diff options
Diffstat (limited to 'src/lib.rs')
| -rw-r--r-- | src/lib.rs | 140 |
1 files changed, 128 insertions, 12 deletions
@@ -62,7 +62,7 @@ //! ``` use std::io; -use std::process::{Child, Command, ExitStatus}; +use std::process::{Child, ChildStderr, ChildStdin, ChildStdout, Command, ExitStatus}; use std::sync::{Condvar, Mutex}; mod sys; @@ -85,16 +85,36 @@ pub struct SharedChild { } impl SharedChild { - /// Spawn a new `SharedChild` from a `std::process::Command`. - pub fn spawn(command: &mut Command) -> io::Result<SharedChild> { + /// Spawn a new `SharedChild` from a + /// [`std::process::Command`](https://doc.rust-lang.org/std/process/struct.Command.html). + pub fn spawn(command: &mut Command) -> io::Result<Self> { let child = command.spawn()?; - Ok(SharedChild { + Ok(Self { child: Mutex::new(child), state_lock: Mutex::new(NotWaiting), state_condvar: Condvar::new(), }) } + /// Construct a new `SharedChild` from an already spawned + /// [`std::process::Child`](https://doc.rust-lang.org/std/process/struct.Child.html). + /// + /// This constructor needs to know whether `child` has already been waited on, and the only way + /// to find that out is to call `child.try_wait()` internally. If the child process is + /// currently a zombie, that call will clean it up as a side effect. The [`SharedChild::spawn`] + /// constructor doesn't need to do this. + pub fn new(mut child: Child) -> io::Result<Self> { + let state = match child.try_wait()? { + Some(status) => Exited(status), + None => NotWaiting, + }; + Ok(Self { + child: Mutex::new(child), + state_lock: Mutex::new(state), + state_condvar: Condvar::new(), + }) + } + /// Return the child process ID. pub fn id(&self) -> u32 { self.child.lock().unwrap().id() @@ -204,15 +224,46 @@ impl SharedChild { self.child.lock().unwrap().kill() } - /// Consume the `SharedChild` and return the `std::process::Child` it - /// contains. + /// Consume the `SharedChild` and return the + /// [`std::process::Child`](https://doc.rust-lang.org/std/process/struct.Child.html) + /// it contains. /// - /// We never reap the child process except through `Child::wait`, so the - /// child object's inner state is correct, even if it was waited on while it - /// was shared. + /// We never reap the child process except by calling `wait` or `try_wait` + /// on it, so the child object's inner state is correct, even if it was + /// waited on while it was shared. pub fn into_inner(self) -> Child { self.child.into_inner().unwrap() } + + /// Take the child's + /// [`stdin`](https://doc.rust-lang.org/std/process/struct.Child.html#structfield.stdin) + /// handle, if any. + /// + /// This will only return `Some` the first time it's called, and then only if the `Command` + /// that created the child was configured with `.stdin(Stdio::piped())`. + pub fn take_stdin(&self) -> Option<ChildStdin> { + self.child.lock().unwrap().stdin.take() + } + + /// Take the child's + /// [`stdout`](https://doc.rust-lang.org/std/process/struct.Child.html#structfield.stdout) + /// handle, if any. + /// + /// This will only return `Some` the first time it's called, and then only if the `Command` + /// that created the child was configured with `.stdout(Stdio::piped())`. + pub fn take_stdout(&self) -> Option<ChildStdout> { + self.child.lock().unwrap().stdout.take() + } + + /// Take the child's + /// [`stderr`](https://doc.rust-lang.org/std/process/struct.Child.html#structfield.stderr) + /// handle, if any. + /// + /// This will only return `Some` the first time it's called, and then only if the `Command` + /// that created the child was configured with `.stderr(Stdio::piped())`. + pub fn take_stderr(&self) -> Option<ChildStderr> { + self.child.lock().unwrap().stderr.take() + } } #[derive(Debug)] @@ -226,9 +277,9 @@ use crate::ChildState::*; #[cfg(test)] mod tests { - use super::{sys, SharedChild}; - use std; - use std::process::Command; + use super::*; + use std::error::Error; + use std::process::{Command, Stdio}; use std::sync::Arc; // Python isn't available on some Unix platforms, e.g. Android, so we need this instead. @@ -244,6 +295,7 @@ mod tests { cmd } + // Python isn't available on some Unix platforms, e.g. Android, so we need this instead. #[cfg(unix)] pub fn sleep_forever_cmd() -> Command { let mut cmd = Command::new("sleep"); @@ -258,6 +310,19 @@ mod tests { cmd } + // Python isn't available on some Unix platforms, e.g. Android, so we need this instead. + #[cfg(unix)] + pub fn cat_cmd() -> Command { + Command::new("cat") + } + + #[cfg(not(unix))] + pub fn cat_cmd() -> Command { + let mut cmd = Command::new("python"); + cmd.arg("-c").arg(""); + cmd + } + #[test] fn test_wait() { let child = SharedChild::spawn(&mut true_cmd()).unwrap(); @@ -345,4 +410,55 @@ mod tests { // But wait should succeed. child.wait().unwrap(); } + + #[test] + fn test_new() -> Result<(), Box<dyn Error>> { + // Spawn a short-lived child. + let mut command = cat_cmd(); + command.stdin(Stdio::piped()); + command.stdout(Stdio::null()); + let mut child = command.spawn()?; + let child_stdin = child.stdin.take().unwrap(); + + // Construct a SharedChild from the Child, which has not yet been waited on. The child is + // blocked on stdin, so we know it hasn't yet exited. + let mut shared_child = SharedChild::new(child).unwrap(); + assert!(matches!( + *shared_child.state_lock.lock().unwrap(), + NotWaiting, + )); + + // Now close the child's stdin. This will cause the child to exit. + drop(child_stdin); + + // Construct more SharedChild objects from the same child, in a loop. Eventually one of + // them will notice that the child has exited. + loop { + shared_child = SharedChild::new(shared_child.into_inner())?; + if let Exited(status) = &*shared_child.state_lock.lock().unwrap() { + assert!(status.success()); + return Ok(()); + } + } + } + + #[test] + fn test_takes() -> Result<(), Box<dyn Error>> { + let mut command = true_cmd(); + command.stdin(Stdio::piped()); + command.stdout(Stdio::piped()); + command.stderr(Stdio::piped()); + let shared_child = SharedChild::spawn(&mut command)?; + + assert!(shared_child.take_stdin().is_some()); + assert!(shared_child.take_stdout().is_some()); + assert!(shared_child.take_stderr().is_some()); + + assert!(shared_child.take_stdin().is_none()); + assert!(shared_child.take_stdout().is_none()); + assert!(shared_child.take_stderr().is_none()); + + shared_child.wait()?; + Ok(()) + } } |