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//! based on https://www.man7.org/linux/man-pages/man2/pidfd_open.2.html
#![cfg(target_os = "linux")]
use std::{
io,
mem::ManuallyDrop,
ops::{Deref, DerefMut},
os::fd::{BorrowedFd, RawFd},
process::{Child, ExitStatus},
ptr,
};
use libc::{SYS_pidfd_open, syscall};
use nix::poll::{PollFd, PollFlags};
pub struct ChildWaiter {
fd: RawFd,
child: Child,
}
#[derive(Debug)]
struct PidFdOpenError;
impl std::fmt::Display for PidFdOpenError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "pid_fd_open")
}
}
impl std::error::Error for PidFdOpenError {}
impl ChildWaiter {
pub fn new(child: Child) -> io::Result<Self> {
let fd = unsafe { syscall(SYS_pidfd_open, child.id(), 0) };
if fd < 0 {
Err(io::Error::other(PidFdOpenError))
} else {
let fd = fd as RawFd;
Ok(Self { child, fd })
}
}
pub fn wait(&mut self, timeout_ms: u16) -> io::Result<Option<ExitStatus>> {
let mut poll_fds = [PollFd::new(
unsafe { BorrowedFd::borrow_raw(self.fd) },
PollFlags::POLLIN,
)];
let _ = nix::poll::poll(&mut poll_fds, timeout_ms);
self.child.try_wait()
}
pub fn into_inner(self) -> Child {
unsafe {
libc::close(self.fd);
}
let this = ManuallyDrop::new(self);
unsafe { ptr::read(&this.child) }
}
}
impl Deref for ChildWaiter {
type Target = Child;
fn deref(&self) -> &Self::Target {
&self.child
}
}
impl DerefMut for ChildWaiter {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.child
}
}
impl Drop for ChildWaiter {
fn drop(&mut self) {
unsafe {
libc::close(self.fd);
}
}
}
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