is not called, the function will fail with silence and do nothing.
-    pub(super) fn set_foreground(process: &std::process::Child) {
-        if atty::is(atty::Stream::Stdin) {
-            if let Err(e) =
-                nix::unistd::tcsetpgrp(nix::libc::STDIN_FILENO, Pid::from_raw(process.id() as i32))
-            {
-                println!("ERROR: set foreground id failed, tcsetpgrp result: {e:?}");
-            }
-        }
-    }
-
-    /// Reset foreground to current process, unblock `SIGTSTP`, `SIGTTOU`, `SIGTTIN`, `SIGCHLD`
-    ///
-    /// ## Safety
-    /// It can only be called when you have called `set_foreground`, or results in undefined behavior.
-    pub(super) unsafe 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:?}");
-            }
-        }
-        unblock()
-    }
-}
-
-// TODO: investigate if we can set foreground process through windows system call.
-#[cfg(target_family = "windows")]
-mod fg_process_setup {
-
-    pub(super) fn prepare_to_foreground(_external_command: &mut std::process::Command) {}
-
-    pub(super) fn set_foreground(_process: &std::process::Child) {}
-
-    pub(super) unsafe fn reset_foreground_id() {}
-}

crates/nu-system/src/lib.rs

@@ -1,15 +1,10 @@
-mod foreground;
 #[cfg(any(target_os = "android", target_os = "linux"))]
 mod linux;
 #[cfg(target_os = "macos")]
 mod macos;
-#[cfg(target_family = "unix")]
-pub mod signal;
-
 #[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")]

crates/nu-system/src/signal.rs

@@ -1,41 +0,0 @@
-use nix::sys::signal::{self, SigHandler, Signal};
-
-/// Blocks the SIGTSTP/SIGTTOU/SIGTTIN/SIGCHLD signals so that the shell never receives
-/// them.
-pub fn block() {
-    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);
-    if let Err(e) = signal::sigprocmask(signal::SigmaskHow::SIG_BLOCK, Some(&sigset), None) {
-        println!("ERROR: Could not block the signals, error message: {e:?}");
-    }
-}
-
-/// Unblocks the SIGTSTP/SIGTTOU/SIGTTIN/SIGCHLD signals so children processes can be
-/// controlled
-/// by the shell.
-pub fn unblock() {
-    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);
-    if let Err(e) = signal::sigprocmask(signal::SigmaskHow::SIG_UNBLOCK, Some(&sigset), None) {
-        println!("ERROR: Could not unblock the signals, error message: {e:?}");
-    }
-}
-
-// It's referenced from `set_unique_pid` function in `ion`.
-pub fn set_terminal_leader() {
-    let stdin_is_a_tty = atty::is(atty::Stream::Stdin);
-    if stdin_is_a_tty {
-        // We have make sure that stdin is a tty, it's ok to ignore SIGTTOU.
-        unsafe {
-            if let Err(e) = signal::signal(Signal::SIGTTOU, SigHandler::SigIgn) {
-                println!("WARN: ignore SIGTTOU failed, error message: {e:?}");
-            }
-        }
-    }
-}

src/main.rs

@@ -135,14 +135,6 @@ fn main() -> Result<()> {
 
     let parsed_nu_cli_args = parse_commandline_args(&nushell_commandline_args, &mut engine_state);
 
-    #[cfg(target_family = "unix")]
-    {
-        // This will block SIGTSTP, SIGTTOU, SIGTTIN, and SIGCHLD, which is required
-        // for this shell to manage its own process group / children / etc.
-        nu_system::signal::block();
-        nu_system::signal::set_terminal_leader()
-    }
-
     if let Ok(ref args) = parsed_nu_cli_args {
         set_config_path(
             &mut engine_state,