//! The libc backend.
//!
//! On most platforms, this uses the `libc` crate to make system calls. On
//! Windows, this uses the Winsock API in `windows-sys`, which can be adapted
//! to have a very `libc`-like interface.
// Every FFI call requires an unsafe block, and there are a lot of FFI
// calls. For now, set this to allow for the libc backend.
#![allow(clippy::undocumented_unsafe_blocks)]
// Lots of libc types vary between platforms, so we often need a `.into()` on
// one platform where it's redundant on another.
#![allow(clippy::useless_conversion)]
mod conv;
#[cfg(windows)]
pub(crate) mod fd {
pub use crate::maybe_polyfill::os::windows::io::{
AsRawSocket, AsSocket, BorrowedSocket as BorrowedFd, FromRawSocket, IntoRawSocket,
OwnedSocket as OwnedFd, RawSocket as RawFd,
};
pub(crate) use windows_sys::Win32::Networking::WinSock::SOCKET as LibcFd;
/// A version of [`AsRawFd`] for use with Winsock API.
///
/// [`AsRawFd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.AsRawFd.html
pub trait AsRawFd {
/// A version of [`as_raw_fd`] for use with Winsock API.
///
/// [`as_raw_fd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#tymethod.as_raw_fd
fn as_raw_fd(&self) -> RawFd;
}
impl<T: AsRawSocket> AsRawFd for T {
#[inline]
fn as_raw_fd(&self) -> RawFd {
self.as_raw_socket()
}
}
/// A version of [`IntoRawFd`] for use with Winsock API.
///
/// [`IntoRawFd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.IntoRawFd.html
pub trait IntoRawFd {
/// A version of [`into_raw_fd`] for use with Winsock API.
///
/// [`into_raw_fd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#tymethod.into_raw_fd
fn into_raw_fd(self) -> RawFd;
}
impl<T: IntoRawSocket> IntoRawFd for T {
#[inline]
fn into_raw_fd(self) -> RawFd {
self.into_raw_socket()
}
}
/// A version of [`FromRawFd`] for use with Winsock API.
///
/// [`FromRawFd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html
pub trait FromRawFd {
/// A version of [`from_raw_fd`] for use with Winsock API.
///
/// # Safety
///
/// See the [safety requirements] for [`from_raw_fd`].
///
/// [`from_raw_fd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#tymethod.from_raw_fd
/// [safety requirements]:
https://doc.rust-lang.org/stable/std/os/fd/trait.FromRawFd.html#safety
unsafe fn from_raw_fd(raw_fd: RawFd) -> Self;
}
impl<T: FromRawSocket> FromRawFd for T {
#[inline]
unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
Self::from_raw_socket(raw_fd)
}
}
/// A version of [`AsFd`] for use with Winsock API.
///
/// [`AsFd`]:
https://doc.rust-lang.org/stable/std/os/fd/trait.AsFd.html
pub trait AsFd {
/// An `as_fd` function for Winsock, where a `Fd` is a `Socket`.
fn as_fd(&self) -> BorrowedFd;
}
impl<T: AsSocket> AsFd for T {
#[inline]
fn as_fd(&self) -> BorrowedFd {
self.as_socket()
}
}
}
#[cfg(not(windows))]
pub(crate) mod fd {
pub use crate::maybe_polyfill::os::fd::{
AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd,
};
#[allow(unused_imports)]
pub(crate) use RawFd as LibcFd;
}
// On Windows we emulate selected libc-compatible interfaces. On non-Windows,
// we just use libc here, since this is the libc backend.
#[cfg_attr(windows, path = "winsock_c.rs")]
pub(crate) mod c;
#[cfg(feature = "event")]
pub(crate) mod event;
#[cfg(not(windows))]
#[cfg(feature = "fs")]
pub(crate) mod fs;
pub(crate) mod io;
#[cfg(linux_kernel)]
#[cfg(feature = "io_uring")]
pub(crate) mod io_uring;
#[cfg(not(any(windows, target_os = "espidf", target_os = "vita", target_os = "wasi")))]
#[cfg(feature = "mm")]
pub(crate) mod mm;
#[cfg(linux_kernel)]
#[cfg(feature = "mount")]
pub(crate) mod mount;
#[cfg(linux_kernel)]
#[cfg(all(feature = "fs", not(feature = "mount")))]
pub(crate) mod mount; // for deprecated mount functions in "fs"
#[cfg(not(any(target_os = "redox", target_os = "wasi")))]
#[cfg(feature = "net")]
pub(crate) mod net;
#[cfg(not(any(windows, target_os = "espidf")))]
#[cfg(any(
feature = "param",
feature = "runtime",
feature = "time",
target_arch = "x86",
))]
pub(crate) mod param;
#[cfg(not(windows))]
#[cfg(feature = "pipe")]
pub(crate) mod pipe;
#[cfg(not(windows))]
#[cfg(feature = "process")]
pub(crate) mod process;
#[cfg(not(windows))]
#[cfg(not(target_os = "wasi"))]
#[cfg(feature = "pty")]
pub(crate) mod pty;
#[cfg(not(windows))]
#[cfg(feature = "rand")]
pub(crate) mod rand;
#[cfg(not(windows))]
#[cfg(not(target_os = "wasi"))]
#[cfg(feature = "system")]
pub(crate) mod system;
#[cfg(not(any(windows, target_os = "vita")))]
#[cfg(feature = "termios")]
pub(crate) mod termios;
#[cfg(not(windows))]
#[cfg(feature = "thread")]
pub(crate) mod thread;
#[cfg(not(any(windows, target_os = "espidf")))]
#[cfg(feature = "time")]
pub(crate) mod time;
/// If the host libc is glibc, return `true` if it is less than version 2.25.
///
/// To restate and clarify, this function returning true does not mean the libc
/// is glibc just that if it is glibc, it is less than version 2.25.
///
/// For now, this function is only available on Linux, but if it ends up being
/// used beyond that, this could be changed to e.g. `#[cfg(unix)]`.
#[cfg(all(unix, target_env = "gnu"))]
pub(crate) fn if_glibc_is_less_than_2_25() -> bool {
// This is also defined inside `weak_or_syscall!` in
// backend/libc/rand/syscalls.rs, but it's not convenient to re-export the
// weak symbol from that macro, so we duplicate it at a small cost here.
weak! { fn getrandom(*mut c::c_void, c::size_t, c::c_uint) -> c::ssize_t }
// glibc 2.25 has `getrandom`, which is how we satisfy the API contract of
// this function. But, there are likely other libc versions which have it.
getrandom.get().is_none()
}
// Private modules used by multiple public modules.
#[cfg(any(feature = "procfs", feature = "process", feature = "runtime"))]
#[cfg(not(any(windows, target_os = "wasi")))]
pub(crate) mod pid;
#[cfg(any(feature = "process", feature = "thread"))]
#[cfg(linux_kernel)]
pub(crate) mod prctl;
#[cfg(not(any(
windows,
target_os = "android",
target_os = "espidf",
target_os = "vita",
target_os = "wasi"
)))]
#[cfg(feature = "shm")]
pub(crate) mod shm;
#[cfg(any(feature = "fs", feature = "thread", feature = "process"))]
#[cfg(not(any(windows, target_os = "wasi")))]
pub(crate) mod ugid;
#[cfg(bsd)]
const MAX_IOV: usize = c::IOV_MAX as usize;
#[cfg(any(linux_kernel, target_os = "emscripten", target_os = "nto"))]
const MAX_IOV: usize = c::UIO_MAXIOV as usize;
#[cfg(not(any(
bsd,
linux_kernel,
windows,
target_os = "emscripten",
target_os = "espidf",
target_os = "nto",
target_os = "horizon",
)))]
const MAX_IOV: usize = 16; // The minimum value required by POSIX.
