mozilla-central/third_party/rust/rustix/src/io/dup.rs (file symbol)

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//! Functions which duplicate file descriptors.
use crate::fd::OwnedFd;
use crate::{backend, io};
use backend::fd::AsFd;
#[cfg(not(target_os = "wasi"))]
pub use backend::io::types::DupFlags;
/// `dup(fd)`—Creates a new `OwnedFd` instance that shares the same
/// underlying [file description] as `fd`.
///
/// This function does not set the `O_CLOEXEC` flag. To do a `dup` that does
/// set `O_CLOEXEC`, use [`fcntl_dupfd_cloexec`].
///
/// POSIX guarantees that `dup` will use the lowest unused file descriptor,
/// however it is not safe in general to rely on this, as file descriptors may
/// be unexpectedly allocated on other threads or in libraries.
///
/// # References
/// - [POSIX]
/// - [Linux]
/// - [Apple]
/// - [FreeBSD]
/// - [NetBSD]
/// - [OpenBSD]
/// - [DragonFly BSD]
/// - [illumos]
/// - [glibc]
///
/// [`fcntl_dupfd_cloexec`]: crate::io::fcntl_dupfd_cloexec
#[cfg(not(target_os = "wasi"))]
#[inline]
pub fn dup<Fd: AsFd>(fd: Fd) -> io::Result<OwnedFd> {
backend::io::syscalls::dup(fd.as_fd())
}
/// `dup2(fd, new)`—Changes the [file description] of a file descriptor.
///
/// `dup2` conceptually closes `new` and then sets the file description for
/// `new` to be the same as the one for `fd`. This is a very unusual operation,
/// and should only be used on file descriptors where you know how `new` will
/// be subsequently used.
///
/// This function does not set the `O_CLOEXEC` flag. To do a `dup2` that does
/// set `O_CLOEXEC`, use [`dup3`] with [`DupFlags::CLOEXEC`] on platforms which
/// support it, or [`fcntl_dupfd_cloexec`]
///
/// For `dup2` to stdin, stdout, and stderr, see [`stdio::dup2_stdin`],
/// [`stdio::dup2_stdout`], and [`stdio::dup2_stderr`].
///
/// # References
/// - [POSIX]
/// - [Linux]
/// - [Apple]
/// - [FreeBSD]
/// - [NetBSD]
/// - [OpenBSD]
/// - [DragonFly BSD]
/// - [illumos]
/// - [glibc]
///
/// [`fcntl_dupfd_cloexec`]: crate::io::fcntl_dupfd_cloexec
#[cfg(not(target_os = "wasi"))]
#[inline]
pub fn dup2<Fd: AsFd>(fd: Fd, new: &mut OwnedFd) -> io::Result<()> {
backend::io::syscalls::dup2(fd.as_fd(), new)
}
/// `dup3(fd, new, flags)`—Changes the [file description] of a file
/// descriptor, with flags.
///
/// `dup3` is the same as [`dup2`] but adds an additional flags operand, and it
/// fails in the case that `fd` and `new` have the same file descriptor value.
/// This additional difference is the reason this function isn't named
/// `dup2_with`.
///
/// # References
/// - [Linux]
/// - [FreeBSD]
/// - [NetBSD]
/// - [OpenBSD]
/// - [DragonFly BSD]
///
#[cfg(not(any(
target_os = "aix",
target_os = "espidf",
target_os = "horizon",
target_os = "nto",
target_os = "vita",
target_os = "wasi"
)))]
#[inline]
pub fn dup3<Fd: AsFd>(fd: Fd, new: &mut OwnedFd, flags: DupFlags) -> io::Result<()> {
backend::io::syscalls::dup3(fd.as_fd(), new, flags)
}