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    //! Functions returning the stdio file descriptors.
    //!
    //! # Safety
    //!
    //! These access the file descriptors by absolute index value, and nothing
    //! prevents them from being closed and reused. They should only be used in
    //! `main` or other situations where one is in control of the process'
    //! stdio streams.
    #![allow(unsafe_code)]

    use crate::backend;
    use crate::fd::OwnedFd;
    use backend::fd::{BorrowedFd, FromRawFd, RawFd};

    /// `STDIN_FILENO`—Standard input, borrowed.
    ///
    /// # Safety
    ///
    /// This function must be called from code which knows how the process'
    /// standard input is being used. Often, this will be the `main` function or
    /// code that knows its relationship with the `main` function.
    ///
    /// The stdin file descriptor can be closed, potentially on other threads, in
    /// which case the file descriptor index value could be dynamically reused for
    /// other purposes, potentially on different threads.
    ///
    /// # Other hazards
    ///
    /// Stdin could be redirected from arbitrary input sources, and unless one
    /// knows how the process' standard input is being used, one could consume
    /// bytes that are expected to be consumed by other parts of the process.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stdin.3.html
    #[doc(alias = "STDIN_FILENO")]
    #[inline]
    pub const unsafe fn stdin() -> BorrowedFd<'static> {
        BorrowedFd::borrow_raw(backend::io::types::STDIN_FILENO as RawFd)
    }

    /// `STDIN_FILENO`—Standard input, owned.
    ///
    /// This is similar to [`stdin`], however it returns an `OwnedFd` which closes
    /// standard input when it is dropped.
    ///
    /// # Safety
    ///
    /// This is unsafe for the same reasons as [`stdin`].
    ///
    /// # Other hazards
    ///
    /// This has the same hazards as [`stdin`].
    ///
    /// And, when the `OwnedFd` is dropped, subsequent newly created file
    /// descriptors may unknowingly reuse the stdin file descriptor number, which
    /// may break common assumptions, so it should typically only be dropped at the
    /// end of a program when no more file descriptors will be created.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stdin.3.html
    #[doc(alias = "STDIN_FILENO")]
    #[inline]
    pub unsafe fn take_stdin() -> OwnedFd {
        backend::fd::OwnedFd::from_raw_fd(backend::io::types::STDIN_FILENO as RawFd)
    }

    /// `STDOUT_FILENO`—Standard output, borrowed.
    ///
    /// # Safety
    ///
    /// This function must be called from code which knows how the process'
    /// standard output is being used. Often, this will be the `main` function or
    /// code that knows its relationship with the `main` function.
    ///
    /// The stdout file descriptor can be closed, potentially on other threads, in
    /// which case the file descriptor index value could be dynamically reused for
    /// other purposes, potentially on different threads.
    ///
    /// # Other hazards
    ///
    /// Stdout could be redirected to arbitrary output sinks, and unless one
    /// knows how the process' standard output is being used, one could
    /// unexpectedly inject bytes into a stream being written by another part of
    /// the process.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stdout.3.html
    #[doc(alias = "STDOUT_FILENO")]
    #[inline]
    pub const unsafe fn stdout() -> BorrowedFd<'static> {
        BorrowedFd::borrow_raw(backend::io::types::STDOUT_FILENO as RawFd)
    }

    /// `STDOUT_FILENO`—Standard output, owned.
    ///
    /// This is similar to [`stdout`], however it returns an `OwnedFd` which closes
    /// standard output when it is dropped.
    ///
    /// # Safety
    ///
    /// This is unsafe for the same reasons as [`stdout`].
    ///
    /// # Other hazards
    ///
    /// This has the same hazards as [`stdout`].
    ///
    /// And, when the `OwnedFd` is dropped, subsequent newly created file
    /// descriptors may unknowingly reuse the stdout file descriptor number, which
    /// may break common assumptions, so it should typically only be dropped at the
    /// end of a program when no more file descriptors will be created.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stdout.3.html
    #[doc(alias = "STDOUT_FILENO")]
    #[inline]
    pub unsafe fn take_stdout() -> OwnedFd {
        backend::fd::OwnedFd::from_raw_fd(backend::io::types::STDOUT_FILENO as RawFd)
    }

    /// `STDERR_FILENO`—Standard error, borrowed.
    ///
    /// # Safety
    ///
    /// This function must be called from code which knows how the process'
    /// standard error is being used. Often, this will be the `main` function or
    /// code that knows its relationship with the `main` function.
    ///
    /// The stderr file descriptor can be closed, potentially on other threads, in
    /// which case the file descriptor index value could be dynamically reused for
    /// other purposes, potentially on different threads.
    ///
    /// # Other hazards
    ///
    /// Stderr could be redirected to arbitrary output sinks, and unless one
    /// knows how the process' standard error is being used, one could unexpectedly
    /// inject bytes into a stream being written by another part of the process.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stderr.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stderr.3.html
    #[doc(alias = "STDERR_FILENO")]
    #[inline]
    pub const unsafe fn stderr() -> BorrowedFd<'static> {
        BorrowedFd::borrow_raw(backend::io::types::STDERR_FILENO as RawFd)
    }

    /// `STDERR_FILENO`—Standard error, owned.
    ///
    /// This is similar to [`stdout`], however it returns an `OwnedFd` which closes
    /// standard output when it is dropped.
    ///
    /// # Safety
    ///
    /// This is unsafe for the same reasons as [`stderr`].
    ///
    /// # Other hazards
    ///
    /// This has the same hazards as [`stderr`].
    ///
    /// And, when the `OwnedFd` is dropped, subsequent newly created file
    /// descriptors may unknowingly reuse the stderr file descriptor number, which
    /// may break common assumptions, so it should typically only be dropped at the
    /// end of a program when no more file descriptors will be created.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stderr.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stderr.3.html
    #[doc(alias = "STDERR_FILENO")]
    #[inline]
    pub unsafe fn take_stderr() -> OwnedFd {
        backend::fd::OwnedFd::from_raw_fd(backend::io::types::STDERR_FILENO as RawFd)
    }

    /// `STDIN_FILENO`—Standard input, raw.
    ///
    /// This is similar to [`stdin`], however it returns a `RawFd`.
    ///
    /// # Other hazards
    ///
    /// This has the same hazards as [`stdin`].
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stdin.3.html
    #[doc(alias = "STDIN_FILENO")]
    #[inline]
    pub const fn raw_stdin() -> RawFd {
        backend::io::types::STDIN_FILENO as RawFd
    }

    /// `STDOUT_FILENO`—Standard output, raw.
    ///
    /// This is similar to [`stdout`], however it returns a `RawFd`.
    ///
    /// # Other hazards
    ///
    /// This has the same hazards as [`stdout`].
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stdout.3.html
    #[doc(alias = "STDOUT_FILENO")]
    #[inline]
    pub const fn raw_stdout() -> RawFd {
        backend::io::types::STDOUT_FILENO as RawFd
    }

    /// `STDERR_FILENO`—Standard error, raw.
    ///
    /// This is similar to [`stderr`], however it returns a `RawFd`.
    ///
    /// # Other hazards
    ///
    /// This has the same hazards as [`stderr`].
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stderr.html
    /// [Linux]: https://man7.org/linux/man-pages/man3/stderr.3.html
    #[doc(alias = "STDERR_FILENO")]
    #[inline]
    pub const fn raw_stderr() -> RawFd {
        backend::io::types::STDERR_FILENO as RawFd
    }