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    #![allow(unsafe_code)]

    use crate::fd::OwnedFd;
    use crate::{backend, io};
    #[cfg(any(target_os = "android", target_os = "linux"))]
    use backend::fd::AsFd;

    #[cfg(not(any(target_os = "ios", target_os = "macos")))]
    pub use backend::io::types::PipeFlags;

    #[cfg(any(target_os = "android", target_os = "linux"))]
    pub use backend::io::types::{IoSliceRaw, SpliceFlags};

    /// `PIPE_BUF`—The maximum length at which writes to a pipe are atomic.
    ///
    /// # References
    ///  - [Linux]
    ///  - [POSIX]
    ///
    /// [Linux]: https://man7.org/linux/man-pages/man7/pipe.7.html
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html
    #[cfg(not(any(
        windows,
        target_os = "haiku",
        target_os = "illumos",
        target_os = "redox",
        target_os = "solaris",
        target_os = "wasi",
    )))]
    pub const PIPE_BUF: usize = backend::io::types::PIPE_BUF;

    /// `pipe()`—Creates a pipe.
    ///
    /// This function creates a pipe and returns two file descriptors, for the
    /// reading and writing ends of the pipe, respectively.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pipe.html
    /// [Linux]: https://man7.org/linux/man-pages/man2/pipe.2.html
    #[inline]
    pub fn pipe() -> io::Result<(OwnedFd, OwnedFd)> {
        backend::io::syscalls::pipe()
    }

    /// `pipe2(flags)`—Creates a pipe, with flags.
    ///
    /// This function creates a pipe and returns two file descriptors, for the
    /// reading and writing ends of the pipe, respectively.
    ///
    /// # References
    ///  - [Linux]
    ///
    /// [Linux]: https://man7.org/linux/man-pages/man2/pipe2.2.html
    #[cfg(not(any(
        target_os = "aix",
        target_os = "haiku",
        target_os = "ios",
        target_os = "macos"
    )))]
    #[inline]
    #[doc(alias = "pipe2")]
    pub fn pipe_with(flags: PipeFlags) -> io::Result<(OwnedFd, OwnedFd)> {
        backend::io::syscalls::pipe_with(flags)
    }

    /// `splice(fd_in, off_in, fd_out, off_out, len, flags)`—Transfer data between a file and a pipe.
    ///
    /// This function transfers up to `len` bytes of data from the file descriptor `fd_in`
    /// to the file descriptor `fd_out`, where one of the file descriptors
    /// must refer to a pipe.
    ///
    /// `off_*` must be `None` if the corresponding fd refers to a pipe.
    /// Otherwise its value points to the starting offset to the file,
    /// from which the data is read/written.
    /// on success the number of bytes read/written is added to the offset.
    ///
    /// passing `None` causes the read/write to start from the file offset,
    /// and the file offset is adjusted appropriately.
    ///
    /// # References
    ///  - [Linux]
    ///
    /// [Linux]: https://man7.org/linux/man-pages/man2/splice.2.html
    #[cfg(any(target_os = "android", target_os = "linux"))]
    #[inline]
    pub fn splice<FdIn: AsFd, FdOut: AsFd>(
        fd_in: FdIn,
        off_in: Option<&mut u64>,
        fd_out: FdOut,
        off_out: Option<&mut u64>,
        len: usize,
        flags: SpliceFlags,
    ) -> io::Result<usize> {
        backend::io::syscalls::splice(fd_in.as_fd(), off_in, fd_out.as_fd(), off_out, len, flags)
    }

    /// `vmsplice(fd, bufs, flags)`—Transfer data between memory and a pipe.
    ///
    /// If `fd` is the write end of the pipe,
    /// the function maps the memory pointer at by `bufs` to the pipe.
    ///
    /// If `fd` is the read end of the pipe,
    /// the function writes data from the pipe to said memory.
    ///
    /// # Safety
    ///
    /// If the memory must not be mutated (such as when `bufs` were originally immutable slices),
    /// it is up to the caller to ensure that the write end of the pipe is placed in `fd`.
    ///
    /// Additionally if `SpliceFlags::GIFT` is set, the caller must also ensure
    /// that the contents of `bufs` in never modified following the call,
    /// and that all of the pointers in `bufs` are page aligned,
    /// and the lengths are multiples of a page size in bytes.
    ///
    /// # References
    ///  - [Linux]
    ///
    /// [Linux]: https://man7.org/linux/man-pages/man2/vmsplice.2.html
    #[cfg(any(target_os = "android", target_os = "linux"))]
    #[inline]
    pub unsafe fn vmsplice<PipeFd: AsFd>(
        fd: PipeFd,
        bufs: &[io::IoSliceRaw],
        flags: SpliceFlags,
    ) -> io::Result<usize> {
        backend::io::syscalls::vmsplice(fd.as_fd(), bufs, flags)
    }