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Diffstat (limited to 'third_party/rust/tokio/src/process/mod.rs')
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diff --git a/third_party/rust/tokio/src/process/mod.rs b/third_party/rust/tokio/src/process/mod.rs new file mode 100644 index 0000000000..4e1a21dd44 --- /dev/null +++ b/third_party/rust/tokio/src/process/mod.rs @@ -0,0 +1,1534 @@ +//! An implementation of asynchronous process management for Tokio. +//! +//! This module provides a [`Command`] struct that imitates the interface of the +//! [`std::process::Command`] type in the standard library, but provides asynchronous versions of +//! functions that create processes. These functions (`spawn`, `status`, `output` and their +//! variants) return "future aware" types that interoperate with Tokio. The asynchronous process +//! support is provided through signal handling on Unix and system APIs on Windows. +//! +//! [`std::process::Command`]: std::process::Command +//! +//! # Examples +//! +//! Here's an example program which will spawn `echo hello world` and then wait +//! for it complete. +//! +//! ```no_run +//! use tokio::process::Command; +//! +//! #[tokio::main] +//! async fn main() -> Result<(), Box<dyn std::error::Error>> { +//! // The usage is similar as with the standard library's `Command` type +//! let mut child = Command::new("echo") +//! .arg("hello") +//! .arg("world") +//! .spawn() +//! .expect("failed to spawn"); +//! +//! // Await until the command completes +//! let status = child.wait().await?; +//! println!("the command exited with: {}", status); +//! Ok(()) +//! } +//! ``` +//! +//! Next, let's take a look at an example where we not only spawn `echo hello +//! world` but we also capture its output. +//! +//! ```no_run +//! use tokio::process::Command; +//! +//! #[tokio::main] +//! async fn main() -> Result<(), Box<dyn std::error::Error>> { +//! // Like above, but use `output` which returns a future instead of +//! // immediately returning the `Child`. +//! let output = Command::new("echo").arg("hello").arg("world") +//! .output(); +//! +//! let output = output.await?; +//! +//! assert!(output.status.success()); +//! assert_eq!(output.stdout, b"hello world\n"); +//! Ok(()) +//! } +//! ``` +//! +//! We can also read input line by line. +//! +//! ```no_run +//! use tokio::io::{BufReader, AsyncBufReadExt}; +//! use tokio::process::Command; +//! +//! use std::process::Stdio; +//! +//! #[tokio::main] +//! async fn main() -> Result<(), Box<dyn std::error::Error>> { +//! let mut cmd = Command::new("cat"); +//! +//! // Specify that we want the command's standard output piped back to us. +//! // By default, standard input/output/error will be inherited from the +//! // current process (for example, this means that standard input will +//! // come from the keyboard and standard output/error will go directly to +//! // the terminal if this process is invoked from the command line). +//! cmd.stdout(Stdio::piped()); +//! +//! let mut child = cmd.spawn() +//! .expect("failed to spawn command"); +//! +//! let stdout = child.stdout.take() +//! .expect("child did not have a handle to stdout"); +//! +//! let mut reader = BufReader::new(stdout).lines(); +//! +//! // Ensure the child process is spawned in the runtime so it can +//! // make progress on its own while we await for any output. +//! tokio::spawn(async move { +//! let status = child.wait().await +//! .expect("child process encountered an error"); +//! +//! println!("child status was: {}", status); +//! }); +//! +//! while let Some(line) = reader.next_line().await? { +//! println!("Line: {}", line); +//! } +//! +//! Ok(()) +//! } +//! ``` +//! +//! Here is another example using `sort` writing into the child process +//! standard input, capturing the output of the sorted text. +//! +//! ```no_run +//! use tokio::io::AsyncWriteExt; +//! use tokio::process::Command; +//! +//! use std::process::Stdio; +//! +//! #[tokio::main] +//! async fn main() -> Result<(), Box<dyn std::error::Error>> { +//! let mut cmd = Command::new("sort"); +//! +//! // Specifying that we want pipe both the output and the input. +//! // Similarily to capturing the output, by configuring the pipe +//! // to stdin it can now be used as an asynchronous writer. +//! cmd.stdout(Stdio::piped()); +//! cmd.stdin(Stdio::piped()); +//! +//! let mut child = cmd.spawn().expect("failed to spawn command"); +//! +//! // These are the animals we want to sort +//! let animals: &[&str] = &["dog", "bird", "frog", "cat", "fish"]; +//! +//! let mut stdin = child +//! .stdin +//! .take() +//! .expect("child did not have a handle to stdin"); +//! +//! // Write our animals to the child process +//! // Note that the behavior of `sort` is to buffer _all input_ before writing any output. +//! // In the general sense, it is recommended to write to the child in a separate task as +//! // awaiting its exit (or output) to avoid deadlocks (for example, the child tries to write +//! // some output but gets stuck waiting on the parent to read from it, meanwhile the parent +//! // is stuck waiting to write its input completely before reading the output). +//! stdin +//! .write(animals.join("\n").as_bytes()) +//! .await +//! .expect("could not write to stdin"); +//! +//! // We drop the handle here which signals EOF to the child process. +//! // This tells the child process that it there is no more data on the pipe. +//! drop(stdin); +//! +//! let op = child.wait_with_output().await?; +//! +//! // Results should come back in sorted order +//! assert_eq!(op.stdout, "bird\ncat\ndog\nfish\nfrog\n".as_bytes()); +//! +//! Ok(()) +//! } +//! ``` +//! +//! With some coordination, we can also pipe the output of one command into +//! another. +//! +//! ```no_run +//! use tokio::join; +//! use tokio::process::Command; +//! use std::convert::TryInto; +//! use std::process::Stdio; +//! +//! #[tokio::main] +//! async fn main() -> Result<(), Box<dyn std::error::Error>> { +//! let mut echo = Command::new("echo") +//! .arg("hello world!") +//! .stdout(Stdio::piped()) +//! .spawn() +//! .expect("failed to spawn echo"); +//! +//! let tr_stdin: Stdio = echo +//! .stdout +//! .take() +//! .unwrap() +//! .try_into() +//! .expect("failed to convert to Stdio"); +//! +//! let tr = Command::new("tr") +//! .arg("a-z") +//! .arg("A-Z") +//! .stdin(tr_stdin) +//! .stdout(Stdio::piped()) +//! .spawn() +//! .expect("failed to spawn tr"); +//! +//! let (echo_result, tr_output) = join!(echo.wait(), tr.wait_with_output()); +//! +//! assert!(echo_result.unwrap().success()); +//! +//! let tr_output = tr_output.expect("failed to await tr"); +//! assert!(tr_output.status.success()); +//! +//! assert_eq!(tr_output.stdout, b"HELLO WORLD!\n"); +//! +//! Ok(()) +//! } +//! ``` +//! +//! # Caveats +//! +//! ## Dropping/Cancellation +//! +//! Similar to the behavior to the standard library, and unlike the futures +//! paradigm of dropping-implies-cancellation, a spawned process will, by +//! default, continue to execute even after the `Child` handle has been dropped. +//! +//! The [`Command::kill_on_drop`] method can be used to modify this behavior +//! and kill the child process if the `Child` wrapper is dropped before it +//! has exited. +//! +//! ## Unix Processes +//! +//! On Unix platforms processes must be "reaped" by their parent process after +//! they have exited in order to release all OS resources. A child process which +//! has exited, but has not yet been reaped by its parent is considered a "zombie" +//! process. Such processes continue to count against limits imposed by the system, +//! and having too many zombie processes present can prevent additional processes +//! from being spawned. +//! +//! The tokio runtime will, on a best-effort basis, attempt to reap and clean up +//! any process which it has spawned. No additional guarantees are made with regards +//! how quickly or how often this procedure will take place. +//! +//! It is recommended to avoid dropping a [`Child`] process handle before it has been +//! fully `await`ed if stricter cleanup guarantees are required. +//! +//! [`Command`]: crate::process::Command +//! [`Command::kill_on_drop`]: crate::process::Command::kill_on_drop +//! [`Child`]: crate::process::Child + +#[path = "unix/mod.rs"] +#[cfg(unix)] +mod imp; + +#[cfg(unix)] +pub(crate) mod unix { + pub(crate) use super::imp::*; +} + +#[path = "windows.rs"] +#[cfg(windows)] +mod imp; + +mod kill; + +use crate::io::{AsyncRead, AsyncWrite, ReadBuf}; +use crate::process::kill::Kill; + +use std::convert::TryInto; +use std::ffi::OsStr; +use std::future::Future; +use std::io; +#[cfg(unix)] +use std::os::unix::process::CommandExt; +#[cfg(windows)] +use std::os::windows::io::{AsRawHandle, RawHandle}; +#[cfg(windows)] +use std::os::windows::process::CommandExt; +use std::path::Path; +use std::pin::Pin; +use std::process::{Command as StdCommand, ExitStatus, Output, Stdio}; +use std::task::Context; +use std::task::Poll; + +/// This structure mimics the API of [`std::process::Command`] found in the standard library, but +/// replaces functions that create a process with an asynchronous variant. The main provided +/// asynchronous functions are [spawn](Command::spawn), [status](Command::status), and +/// [output](Command::output). +/// +/// `Command` uses asynchronous versions of some `std` types (for example [`Child`]). +/// +/// [`std::process::Command`]: std::process::Command +/// [`Child`]: struct@Child +#[derive(Debug)] +pub struct Command { + std: StdCommand, + kill_on_drop: bool, +} + +pub(crate) struct SpawnedChild { + child: imp::Child, + stdin: Option<imp::ChildStdio>, + stdout: Option<imp::ChildStdio>, + stderr: Option<imp::ChildStdio>, +} + +impl Command { + /// Constructs a new `Command` for launching the program at + /// path `program`, with the following default configuration: + /// + /// * No arguments to the program + /// * Inherit the current process's environment + /// * Inherit the current process's working directory + /// * Inherit stdin/stdout/stderr for `spawn` or `status`, but create pipes for `output` + /// + /// Builder methods are provided to change these defaults and + /// otherwise configure the process. + /// + /// If `program` is not an absolute path, the `PATH` will be searched in + /// an OS-defined way. + /// + /// The search path to be used may be controlled by setting the + /// `PATH` environment variable on the Command, + /// but this has some implementation limitations on Windows + /// (see issue [rust-lang/rust#37519]). + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// let command = Command::new("sh"); + /// ``` + /// + /// [rust-lang/rust#37519]: https://github.com/rust-lang/rust/issues/37519 + pub fn new<S: AsRef<OsStr>>(program: S) -> Command { + Self::from(StdCommand::new(program)) + } + + /// Cheaply convert to a `&std::process::Command` for places where the type from the standard + /// library is expected. + pub fn as_std(&self) -> &StdCommand { + &self.std + } + + /// Adds an argument to pass to the program. + /// + /// Only one argument can be passed per use. So instead of: + /// + /// ```no_run + /// tokio::process::Command::new("sh") + /// .arg("-C /path/to/repo"); + /// ``` + /// + /// usage would be: + /// + /// ```no_run + /// tokio::process::Command::new("sh") + /// .arg("-C") + /// .arg("/path/to/repo"); + /// ``` + /// + /// To pass multiple arguments see [`args`]. + /// + /// [`args`]: method@Self::args + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .arg("-l") + /// .arg("-a"); + /// ``` + pub fn arg<S: AsRef<OsStr>>(&mut self, arg: S) -> &mut Command { + self.std.arg(arg); + self + } + + /// Adds multiple arguments to pass to the program. + /// + /// To pass a single argument see [`arg`]. + /// + /// [`arg`]: method@Self::arg + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .args(&["-l", "-a"]); + /// ``` + pub fn args<I, S>(&mut self, args: I) -> &mut Command + where + I: IntoIterator<Item = S>, + S: AsRef<OsStr>, + { + self.std.args(args); + self + } + + /// Inserts or updates an environment variable mapping. + /// + /// Note that environment variable names are case-insensitive (but case-preserving) on Windows, + /// and case-sensitive on all other platforms. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .env("PATH", "/bin"); + /// ``` + pub fn env<K, V>(&mut self, key: K, val: V) -> &mut Command + where + K: AsRef<OsStr>, + V: AsRef<OsStr>, + { + self.std.env(key, val); + self + } + + /// Adds or updates multiple environment variable mappings. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// use std::process::{Stdio}; + /// use std::env; + /// use std::collections::HashMap; + /// + /// let filtered_env : HashMap<String, String> = + /// env::vars().filter(|&(ref k, _)| + /// k == "TERM" || k == "TZ" || k == "LANG" || k == "PATH" + /// ).collect(); + /// + /// let command = Command::new("printenv") + /// .stdin(Stdio::null()) + /// .stdout(Stdio::inherit()) + /// .env_clear() + /// .envs(&filtered_env); + /// ``` + pub fn envs<I, K, V>(&mut self, vars: I) -> &mut Command + where + I: IntoIterator<Item = (K, V)>, + K: AsRef<OsStr>, + V: AsRef<OsStr>, + { + self.std.envs(vars); + self + } + + /// Removes an environment variable mapping. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .env_remove("PATH"); + /// ``` + pub fn env_remove<K: AsRef<OsStr>>(&mut self, key: K) -> &mut Command { + self.std.env_remove(key); + self + } + + /// Clears the entire environment map for the child process. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .env_clear(); + /// ``` + pub fn env_clear(&mut self) -> &mut Command { + self.std.env_clear(); + self + } + + /// Sets the working directory for the child process. + /// + /// # Platform-specific behavior + /// + /// If the program path is relative (e.g., `"./script.sh"`), it's ambiguous + /// whether it should be interpreted relative to the parent's working + /// directory or relative to `current_dir`. The behavior in this case is + /// platform specific and unstable, and it's recommended to use + /// [`canonicalize`] to get an absolute program path instead. + /// + /// [`canonicalize`]: crate::fs::canonicalize() + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .current_dir("/bin"); + /// ``` + pub fn current_dir<P: AsRef<Path>>(&mut self, dir: P) -> &mut Command { + self.std.current_dir(dir); + self + } + + /// Sets configuration for the child process's standard input (stdin) handle. + /// + /// Defaults to [`inherit`] when used with `spawn` or `status`, and + /// defaults to [`piped`] when used with `output`. + /// + /// [`inherit`]: std::process::Stdio::inherit + /// [`piped`]: std::process::Stdio::piped + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use std::process::{Stdio}; + /// use tokio::process::Command; + /// + /// let command = Command::new("ls") + /// .stdin(Stdio::null()); + /// ``` + pub fn stdin<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command { + self.std.stdin(cfg); + self + } + + /// Sets configuration for the child process's standard output (stdout) handle. + /// + /// Defaults to [`inherit`] when used with `spawn` or `status`, and + /// defaults to [`piped`] when used with `output`. + /// + /// [`inherit`]: std::process::Stdio::inherit + /// [`piped`]: std::process::Stdio::piped + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// use std::process::Stdio; + /// + /// let command = Command::new("ls") + /// .stdout(Stdio::null()); + /// ``` + pub fn stdout<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command { + self.std.stdout(cfg); + self + } + + /// Sets configuration for the child process's standard error (stderr) handle. + /// + /// Defaults to [`inherit`] when used with `spawn` or `status`, and + /// defaults to [`piped`] when used with `output`. + /// + /// [`inherit`]: std::process::Stdio::inherit + /// [`piped`]: std::process::Stdio::piped + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// use std::process::{Stdio}; + /// + /// let command = Command::new("ls") + /// .stderr(Stdio::null()); + /// ``` + pub fn stderr<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command { + self.std.stderr(cfg); + self + } + + /// Controls whether a `kill` operation should be invoked on a spawned child + /// process when its corresponding `Child` handle is dropped. + /// + /// By default, this value is assumed to be `false`, meaning the next spawned + /// process will not be killed on drop, similar to the behavior of the standard + /// library. + /// + /// # Caveats + /// + /// On Unix platforms processes must be "reaped" by their parent process after + /// they have exited in order to release all OS resources. A child process which + /// has exited, but has not yet been reaped by its parent is considered a "zombie" + /// process. Such processes continue to count against limits imposed by the system, + /// and having too many zombie processes present can prevent additional processes + /// from being spawned. + /// + /// Although issuing a `kill` signal to the child process is a synchronous + /// operation, the resulting zombie process cannot be `.await`ed inside of the + /// destructor to avoid blocking other tasks. The tokio runtime will, on a + /// best-effort basis, attempt to reap and clean up such processes in the + /// background, but makes no additional guarantees are made with regards + /// how quickly or how often this procedure will take place. + /// + /// If stronger guarantees are required, it is recommended to avoid dropping + /// a [`Child`] handle where possible, and instead utilize `child.wait().await` + /// or `child.kill().await` where possible. + pub fn kill_on_drop(&mut self, kill_on_drop: bool) -> &mut Command { + self.kill_on_drop = kill_on_drop; + self + } + + /// Sets the [process creation flags][1] to be passed to `CreateProcess`. + /// + /// These will always be ORed with `CREATE_UNICODE_ENVIRONMENT`. + /// + /// [1]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms684863(v=vs.85).aspx + #[cfg(windows)] + #[cfg_attr(docsrs, doc(cfg(windows)))] + pub fn creation_flags(&mut self, flags: u32) -> &mut Command { + self.std.creation_flags(flags); + self + } + + /// Sets the child process's user ID. This translates to a + /// `setuid` call in the child process. Failure in the `setuid` + /// call will cause the spawn to fail. + #[cfg(unix)] + #[cfg_attr(docsrs, doc(cfg(unix)))] + pub fn uid(&mut self, id: u32) -> &mut Command { + self.std.uid(id); + self + } + + /// Similar to `uid` but sets the group ID of the child process. This has + /// the same semantics as the `uid` field. + #[cfg(unix)] + #[cfg_attr(docsrs, doc(cfg(unix)))] + pub fn gid(&mut self, id: u32) -> &mut Command { + self.std.gid(id); + self + } + + /// Sets executable argument. + /// + /// Set the first process argument, `argv[0]`, to something other than the + /// default executable path. + #[cfg(unix)] + #[cfg_attr(docsrs, doc(cfg(unix)))] + pub fn arg0<S>(&mut self, arg: S) -> &mut Command + where + S: AsRef<OsStr>, + { + self.std.arg0(arg); + self + } + + /// Schedules a closure to be run just before the `exec` function is + /// invoked. + /// + /// The closure is allowed to return an I/O error whose OS error code will + /// be communicated back to the parent and returned as an error from when + /// the spawn was requested. + /// + /// Multiple closures can be registered and they will be called in order of + /// their registration. If a closure returns `Err` then no further closures + /// will be called and the spawn operation will immediately return with a + /// failure. + /// + /// # Safety + /// + /// This closure will be run in the context of the child process after a + /// `fork`. This primarily means that any modifications made to memory on + /// behalf of this closure will **not** be visible to the parent process. + /// This is often a very constrained environment where normal operations + /// like `malloc` or acquiring a mutex are not guaranteed to work (due to + /// other threads perhaps still running when the `fork` was run). + /// + /// This also means that all resources such as file descriptors and + /// memory-mapped regions got duplicated. It is your responsibility to make + /// sure that the closure does not violate library invariants by making + /// invalid use of these duplicates. + /// + /// When this closure is run, aspects such as the stdio file descriptors and + /// working directory have successfully been changed, so output to these + /// locations may not appear where intended. + #[cfg(unix)] + #[cfg_attr(docsrs, doc(cfg(unix)))] + pub unsafe fn pre_exec<F>(&mut self, f: F) -> &mut Command + where + F: FnMut() -> io::Result<()> + Send + Sync + 'static, + { + self.std.pre_exec(f); + self + } + + /// Executes the command as a child process, returning a handle to it. + /// + /// By default, stdin, stdout and stderr are inherited from the parent. + /// + /// This method will spawn the child process synchronously and return a + /// handle to a future-aware child process. The `Child` returned implements + /// `Future` itself to acquire the `ExitStatus` of the child, and otherwise + /// the `Child` has methods to acquire handles to the stdin, stdout, and + /// stderr streams. + /// + /// All I/O this child does will be associated with the current default + /// event loop. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// async fn run_ls() -> std::process::ExitStatus { + /// Command::new("ls") + /// .spawn() + /// .expect("ls command failed to start") + /// .wait() + /// .await + /// .expect("ls command failed to run") + /// } + /// ``` + /// + /// # Caveats + /// + /// ## Dropping/Cancellation + /// + /// Similar to the behavior to the standard library, and unlike the futures + /// paradigm of dropping-implies-cancellation, a spawned process will, by + /// default, continue to execute even after the `Child` handle has been dropped. + /// + /// The [`Command::kill_on_drop`] method can be used to modify this behavior + /// and kill the child process if the `Child` wrapper is dropped before it + /// has exited. + /// + /// ## Unix Processes + /// + /// On Unix platforms processes must be "reaped" by their parent process after + /// they have exited in order to release all OS resources. A child process which + /// has exited, but has not yet been reaped by its parent is considered a "zombie" + /// process. Such processes continue to count against limits imposed by the system, + /// and having too many zombie processes present can prevent additional processes + /// from being spawned. + /// + /// The tokio runtime will, on a best-effort basis, attempt to reap and clean up + /// any process which it has spawned. No additional guarantees are made with regards + /// how quickly or how often this procedure will take place. + /// + /// It is recommended to avoid dropping a [`Child`] process handle before it has been + /// fully `await`ed if stricter cleanup guarantees are required. + /// + /// [`Command`]: crate::process::Command + /// [`Command::kill_on_drop`]: crate::process::Command::kill_on_drop + /// [`Child`]: crate::process::Child + /// + /// # Errors + /// + /// On Unix platforms this method will fail with `std::io::ErrorKind::WouldBlock` + /// if the system process limit is reached (which includes other applications + /// running on the system). + pub fn spawn(&mut self) -> io::Result<Child> { + imp::spawn_child(&mut self.std).map(|spawned_child| Child { + child: FusedChild::Child(ChildDropGuard { + inner: spawned_child.child, + kill_on_drop: self.kill_on_drop, + }), + stdin: spawned_child.stdin.map(|inner| ChildStdin { inner }), + stdout: spawned_child.stdout.map(|inner| ChildStdout { inner }), + stderr: spawned_child.stderr.map(|inner| ChildStderr { inner }), + }) + } + + /// Executes the command as a child process, waiting for it to finish and + /// collecting its exit status. + /// + /// By default, stdin, stdout and stderr are inherited from the parent. + /// If any input/output handles are set to a pipe then they will be immediately + /// closed after the child is spawned. + /// + /// All I/O this child does will be associated with the current default + /// event loop. + /// + /// The destructor of the future returned by this function will kill + /// the child if [`kill_on_drop`] is set to true. + /// + /// [`kill_on_drop`]: fn@Self::kill_on_drop + /// + /// # Errors + /// + /// This future will return an error if the child process cannot be spawned + /// or if there is an error while awaiting its status. + /// + /// On Unix platforms this method will fail with `std::io::ErrorKind::WouldBlock` + /// if the system process limit is reached (which includes other applications + /// running on the system). + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// async fn run_ls() -> std::process::ExitStatus { + /// Command::new("ls") + /// .status() + /// .await + /// .expect("ls command failed to run") + /// } + /// ``` + pub fn status(&mut self) -> impl Future<Output = io::Result<ExitStatus>> { + let child = self.spawn(); + + async { + let mut child = child?; + + // Ensure we close any stdio handles so we can't deadlock + // waiting on the child which may be waiting to read/write + // to a pipe we're holding. + child.stdin.take(); + child.stdout.take(); + child.stderr.take(); + + child.wait().await + } + } + + /// Executes the command as a child process, waiting for it to finish and + /// collecting all of its output. + /// + /// > **Note**: this method, unlike the standard library, will + /// > unconditionally configure the stdout/stderr handles to be pipes, even + /// > if they have been previously configured. If this is not desired then + /// > the `spawn` method should be used in combination with the + /// > `wait_with_output` method on child. + /// + /// This method will return a future representing the collection of the + /// child process's stdout/stderr. It will resolve to + /// the `Output` type in the standard library, containing `stdout` and + /// `stderr` as `Vec<u8>` along with an `ExitStatus` representing how the + /// process exited. + /// + /// All I/O this child does will be associated with the current default + /// event loop. + /// + /// The destructor of the future returned by this function will kill + /// the child if [`kill_on_drop`] is set to true. + /// + /// [`kill_on_drop`]: fn@Self::kill_on_drop + /// + /// # Errors + /// + /// This future will return an error if the child process cannot be spawned + /// or if there is an error while awaiting its status. + /// + /// On Unix platforms this method will fail with `std::io::ErrorKind::WouldBlock` + /// if the system process limit is reached (which includes other applications + /// running on the system). + /// # Examples + /// + /// Basic usage: + /// + /// ```no_run + /// use tokio::process::Command; + /// + /// async fn run_ls() { + /// let output: std::process::Output = Command::new("ls") + /// .output() + /// .await + /// .expect("ls command failed to run"); + /// println!("stderr of ls: {:?}", output.stderr); + /// } + /// ``` + pub fn output(&mut self) -> impl Future<Output = io::Result<Output>> { + self.std.stdout(Stdio::piped()); + self.std.stderr(Stdio::piped()); + + let child = self.spawn(); + + async { child?.wait_with_output().await } + } +} + +impl From<StdCommand> for Command { + fn from(std: StdCommand) -> Command { + Command { + std, + kill_on_drop: false, + } + } +} + +/// A drop guard which can ensure the child process is killed on drop if specified. +#[derive(Debug)] +struct ChildDropGuard<T: Kill> { + inner: T, + kill_on_drop: bool, +} + +impl<T: Kill> Kill for ChildDropGuard<T> { + fn kill(&mut self) -> io::Result<()> { + let ret = self.inner.kill(); + + if ret.is_ok() { + self.kill_on_drop = false; + } + + ret + } +} + +impl<T: Kill> Drop for ChildDropGuard<T> { + fn drop(&mut self) { + if self.kill_on_drop { + drop(self.kill()); + } + } +} + +impl<T, E, F> Future for ChildDropGuard<F> +where + F: Future<Output = Result<T, E>> + Kill + Unpin, +{ + type Output = Result<T, E>; + + fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + // Keep track of task budget + let coop = ready!(crate::coop::poll_proceed(cx)); + + let ret = Pin::new(&mut self.inner).poll(cx); + + if let Poll::Ready(Ok(_)) = ret { + // Avoid the overhead of trying to kill a reaped process + self.kill_on_drop = false; + } + + if ret.is_ready() { + coop.made_progress(); + } + + ret + } +} + +/// Keeps track of the exit status of a child process without worrying about +/// polling the underlying futures even after they have completed. +#[derive(Debug)] +enum FusedChild { + Child(ChildDropGuard<imp::Child>), + Done(ExitStatus), +} + +/// Representation of a child process spawned onto an event loop. +/// +/// # Caveats +/// Similar to the behavior to the standard library, and unlike the futures +/// paradigm of dropping-implies-cancellation, a spawned process will, by +/// default, continue to execute even after the `Child` handle has been dropped. +/// +/// The `Command::kill_on_drop` method can be used to modify this behavior +/// and kill the child process if the `Child` wrapper is dropped before it +/// has exited. +#[derive(Debug)] +pub struct Child { + child: FusedChild, + + /// The handle for writing to the child's standard input (stdin), if it has + /// been captured. To avoid partially moving the `child` and thus blocking + /// yourself from calling functions on `child` while using `stdin`, you might + /// find it helpful to do: + /// + /// ```no_run + /// # let mut child = tokio::process::Command::new("echo").spawn().unwrap(); + /// let stdin = child.stdin.take().unwrap(); + /// ``` + pub stdin: Option<ChildStdin>, + + /// The handle for reading from the child's standard output (stdout), if it + /// has been captured. You might find it helpful to do + /// + /// ```no_run + /// # let mut child = tokio::process::Command::new("echo").spawn().unwrap(); + /// let stdout = child.stdout.take().unwrap(); + /// ``` + /// + /// to avoid partially moving the `child` and thus blocking yourself from calling + /// functions on `child` while using `stdout`. + pub stdout: Option<ChildStdout>, + + /// The handle for reading from the child's standard error (stderr), if it + /// has been captured. You might find it helpful to do + /// + /// ```no_run + /// # let mut child = tokio::process::Command::new("echo").spawn().unwrap(); + /// let stderr = child.stderr.take().unwrap(); + /// ``` + /// + /// to avoid partially moving the `child` and thus blocking yourself from calling + /// functions on `child` while using `stderr`. + pub stderr: Option<ChildStderr>, +} + +impl Child { + /// Returns the OS-assigned process identifier associated with this child + /// while it is still running. + /// + /// Once the child has been polled to completion this will return `None`. + /// This is done to avoid confusion on platforms like Unix where the OS + /// identifier could be reused once the process has completed. + pub fn id(&self) -> Option<u32> { + match &self.child { + FusedChild::Child(child) => Some(child.inner.id()), + FusedChild::Done(_) => None, + } + } + + /// Extracts the raw handle of the process associated with this child while + /// it is still running. Returns `None` if the child has exited. + #[cfg(windows)] + pub fn raw_handle(&self) -> Option<RawHandle> { + match &self.child { + FusedChild::Child(c) => Some(c.inner.as_raw_handle()), + FusedChild::Done(_) => None, + } + } + + /// Attempts to force the child to exit, but does not wait for the request + /// to take effect. + /// + /// On Unix platforms, this is the equivalent to sending a SIGKILL. Note + /// that on Unix platforms it is possible for a zombie process to remain + /// after a kill is sent; to avoid this, the caller should ensure that either + /// `child.wait().await` or `child.try_wait()` is invoked successfully. + pub fn start_kill(&mut self) -> io::Result<()> { + match &mut self.child { + FusedChild::Child(child) => child.kill(), + FusedChild::Done(_) => Err(io::Error::new( + io::ErrorKind::InvalidInput, + "invalid argument: can't kill an exited process", + )), + } + } + + /// Forces the child to exit. + /// + /// This is equivalent to sending a SIGKILL on unix platforms. + /// + /// If the child has to be killed remotely, it is possible to do it using + /// a combination of the select! macro and a oneshot channel. In the following + /// example, the child will run until completion unless a message is sent on + /// the oneshot channel. If that happens, the child is killed immediately + /// using the `.kill()` method. + /// + /// ```no_run + /// use tokio::process::Command; + /// use tokio::sync::oneshot::channel; + /// + /// #[tokio::main] + /// async fn main() { + /// let (send, recv) = channel::<()>(); + /// let mut child = Command::new("sleep").arg("1").spawn().unwrap(); + /// tokio::spawn(async move { send.send(()) }); + /// tokio::select! { + /// _ = child.wait() => {} + /// _ = recv => child.kill().await.expect("kill failed"), + /// } + /// } + /// ``` + pub async fn kill(&mut self) -> io::Result<()> { + self.start_kill()?; + self.wait().await?; + Ok(()) + } + + /// Waits for the child to exit completely, returning the status that it + /// exited with. This function will continue to have the same return value + /// after it has been called at least once. + /// + /// The stdin handle to the child process, if any, will be closed + /// before waiting. This helps avoid deadlock: it ensures that the + /// child does not block waiting for input from the parent, while + /// the parent waits for the child to exit. + /// + /// If the caller wishes to explicitly control when the child's stdin + /// handle is closed, they may `.take()` it before calling `.wait()`: + /// + /// ``` + /// # #[cfg(not(unix))]fn main(){} + /// # #[cfg(unix)] + /// use tokio::io::AsyncWriteExt; + /// # #[cfg(unix)] + /// use tokio::process::Command; + /// # #[cfg(unix)] + /// use std::process::Stdio; + /// + /// # #[cfg(unix)] + /// #[tokio::main] + /// async fn main() { + /// let mut child = Command::new("cat") + /// .stdin(Stdio::piped()) + /// .spawn() + /// .unwrap(); + /// + /// let mut stdin = child.stdin.take().unwrap(); + /// tokio::spawn(async move { + /// // do something with stdin here... + /// stdin.write_all(b"hello world\n").await.unwrap(); + /// + /// // then drop when finished + /// drop(stdin); + /// }); + /// + /// // wait for the process to complete + /// let _ = child.wait().await; + /// } + /// ``` + pub async fn wait(&mut self) -> io::Result<ExitStatus> { + // Ensure stdin is closed so the child isn't stuck waiting on + // input while the parent is waiting for it to exit. + drop(self.stdin.take()); + + match &mut self.child { + FusedChild::Done(exit) => Ok(*exit), + FusedChild::Child(child) => { + let ret = child.await; + + if let Ok(exit) = ret { + self.child = FusedChild::Done(exit); + } + + ret + } + } + } + + /// Attempts to collect the exit status of the child if it has already + /// exited. + /// + /// This function will not block the calling thread and will only + /// check to see if the child process has exited or not. If the child has + /// exited then on Unix the process ID is reaped. This function is + /// guaranteed to repeatedly return a successful exit status so long as the + /// child has already exited. + /// + /// If the child has exited, then `Ok(Some(status))` is returned. If the + /// exit status is not available at this time then `Ok(None)` is returned. + /// If an error occurs, then that error is returned. + /// + /// Note that unlike `wait`, this function will not attempt to drop stdin, + /// nor will it wake the current task if the child exits. + pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> { + match &mut self.child { + FusedChild::Done(exit) => Ok(Some(*exit)), + FusedChild::Child(guard) => { + let ret = guard.inner.try_wait(); + + if let Ok(Some(exit)) = ret { + // Avoid the overhead of trying to kill a reaped process + guard.kill_on_drop = false; + self.child = FusedChild::Done(exit); + } + + ret + } + } + } + + /// Returns a future that will resolve to an `Output`, containing the exit + /// status, stdout, and stderr of the child process. + /// + /// The returned future will simultaneously waits for the child to exit and + /// collect all remaining output on the stdout/stderr handles, returning an + /// `Output` instance. + /// + /// The stdin handle to the child process, if any, will be closed before + /// waiting. This helps avoid deadlock: it ensures that the child does not + /// block waiting for input from the parent, while the parent waits for the + /// child to exit. + /// + /// By default, stdin, stdout and stderr are inherited from the parent. In + /// order to capture the output into this `Output` it is necessary to create + /// new pipes between parent and child. Use `stdout(Stdio::piped())` or + /// `stderr(Stdio::piped())`, respectively, when creating a `Command`. + pub async fn wait_with_output(mut self) -> io::Result<Output> { + use crate::future::try_join3; + + async fn read_to_end<A: AsyncRead + Unpin>(io: &mut Option<A>) -> io::Result<Vec<u8>> { + let mut vec = Vec::new(); + if let Some(io) = io.as_mut() { + crate::io::util::read_to_end(io, &mut vec).await?; + } + Ok(vec) + } + + let mut stdout_pipe = self.stdout.take(); + let mut stderr_pipe = self.stderr.take(); + + let stdout_fut = read_to_end(&mut stdout_pipe); + let stderr_fut = read_to_end(&mut stderr_pipe); + + let (status, stdout, stderr) = try_join3(self.wait(), stdout_fut, stderr_fut).await?; + + // Drop happens after `try_join` due to <https://github.com/tokio-rs/tokio/issues/4309> + drop(stdout_pipe); + drop(stderr_pipe); + + Ok(Output { + status, + stdout, + stderr, + }) + } +} + +/// The standard input stream for spawned children. +/// +/// This type implements the `AsyncWrite` trait to pass data to the stdin handle of +/// handle of a child process asynchronously. +#[derive(Debug)] +pub struct ChildStdin { + inner: imp::ChildStdio, +} + +/// The standard output stream for spawned children. +/// +/// This type implements the `AsyncRead` trait to read data from the stdout +/// handle of a child process asynchronously. +#[derive(Debug)] +pub struct ChildStdout { + inner: imp::ChildStdio, +} + +/// The standard error stream for spawned children. +/// +/// This type implements the `AsyncRead` trait to read data from the stderr +/// handle of a child process asynchronously. +#[derive(Debug)] +pub struct ChildStderr { + inner: imp::ChildStdio, +} + +impl ChildStdin { + /// Creates an asynchronous `ChildStdin` from a synchronous one. + /// + /// # Errors + /// + /// This method may fail if an error is encountered when setting the pipe to + /// non-blocking mode, or when registering the pipe with the runtime's IO + /// driver. + pub fn from_std(inner: std::process::ChildStdin) -> io::Result<Self> { + Ok(Self { + inner: imp::stdio(inner)?, + }) + } +} + +impl ChildStdout { + /// Creates an asynchronous `ChildStderr` from a synchronous one. + /// + /// # Errors + /// + /// This method may fail if an error is encountered when setting the pipe to + /// non-blocking mode, or when registering the pipe with the runtime's IO + /// driver. + pub fn from_std(inner: std::process::ChildStdout) -> io::Result<Self> { + Ok(Self { + inner: imp::stdio(inner)?, + }) + } +} + +impl ChildStderr { + /// Creates an asynchronous `ChildStderr` from a synchronous one. + /// + /// # Errors + /// + /// This method may fail if an error is encountered when setting the pipe to + /// non-blocking mode, or when registering the pipe with the runtime's IO + /// driver. + pub fn from_std(inner: std::process::ChildStderr) -> io::Result<Self> { + Ok(Self { + inner: imp::stdio(inner)?, + }) + } +} + +impl AsyncWrite for ChildStdin { + fn poll_write( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + buf: &[u8], + ) -> Poll<io::Result<usize>> { + self.inner.poll_write(cx, buf) + } + + fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> { + Poll::Ready(Ok(())) + } + + fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> { + Poll::Ready(Ok(())) + } +} + +impl AsyncRead for ChildStdout { + fn poll_read( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + buf: &mut ReadBuf<'_>, + ) -> Poll<io::Result<()>> { + // Safety: pipes support reading into uninitialized memory + unsafe { self.inner.poll_read(cx, buf) } + } +} + +impl AsyncRead for ChildStderr { + fn poll_read( + self: Pin<&mut Self>, + cx: &mut Context<'_>, + buf: &mut ReadBuf<'_>, + ) -> Poll<io::Result<()>> { + // Safety: pipes support reading into uninitialized memory + unsafe { self.inner.poll_read(cx, buf) } + } +} + +impl TryInto<Stdio> for ChildStdin { + type Error = io::Error; + + fn try_into(self) -> Result<Stdio, Self::Error> { + imp::convert_to_stdio(self.inner) + } +} + +impl TryInto<Stdio> for ChildStdout { + type Error = io::Error; + + fn try_into(self) -> Result<Stdio, Self::Error> { + imp::convert_to_stdio(self.inner) + } +} + +impl TryInto<Stdio> for ChildStderr { + type Error = io::Error; + + fn try_into(self) -> Result<Stdio, Self::Error> { + imp::convert_to_stdio(self.inner) + } +} + +#[cfg(unix)] +mod sys { + use std::os::unix::io::{AsRawFd, RawFd}; + + use super::{ChildStderr, ChildStdin, ChildStdout}; + + impl AsRawFd for ChildStdin { + fn as_raw_fd(&self) -> RawFd { + self.inner.as_raw_fd() + } + } + + impl AsRawFd for ChildStdout { + fn as_raw_fd(&self) -> RawFd { + self.inner.as_raw_fd() + } + } + + impl AsRawFd for ChildStderr { + fn as_raw_fd(&self) -> RawFd { + self.inner.as_raw_fd() + } + } +} + +#[cfg(windows)] +mod sys { + use std::os::windows::io::{AsRawHandle, RawHandle}; + + use super::{ChildStderr, ChildStdin, ChildStdout}; + + impl AsRawHandle for ChildStdin { + fn as_raw_handle(&self) -> RawHandle { + self.inner.as_raw_handle() + } + } + + impl AsRawHandle for ChildStdout { + fn as_raw_handle(&self) -> RawHandle { + self.inner.as_raw_handle() + } + } + + impl AsRawHandle for ChildStderr { + fn as_raw_handle(&self) -> RawHandle { + self.inner.as_raw_handle() + } + } +} + +#[cfg(all(test, not(loom)))] +mod test { + use super::kill::Kill; + use super::ChildDropGuard; + + use futures::future::FutureExt; + use std::future::Future; + use std::io; + use std::pin::Pin; + use std::task::{Context, Poll}; + + struct Mock { + num_kills: usize, + num_polls: usize, + poll_result: Poll<Result<(), ()>>, + } + + impl Mock { + fn new() -> Self { + Self::with_result(Poll::Pending) + } + + fn with_result(result: Poll<Result<(), ()>>) -> Self { + Self { + num_kills: 0, + num_polls: 0, + poll_result: result, + } + } + } + + impl Kill for Mock { + fn kill(&mut self) -> io::Result<()> { + self.num_kills += 1; + Ok(()) + } + } + + impl Future for Mock { + type Output = Result<(), ()>; + + fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> { + let inner = Pin::get_mut(self); + inner.num_polls += 1; + inner.poll_result + } + } + + #[test] + fn kills_on_drop_if_specified() { + let mut mock = Mock::new(); + + { + let guard = ChildDropGuard { + inner: &mut mock, + kill_on_drop: true, + }; + drop(guard); + } + + assert_eq!(1, mock.num_kills); + assert_eq!(0, mock.num_polls); + } + + #[test] + fn no_kill_on_drop_by_default() { + let mut mock = Mock::new(); + + { + let guard = ChildDropGuard { + inner: &mut mock, + kill_on_drop: false, + }; + drop(guard); + } + + assert_eq!(0, mock.num_kills); + assert_eq!(0, mock.num_polls); + } + + #[test] + fn no_kill_if_already_killed() { + let mut mock = Mock::new(); + + { + let mut guard = ChildDropGuard { + inner: &mut mock, + kill_on_drop: true, + }; + let _ = guard.kill(); + drop(guard); + } + + assert_eq!(1, mock.num_kills); + assert_eq!(0, mock.num_polls); + } + + #[test] + fn no_kill_if_reaped() { + let mut mock_pending = Mock::with_result(Poll::Pending); + let mut mock_reaped = Mock::with_result(Poll::Ready(Ok(()))); + let mut mock_err = Mock::with_result(Poll::Ready(Err(()))); + + let waker = futures::task::noop_waker(); + let mut context = Context::from_waker(&waker); + { + let mut guard = ChildDropGuard { + inner: &mut mock_pending, + kill_on_drop: true, + }; + let _ = guard.poll_unpin(&mut context); + + let mut guard = ChildDropGuard { + inner: &mut mock_reaped, + kill_on_drop: true, + }; + let _ = guard.poll_unpin(&mut context); + + let mut guard = ChildDropGuard { + inner: &mut mock_err, + kill_on_drop: true, + }; + let _ = guard.poll_unpin(&mut context); + } + + assert_eq!(1, mock_pending.num_kills); + assert_eq!(1, mock_pending.num_polls); + + assert_eq!(0, mock_reaped.num_kills); + assert_eq!(1, mock_reaped.num_polls); + + assert_eq!(1, mock_err.num_kills); + assert_eq!(1, mock_err.num_polls); + } +} |