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//! Define the `OwnsRaw` trait and implement it for well-known types.

#[cfg(feature = "os_pipe")]
use os_pipe::{PipeReader, PipeWriter};
#[cfg(unix)]
use std::os::unix::net::{UnixListener, UnixStream};
use std::{
    fs::File,
    io::{Stderr, StderrLock, Stdin, StdinLock, Stdout, StdoutLock},
    net::{TcpListener, TcpStream, UdpSocket},
    process::{ChildStderr, ChildStdin, ChildStdout},
};

/// The `AsRaw*` and `IntoRaw*` traits by themselves are not sufficient to
/// describe the ownership of the file descriptor, as they aren't unsafe to
/// implement. See the discussion in [rust-lang/rust#76969] for additional
/// background. The `UnsafeHandle` type provided by this crate serves as an
/// implementation of [this suggestion].
///
/// `OwnsRaw` is a trait that types can implement to declare that they
/// own their file descriptors.
///
/// [rust-lang/rust#76969]: https://github.com/rust-lang/rust/issues/76969
/// [this suggestion]: https://github.com/rust-lang/rust/pull/76969#issuecomment-696275470
///
/// # Safety
///
/// Types implementing `OwnsRaw` must own the handles they return in their
/// `AsRaw*` and `IntoRaw*` implementations.
pub unsafe trait OwnsRaw {}

// Safety: The following standard-library types are all known to own their file
// descriptors.
unsafe impl OwnsRaw for Stdin {}
unsafe impl<'a> OwnsRaw for StdinLock<'a> {}
unsafe impl OwnsRaw for Stdout {}
unsafe impl<'a> OwnsRaw for StdoutLock<'a> {}
unsafe impl OwnsRaw for Stderr {}
unsafe impl<'a> OwnsRaw for StderrLock<'a> {}
unsafe impl OwnsRaw for File {}
unsafe impl OwnsRaw for ChildStdin {}
unsafe impl OwnsRaw for ChildStdout {}
unsafe impl OwnsRaw for ChildStderr {}
unsafe impl OwnsRaw for TcpStream {}
unsafe impl OwnsRaw for TcpListener {}
unsafe impl OwnsRaw for UdpSocket {}
#[cfg(feature = "os_pipe")]
unsafe impl OwnsRaw for PipeReader {}
#[cfg(feature = "os_pipe")]
unsafe impl OwnsRaw for PipeWriter {}
#[cfg(unix)]
unsafe impl OwnsRaw for UnixStream {}
#[cfg(unix)]
unsafe impl OwnsRaw for UnixListener {}