// SPDX-License-Identifier: GPL-2.0// Copyright (c) 2024 Christian Brauner <brauner@kernel.org>//! Pid namespaces.//!//! C header: [`include/linux/pid_namespace.h`](srctree/include/linux/pid_namespace.h) and//! [`include/linux/pid.h`](srctree/include/linux/pid.h)use crate::{bindings, sync::aref::AlwaysRefCounted, types::Opaque};use core::ptr;/// Wraps the kernel's `struct pid_namespace`. Thread safe.////// This structure represents the Rust abstraction for a C `struct pid_namespace`. This/// implementation abstracts the usage of an already existing C `struct pid_namespace` within Rust/// code that we get passed from the C side.#[repr(transparent)]pub struct PidNamespace { inner: Opaque<bindings::pid_namespace>,}impl PidNamespace { /// Returns a raw pointer to the inner C struct. #[inline] pub fn as_ptr(&self) -> *mut bindings::pid_namespace { self.inner.get() } /// Creates a reference to a [`PidNamespace`] from a valid pointer. /// /// # Safety /// /// The caller must ensure that `ptr` is valid and remains valid for the lifetime of the /// returned [`PidNamespace`] reference. pub unsafe fn from_ptr<'a>(ptr: *const bindings::pid_namespace) -> &'a Self { // SAFETY: The safety requirements guarantee the validity of the dereference, while the // `PidNamespace` type being transparent makes the cast ok. unsafe { &*ptr.cast() } }}// SAFETY: Instances of `PidNamespace` are always reference-counted.unsafe impl AlwaysRefCounted for PidNamespace { #[inline] fn inc_ref(&self) { // SAFETY: The existence of a shared reference means that the refcount is nonzero. unsafe { bindings::get_pid_ns(self.as_ptr()) }; } #[inline] unsafe fn dec_ref(obj: ptr::NonNull<PidNamespace>) { // SAFETY: The safety requirements guarantee that the refcount is non-zero. unsafe { bindings::put_pid_ns(obj.cast().as_ptr()) } }}// SAFETY:// - `PidNamespace::dec_ref` can be called from any thread.// - It is okay to send ownership of `PidNamespace` across thread boundaries.unsafe impl Send for PidNamespace {}// SAFETY: It's OK to access `PidNamespace` through shared references from other threads because// we're either accessing properties that don't change or that are properly synchronised by C code.unsafe impl Sync for PidNamespace {}
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2024 Christian Brauner <brauner@kernel.org>
//! Pid namespaces.
//!
//! C header: [`include/linux/pid_namespace.h`](srctree/include/linux/pid_namespace.h) and
//! [`include/linux/pid.h`](srctree/include/linux/pid.h)
use crate::{bindings, sync::aref::AlwaysRefCounted, types::Opaque};
use core::ptr;
/// Wraps the kernel's `struct pid_namespace`. Thread safe.
///
/// This structure represents the Rust abstraction for a C `struct pid_namespace`. This
/// implementation abstracts the usage of an already existing C `struct pid_namespace` within Rust
/// code that we get passed from the C side.
#[repr(transparent)]
pub struct PidNamespace {
inner: Opaque<bindings::pid_namespace>,
}
impl PidNamespace {
/// Returns a raw pointer to the inner C struct.
#[inline]
pub fn as_ptr(&self) -> *mut bindings::pid_namespace {
self.inner.get()
}
/// Creates a reference to a [`PidNamespace`] from a valid pointer.
///
/// # Safety
///
/// The caller must ensure that `ptr` is valid and remains valid for the lifetime of the
/// returned [`PidNamespace`] reference.
pub unsafe fn from_ptr<'a>(ptr: *const bindings::pid_namespace) -> &'a Self {
// SAFETY: The safety requirements guarantee the validity of the dereference, while the
// `PidNamespace` type being transparent makes the cast ok.
unsafe { &*ptr.cast() }
}
}
// SAFETY: Instances of `PidNamespace` are always reference-counted.
unsafe impl AlwaysRefCounted for PidNamespace {
#[inline]
fn inc_ref(&self) {
// SAFETY: The existence of a shared reference means that the refcount is nonzero.
unsafe { bindings::get_pid_ns(self.as_ptr()) };
}
#[inline]
unsafe fn dec_ref(obj: ptr::NonNull<PidNamespace>) {
// SAFETY: The safety requirements guarantee that the refcount is non-zero.
unsafe { bindings::put_pid_ns(obj.cast().as_ptr()) }
}
}
// SAFETY:
// - `PidNamespace::dec_ref` can be called from any thread.
// - It is okay to send ownership of `PidNamespace` across thread boundaries.
unsafe impl Send for PidNamespace {}
// SAFETY: It's OK to access `PidNamespace` through shared references from other threads because
// we're either accessing properties that don't change or that are properly synchronised by C code.
unsafe impl Sync for PidNamespace {}