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//! This crate allows running a process with a timeout, with the option to //! terminate it automatically afterward. The latter is surprisingly difficult //! to achieve on Unix, since process identifiers can be arbitrarily reassigned //! when no longer used. Thus, it would be extremely easy to inadvertently //! terminate an unexpected process. This crate protects against that //! possibility. //! //! Methods for creating timeouts are available on [`ChildExt`], which is //! implemented for [`Child`]. They each return a builder of options to //! configure how the timeout should be applied. //! //! # Implementation //! //! All traits are [sealed], meaning that they can only be implemented by this //! crate. Otherwise, backward compatibility would be more difficult to //! maintain for new features. //! //! # Comparable Crates //! //! - [wait-timeout] - //! Made for a related purpose but does not provide the same functionality. //! Processes cannot be terminated automatically, and there is no counterpart //! of [`Child::wait_with_output`] to read output while setting a timeout. //! This crate aims to fill in those gaps and simplify the implementation, //! now that [`Receiver::recv_timeout`] exists. //! //! # Examples //! //! ``` //! use std::io; //! use std::process::Command; //! use std::process::Stdio; //! use std::time::Duration; //! //! use process_control::ChildExt; //! use process_control::Timeout; //! //! let process = Command::new("echo") //! .arg("hello") //! .stdout(Stdio::piped()) //! .spawn()?; //! //! let output = process //! .with_output_timeout(Duration::from_secs(1)) //! .terminating() //! .wait()? //! .ok_or_else(|| { //! io::Error::new(io::ErrorKind::TimedOut, "Process timed out") //! })?; //! assert_eq!(b"hello", &output.stdout[..5]); //! # //! # Ok::<_, io::Error>(()) //! ``` //! //! [`Child`]: https://doc.rust-lang.org/std/process/struct.Child.html //! [`ChildExt`]: trait.ChildExt.html //! [`Child::wait_with_output`]: https://doc.rust-lang.org/std/process/struct.Child.html#method.wait_with_output //! [`Receiver::recv_timeout`]: https://doc.rust-lang.org/std/sync/mpsc/struct.Receiver.html#method.recv_timeout //! [sealed]: https://rust-lang.github.io/api-guidelines/future-proofing.html#c-sealed //! [wait-timeout]: https://crates.io/crates/wait-timeout #![doc(html_root_url = "https://docs.rs/process_control/*")] // Only require a nightly compiler when building documentation for docs.rs. // This is a private option that should not be used. // https://github.com/rust-lang/docs.rs/issues/147#issuecomment-389544407 #![cfg_attr(process_control_docs_rs, feature(doc_cfg))] #![warn(unused_results)] use std::fmt; use std::fmt::Display; use std::fmt::Formatter; use std::io; use std::process; use std::process::Child; use std::time::Duration; #[cfg(unix)] #[path = "unix.rs"] mod imp; #[cfg(windows)] #[path = "windows.rs"] mod imp; mod timeout; /// A wrapper that stores enough information to terminate a process. /// /// Instances can only be constructed using [`ChildExt::terminator`]. /// /// [`ChildExt::terminator`]: trait.ChildExt.html#tymethod.terminator #[derive(Debug)] pub struct Terminator(imp::Handle); impl Terminator { /// Terminates a process as immediately as the operating system allows. /// /// Behavior should be equivalent to calling [`Child::kill`] for the same /// process. However, this method does not require a reference of any kind /// to the [`Child`] instance of the process, meaning that it can be called /// even in some unsafe circumstances. /// /// # Safety /// /// If the process is no longer running, a different process may be /// terminated on some operating systems. Reuse of process identifiers /// makes it impossible for this method to determine if the intended /// process still exists. /// /// Thus, this method should not be used in production code, as /// [`Child::kill`] more safely provides the same functionality. It is only /// used for testing in this crate and may be used similarly in others. /// /// # Examples /// /// ``` /// # use std::io; /// use std::path::Path; /// use std::process::Command; /// use std::thread; /// /// use process_control::ChildExt; /// /// let dir = Path::new("hello"); /// let mut process = Command::new("mkdir").arg(dir).spawn()?; /// let terminator = process.terminator()?; /// /// let thread = thread::spawn(move || process.wait()); /// if !dir.exists() { /// // [process.kill] requires a mutable reference. /// unsafe { terminator.terminate()? } /// } /// /// let exit_status = thread.join().expect("thread panicked")?; /// println!("exited {}", exit_status); /// # /// # Ok::<_, io::Error>(()) /// ``` /// /// [`Child`]: https://doc.rust-lang.org/std/process/struct.Child.html /// [`Child::kill`]: https://doc.rust-lang.org/std/process/struct.Child.html#method.kill #[inline] pub unsafe fn terminate(&self) -> io::Result<()> { self.0.terminate() } } /// Equivalent to [`ExitStatus`] in the standard library but allows for greater /// accuracy. /// /// [`ExitStatus`]: https://doc.rust-lang.org/std/process/struct.ExitStatus.html #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub struct ExitStatus(imp::ExitStatus); impl ExitStatus { /// Equivalent to [`ExitStatus::success`]. /// /// [`ExitStatus::success`]: https://doc.rust-lang.org/std/process/struct.ExitStatus.html#method.success #[inline] #[must_use] pub fn success(self) -> bool { self.0.success() } /// Equivalent to [`ExitStatus::code`], but a more accurate value will be /// returned if possible. /// /// [`ExitStatus::code`]: https://doc.rust-lang.org/std/process/struct.ExitStatus.html#method.code #[inline] #[must_use] pub fn code(self) -> Option<i64> { self.0.code().map(Into::into) } /// Equivalent to [`ExitStatusExt::signal`]. /// /// [`ExitStatusExt::signal`]: https://doc.rust-lang.org/std/os/unix/process/trait.ExitStatusExt.html#tymethod.signal #[cfg(any(unix, doc))] #[cfg_attr(process_control_docs_rs, doc(cfg(unix)))] #[inline] #[must_use] pub fn signal(self) -> Option<::std::os::raw::c_int> { self.0.signal() } } impl Display for ExitStatus { #[inline] fn fmt(&self, formatter: &mut Formatter<'_>) -> fmt::Result { self.0.fmt(formatter) } } impl From<process::ExitStatus> for ExitStatus { #[inline] fn from(value: process::ExitStatus) -> Self { Self(value.into()) } } /// Equivalent to [`Output`] in the standard library but holds an instance of /// [`ExitStatus`] from this crate. /// /// [`ExitStatus`]: struct.ExitStatus.html /// [`Output`]: https://doc.rust-lang.org/std/process/struct.Output.html #[derive(Clone, Debug, Eq, PartialEq)] pub struct Output { /// Equivalent to [`Output::status`]. /// /// [`Output::status`]: https://doc.rust-lang.org/std/process/struct.Output.html#structfield.status pub status: ExitStatus, /// Equivalent to [`Output::stdout`]. /// /// [`Output::stdout`]: https://doc.rust-lang.org/std/process/struct.Output.html#structfield.stdout pub stdout: Vec<u8>, /// Equivalent to [`Output::stderr`]. /// /// [`Output::stderr`]: https://doc.rust-lang.org/std/process/struct.Output.html#structfield.stderr pub stderr: Vec<u8>, } impl From<process::Output> for Output { #[inline] fn from(value: process::Output) -> Self { Self { status: value.status.into(), stdout: value.stdout, stderr: value.stderr, } } } /// A temporary wrapper for a process timeout. pub trait Timeout: private::Sealed { /// The type returned by [`wait`]. /// /// [`wait`]: #tymethod.wait type Result; /// Causes [`wait`] to never suppress an error. /// /// Typically, errors terminating the process will be ignored, as they are /// often less important than the result. However, when this method is /// called, those errors will be returned as well. /// /// [`wait`]: #tymethod.wait #[must_use] fn strict_errors(self) -> Self; /// Causes the process to be terminated if it exceeds the time limit. /// /// Process identifier reuse by the system will be mitigated. There should /// never be a scenario that causes an unintended process to be terminated. #[must_use] fn terminating(self) -> Self; /// Runs the process to completion, aborting if it exceeds the time limit. /// /// At least one thread will be created to wait on the process without /// blocking the current thread. /// /// If the time limit is exceeded before the process finishes, `Ok(None)` /// will be returned. However, the process will not be terminated in that /// case unless [`terminating`] is called beforehand. It is recommended to /// always call that method to allow system resources to be freed. /// /// The stdin handle to the process, if it exists, will be closed before /// waiting. Otherwise, the process would assuredly time out when reading /// from that pipe. /// /// This method cannot guarantee that the same [`ErrorKind`] variants will /// be returned in the future for the same types of failures. Allowing /// these breakages is required to be compatible with the [`Error`] type. /// /// [`Error`]: https://doc.rust-lang.org/std/io/struct.Error.html /// [`ErrorKind`]: https://doc.rust-lang.org/std/io/enum.ErrorKind.html /// [`terminating`]: #tymethod.terminating fn wait(self) -> io::Result<Option<Self::Result>>; } /// Extensions to [`Child`] for easily terminating processes. /// /// For more information, see [the module-level documentation][module]. /// /// [module]: index.html /// [`Child`]: https://doc.rust-lang.org/std/process/struct.Child.html pub trait ChildExt<'a>: private::Sealed { /// The type returned by [`with_timeout`]. /// /// [`with_timeout`]: #tymethod.with_timeout type ExitStatusTimeout: 'a + Timeout<Result = ExitStatus>; /// The type returned by [`with_output_timeout`]. /// /// [`with_output_timeout`]: #tymethod.with_output_timeout type OutputTimeout: Timeout<Result = Output>; /// Creates an instance of [`Terminator`] for this process. /// /// # Examples /// /// ``` /// # use std::io; /// use std::process::Command; /// /// use process_control::ChildExt; /// /// let process = Command::new("echo").spawn()?; /// # #[allow(unused_variables)] /// let terminator = process.terminator()?; /// # /// # Ok::<_, io::Error>(()) /// ``` /// /// [`Terminator`]: struct.Terminator.html fn terminator(&self) -> io::Result<Terminator>; /// Creates an instance of [`Timeout`] that yields [`ExitStatus`] for this /// process. /// /// This method parallels [`Child::wait`] when the process must finish /// within a time limit. /// /// # Examples /// /// ``` /// # use std::io; /// use std::process::Command; /// use std::time::Duration; /// /// use process_control::ChildExt; /// use process_control::Timeout; /// /// let exit_status = Command::new("echo") /// .spawn()? /// .with_timeout(Duration::from_secs(1)) /// .terminating() /// .wait()? /// .expect("process timed out"); /// assert!(exit_status.success()); /// # /// # Ok::<_, io::Error>(()) /// ``` /// /// [`Child::wait`]: https://doc.rust-lang.org/std/process/struct.Child.html#method.wait /// [`ExitStatus`]: struct.ExitStatus.html /// [`Timeout`]: trait.Timeout.html #[must_use] fn with_timeout( &'a mut self, time_limit: Duration, ) -> Self::ExitStatusTimeout; /// Creates an instance of [`Timeout`] that yields [`Output`] for this /// process. /// /// This method parallels [`Child::wait_with_output`] when the process must /// finish within a time limit. /// /// # Examples /// /// ``` /// # use std::io; /// use std::process::Command; /// use std::time::Duration; /// /// use process_control::ChildExt; /// use process_control::Timeout; /// /// let output = Command::new("echo") /// .spawn()? /// .with_output_timeout(Duration::from_secs(1)) /// .terminating() /// .wait()? /// .expect("process timed out"); /// assert!(output.status.success()); /// # /// # Ok::<_, io::Error>(()) /// ``` /// /// [`Child::wait_with_output`]: https://doc.rust-lang.org/std/process/struct.Child.html#method.wait_with_output /// [`Output`]: struct.Output.html /// [`Timeout`]: trait.Timeout.html #[must_use] fn with_output_timeout(self, time_limit: Duration) -> Self::OutputTimeout; } impl<'a> ChildExt<'a> for Child { type ExitStatusTimeout = timeout::ExitStatusTimeout<'a>; type OutputTimeout = timeout::OutputTimeout; #[inline] fn terminator(&self) -> io::Result<Terminator> { imp::Handle::new(self).map(Terminator) } #[inline] fn with_timeout( &'a mut self, time_limit: Duration, ) -> Self::ExitStatusTimeout { Self::ExitStatusTimeout::new(self, time_limit) } #[inline] fn with_output_timeout(self, time_limit: Duration) -> Self::OutputTimeout { Self::OutputTimeout::new(self, time_limit) } } mod private { use std::process::Child; use super::timeout; pub trait Sealed {} impl Sealed for Child {} impl Sealed for timeout::ExitStatusTimeout<'_> {} impl Sealed for timeout::OutputTimeout {} }