diff options
Diffstat (limited to 'rust/pin-init')
| -rw-r--r-- | rust/pin-init/README.md | 14 | ||||
| -rw-r--r-- | rust/pin-init/examples/linked_list.rs | 1 | ||||
| -rw-r--r-- | rust/pin-init/examples/mutex.rs | 1 | ||||
| -rw-r--r-- | rust/pin-init/examples/pthread_mutex.rs | 4 | ||||
| -rw-r--r-- | rust/pin-init/examples/static_init.rs | 1 | ||||
| -rw-r--r-- | rust/pin-init/internal/src/lib.rs | 6 | ||||
| -rw-r--r-- | rust/pin-init/internal/src/pinned_drop.rs | 3 | ||||
| -rw-r--r-- | rust/pin-init/internal/src/zeroable.rs | 27 | ||||
| -rw-r--r-- | rust/pin-init/src/lib.rs | 144 | ||||
| -rw-r--r-- | rust/pin-init/src/macros.rs | 91 |
10 files changed, 280 insertions, 12 deletions
diff --git a/rust/pin-init/README.md b/rust/pin-init/README.md index 3d04796b212b..2d0cda961d45 100644 --- a/rust/pin-init/README.md +++ b/rust/pin-init/README.md @@ -40,6 +40,12 @@ However, using the crate on stable compilers is possible by disabling `alloc`. I will require the `std` feature, because stable compilers have neither `Box` nor `Arc` in no-std mode. +### Nightly needed for `unsafe-pinned` feature + +This feature enables the `Wrapper` implementation on the unstable `core::pin::UnsafePinned` type. +This requires the [`unsafe_pinned` unstable feature](https://github.com/rust-lang/rust/issues/125735) +and therefore a nightly compiler. Note that this feature is not enabled by default. + ## Overview To initialize a `struct` with an in-place constructor you will need two things: @@ -216,13 +222,15 @@ the `kernel` crate. The [`sync`] module is a good starting point. [`sync`]: https://rust.docs.kernel.org/kernel/sync/index.html [pinning]: https://doc.rust-lang.org/std/pin/index.html -[structurally pinned fields]: https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural-for-field +[structurally pinned fields]: https://doc.rust-lang.org/std/pin/index.html#projections-and-structural-pinning [stack]: https://docs.rs/pin-init/latest/pin_init/macro.stack_pin_init.html -[`Arc<T>`]: https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html -[`Box<T>`]: https://doc.rust-lang.org/stable/alloc/boxed/struct.Box.html [`impl PinInit<Foo>`]: https://docs.rs/pin-init/latest/pin_init/trait.PinInit.html [`impl PinInit<T, E>`]: https://docs.rs/pin-init/latest/pin_init/trait.PinInit.html [`impl Init<T, E>`]: https://docs.rs/pin-init/latest/pin_init/trait.Init.html [Rust-for-Linux]: https://rust-for-linux.com/ <!-- cargo-rdme end --> + +<!-- These links are not picked up by cargo-rdme, since they are behind cfgs... --> +[`Arc<T>`]: https://doc.rust-lang.org/stable/alloc/sync/struct.Arc.html +[`Box<T>`]: https://doc.rust-lang.org/stable/alloc/boxed/struct.Box.html diff --git a/rust/pin-init/examples/linked_list.rs b/rust/pin-init/examples/linked_list.rs index 6d7eb0a0ec0d..0bbc7b8d83a1 100644 --- a/rust/pin-init/examples/linked_list.rs +++ b/rust/pin-init/examples/linked_list.rs @@ -2,6 +2,7 @@ #![allow(clippy::undocumented_unsafe_blocks)] #![cfg_attr(feature = "alloc", feature(allocator_api))] +#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))] use core::{ cell::Cell, diff --git a/rust/pin-init/examples/mutex.rs b/rust/pin-init/examples/mutex.rs index 073bb79341d1..3e3630780c96 100644 --- a/rust/pin-init/examples/mutex.rs +++ b/rust/pin-init/examples/mutex.rs @@ -2,6 +2,7 @@ #![allow(clippy::undocumented_unsafe_blocks)] #![cfg_attr(feature = "alloc", feature(allocator_api))] +#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))] #![allow(clippy::missing_safety_doc)] use core::{ diff --git a/rust/pin-init/examples/pthread_mutex.rs b/rust/pin-init/examples/pthread_mutex.rs index 5ac22f1880d2..5acc5108b954 100644 --- a/rust/pin-init/examples/pthread_mutex.rs +++ b/rust/pin-init/examples/pthread_mutex.rs @@ -3,6 +3,8 @@ // inspired by <https://github.com/nbdd0121/pin-init/blob/trunk/examples/pthread_mutex.rs> #![allow(clippy::undocumented_unsafe_blocks)] #![cfg_attr(feature = "alloc", feature(allocator_api))] +#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))] + #[cfg(not(windows))] mod pthread_mtx { #[cfg(feature = "alloc")] @@ -40,7 +42,7 @@ mod pthread_mtx { #[derive(Debug)] pub enum Error { - #[expect(dead_code)] + #[allow(dead_code)] IO(std::io::Error), Alloc, } diff --git a/rust/pin-init/examples/static_init.rs b/rust/pin-init/examples/static_init.rs index 3487d761aa26..48531413ab94 100644 --- a/rust/pin-init/examples/static_init.rs +++ b/rust/pin-init/examples/static_init.rs @@ -2,6 +2,7 @@ #![allow(clippy::undocumented_unsafe_blocks)] #![cfg_attr(feature = "alloc", feature(allocator_api))] +#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))] use core::{ cell::{Cell, UnsafeCell}, diff --git a/rust/pin-init/internal/src/lib.rs b/rust/pin-init/internal/src/lib.rs index babe5e878550..297b0129a5bf 100644 --- a/rust/pin-init/internal/src/lib.rs +++ b/rust/pin-init/internal/src/lib.rs @@ -22,6 +22,7 @@ use proc_macro::TokenStream; #[cfg(kernel)] #[path = "../../../macros/quote.rs"] #[macro_use] +#[cfg_attr(not(kernel), rustfmt::skip)] mod quote; #[cfg(not(kernel))] #[macro_use] @@ -46,3 +47,8 @@ pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { pub fn derive_zeroable(input: TokenStream) -> TokenStream { zeroable::derive(input.into()).into() } + +#[proc_macro_derive(MaybeZeroable)] +pub fn maybe_derive_zeroable(input: TokenStream) -> TokenStream { + zeroable::maybe_derive(input.into()).into() +} diff --git a/rust/pin-init/internal/src/pinned_drop.rs b/rust/pin-init/internal/src/pinned_drop.rs index c824dd8b436d..c4ca7a70b726 100644 --- a/rust/pin-init/internal/src/pinned_drop.rs +++ b/rust/pin-init/internal/src/pinned_drop.rs @@ -28,8 +28,7 @@ pub(crate) fn pinned_drop(_args: TokenStream, input: TokenStream) -> TokenStream // Found the end of the generics, this should be `PinnedDrop`. assert!( matches!(tt, TokenTree::Ident(i) if i.to_string() == "PinnedDrop"), - "expected 'PinnedDrop', found: '{:?}'", - tt + "expected 'PinnedDrop', found: '{tt:?}'" ); pinned_drop_idx = Some(i); break; diff --git a/rust/pin-init/internal/src/zeroable.rs b/rust/pin-init/internal/src/zeroable.rs index acc94008c152..e0ed3998445c 100644 --- a/rust/pin-init/internal/src/zeroable.rs +++ b/rust/pin-init/internal/src/zeroable.rs @@ -6,7 +6,14 @@ use proc_macro2 as proc_macro; use crate::helpers::{parse_generics, Generics}; use proc_macro::{TokenStream, TokenTree}; -pub(crate) fn derive(input: TokenStream) -> TokenStream { +pub(crate) fn parse_zeroable_derive_input( + input: TokenStream, +) -> ( + Vec<TokenTree>, + Vec<TokenTree>, + Vec<TokenTree>, + Option<TokenTree>, +) { let ( Generics { impl_generics, @@ -64,6 +71,11 @@ pub(crate) fn derive(input: TokenStream) -> TokenStream { if in_generic && !inserted { new_impl_generics.extend(quote! { : ::pin_init::Zeroable }); } + (rest, new_impl_generics, ty_generics, last) +} + +pub(crate) fn derive(input: TokenStream) -> TokenStream { + let (rest, new_impl_generics, ty_generics, last) = parse_zeroable_derive_input(input); quote! { ::pin_init::__derive_zeroable!( parse_input: @@ -74,3 +86,16 @@ pub(crate) fn derive(input: TokenStream) -> TokenStream { ); } } + +pub(crate) fn maybe_derive(input: TokenStream) -> TokenStream { + let (rest, new_impl_generics, ty_generics, last) = parse_zeroable_derive_input(input); + quote! { + ::pin_init::__maybe_derive_zeroable!( + parse_input: + @sig(#(#rest)*), + @impl_generics(#(#new_impl_generics)*), + @ty_generics(#(#ty_generics)*), + @body(#last), + ); + } +} diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs index 0806c689f693..9ab34036e6bc 100644 --- a/rust/pin-init/src/lib.rs +++ b/rust/pin-init/src/lib.rs @@ -32,6 +32,12 @@ //! will require the `std` feature, because stable compilers have neither `Box` nor `Arc` in no-std //! mode. //! +//! ## Nightly needed for `unsafe-pinned` feature +//! +//! This feature enables the `Wrapper` implementation on the unstable `core::pin::UnsafePinned` type. +//! This requires the [`unsafe_pinned` unstable feature](https://github.com/rust-lang/rust/issues/125735) +//! and therefore a nightly compiler. Note that this feature is not enabled by default. +//! //! # Overview //! //! To initialize a `struct` with an in-place constructor you will need two things: @@ -241,7 +247,7 @@ //! [`sync`]: https://rust.docs.kernel.org/kernel/sync/index.html //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: -//! https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural-for-field +//! https://doc.rust-lang.org/std/pin/index.html#projections-and-structural-pinning //! [stack]: crate::stack_pin_init #![cfg_attr( kernel, @@ -269,6 +275,10 @@ #![forbid(missing_docs, unsafe_op_in_unsafe_fn)] #![cfg_attr(not(feature = "std"), no_std)] #![cfg_attr(feature = "alloc", feature(allocator_api))] +#![cfg_attr( + all(feature = "unsafe-pinned", CONFIG_RUSTC_HAS_UNSAFE_PINNED), + feature(unsafe_pinned) +)] use core::{ cell::UnsafeCell, @@ -385,9 +395,10 @@ pub use ::pin_init_internal::pin_data; /// ``` pub use ::pin_init_internal::pinned_drop; -/// Derives the [`Zeroable`] trait for the given struct. +/// Derives the [`Zeroable`] trait for the given `struct` or `union`. /// -/// This can only be used for structs where every field implements the [`Zeroable`] trait. +/// This can only be used for `struct`s/`union`s where every field implements the [`Zeroable`] +/// trait. /// /// # Examples /// @@ -396,13 +407,54 @@ pub use ::pin_init_internal::pinned_drop; /// /// #[derive(Zeroable)] /// pub struct DriverData { -/// id: i64, +/// pub(crate) id: i64, /// buf_ptr: *mut u8, /// len: usize, /// } /// ``` +/// +/// ``` +/// use pin_init::Zeroable; +/// +/// #[derive(Zeroable)] +/// pub union SignCast { +/// signed: i64, +/// unsigned: u64, +/// } +/// ``` pub use ::pin_init_internal::Zeroable; +/// Derives the [`Zeroable`] trait for the given `struct` or `union` if all fields implement +/// [`Zeroable`]. +/// +/// Contrary to the derive macro named [`macro@Zeroable`], this one silently fails when a field +/// doesn't implement [`Zeroable`]. +/// +/// # Examples +/// +/// ``` +/// use pin_init::MaybeZeroable; +/// +/// // implmements `Zeroable` +/// #[derive(MaybeZeroable)] +/// pub struct DriverData { +/// pub(crate) id: i64, +/// buf_ptr: *mut u8, +/// len: usize, +/// } +/// +/// // does not implmement `Zeroable` +/// #[derive(MaybeZeroable)] +/// pub struct DriverData2 { +/// pub(crate) id: i64, +/// buf_ptr: *mut u8, +/// len: usize, +/// // this field doesn't implement `Zeroable` +/// other_data: &'static i32, +/// } +/// ``` +pub use ::pin_init_internal::MaybeZeroable; + /// Initialize and pin a type directly on the stack. /// /// # Examples @@ -1216,6 +1268,38 @@ pub const unsafe fn init_from_closure<T: ?Sized, E>( __internal::InitClosure(f, PhantomData) } +/// Changes the to be initialized type. +/// +/// # Safety +/// +/// - `*mut U` must be castable to `*mut T` and any value of type `T` written through such a +/// pointer must result in a valid `U`. +#[expect(clippy::let_and_return)] +pub const unsafe fn cast_pin_init<T, U, E>(init: impl PinInit<T, E>) -> impl PinInit<U, E> { + // SAFETY: initialization delegated to a valid initializer. Cast is valid by function safety + // requirements. + let res = unsafe { pin_init_from_closure(|ptr: *mut U| init.__pinned_init(ptr.cast::<T>())) }; + // FIXME: remove the let statement once the nightly-MSRV allows it (1.78 otherwise encounters a + // cycle when computing the type returned by this function) + res +} + +/// Changes the to be initialized type. +/// +/// # Safety +/// +/// - `*mut U` must be castable to `*mut T` and any value of type `T` written through such a +/// pointer must result in a valid `U`. +#[expect(clippy::let_and_return)] +pub const unsafe fn cast_init<T, U, E>(init: impl Init<T, E>) -> impl Init<U, E> { + // SAFETY: initialization delegated to a valid initializer. Cast is valid by function safety + // requirements. + let res = unsafe { init_from_closure(|ptr: *mut U| init.__init(ptr.cast::<T>())) }; + // FIXME: remove the let statement once the nightly-MSRV allows it (1.78 otherwise encounters a + // cycle when computing the type returned by this function) + res +} + /// An initializer that leaves the memory uninitialized. /// /// The initializer is a no-op. The `slot` memory is not changed. @@ -1481,3 +1565,55 @@ macro_rules! impl_tuple_zeroable { } impl_tuple_zeroable!(A, B, C, D, E, F, G, H, I, J); + +/// This trait allows creating an instance of `Self` which contains exactly one +/// [structurally pinned value](https://doc.rust-lang.org/std/pin/index.html#projections-and-structural-pinning). +/// +/// This is useful when using wrapper `struct`s like [`UnsafeCell`] or with new-type `struct`s. +/// +/// # Examples +/// +/// ``` +/// # use core::cell::UnsafeCell; +/// # use pin_init::{pin_data, pin_init, Wrapper}; +/// +/// #[pin_data] +/// struct Foo {} +/// +/// #[pin_data] +/// struct Bar { +/// #[pin] +/// content: UnsafeCell<Foo> +/// }; +/// +/// let foo_initializer = pin_init!(Foo{}); +/// let initializer = pin_init!(Bar { +/// content <- UnsafeCell::pin_init(foo_initializer) +/// }); +/// ``` +pub trait Wrapper<T> { + /// Creates an pin-initializer for a [`Self`] containing `T` from the `value_init` initializer. + fn pin_init<E>(value_init: impl PinInit<T, E>) -> impl PinInit<Self, E>; +} + +impl<T> Wrapper<T> for UnsafeCell<T> { + fn pin_init<E>(value_init: impl PinInit<T, E>) -> impl PinInit<Self, E> { + // SAFETY: `UnsafeCell<T>` has a compatible layout to `T`. + unsafe { cast_pin_init(value_init) } + } +} + +impl<T> Wrapper<T> for MaybeUninit<T> { + fn pin_init<E>(value_init: impl PinInit<T, E>) -> impl PinInit<Self, E> { + // SAFETY: `MaybeUninit<T>` has a compatible layout to `T`. + unsafe { cast_pin_init(value_init) } + } +} + +#[cfg(all(feature = "unsafe-pinned", CONFIG_RUSTC_HAS_UNSAFE_PINNED))] +impl<T> Wrapper<T> for core::pin::UnsafePinned<T> { + fn pin_init<E>(init: impl PinInit<T, E>) -> impl PinInit<Self, E> { + // SAFETY: `UnsafePinned<T>` has a compatible layout to `T`. + unsafe { cast_pin_init(init) } + } +} diff --git a/rust/pin-init/src/macros.rs b/rust/pin-init/src/macros.rs index 361623324d5c..935d77745d1d 100644 --- a/rust/pin-init/src/macros.rs +++ b/rust/pin-init/src/macros.rs @@ -1393,7 +1393,7 @@ macro_rules! __derive_zeroable { @body({ $( $(#[$($field_attr:tt)*])* - $field:ident : $field_ty:ty + $field_vis:vis $field:ident : $field_ty:ty ),* $(,)? }), ) => { @@ -1412,4 +1412,93 @@ macro_rules! __derive_zeroable { } }; }; + (parse_input: + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis union $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ + $( + $(#[$($field_attr:tt)*])* + $field_vis:vis $field:ident : $field_ty:ty + ),* $(,)? + }), + ) => { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> + where + $($($whr)*)? + {} + const _: () = { + fn assert_zeroable<T: ?::core::marker::Sized + $crate::Zeroable>() {} + fn ensure_zeroable<$($impl_generics)*>() + where $($($whr)*)? + { + $(assert_zeroable::<$field_ty>();)* + } + }; + }; +} + +#[doc(hidden)] +#[macro_export] +macro_rules! __maybe_derive_zeroable { + (parse_input: + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis struct $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ + $( + $(#[$($field_attr:tt)*])* + $field_vis:vis $field:ident : $field_ty:ty + ),* $(,)? + }), + ) => { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> + where + $( + // the `for<'__dummy>` HRTB makes this not error without the `trivial_bounds` + // feature <https://github.com/rust-lang/rust/issues/48214#issuecomment-2557829956>. + $field_ty: for<'__dummy> $crate::Zeroable, + )* + $($($whr)*)? + {} + }; + (parse_input: + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis union $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ + $( + $(#[$($field_attr:tt)*])* + $field_vis:vis $field:ident : $field_ty:ty + ),* $(,)? + }), + ) => { + // SAFETY: Every field type implements `Zeroable` and padding bytes may be zero. + #[automatically_derived] + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> + where + $( + // the `for<'__dummy>` HRTB makes this not error without the `trivial_bounds` + // feature <https://github.com/rust-lang/rust/issues/48214#issuecomment-2557829956>. + $field_ty: for<'__dummy> $crate::Zeroable, + )* + $($($whr)*)? + {} + }; } |