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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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#[cfg(all(feature = "alloc", not(feature = "std")))]use alloc::{boxed::Box, sync::Arc};#[cfg(feature = "alloc")]use core::alloc::AllocError;use core::{mem::MaybeUninit, pin::Pin};#[cfg(feature = "std")]use std::sync::Arc;
#[cfg(not(feature = "alloc"))]type AllocError = core::convert::Infallible;
use crate::{ init_from_closure, pin_init_from_closure, InPlaceWrite, Init, PinInit, ZeroableOption,};
pub extern crate alloc;
// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:// <https://doc.rust-lang.org/stable/std/option/index.html#representation>).unsafe impl<T> ZeroableOption for Box<T> {}
/// Smart pointer that can initialize memory in-place.pub trait InPlaceInit<T>: Sized { /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this /// type. /// /// If `T: !Unpin` it will not be able to move afterwards. fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E> where E: From<AllocError>;
/// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this /// type. /// /// If `T: !Unpin` it will not be able to move afterwards. #[inline] fn pin_init(init: impl PinInit<T>) -> Result<Pin<Self>, AllocError> { // SAFETY: We delegate to `init` and only change the error type. let init = unsafe { pin_init_from_closure(|slot| match init.__init(slot) { Ok(()) => Ok(()), Err(i) => match i {}, }) }; Self::try_pin_init(init) }
/// Use the given initializer to in-place initialize a `T`. fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E> where E: From<AllocError>;
/// Use the given initializer to in-place initialize a `T`. #[inline] fn init(init: impl Init<T>) -> Result<Self, AllocError> { // SAFETY: We delegate to `init` and only change the error type. let init = unsafe { init_from_closure(|slot| match init.__init(slot) { Ok(()) => Ok(()), Err(i) => match i {}, }) }; Self::try_init(init) }}
#[cfg(feature = "alloc")]macro_rules! try_new_uninit { ($type:ident) => { $type::try_new_uninit()? };}#[cfg(all(feature = "std", not(feature = "alloc")))]macro_rules! try_new_uninit { ($type:ident) => { $type::new_uninit() };}
impl<T> InPlaceInit<T> for Box<T> { #[inline] fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E> where E: From<AllocError>, { try_new_uninit!(Box).write_pin_init(init) }
#[inline] fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E> where E: From<AllocError>, { try_new_uninit!(Box).write_init(init) }}
impl<T> InPlaceInit<T> for Arc<T> { #[inline] fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E> where E: From<AllocError>, { let mut this = try_new_uninit!(Arc); let Some(slot) = Arc::get_mut(&mut this) else { // SAFETY: the Arc has just been created and has no external references unsafe { core::hint::unreachable_unchecked() } }; let slot = slot.as_mut_ptr(); // SAFETY: When init errors/panics, slot will get deallocated but not dropped, // slot is valid and will not be moved, because we pin it later. unsafe { init.__init(slot)? }; // SAFETY: All fields have been initialized and this is the only `Arc` to that data. Ok(unsafe { Pin::new_unchecked(this.assume_init()) }) }
#[inline] fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E> where E: From<AllocError>, { let mut this = try_new_uninit!(Arc); let Some(slot) = Arc::get_mut(&mut this) else { // SAFETY: the Arc has just been created and has no external references unsafe { core::hint::unreachable_unchecked() } }; let slot = slot.as_mut_ptr(); // SAFETY: When init errors/panics, slot will get deallocated but not dropped, // slot is valid. unsafe { init.__init(slot)? }; // SAFETY: All fields have been initialized. Ok(unsafe { this.assume_init() }) }}
impl<T> InPlaceWrite<T> for Box<MaybeUninit<T>> { type Initialized = Box<T>;
#[inline] fn write_init<E>(mut self, init: impl Init<T, E>) -> Result<Self::Initialized, E> { let slot = self.as_mut_ptr(); // SAFETY: When init errors/panics, slot will get deallocated but not dropped, // slot is valid. unsafe { init.__init(slot)? }; // SAFETY: All fields have been initialized. Ok(unsafe { self.assume_init() }) }
#[inline] fn write_pin_init<E>(mut self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E> { let slot = self.as_mut_ptr(); // SAFETY: When init errors/panics, slot will get deallocated but not dropped, // slot is valid and will not be moved, because we pin it later. unsafe { init.__init(slot)? }; // SAFETY: All fields have been initialized. Ok(unsafe { self.assume_init() }.into()) }}