1 // SPDX-License-Identifier: Apache-2.0 OR MIT 1 // SPDX-License-Identifier: Apache-2.0 OR MIT
2 2
3 //! API to safely and fallibly initialize pinn 3 //! API to safely and fallibly initialize pinned `struct`s using in-place constructors.
4 //! 4 //!
5 //! It also allows in-place initialization of 5 //! It also allows in-place initialization of big `struct`s that would otherwise produce a stack
6 //! overflow. 6 //! overflow.
7 //! 7 //!
8 //! Most `struct`s from the [`sync`] module ne 8 //! Most `struct`s from the [`sync`] module need to be pinned, because they contain self-referential
9 //! `struct`s from C. [Pinning][pinning] is Ru 9 //! `struct`s from C. [Pinning][pinning] is Rust's way of ensuring data does not move.
10 //! 10 //!
11 //! # Overview 11 //! # Overview
12 //! 12 //!
13 //! To initialize a `struct` with an in-place 13 //! To initialize a `struct` with an in-place constructor you will need two things:
14 //! - an in-place constructor, 14 //! - an in-place constructor,
15 //! - a memory location that can hold your `st 15 //! - a memory location that can hold your `struct` (this can be the [stack], an [`Arc<T>`],
16 //! [`UniqueArc<T>`], [`Box<T>`] or any othe 16 //! [`UniqueArc<T>`], [`Box<T>`] or any other smart pointer that implements [`InPlaceInit`]).
17 //! 17 //!
18 //! To get an in-place constructor there are g 18 //! To get an in-place constructor there are generally three options:
19 //! - directly creating an in-place constructo 19 //! - directly creating an in-place constructor using the [`pin_init!`] macro,
20 //! - a custom function/macro returning an in- 20 //! - a custom function/macro returning an in-place constructor provided by someone else,
21 //! - using the unsafe function [`pin_init_fro 21 //! - using the unsafe function [`pin_init_from_closure()`] to manually create an initializer.
22 //! 22 //!
23 //! Aside from pinned initialization, this API 23 //! Aside from pinned initialization, this API also supports in-place construction without pinning,
24 //! the macros/types/functions are generally n 24 //! the macros/types/functions are generally named like the pinned variants without the `pin`
25 //! prefix. 25 //! prefix.
26 //! 26 //!
27 //! # Examples 27 //! # Examples
28 //! 28 //!
29 //! ## Using the [`pin_init!`] macro 29 //! ## Using the [`pin_init!`] macro
30 //! 30 //!
31 //! If you want to use [`PinInit`], then you w 31 //! If you want to use [`PinInit`], then you will have to annotate your `struct` with
32 //! `#[`[`pin_data`]`]`. It is a macro that us 32 //! `#[`[`pin_data`]`]`. It is a macro that uses `#[pin]` as a marker for
33 //! [structurally pinned fields]. After doing 33 //! [structurally pinned fields]. After doing this, you can then create an in-place constructor via
34 //! [`pin_init!`]. The syntax is almost the sa 34 //! [`pin_init!`]. The syntax is almost the same as normal `struct` initializers. The difference is
35 //! that you need to write `<-` instead of `:` 35 //! that you need to write `<-` instead of `:` for fields that you want to initialize in-place.
36 //! 36 //!
37 //! ```rust 37 //! ```rust
38 //! # #![allow(clippy::disallowed_names)] 38 //! # #![allow(clippy::disallowed_names)]
39 //! use kernel::sync::{new_mutex, Mutex}; 39 //! use kernel::sync::{new_mutex, Mutex};
40 //! # use core::pin::Pin; 40 //! # use core::pin::Pin;
41 //! #[pin_data] 41 //! #[pin_data]
42 //! struct Foo { 42 //! struct Foo {
43 //! #[pin] 43 //! #[pin]
44 //! a: Mutex<usize>, 44 //! a: Mutex<usize>,
45 //! b: u32, 45 //! b: u32,
46 //! } 46 //! }
47 //! 47 //!
48 //! let foo = pin_init!(Foo { 48 //! let foo = pin_init!(Foo {
49 //! a <- new_mutex!(42, "Foo::a"), 49 //! a <- new_mutex!(42, "Foo::a"),
50 //! b: 24, 50 //! b: 24,
51 //! }); 51 //! });
52 //! ``` 52 //! ```
53 //! 53 //!
54 //! `foo` now is of the type [`impl PinInit<Fo 54 //! `foo` now is of the type [`impl PinInit<Foo>`]. We can now use any smart pointer that we like
55 //! (or just the stack) to actually initialize 55 //! (or just the stack) to actually initialize a `Foo`:
56 //! 56 //!
57 //! ```rust 57 //! ```rust
58 //! # #![allow(clippy::disallowed_names)] 58 //! # #![allow(clippy::disallowed_names)]
59 //! # use kernel::sync::{new_mutex, Mutex}; 59 //! # use kernel::sync::{new_mutex, Mutex};
60 //! # use core::pin::Pin; 60 //! # use core::pin::Pin;
61 //! # #[pin_data] 61 //! # #[pin_data]
62 //! # struct Foo { 62 //! # struct Foo {
63 //! # #[pin] 63 //! # #[pin]
64 //! # a: Mutex<usize>, 64 //! # a: Mutex<usize>,
65 //! # b: u32, 65 //! # b: u32,
66 //! # } 66 //! # }
67 //! # let foo = pin_init!(Foo { 67 //! # let foo = pin_init!(Foo {
68 //! # a <- new_mutex!(42, "Foo::a"), 68 //! # a <- new_mutex!(42, "Foo::a"),
69 //! # b: 24, 69 //! # b: 24,
70 //! # }); 70 //! # });
71 //! let foo: Result<Pin<Box<Foo>>> = Box::pin_ !! 71 //! let foo: Result<Pin<Box<Foo>>> = Box::pin_init(foo);
72 //! ``` 72 //! ```
73 //! 73 //!
74 //! For more information see the [`pin_init!`] 74 //! For more information see the [`pin_init!`] macro.
75 //! 75 //!
76 //! ## Using a custom function/macro that retu 76 //! ## Using a custom function/macro that returns an initializer
77 //! 77 //!
78 //! Many types from the kernel supply a functi 78 //! Many types from the kernel supply a function/macro that returns an initializer, because the
79 //! above method only works for types where yo 79 //! above method only works for types where you can access the fields.
80 //! 80 //!
81 //! ```rust 81 //! ```rust
82 //! # use kernel::sync::{new_mutex, Arc, Mutex 82 //! # use kernel::sync::{new_mutex, Arc, Mutex};
83 //! let mtx: Result<Arc<Mutex<usize>>> = !! 83 //! let mtx: Result<Arc<Mutex<usize>>> = Arc::pin_init(new_mutex!(42, "example::mtx"));
84 //! Arc::pin_init(new_mutex!(42, "example: <<
85 //! ``` 84 //! ```
86 //! 85 //!
87 //! To declare an init macro/function you just 86 //! To declare an init macro/function you just return an [`impl PinInit<T, E>`]:
88 //! 87 //!
89 //! ```rust 88 //! ```rust
90 //! # #![allow(clippy::disallowed_names)] 89 //! # #![allow(clippy::disallowed_names)]
91 //! # use kernel::{sync::Mutex, new_mutex, ini !! 90 //! # use kernel::{sync::Mutex, prelude::*, new_mutex, init::PinInit, try_pin_init};
92 //! #[pin_data] 91 //! #[pin_data]
93 //! struct DriverData { 92 //! struct DriverData {
94 //! #[pin] 93 //! #[pin]
95 //! status: Mutex<i32>, 94 //! status: Mutex<i32>,
96 //! buffer: Box<[u8; 1_000_000]>, 95 //! buffer: Box<[u8; 1_000_000]>,
97 //! } 96 //! }
98 //! 97 //!
99 //! impl DriverData { 98 //! impl DriverData {
100 //! fn new() -> impl PinInit<Self, Error> 99 //! fn new() -> impl PinInit<Self, Error> {
101 //! try_pin_init!(Self { 100 //! try_pin_init!(Self {
102 //! status <- new_mutex!(0, "Drive 101 //! status <- new_mutex!(0, "DriverData::status"),
103 //! buffer: Box::init(kernel::init !! 102 //! buffer: Box::init(kernel::init::zeroed())?,
104 //! }) 103 //! })
105 //! } 104 //! }
106 //! } 105 //! }
107 //! ``` 106 //! ```
108 //! 107 //!
109 //! ## Manual creation of an initializer 108 //! ## Manual creation of an initializer
110 //! 109 //!
111 //! Often when working with primitives the pre 110 //! Often when working with primitives the previous approaches are not sufficient. That is where
112 //! [`pin_init_from_closure()`] comes in. This 111 //! [`pin_init_from_closure()`] comes in. This `unsafe` function allows you to create a
113 //! [`impl PinInit<T, E>`] directly from a clo 112 //! [`impl PinInit<T, E>`] directly from a closure. Of course you have to ensure that the closure
114 //! actually does the initialization in the co 113 //! actually does the initialization in the correct way. Here are the things to look out for
115 //! (we are calling the parameter to the closu 114 //! (we are calling the parameter to the closure `slot`):
116 //! - when the closure returns `Ok(())`, then 115 //! - when the closure returns `Ok(())`, then it has completed the initialization successfully, so
117 //! `slot` now contains a valid bit pattern 116 //! `slot` now contains a valid bit pattern for the type `T`,
118 //! - when the closure returns `Err(e)`, then 117 //! - when the closure returns `Err(e)`, then the caller may deallocate the memory at `slot`, so
119 //! you need to take care to clean up anythi 118 //! you need to take care to clean up anything if your initialization fails mid-way,
120 //! - you may assume that `slot` will stay pin 119 //! - you may assume that `slot` will stay pinned even after the closure returns until `drop` of
121 //! `slot` gets called. 120 //! `slot` gets called.
122 //! 121 //!
123 //! ```rust 122 //! ```rust
124 //! # #![allow(unreachable_pub, clippy::disall 123 //! # #![allow(unreachable_pub, clippy::disallowed_names)]
125 //! use kernel::{init, types::Opaque}; !! 124 //! use kernel::{prelude::*, init, types::Opaque};
126 //! use core::{ptr::addr_of_mut, marker::Phant 125 //! use core::{ptr::addr_of_mut, marker::PhantomPinned, pin::Pin};
127 //! # mod bindings { 126 //! # mod bindings {
128 //! # #![allow(non_camel_case_types)] 127 //! # #![allow(non_camel_case_types)]
129 //! # pub struct foo; 128 //! # pub struct foo;
130 //! # pub unsafe fn init_foo(_ptr: *mut fo 129 //! # pub unsafe fn init_foo(_ptr: *mut foo) {}
131 //! # pub unsafe fn destroy_foo(_ptr: *mut 130 //! # pub unsafe fn destroy_foo(_ptr: *mut foo) {}
132 //! # pub unsafe fn enable_foo(_ptr: *mut 131 //! # pub unsafe fn enable_foo(_ptr: *mut foo, _flags: u32) -> i32 { 0 }
133 //! # } 132 //! # }
134 //! # // `Error::from_errno` is `pub(crate)` i 133 //! # // `Error::from_errno` is `pub(crate)` in the `kernel` crate, thus provide a workaround.
135 //! # trait FromErrno { 134 //! # trait FromErrno {
136 //! # fn from_errno(errno: core::ffi::c_in 135 //! # fn from_errno(errno: core::ffi::c_int) -> Error {
137 //! # // Dummy error that can be const 136 //! # // Dummy error that can be constructed outside the `kernel` crate.
138 //! # Error::from(core::fmt::Error) 137 //! # Error::from(core::fmt::Error)
139 //! # } 138 //! # }
140 //! # } 139 //! # }
141 //! # impl FromErrno for Error {} 140 //! # impl FromErrno for Error {}
142 //! /// # Invariants 141 //! /// # Invariants
143 //! /// 142 //! ///
144 //! /// `foo` is always initialized 143 //! /// `foo` is always initialized
145 //! #[pin_data(PinnedDrop)] 144 //! #[pin_data(PinnedDrop)]
146 //! pub struct RawFoo { 145 //! pub struct RawFoo {
147 //! #[pin] 146 //! #[pin]
148 //! foo: Opaque<bindings::foo>, 147 //! foo: Opaque<bindings::foo>,
149 //! #[pin] 148 //! #[pin]
150 //! _p: PhantomPinned, 149 //! _p: PhantomPinned,
151 //! } 150 //! }
152 //! 151 //!
153 //! impl RawFoo { 152 //! impl RawFoo {
154 //! pub fn new(flags: u32) -> impl PinInit 153 //! pub fn new(flags: u32) -> impl PinInit<Self, Error> {
155 //! // SAFETY: 154 //! // SAFETY:
156 //! // - when the closure returns `Ok( 155 //! // - when the closure returns `Ok(())`, then it has successfully initialized and
157 //! // enabled `foo`, 156 //! // enabled `foo`,
158 //! // - when it returns `Err(e)`, the 157 //! // - when it returns `Err(e)`, then it has cleaned up before
159 //! unsafe { 158 //! unsafe {
160 //! init::pin_init_from_closure(mo 159 //! init::pin_init_from_closure(move |slot: *mut Self| {
161 //! // `slot` contains uninit 160 //! // `slot` contains uninit memory, avoid creating a reference.
162 //! let foo = addr_of_mut!((*s 161 //! let foo = addr_of_mut!((*slot).foo);
163 //! 162 //!
164 //! // Initialize the `foo` 163 //! // Initialize the `foo`
165 //! bindings::init_foo(Opaque: 164 //! bindings::init_foo(Opaque::raw_get(foo));
166 //! 165 //!
167 //! // Try to enable it. 166 //! // Try to enable it.
168 //! let err = bindings::enable 167 //! let err = bindings::enable_foo(Opaque::raw_get(foo), flags);
169 //! if err != 0 { 168 //! if err != 0 {
170 //! // Enabling has failed 169 //! // Enabling has failed, first clean up the foo and then return the error.
171 //! bindings::destroy_foo( 170 //! bindings::destroy_foo(Opaque::raw_get(foo));
172 //! return Err(Error::from 171 //! return Err(Error::from_errno(err));
173 //! } 172 //! }
174 //! 173 //!
175 //! // All fields of `RawFoo` 174 //! // All fields of `RawFoo` have been initialized, since `_p` is a ZST.
176 //! Ok(()) 175 //! Ok(())
177 //! }) 176 //! })
178 //! } 177 //! }
179 //! } 178 //! }
180 //! } 179 //! }
181 //! 180 //!
182 //! #[pinned_drop] 181 //! #[pinned_drop]
183 //! impl PinnedDrop for RawFoo { 182 //! impl PinnedDrop for RawFoo {
184 //! fn drop(self: Pin<&mut Self>) { 183 //! fn drop(self: Pin<&mut Self>) {
185 //! // SAFETY: Since `foo` is initiali 184 //! // SAFETY: Since `foo` is initialized, destroying is safe.
186 //! unsafe { bindings::destroy_foo(sel 185 //! unsafe { bindings::destroy_foo(self.foo.get()) };
187 //! } 186 //! }
188 //! } 187 //! }
189 //! ``` 188 //! ```
190 //! 189 //!
191 //! For the special case where initializing a 190 //! For the special case where initializing a field is a single FFI-function call that cannot fail,
192 //! there exist the helper function [`Opaque:: 191 //! there exist the helper function [`Opaque::ffi_init`]. This function initialize a single
193 //! [`Opaque`] field by just delegating to the 192 //! [`Opaque`] field by just delegating to the supplied closure. You can use these in combination
194 //! with [`pin_init!`]. 193 //! with [`pin_init!`].
195 //! 194 //!
196 //! For more information on how to use [`pin_i 195 //! For more information on how to use [`pin_init_from_closure()`], take a look at the uses inside
197 //! the `kernel` crate. The [`sync`] module is 196 //! the `kernel` crate. The [`sync`] module is a good starting point.
198 //! 197 //!
199 //! [`sync`]: kernel::sync 198 //! [`sync`]: kernel::sync
200 //! [pinning]: https://doc.rust-lang.org/std/p 199 //! [pinning]: https://doc.rust-lang.org/std/pin/index.html
201 //! [structurally pinned fields]: 200 //! [structurally pinned fields]:
202 //! https://doc.rust-lang.org/std/pin/inde 201 //! https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural-for-field
203 //! [stack]: crate::stack_pin_init 202 //! [stack]: crate::stack_pin_init
204 //! [`Arc<T>`]: crate::sync::Arc 203 //! [`Arc<T>`]: crate::sync::Arc
205 //! [`impl PinInit<Foo>`]: PinInit 204 //! [`impl PinInit<Foo>`]: PinInit
206 //! [`impl PinInit<T, E>`]: PinInit 205 //! [`impl PinInit<T, E>`]: PinInit
207 //! [`impl Init<T, E>`]: Init 206 //! [`impl Init<T, E>`]: Init
208 //! [`Opaque`]: kernel::types::Opaque 207 //! [`Opaque`]: kernel::types::Opaque
209 //! [`Opaque::ffi_init`]: kernel::types::Opaqu 208 //! [`Opaque::ffi_init`]: kernel::types::Opaque::ffi_init
210 //! [`pin_data`]: ::macros::pin_data 209 //! [`pin_data`]: ::macros::pin_data
211 //! [`pin_init!`]: crate::pin_init! 210 //! [`pin_init!`]: crate::pin_init!
212 211
213 use crate::{ 212 use crate::{
214 alloc::{box_ext::BoxExt, AllocError, Flags <<
215 error::{self, Error}, 213 error::{self, Error},
216 sync::Arc, <<
217 sync::UniqueArc, 214 sync::UniqueArc,
218 types::{Opaque, ScopeGuard}, 215 types::{Opaque, ScopeGuard},
219 }; 216 };
220 use alloc::boxed::Box; 217 use alloc::boxed::Box;
221 use core::{ 218 use core::{
>> 219 alloc::AllocError,
222 cell::UnsafeCell, 220 cell::UnsafeCell,
223 convert::Infallible, 221 convert::Infallible,
224 marker::PhantomData, 222 marker::PhantomData,
225 mem::MaybeUninit, 223 mem::MaybeUninit,
226 num::*, 224 num::*,
227 pin::Pin, 225 pin::Pin,
228 ptr::{self, NonNull}, 226 ptr::{self, NonNull},
229 }; 227 };
230 228
231 #[doc(hidden)] 229 #[doc(hidden)]
232 pub mod __internal; 230 pub mod __internal;
233 #[doc(hidden)] 231 #[doc(hidden)]
234 pub mod macros; 232 pub mod macros;
235 233
236 /// Initialize and pin a type directly on the 234 /// Initialize and pin a type directly on the stack.
237 /// 235 ///
238 /// # Examples 236 /// # Examples
239 /// 237 ///
240 /// ```rust 238 /// ```rust
241 /// # #![allow(clippy::disallowed_names)] 239 /// # #![allow(clippy::disallowed_names)]
242 /// # use kernel::{init, macros::pin_data, pin 240 /// # use kernel::{init, macros::pin_data, pin_init, stack_pin_init, init::*, sync::Mutex, new_mutex};
243 /// # use core::pin::Pin; 241 /// # use core::pin::Pin;
244 /// #[pin_data] 242 /// #[pin_data]
245 /// struct Foo { 243 /// struct Foo {
246 /// #[pin] 244 /// #[pin]
247 /// a: Mutex<usize>, 245 /// a: Mutex<usize>,
248 /// b: Bar, 246 /// b: Bar,
249 /// } 247 /// }
250 /// 248 ///
251 /// #[pin_data] 249 /// #[pin_data]
252 /// struct Bar { 250 /// struct Bar {
253 /// x: u32, 251 /// x: u32,
254 /// } 252 /// }
255 /// 253 ///
256 /// stack_pin_init!(let foo = pin_init!(Foo { 254 /// stack_pin_init!(let foo = pin_init!(Foo {
257 /// a <- new_mutex!(42), 255 /// a <- new_mutex!(42),
258 /// b: Bar { 256 /// b: Bar {
259 /// x: 64, 257 /// x: 64,
260 /// }, 258 /// },
261 /// })); 259 /// }));
262 /// let foo: Pin<&mut Foo> = foo; 260 /// let foo: Pin<&mut Foo> = foo;
263 /// pr_info!("a: {}", &*foo.a.lock()); 261 /// pr_info!("a: {}", &*foo.a.lock());
264 /// ``` 262 /// ```
265 /// 263 ///
266 /// # Syntax 264 /// # Syntax
267 /// 265 ///
268 /// A normal `let` binding with optional type 266 /// A normal `let` binding with optional type annotation. The expression is expected to implement
269 /// [`PinInit`]/[`Init`] with the error type [ 267 /// [`PinInit`]/[`Init`] with the error type [`Infallible`]. If you want to use a different error
270 /// type, then use [`stack_try_pin_init!`]. 268 /// type, then use [`stack_try_pin_init!`].
271 /// 269 ///
272 /// [`stack_try_pin_init!`]: crate::stack_try_ 270 /// [`stack_try_pin_init!`]: crate::stack_try_pin_init!
273 #[macro_export] 271 #[macro_export]
274 macro_rules! stack_pin_init { 272 macro_rules! stack_pin_init {
275 (let $var:ident $(: $t:ty)? = $val:expr) = 273 (let $var:ident $(: $t:ty)? = $val:expr) => {
276 let val = $val; 274 let val = $val;
277 let mut $var = ::core::pin::pin!($crat 275 let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit());
278 let mut $var = match $crate::init::__i 276 let mut $var = match $crate::init::__internal::StackInit::init($var, val) {
279 Ok(res) => res, 277 Ok(res) => res,
280 Err(x) => { 278 Err(x) => {
281 let x: ::core::convert::Infall 279 let x: ::core::convert::Infallible = x;
282 match x {} 280 match x {}
283 } 281 }
284 }; 282 };
285 }; 283 };
286 } 284 }
287 285
288 /// Initialize and pin a type directly on the 286 /// Initialize and pin a type directly on the stack.
289 /// 287 ///
290 /// # Examples 288 /// # Examples
291 /// 289 ///
292 /// ```rust,ignore 290 /// ```rust,ignore
293 /// # #![allow(clippy::disallowed_names)] 291 /// # #![allow(clippy::disallowed_names)]
294 /// # use kernel::{init, pin_init, stack_try_p 292 /// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mutex, new_mutex};
295 /// # use macros::pin_data; 293 /// # use macros::pin_data;
296 /// # use core::{alloc::AllocError, pin::Pin}; 294 /// # use core::{alloc::AllocError, pin::Pin};
297 /// #[pin_data] 295 /// #[pin_data]
298 /// struct Foo { 296 /// struct Foo {
299 /// #[pin] 297 /// #[pin]
300 /// a: Mutex<usize>, 298 /// a: Mutex<usize>,
301 /// b: Box<Bar>, 299 /// b: Box<Bar>,
302 /// } 300 /// }
303 /// 301 ///
304 /// struct Bar { 302 /// struct Bar {
305 /// x: u32, 303 /// x: u32,
306 /// } 304 /// }
307 /// 305 ///
308 /// stack_try_pin_init!(let foo: Result<Pin<&m 306 /// stack_try_pin_init!(let foo: Result<Pin<&mut Foo>, AllocError> = pin_init!(Foo {
309 /// a <- new_mutex!(42), 307 /// a <- new_mutex!(42),
310 /// b: Box::new(Bar { !! 308 /// b: Box::try_new(Bar {
311 /// x: 64, 309 /// x: 64,
312 /// }, GFP_KERNEL)?, !! 310 /// })?,
313 /// })); 311 /// }));
314 /// let foo = foo.unwrap(); 312 /// let foo = foo.unwrap();
315 /// pr_info!("a: {}", &*foo.a.lock()); 313 /// pr_info!("a: {}", &*foo.a.lock());
316 /// ``` 314 /// ```
317 /// 315 ///
318 /// ```rust,ignore 316 /// ```rust,ignore
319 /// # #![allow(clippy::disallowed_names)] 317 /// # #![allow(clippy::disallowed_names)]
320 /// # use kernel::{init, pin_init, stack_try_p 318 /// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mutex, new_mutex};
321 /// # use macros::pin_data; 319 /// # use macros::pin_data;
322 /// # use core::{alloc::AllocError, pin::Pin}; 320 /// # use core::{alloc::AllocError, pin::Pin};
323 /// #[pin_data] 321 /// #[pin_data]
324 /// struct Foo { 322 /// struct Foo {
325 /// #[pin] 323 /// #[pin]
326 /// a: Mutex<usize>, 324 /// a: Mutex<usize>,
327 /// b: Box<Bar>, 325 /// b: Box<Bar>,
328 /// } 326 /// }
329 /// 327 ///
330 /// struct Bar { 328 /// struct Bar {
331 /// x: u32, 329 /// x: u32,
332 /// } 330 /// }
333 /// 331 ///
334 /// stack_try_pin_init!(let foo: Pin<&mut Foo> 332 /// stack_try_pin_init!(let foo: Pin<&mut Foo> =? pin_init!(Foo {
335 /// a <- new_mutex!(42), 333 /// a <- new_mutex!(42),
336 /// b: Box::new(Bar { !! 334 /// b: Box::try_new(Bar {
337 /// x: 64, 335 /// x: 64,
338 /// }, GFP_KERNEL)?, !! 336 /// })?,
339 /// })); 337 /// }));
340 /// pr_info!("a: {}", &*foo.a.lock()); 338 /// pr_info!("a: {}", &*foo.a.lock());
341 /// # Ok::<_, AllocError>(()) 339 /// # Ok::<_, AllocError>(())
342 /// ``` 340 /// ```
343 /// 341 ///
344 /// # Syntax 342 /// # Syntax
345 /// 343 ///
346 /// A normal `let` binding with optional type 344 /// A normal `let` binding with optional type annotation. The expression is expected to implement
347 /// [`PinInit`]/[`Init`]. This macro assigns a 345 /// [`PinInit`]/[`Init`]. This macro assigns a result to the given variable, adding a `?` after the
348 /// `=` will propagate this error. 346 /// `=` will propagate this error.
349 #[macro_export] 347 #[macro_export]
350 macro_rules! stack_try_pin_init { 348 macro_rules! stack_try_pin_init {
351 (let $var:ident $(: $t:ty)? = $val:expr) = 349 (let $var:ident $(: $t:ty)? = $val:expr) => {
352 let val = $val; 350 let val = $val;
353 let mut $var = ::core::pin::pin!($crat 351 let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit());
354 let mut $var = $crate::init::__interna 352 let mut $var = $crate::init::__internal::StackInit::init($var, val);
355 }; 353 };
356 (let $var:ident $(: $t:ty)? =? $val:expr) 354 (let $var:ident $(: $t:ty)? =? $val:expr) => {
357 let val = $val; 355 let val = $val;
358 let mut $var = ::core::pin::pin!($crat 356 let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit());
359 let mut $var = $crate::init::__interna 357 let mut $var = $crate::init::__internal::StackInit::init($var, val)?;
360 }; 358 };
361 } 359 }
362 360
363 /// Construct an in-place, pinned initializer 361 /// Construct an in-place, pinned initializer for `struct`s.
364 /// 362 ///
365 /// This macro defaults the error to [`Infalli 363 /// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use
366 /// [`try_pin_init!`]. 364 /// [`try_pin_init!`].
367 /// 365 ///
368 /// The syntax is almost identical to that of 366 /// The syntax is almost identical to that of a normal `struct` initializer:
369 /// 367 ///
370 /// ```rust 368 /// ```rust
371 /// # #![allow(clippy::disallowed_names)] 369 /// # #![allow(clippy::disallowed_names)]
372 /// # use kernel::{init, pin_init, macros::pin 370 /// # use kernel::{init, pin_init, macros::pin_data, init::*};
373 /// # use core::pin::Pin; 371 /// # use core::pin::Pin;
374 /// #[pin_data] 372 /// #[pin_data]
375 /// struct Foo { 373 /// struct Foo {
376 /// a: usize, 374 /// a: usize,
377 /// b: Bar, 375 /// b: Bar,
378 /// } 376 /// }
379 /// 377 ///
380 /// #[pin_data] 378 /// #[pin_data]
381 /// struct Bar { 379 /// struct Bar {
382 /// x: u32, 380 /// x: u32,
383 /// } 381 /// }
384 /// 382 ///
385 /// # fn demo() -> impl PinInit<Foo> { 383 /// # fn demo() -> impl PinInit<Foo> {
386 /// let a = 42; 384 /// let a = 42;
387 /// 385 ///
388 /// let initializer = pin_init!(Foo { 386 /// let initializer = pin_init!(Foo {
389 /// a, 387 /// a,
390 /// b: Bar { 388 /// b: Bar {
391 /// x: 64, 389 /// x: 64,
392 /// }, 390 /// },
393 /// }); 391 /// });
394 /// # initializer } 392 /// # initializer }
395 /// # Box::pin_init(demo(), GFP_KERNEL).unwrap !! 393 /// # Box::pin_init(demo()).unwrap();
396 /// ``` 394 /// ```
397 /// 395 ///
398 /// Arbitrary Rust expressions can be used to 396 /// Arbitrary Rust expressions can be used to set the value of a variable.
399 /// 397 ///
400 /// The fields are initialized in the order th 398 /// The fields are initialized in the order that they appear in the initializer. So it is possible
401 /// to read already initialized fields using r 399 /// to read already initialized fields using raw pointers.
402 /// 400 ///
403 /// IMPORTANT: You are not allowed to create r 401 /// IMPORTANT: You are not allowed to create references to fields of the struct inside of the
404 /// initializer. 402 /// initializer.
405 /// 403 ///
406 /// # Init-functions 404 /// # Init-functions
407 /// 405 ///
408 /// When working with this API it is often des 406 /// When working with this API it is often desired to let others construct your types without
409 /// giving access to all fields. This is where 407 /// giving access to all fields. This is where you would normally write a plain function `new`
410 /// that would return a new instance of your t 408 /// that would return a new instance of your type. With this API that is also possible.
411 /// However, there are a few extra things to k 409 /// However, there are a few extra things to keep in mind.
412 /// 410 ///
413 /// To create an initializer function, simply 411 /// To create an initializer function, simply declare it like this:
414 /// 412 ///
415 /// ```rust 413 /// ```rust
416 /// # #![allow(clippy::disallowed_names)] 414 /// # #![allow(clippy::disallowed_names)]
417 /// # use kernel::{init, pin_init, init::*}; !! 415 /// # use kernel::{init, pin_init, prelude::*, init::*};
418 /// # use core::pin::Pin; 416 /// # use core::pin::Pin;
419 /// # #[pin_data] 417 /// # #[pin_data]
420 /// # struct Foo { 418 /// # struct Foo {
421 /// # a: usize, 419 /// # a: usize,
422 /// # b: Bar, 420 /// # b: Bar,
423 /// # } 421 /// # }
424 /// # #[pin_data] 422 /// # #[pin_data]
425 /// # struct Bar { 423 /// # struct Bar {
426 /// # x: u32, 424 /// # x: u32,
427 /// # } 425 /// # }
428 /// impl Foo { 426 /// impl Foo {
429 /// fn new() -> impl PinInit<Self> { 427 /// fn new() -> impl PinInit<Self> {
430 /// pin_init!(Self { 428 /// pin_init!(Self {
431 /// a: 42, 429 /// a: 42,
432 /// b: Bar { 430 /// b: Bar {
433 /// x: 64, 431 /// x: 64,
434 /// }, 432 /// },
435 /// }) 433 /// })
436 /// } 434 /// }
437 /// } 435 /// }
438 /// ``` 436 /// ```
439 /// 437 ///
440 /// Users of `Foo` can now create it like this 438 /// Users of `Foo` can now create it like this:
441 /// 439 ///
442 /// ```rust 440 /// ```rust
443 /// # #![allow(clippy::disallowed_names)] 441 /// # #![allow(clippy::disallowed_names)]
444 /// # use kernel::{init, pin_init, macros::pin 442 /// # use kernel::{init, pin_init, macros::pin_data, init::*};
445 /// # use core::pin::Pin; 443 /// # use core::pin::Pin;
446 /// # #[pin_data] 444 /// # #[pin_data]
447 /// # struct Foo { 445 /// # struct Foo {
448 /// # a: usize, 446 /// # a: usize,
449 /// # b: Bar, 447 /// # b: Bar,
450 /// # } 448 /// # }
451 /// # #[pin_data] 449 /// # #[pin_data]
452 /// # struct Bar { 450 /// # struct Bar {
453 /// # x: u32, 451 /// # x: u32,
454 /// # } 452 /// # }
455 /// # impl Foo { 453 /// # impl Foo {
456 /// # fn new() -> impl PinInit<Self> { 454 /// # fn new() -> impl PinInit<Self> {
457 /// # pin_init!(Self { 455 /// # pin_init!(Self {
458 /// # a: 42, 456 /// # a: 42,
459 /// # b: Bar { 457 /// # b: Bar {
460 /// # x: 64, 458 /// # x: 64,
461 /// # }, 459 /// # },
462 /// # }) 460 /// # })
463 /// # } 461 /// # }
464 /// # } 462 /// # }
465 /// let foo = Box::pin_init(Foo::new(), GFP_KE !! 463 /// let foo = Box::pin_init(Foo::new());
466 /// ``` 464 /// ```
467 /// 465 ///
468 /// They can also easily embed it into their o 466 /// They can also easily embed it into their own `struct`s:
469 /// 467 ///
470 /// ```rust 468 /// ```rust
471 /// # #![allow(clippy::disallowed_names)] 469 /// # #![allow(clippy::disallowed_names)]
472 /// # use kernel::{init, pin_init, macros::pin 470 /// # use kernel::{init, pin_init, macros::pin_data, init::*};
473 /// # use core::pin::Pin; 471 /// # use core::pin::Pin;
474 /// # #[pin_data] 472 /// # #[pin_data]
475 /// # struct Foo { 473 /// # struct Foo {
476 /// # a: usize, 474 /// # a: usize,
477 /// # b: Bar, 475 /// # b: Bar,
478 /// # } 476 /// # }
479 /// # #[pin_data] 477 /// # #[pin_data]
480 /// # struct Bar { 478 /// # struct Bar {
481 /// # x: u32, 479 /// # x: u32,
482 /// # } 480 /// # }
483 /// # impl Foo { 481 /// # impl Foo {
484 /// # fn new() -> impl PinInit<Self> { 482 /// # fn new() -> impl PinInit<Self> {
485 /// # pin_init!(Self { 483 /// # pin_init!(Self {
486 /// # a: 42, 484 /// # a: 42,
487 /// # b: Bar { 485 /// # b: Bar {
488 /// # x: 64, 486 /// # x: 64,
489 /// # }, 487 /// # },
490 /// # }) 488 /// # })
491 /// # } 489 /// # }
492 /// # } 490 /// # }
493 /// #[pin_data] 491 /// #[pin_data]
494 /// struct FooContainer { 492 /// struct FooContainer {
495 /// #[pin] 493 /// #[pin]
496 /// foo1: Foo, 494 /// foo1: Foo,
497 /// #[pin] 495 /// #[pin]
498 /// foo2: Foo, 496 /// foo2: Foo,
499 /// other: u32, 497 /// other: u32,
500 /// } 498 /// }
501 /// 499 ///
502 /// impl FooContainer { 500 /// impl FooContainer {
503 /// fn new(other: u32) -> impl PinInit<Sel 501 /// fn new(other: u32) -> impl PinInit<Self> {
504 /// pin_init!(Self { 502 /// pin_init!(Self {
505 /// foo1 <- Foo::new(), 503 /// foo1 <- Foo::new(),
506 /// foo2 <- Foo::new(), 504 /// foo2 <- Foo::new(),
507 /// other, 505 /// other,
508 /// }) 506 /// })
509 /// } 507 /// }
510 /// } 508 /// }
511 /// ``` 509 /// ```
512 /// 510 ///
513 /// Here we see that when using `pin_init!` wi 511 /// Here we see that when using `pin_init!` with `PinInit`, one needs to write `<-` instead of `:`.
514 /// This signifies that the given field is ini 512 /// This signifies that the given field is initialized in-place. As with `struct` initializers, just
515 /// writing the field (in this case `other`) w 513 /// writing the field (in this case `other`) without `:` or `<-` means `other: other,`.
516 /// 514 ///
517 /// # Syntax 515 /// # Syntax
518 /// 516 ///
519 /// As already mentioned in the examples above 517 /// As already mentioned in the examples above, inside of `pin_init!` a `struct` initializer with
520 /// the following modifications is expected: 518 /// the following modifications is expected:
521 /// - Fields that you want to initialize in-pl 519 /// - Fields that you want to initialize in-place have to use `<-` instead of `:`.
522 /// - In front of the initializer you can writ 520 /// - In front of the initializer you can write `&this in` to have access to a [`NonNull<Self>`]
523 /// pointer named `this` inside of the initi 521 /// pointer named `this` inside of the initializer.
524 /// - Using struct update syntax one can place 522 /// - Using struct update syntax one can place `..Zeroable::zeroed()` at the very end of the
525 /// struct, this initializes every field wit 523 /// struct, this initializes every field with 0 and then runs all initializers specified in the
526 /// body. This can only be done if [`Zeroabl 524 /// body. This can only be done if [`Zeroable`] is implemented for the struct.
527 /// 525 ///
528 /// For instance: 526 /// For instance:
529 /// 527 ///
530 /// ```rust 528 /// ```rust
531 /// # use kernel::{macros::{Zeroable, pin_data 529 /// # use kernel::{macros::{Zeroable, pin_data}, pin_init};
532 /// # use core::{ptr::addr_of_mut, marker::Pha 530 /// # use core::{ptr::addr_of_mut, marker::PhantomPinned};
533 /// #[pin_data] 531 /// #[pin_data]
534 /// #[derive(Zeroable)] 532 /// #[derive(Zeroable)]
535 /// struct Buf { 533 /// struct Buf {
536 /// // `ptr` points into `buf`. 534 /// // `ptr` points into `buf`.
537 /// ptr: *mut u8, 535 /// ptr: *mut u8,
538 /// buf: [u8; 64], 536 /// buf: [u8; 64],
539 /// #[pin] 537 /// #[pin]
540 /// pin: PhantomPinned, 538 /// pin: PhantomPinned,
541 /// } 539 /// }
542 /// pin_init!(&this in Buf { 540 /// pin_init!(&this in Buf {
543 /// buf: [0; 64], 541 /// buf: [0; 64],
544 /// ptr: unsafe { addr_of_mut!((*this.as_p 542 /// ptr: unsafe { addr_of_mut!((*this.as_ptr()).buf).cast() },
545 /// pin: PhantomPinned, 543 /// pin: PhantomPinned,
546 /// }); 544 /// });
547 /// pin_init!(Buf { 545 /// pin_init!(Buf {
548 /// buf: [1; 64], 546 /// buf: [1; 64],
549 /// ..Zeroable::zeroed() 547 /// ..Zeroable::zeroed()
550 /// }); 548 /// });
551 /// ``` 549 /// ```
552 /// 550 ///
553 /// [`try_pin_init!`]: kernel::try_pin_init 551 /// [`try_pin_init!`]: kernel::try_pin_init
554 /// [`NonNull<Self>`]: core::ptr::NonNull 552 /// [`NonNull<Self>`]: core::ptr::NonNull
555 // For a detailed example of how this macro wo 553 // For a detailed example of how this macro works, see the module documentation of the hidden
556 // module `__internal` inside of `init/__inter 554 // module `__internal` inside of `init/__internal.rs`.
557 #[macro_export] 555 #[macro_export]
558 macro_rules! pin_init { 556 macro_rules! pin_init {
559 ($(&$this:ident in)? $t:ident $(::<$($gene 557 ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
560 $($fields:tt)* 558 $($fields:tt)*
561 }) => { 559 }) => {
562 $crate::__init_internal!( 560 $crate::__init_internal!(
563 @this($($this)?), 561 @this($($this)?),
564 @typ($t $(::<$($generics),*>)?), 562 @typ($t $(::<$($generics),*>)?),
565 @fields($($fields)*), 563 @fields($($fields)*),
566 @error(::core::convert::Infallible 564 @error(::core::convert::Infallible),
567 @data(PinData, use_data), 565 @data(PinData, use_data),
568 @has_data(HasPinData, __pin_data), 566 @has_data(HasPinData, __pin_data),
569 @construct_closure(pin_init_from_c 567 @construct_closure(pin_init_from_closure),
570 @munch_fields($($fields)*), 568 @munch_fields($($fields)*),
571 ) 569 )
572 }; 570 };
573 } 571 }
574 572
575 /// Construct an in-place, fallible pinned ini 573 /// Construct an in-place, fallible pinned initializer for `struct`s.
576 /// 574 ///
577 /// If the initialization can complete without 575 /// If the initialization can complete without error (or [`Infallible`]), then use [`pin_init!`].
578 /// 576 ///
579 /// You can use the `?` operator or use `retur 577 /// You can use the `?` operator or use `return Err(err)` inside the initializer to stop
580 /// initialization and return the error. 578 /// initialization and return the error.
581 /// 579 ///
582 /// IMPORTANT: if you have `unsafe` code insid 580 /// IMPORTANT: if you have `unsafe` code inside of the initializer you have to ensure that when
583 /// initialization fails, the memory can be sa 581 /// initialization fails, the memory can be safely deallocated without any further modifications.
584 /// 582 ///
585 /// This macro defaults the error to [`Error`] 583 /// This macro defaults the error to [`Error`].
586 /// 584 ///
587 /// The syntax is identical to [`pin_init!`] w 585 /// The syntax is identical to [`pin_init!`] with the following exception: you can append `? $type`
588 /// after the `struct` initializer to specify 586 /// after the `struct` initializer to specify the error type you want to use.
589 /// 587 ///
590 /// # Examples 588 /// # Examples
591 /// 589 ///
592 /// ```rust 590 /// ```rust
593 /// # #![feature(new_uninit)] 591 /// # #![feature(new_uninit)]
594 /// use kernel::{init::{self, PinInit}, error: 592 /// use kernel::{init::{self, PinInit}, error::Error};
595 /// #[pin_data] 593 /// #[pin_data]
596 /// struct BigBuf { 594 /// struct BigBuf {
597 /// big: Box<[u8; 1024 * 1024 * 1024]>, 595 /// big: Box<[u8; 1024 * 1024 * 1024]>,
598 /// small: [u8; 1024 * 1024], 596 /// small: [u8; 1024 * 1024],
599 /// ptr: *mut u8, 597 /// ptr: *mut u8,
600 /// } 598 /// }
601 /// 599 ///
602 /// impl BigBuf { 600 /// impl BigBuf {
603 /// fn new() -> impl PinInit<Self, Error> 601 /// fn new() -> impl PinInit<Self, Error> {
604 /// try_pin_init!(Self { 602 /// try_pin_init!(Self {
605 /// big: Box::init(init::zeroed(), !! 603 /// big: Box::init(init::zeroed())?,
606 /// small: [0; 1024 * 1024], 604 /// small: [0; 1024 * 1024],
607 /// ptr: core::ptr::null_mut(), 605 /// ptr: core::ptr::null_mut(),
608 /// }? Error) 606 /// }? Error)
609 /// } 607 /// }
610 /// } 608 /// }
611 /// ``` 609 /// ```
612 // For a detailed example of how this macro wo 610 // For a detailed example of how this macro works, see the module documentation of the hidden
613 // module `__internal` inside of `init/__inter 611 // module `__internal` inside of `init/__internal.rs`.
614 #[macro_export] 612 #[macro_export]
615 macro_rules! try_pin_init { 613 macro_rules! try_pin_init {
616 ($(&$this:ident in)? $t:ident $(::<$($gene 614 ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
617 $($fields:tt)* 615 $($fields:tt)*
618 }) => { 616 }) => {
619 $crate::__init_internal!( 617 $crate::__init_internal!(
620 @this($($this)?), 618 @this($($this)?),
621 @typ($t $(::<$($generics),*>)? ), 619 @typ($t $(::<$($generics),*>)? ),
622 @fields($($fields)*), 620 @fields($($fields)*),
623 @error($crate::error::Error), 621 @error($crate::error::Error),
624 @data(PinData, use_data), 622 @data(PinData, use_data),
625 @has_data(HasPinData, __pin_data), 623 @has_data(HasPinData, __pin_data),
626 @construct_closure(pin_init_from_c 624 @construct_closure(pin_init_from_closure),
627 @munch_fields($($fields)*), 625 @munch_fields($($fields)*),
628 ) 626 )
629 }; 627 };
630 ($(&$this:ident in)? $t:ident $(::<$($gene 628 ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
631 $($fields:tt)* 629 $($fields:tt)*
632 }? $err:ty) => { 630 }? $err:ty) => {
633 $crate::__init_internal!( 631 $crate::__init_internal!(
634 @this($($this)?), 632 @this($($this)?),
635 @typ($t $(::<$($generics),*>)? ), 633 @typ($t $(::<$($generics),*>)? ),
636 @fields($($fields)*), 634 @fields($($fields)*),
637 @error($err), 635 @error($err),
638 @data(PinData, use_data), 636 @data(PinData, use_data),
639 @has_data(HasPinData, __pin_data), 637 @has_data(HasPinData, __pin_data),
640 @construct_closure(pin_init_from_c 638 @construct_closure(pin_init_from_closure),
641 @munch_fields($($fields)*), 639 @munch_fields($($fields)*),
642 ) 640 )
643 }; 641 };
644 } 642 }
645 643
646 /// Construct an in-place initializer for `str 644 /// Construct an in-place initializer for `struct`s.
647 /// 645 ///
648 /// This macro defaults the error to [`Infalli 646 /// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use
649 /// [`try_init!`]. 647 /// [`try_init!`].
650 /// 648 ///
651 /// The syntax is identical to [`pin_init!`] a 649 /// The syntax is identical to [`pin_init!`] and its safety caveats also apply:
652 /// - `unsafe` code must guarantee either full 650 /// - `unsafe` code must guarantee either full initialization or return an error and allow
653 /// deallocation of the memory. 651 /// deallocation of the memory.
654 /// - the fields are initialized in the order 652 /// - the fields are initialized in the order given in the initializer.
655 /// - no references to fields are allowed to b 653 /// - no references to fields are allowed to be created inside of the initializer.
656 /// 654 ///
657 /// This initializer is for initializing data 655 /// This initializer is for initializing data in-place that might later be moved. If you want to
658 /// pin-initialize, use [`pin_init!`]. 656 /// pin-initialize, use [`pin_init!`].
659 /// 657 ///
660 /// [`try_init!`]: crate::try_init! 658 /// [`try_init!`]: crate::try_init!
661 // For a detailed example of how this macro wo 659 // For a detailed example of how this macro works, see the module documentation of the hidden
662 // module `__internal` inside of `init/__inter 660 // module `__internal` inside of `init/__internal.rs`.
663 #[macro_export] 661 #[macro_export]
664 macro_rules! init { 662 macro_rules! init {
665 ($(&$this:ident in)? $t:ident $(::<$($gene 663 ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
666 $($fields:tt)* 664 $($fields:tt)*
667 }) => { 665 }) => {
668 $crate::__init_internal!( 666 $crate::__init_internal!(
669 @this($($this)?), 667 @this($($this)?),
670 @typ($t $(::<$($generics),*>)?), 668 @typ($t $(::<$($generics),*>)?),
671 @fields($($fields)*), 669 @fields($($fields)*),
672 @error(::core::convert::Infallible 670 @error(::core::convert::Infallible),
673 @data(InitData, /*no use_data*/), 671 @data(InitData, /*no use_data*/),
674 @has_data(HasInitData, __init_data 672 @has_data(HasInitData, __init_data),
675 @construct_closure(init_from_closu 673 @construct_closure(init_from_closure),
676 @munch_fields($($fields)*), 674 @munch_fields($($fields)*),
677 ) 675 )
678 } 676 }
679 } 677 }
680 678
681 /// Construct an in-place fallible initializer 679 /// Construct an in-place fallible initializer for `struct`s.
682 /// 680 ///
683 /// This macro defaults the error to [`Error`] 681 /// This macro defaults the error to [`Error`]. If you need [`Infallible`], then use
684 /// [`init!`]. 682 /// [`init!`].
685 /// 683 ///
686 /// The syntax is identical to [`try_pin_init! 684 /// The syntax is identical to [`try_pin_init!`]. If you want to specify a custom error,
687 /// append `? $type` after the `struct` initia 685 /// append `? $type` after the `struct` initializer.
688 /// The safety caveats from [`try_pin_init!`] 686 /// The safety caveats from [`try_pin_init!`] also apply:
689 /// - `unsafe` code must guarantee either full 687 /// - `unsafe` code must guarantee either full initialization or return an error and allow
690 /// deallocation of the memory. 688 /// deallocation of the memory.
691 /// - the fields are initialized in the order 689 /// - the fields are initialized in the order given in the initializer.
692 /// - no references to fields are allowed to b 690 /// - no references to fields are allowed to be created inside of the initializer.
693 /// 691 ///
694 /// # Examples 692 /// # Examples
695 /// 693 ///
696 /// ```rust 694 /// ```rust
697 /// use kernel::{init::{PinInit, zeroed}, erro 695 /// use kernel::{init::{PinInit, zeroed}, error::Error};
698 /// struct BigBuf { 696 /// struct BigBuf {
699 /// big: Box<[u8; 1024 * 1024 * 1024]>, 697 /// big: Box<[u8; 1024 * 1024 * 1024]>,
700 /// small: [u8; 1024 * 1024], 698 /// small: [u8; 1024 * 1024],
701 /// } 699 /// }
702 /// 700 ///
703 /// impl BigBuf { 701 /// impl BigBuf {
704 /// fn new() -> impl Init<Self, Error> { 702 /// fn new() -> impl Init<Self, Error> {
705 /// try_init!(Self { 703 /// try_init!(Self {
706 /// big: Box::init(zeroed(), GFP_K !! 704 /// big: Box::init(zeroed())?,
707 /// small: [0; 1024 * 1024], 705 /// small: [0; 1024 * 1024],
708 /// }? Error) 706 /// }? Error)
709 /// } 707 /// }
710 /// } 708 /// }
711 /// ``` 709 /// ```
712 // For a detailed example of how this macro wo 710 // For a detailed example of how this macro works, see the module documentation of the hidden
713 // module `__internal` inside of `init/__inter 711 // module `__internal` inside of `init/__internal.rs`.
714 #[macro_export] 712 #[macro_export]
715 macro_rules! try_init { 713 macro_rules! try_init {
716 ($(&$this:ident in)? $t:ident $(::<$($gene 714 ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
717 $($fields:tt)* 715 $($fields:tt)*
718 }) => { 716 }) => {
719 $crate::__init_internal!( 717 $crate::__init_internal!(
720 @this($($this)?), 718 @this($($this)?),
721 @typ($t $(::<$($generics),*>)?), 719 @typ($t $(::<$($generics),*>)?),
722 @fields($($fields)*), 720 @fields($($fields)*),
723 @error($crate::error::Error), 721 @error($crate::error::Error),
724 @data(InitData, /*no use_data*/), 722 @data(InitData, /*no use_data*/),
725 @has_data(HasInitData, __init_data 723 @has_data(HasInitData, __init_data),
726 @construct_closure(init_from_closu 724 @construct_closure(init_from_closure),
727 @munch_fields($($fields)*), 725 @munch_fields($($fields)*),
728 ) 726 )
729 }; 727 };
730 ($(&$this:ident in)? $t:ident $(::<$($gene 728 ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
731 $($fields:tt)* 729 $($fields:tt)*
732 }? $err:ty) => { 730 }? $err:ty) => {
733 $crate::__init_internal!( 731 $crate::__init_internal!(
734 @this($($this)?), 732 @this($($this)?),
735 @typ($t $(::<$($generics),*>)?), 733 @typ($t $(::<$($generics),*>)?),
736 @fields($($fields)*), 734 @fields($($fields)*),
737 @error($err), 735 @error($err),
738 @data(InitData, /*no use_data*/), 736 @data(InitData, /*no use_data*/),
739 @has_data(HasInitData, __init_data 737 @has_data(HasInitData, __init_data),
740 @construct_closure(init_from_closu 738 @construct_closure(init_from_closure),
741 @munch_fields($($fields)*), 739 @munch_fields($($fields)*),
742 ) 740 )
743 }; 741 };
744 } 742 }
745 743
746 /// Asserts that a field on a struct using `#[ <<
747 /// structurally pinned. <<
748 /// <<
749 /// # Example <<
750 /// <<
751 /// This will succeed: <<
752 /// ``` <<
753 /// use kernel::assert_pinned; <<
754 /// #[pin_data] <<
755 /// struct MyStruct { <<
756 /// #[pin] <<
757 /// some_field: u64, <<
758 /// } <<
759 /// <<
760 /// assert_pinned!(MyStruct, some_field, u64); <<
761 /// ``` <<
762 /// <<
763 /// This will fail: <<
764 // TODO: replace with `compile_fail` when supp <<
765 /// ```ignore <<
766 /// use kernel::assert_pinned; <<
767 /// #[pin_data] <<
768 /// struct MyStruct { <<
769 /// some_field: u64, <<
770 /// } <<
771 /// <<
772 /// assert_pinned!(MyStruct, some_field, u64); <<
773 /// ``` <<
774 /// <<
775 /// Some uses of the macro may trigger the `ca <<
776 /// work around this, you may pass the `inline <<
777 /// only be used when the macro is invoked fro <<
778 /// ``` <<
779 /// use kernel::assert_pinned; <<
780 /// #[pin_data] <<
781 /// struct Foo<T> { <<
782 /// #[pin] <<
783 /// elem: T, <<
784 /// } <<
785 /// <<
786 /// impl<T> Foo<T> { <<
787 /// fn project(self: Pin<&mut Self>) -> Pi <<
788 /// assert_pinned!(Foo<T>, elem, T, in <<
789 /// <<
790 /// // SAFETY: The field is structural <<
791 /// unsafe { self.map_unchecked_mut(|m <<
792 /// } <<
793 /// } <<
794 /// ``` <<
795 #[macro_export] <<
796 macro_rules! assert_pinned { <<
797 ($ty:ty, $field:ident, $field_ty:ty, inlin <<
798 let _ = move |ptr: *mut $field_ty| { <<
799 // SAFETY: This code is unreachabl <<
800 let data = unsafe { <$ty as $crate <<
801 let init = $crate::init::__interna <<
802 // SAFETY: This code is unreachabl <<
803 unsafe { data.$field(ptr, init) }. <<
804 }; <<
805 }; <<
806 <<
807 ($ty:ty, $field:ident, $field_ty:ty) => { <<
808 const _: () = { <<
809 $crate::assert_pinned!($ty, $field <<
810 }; <<
811 }; <<
812 } <<
813 <<
814 /// A pin-initializer for the type `T`. 744 /// A pin-initializer for the type `T`.
815 /// 745 ///
816 /// To use this initializer, you will need a s 746 /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can
817 /// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>` 747 /// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`] or even the stack (see [`stack_pin_init!`]). Use the
818 /// [`InPlaceInit::pin_init`] function of a sm 748 /// [`InPlaceInit::pin_init`] function of a smart pointer like [`Arc<T>`] on this.
819 /// 749 ///
820 /// Also see the [module description](self). 750 /// Also see the [module description](self).
821 /// 751 ///
822 /// # Safety 752 /// # Safety
823 /// 753 ///
824 /// When implementing this trait you will need 754 /// When implementing this trait you will need to take great care. Also there are probably very few
825 /// cases where a manual implementation is nec 755 /// cases where a manual implementation is necessary. Use [`pin_init_from_closure`] where possible.
826 /// 756 ///
827 /// The [`PinInit::__pinned_init`] function: 757 /// The [`PinInit::__pinned_init`] function:
828 /// - returns `Ok(())` if it initialized every 758 /// - returns `Ok(())` if it initialized every field of `slot`,
829 /// - returns `Err(err)` if it encountered an 759 /// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means:
830 /// - `slot` can be deallocated without UB 760 /// - `slot` can be deallocated without UB occurring,
831 /// - `slot` does not need to be dropped, 761 /// - `slot` does not need to be dropped,
832 /// - `slot` is not partially initialized. 762 /// - `slot` is not partially initialized.
833 /// - while constructing the `T` at `slot` it 763 /// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`.
834 /// 764 ///
835 /// [`Arc<T>`]: crate::sync::Arc 765 /// [`Arc<T>`]: crate::sync::Arc
836 /// [`Arc::pin_init`]: crate::sync::Arc::pin_i 766 /// [`Arc::pin_init`]: crate::sync::Arc::pin_init
837 #[must_use = "An initializer must be used in o 767 #[must_use = "An initializer must be used in order to create its value."]
838 pub unsafe trait PinInit<T: ?Sized, E = Infall 768 pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
839 /// Initializes `slot`. 769 /// Initializes `slot`.
840 /// 770 ///
841 /// # Safety 771 /// # Safety
842 /// 772 ///
843 /// - `slot` is a valid pointer to uniniti 773 /// - `slot` is a valid pointer to uninitialized memory.
844 /// - the caller does not touch `slot` whe 774 /// - the caller does not touch `slot` when `Err` is returned, they are only permitted to
845 /// deallocate. 775 /// deallocate.
846 /// - `slot` will not move until it is dro 776 /// - `slot` will not move until it is dropped, i.e. it will be pinned.
847 unsafe fn __pinned_init(self, slot: *mut T 777 unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E>;
848 778
849 /// First initializes the value using `sel 779 /// First initializes the value using `self` then calls the function `f` with the initialized
850 /// value. 780 /// value.
851 /// 781 ///
852 /// If `f` returns an error the value is d 782 /// If `f` returns an error the value is dropped and the initializer will forward the error.
853 /// 783 ///
854 /// # Examples 784 /// # Examples
855 /// 785 ///
856 /// ```rust 786 /// ```rust
857 /// # #![allow(clippy::disallowed_names)] 787 /// # #![allow(clippy::disallowed_names)]
858 /// use kernel::{types::Opaque, init::pin_ 788 /// use kernel::{types::Opaque, init::pin_init_from_closure};
859 /// #[repr(C)] 789 /// #[repr(C)]
860 /// struct RawFoo([u8; 16]); 790 /// struct RawFoo([u8; 16]);
861 /// extern { 791 /// extern {
862 /// fn init_foo(_: *mut RawFoo); 792 /// fn init_foo(_: *mut RawFoo);
863 /// } 793 /// }
864 /// 794 ///
865 /// #[pin_data] 795 /// #[pin_data]
866 /// struct Foo { 796 /// struct Foo {
867 /// #[pin] 797 /// #[pin]
868 /// raw: Opaque<RawFoo>, 798 /// raw: Opaque<RawFoo>,
869 /// } 799 /// }
870 /// 800 ///
871 /// impl Foo { 801 /// impl Foo {
872 /// fn setup(self: Pin<&mut Self>) { 802 /// fn setup(self: Pin<&mut Self>) {
873 /// pr_info!("Setting up foo"); 803 /// pr_info!("Setting up foo");
874 /// } 804 /// }
875 /// } 805 /// }
876 /// 806 ///
877 /// let foo = pin_init!(Foo { 807 /// let foo = pin_init!(Foo {
878 /// raw <- unsafe { 808 /// raw <- unsafe {
879 /// Opaque::ffi_init(|s| { 809 /// Opaque::ffi_init(|s| {
880 /// init_foo(s); 810 /// init_foo(s);
881 /// }) 811 /// })
882 /// }, 812 /// },
883 /// }).pin_chain(|foo| { 813 /// }).pin_chain(|foo| {
884 /// foo.setup(); 814 /// foo.setup();
885 /// Ok(()) 815 /// Ok(())
886 /// }); 816 /// });
887 /// ``` 817 /// ```
888 fn pin_chain<F>(self, f: F) -> ChainPinIni 818 fn pin_chain<F>(self, f: F) -> ChainPinInit<Self, F, T, E>
889 where 819 where
890 F: FnOnce(Pin<&mut T>) -> Result<(), E 820 F: FnOnce(Pin<&mut T>) -> Result<(), E>,
891 { 821 {
892 ChainPinInit(self, f, PhantomData) 822 ChainPinInit(self, f, PhantomData)
893 } 823 }
894 } 824 }
895 825
896 /// An initializer returned by [`PinInit::pin_ 826 /// An initializer returned by [`PinInit::pin_chain`].
897 pub struct ChainPinInit<I, F, T: ?Sized, E>(I, 827 pub struct ChainPinInit<I, F, T: ?Sized, E>(I, F, __internal::Invariant<(E, Box<T>)>);
898 828
899 // SAFETY: The `__pinned_init` function is imp 829 // SAFETY: The `__pinned_init` function is implemented such that it
900 // - returns `Ok(())` on successful initializa 830 // - returns `Ok(())` on successful initialization,
901 // - returns `Err(err)` on error and in this c 831 // - returns `Err(err)` on error and in this case `slot` will be dropped.
902 // - considers `slot` pinned. 832 // - considers `slot` pinned.
903 unsafe impl<T: ?Sized, E, I, F> PinInit<T, E> 833 unsafe impl<T: ?Sized, E, I, F> PinInit<T, E> for ChainPinInit<I, F, T, E>
904 where 834 where
905 I: PinInit<T, E>, 835 I: PinInit<T, E>,
906 F: FnOnce(Pin<&mut T>) -> Result<(), E>, 836 F: FnOnce(Pin<&mut T>) -> Result<(), E>,
907 { 837 {
908 unsafe fn __pinned_init(self, slot: *mut T 838 unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
909 // SAFETY: All requirements fulfilled 839 // SAFETY: All requirements fulfilled since this function is `__pinned_init`.
910 unsafe { self.0.__pinned_init(slot)? } 840 unsafe { self.0.__pinned_init(slot)? };
911 // SAFETY: The above call initialized 841 // SAFETY: The above call initialized `slot` and we still have unique access.
912 let val = unsafe { &mut *slot }; 842 let val = unsafe { &mut *slot };
913 // SAFETY: `slot` is considered pinned 843 // SAFETY: `slot` is considered pinned.
914 let val = unsafe { Pin::new_unchecked( 844 let val = unsafe { Pin::new_unchecked(val) };
915 // SAFETY: `slot` was initialized abov !! 845 (self.1)(val).map_err(|e| {
916 (self.1)(val).inspect_err(|_| unsafe { !! 846 // SAFETY: `slot` was initialized above.
>> 847 unsafe { core::ptr::drop_in_place(slot) };
>> 848 e
>> 849 })
917 } 850 }
918 } 851 }
919 852
920 /// An initializer for `T`. 853 /// An initializer for `T`.
921 /// 854 ///
922 /// To use this initializer, you will need a s 855 /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can
923 /// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>` 856 /// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`] or even the stack (see [`stack_pin_init!`]). Use the
924 /// [`InPlaceInit::init`] function of a smart 857 /// [`InPlaceInit::init`] function of a smart pointer like [`Arc<T>`] on this. Because
925 /// [`PinInit<T, E>`] is a super trait, you ca 858 /// [`PinInit<T, E>`] is a super trait, you can use every function that takes it as well.
926 /// 859 ///
927 /// Also see the [module description](self). 860 /// Also see the [module description](self).
928 /// 861 ///
929 /// # Safety 862 /// # Safety
930 /// 863 ///
931 /// When implementing this trait you will need 864 /// When implementing this trait you will need to take great care. Also there are probably very few
932 /// cases where a manual implementation is nec 865 /// cases where a manual implementation is necessary. Use [`init_from_closure`] where possible.
933 /// 866 ///
934 /// The [`Init::__init`] function: 867 /// The [`Init::__init`] function:
935 /// - returns `Ok(())` if it initialized every 868 /// - returns `Ok(())` if it initialized every field of `slot`,
936 /// - returns `Err(err)` if it encountered an 869 /// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means:
937 /// - `slot` can be deallocated without UB 870 /// - `slot` can be deallocated without UB occurring,
938 /// - `slot` does not need to be dropped, 871 /// - `slot` does not need to be dropped,
939 /// - `slot` is not partially initialized. 872 /// - `slot` is not partially initialized.
940 /// - while constructing the `T` at `slot` it 873 /// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`.
941 /// 874 ///
942 /// The `__pinned_init` function from the supe 875 /// The `__pinned_init` function from the supertrait [`PinInit`] needs to execute the exact same
943 /// code as `__init`. 876 /// code as `__init`.
944 /// 877 ///
945 /// Contrary to its supertype [`PinInit<T, E>` 878 /// Contrary to its supertype [`PinInit<T, E>`] the caller is allowed to
946 /// move the pointee after initialization. 879 /// move the pointee after initialization.
947 /// 880 ///
948 /// [`Arc<T>`]: crate::sync::Arc 881 /// [`Arc<T>`]: crate::sync::Arc
949 #[must_use = "An initializer must be used in o 882 #[must_use = "An initializer must be used in order to create its value."]
950 pub unsafe trait Init<T: ?Sized, E = Infallibl 883 pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
951 /// Initializes `slot`. 884 /// Initializes `slot`.
952 /// 885 ///
953 /// # Safety 886 /// # Safety
954 /// 887 ///
955 /// - `slot` is a valid pointer to uniniti 888 /// - `slot` is a valid pointer to uninitialized memory.
956 /// - the caller does not touch `slot` whe 889 /// - the caller does not touch `slot` when `Err` is returned, they are only permitted to
957 /// deallocate. 890 /// deallocate.
958 unsafe fn __init(self, slot: *mut T) -> Re 891 unsafe fn __init(self, slot: *mut T) -> Result<(), E>;
959 892
960 /// First initializes the value using `sel 893 /// First initializes the value using `self` then calls the function `f` with the initialized
961 /// value. 894 /// value.
962 /// 895 ///
963 /// If `f` returns an error the value is d 896 /// If `f` returns an error the value is dropped and the initializer will forward the error.
964 /// 897 ///
965 /// # Examples 898 /// # Examples
966 /// 899 ///
967 /// ```rust 900 /// ```rust
968 /// # #![allow(clippy::disallowed_names)] 901 /// # #![allow(clippy::disallowed_names)]
969 /// use kernel::{types::Opaque, init::{sel 902 /// use kernel::{types::Opaque, init::{self, init_from_closure}};
970 /// struct Foo { 903 /// struct Foo {
971 /// buf: [u8; 1_000_000], 904 /// buf: [u8; 1_000_000],
972 /// } 905 /// }
973 /// 906 ///
974 /// impl Foo { 907 /// impl Foo {
975 /// fn setup(&mut self) { 908 /// fn setup(&mut self) {
976 /// pr_info!("Setting up foo"); 909 /// pr_info!("Setting up foo");
977 /// } 910 /// }
978 /// } 911 /// }
979 /// 912 ///
980 /// let foo = init!(Foo { 913 /// let foo = init!(Foo {
981 /// buf <- init::zeroed() 914 /// buf <- init::zeroed()
982 /// }).chain(|foo| { 915 /// }).chain(|foo| {
983 /// foo.setup(); 916 /// foo.setup();
984 /// Ok(()) 917 /// Ok(())
985 /// }); 918 /// });
986 /// ``` 919 /// ```
987 fn chain<F>(self, f: F) -> ChainInit<Self, 920 fn chain<F>(self, f: F) -> ChainInit<Self, F, T, E>
988 where 921 where
989 F: FnOnce(&mut T) -> Result<(), E>, 922 F: FnOnce(&mut T) -> Result<(), E>,
990 { 923 {
991 ChainInit(self, f, PhantomData) 924 ChainInit(self, f, PhantomData)
992 } 925 }
993 } 926 }
994 927
995 /// An initializer returned by [`Init::chain`] 928 /// An initializer returned by [`Init::chain`].
996 pub struct ChainInit<I, F, T: ?Sized, E>(I, F, 929 pub struct ChainInit<I, F, T: ?Sized, E>(I, F, __internal::Invariant<(E, Box<T>)>);
997 930
998 // SAFETY: The `__init` function is implemente 931 // SAFETY: The `__init` function is implemented such that it
999 // - returns `Ok(())` on successful initializa 932 // - returns `Ok(())` on successful initialization,
1000 // - returns `Err(err)` on error and in this 933 // - returns `Err(err)` on error and in this case `slot` will be dropped.
1001 unsafe impl<T: ?Sized, E, I, F> Init<T, E> fo 934 unsafe impl<T: ?Sized, E, I, F> Init<T, E> for ChainInit<I, F, T, E>
1002 where 935 where
1003 I: Init<T, E>, 936 I: Init<T, E>,
1004 F: FnOnce(&mut T) -> Result<(), E>, 937 F: FnOnce(&mut T) -> Result<(), E>,
1005 { 938 {
1006 unsafe fn __init(self, slot: *mut T) -> R 939 unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
1007 // SAFETY: All requirements fulfilled 940 // SAFETY: All requirements fulfilled since this function is `__init`.
1008 unsafe { self.0.__pinned_init(slot)? 941 unsafe { self.0.__pinned_init(slot)? };
1009 // SAFETY: The above call initialized 942 // SAFETY: The above call initialized `slot` and we still have unique access.
1010 (self.1)(unsafe { &mut *slot }).inspe !! 943 (self.1)(unsafe { &mut *slot }).map_err(|e| {
1011 // SAFETY: `slot` was initialized 944 // SAFETY: `slot` was initialized above.
1012 unsafe { core::ptr::drop_in_place !! 945 unsafe { core::ptr::drop_in_place(slot) };
>> 946 e
>> 947 })
1013 } 948 }
1014 } 949 }
1015 950
1016 // SAFETY: `__pinned_init` behaves exactly th 951 // SAFETY: `__pinned_init` behaves exactly the same as `__init`.
1017 unsafe impl<T: ?Sized, E, I, F> PinInit<T, E> 952 unsafe impl<T: ?Sized, E, I, F> PinInit<T, E> for ChainInit<I, F, T, E>
1018 where 953 where
1019 I: Init<T, E>, 954 I: Init<T, E>,
1020 F: FnOnce(&mut T) -> Result<(), E>, 955 F: FnOnce(&mut T) -> Result<(), E>,
1021 { 956 {
1022 unsafe fn __pinned_init(self, slot: *mut 957 unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
1023 // SAFETY: `__init` has less strict r 958 // SAFETY: `__init` has less strict requirements compared to `__pinned_init`.
1024 unsafe { self.__init(slot) } 959 unsafe { self.__init(slot) }
1025 } 960 }
1026 } 961 }
1027 962
1028 /// Creates a new [`PinInit<T, E>`] from the 963 /// Creates a new [`PinInit<T, E>`] from the given closure.
1029 /// 964 ///
1030 /// # Safety 965 /// # Safety
1031 /// 966 ///
1032 /// The closure: 967 /// The closure:
1033 /// - returns `Ok(())` if it initialized ever 968 /// - returns `Ok(())` if it initialized every field of `slot`,
1034 /// - returns `Err(err)` if it encountered an 969 /// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means:
1035 /// - `slot` can be deallocated without U 970 /// - `slot` can be deallocated without UB occurring,
1036 /// - `slot` does not need to be dropped, 971 /// - `slot` does not need to be dropped,
1037 /// - `slot` is not partially initialized 972 /// - `slot` is not partially initialized.
1038 /// - may assume that the `slot` does not mov 973 /// - may assume that the `slot` does not move if `T: !Unpin`,
1039 /// - while constructing the `T` at `slot` it 974 /// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`.
1040 #[inline] 975 #[inline]
1041 pub const unsafe fn pin_init_from_closure<T: 976 pub const unsafe fn pin_init_from_closure<T: ?Sized, E>(
1042 f: impl FnOnce(*mut T) -> Result<(), E>, 977 f: impl FnOnce(*mut T) -> Result<(), E>,
1043 ) -> impl PinInit<T, E> { 978 ) -> impl PinInit<T, E> {
1044 __internal::InitClosure(f, PhantomData) 979 __internal::InitClosure(f, PhantomData)
1045 } 980 }
1046 981
1047 /// Creates a new [`Init<T, E>`] from the giv 982 /// Creates a new [`Init<T, E>`] from the given closure.
1048 /// 983 ///
1049 /// # Safety 984 /// # Safety
1050 /// 985 ///
1051 /// The closure: 986 /// The closure:
1052 /// - returns `Ok(())` if it initialized ever 987 /// - returns `Ok(())` if it initialized every field of `slot`,
1053 /// - returns `Err(err)` if it encountered an 988 /// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means:
1054 /// - `slot` can be deallocated without U 989 /// - `slot` can be deallocated without UB occurring,
1055 /// - `slot` does not need to be dropped, 990 /// - `slot` does not need to be dropped,
1056 /// - `slot` is not partially initialized 991 /// - `slot` is not partially initialized.
1057 /// - the `slot` may move after initializatio 992 /// - the `slot` may move after initialization.
1058 /// - while constructing the `T` at `slot` it 993 /// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`.
1059 #[inline] 994 #[inline]
1060 pub const unsafe fn init_from_closure<T: ?Siz 995 pub const unsafe fn init_from_closure<T: ?Sized, E>(
1061 f: impl FnOnce(*mut T) -> Result<(), E>, 996 f: impl FnOnce(*mut T) -> Result<(), E>,
1062 ) -> impl Init<T, E> { 997 ) -> impl Init<T, E> {
1063 __internal::InitClosure(f, PhantomData) 998 __internal::InitClosure(f, PhantomData)
1064 } 999 }
1065 1000
1066 /// An initializer that leaves the memory uni 1001 /// An initializer that leaves the memory uninitialized.
1067 /// 1002 ///
1068 /// The initializer is a no-op. The `slot` me 1003 /// The initializer is a no-op. The `slot` memory is not changed.
1069 #[inline] 1004 #[inline]
1070 pub fn uninit<T, E>() -> impl Init<MaybeUnini 1005 pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> {
1071 // SAFETY: The memory is allowed to be un 1006 // SAFETY: The memory is allowed to be uninitialized.
1072 unsafe { init_from_closure(|_| Ok(())) } 1007 unsafe { init_from_closure(|_| Ok(())) }
1073 } 1008 }
1074 1009
1075 /// Initializes an array by initializing each 1010 /// Initializes an array by initializing each element via the provided initializer.
1076 /// 1011 ///
1077 /// # Examples 1012 /// # Examples
1078 /// 1013 ///
1079 /// ```rust 1014 /// ```rust
1080 /// use kernel::{error::Error, init::init_arr 1015 /// use kernel::{error::Error, init::init_array_from_fn};
1081 /// let array: Box<[usize; 1_000]> = Box::ini !! 1016 /// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i)).unwrap();
1082 /// assert_eq!(array.len(), 1_000); 1017 /// assert_eq!(array.len(), 1_000);
1083 /// ``` 1018 /// ```
1084 pub fn init_array_from_fn<I, const N: usize, 1019 pub fn init_array_from_fn<I, const N: usize, T, E>(
1085 mut make_init: impl FnMut(usize) -> I, 1020 mut make_init: impl FnMut(usize) -> I,
1086 ) -> impl Init<[T; N], E> 1021 ) -> impl Init<[T; N], E>
1087 where 1022 where
1088 I: Init<T, E>, 1023 I: Init<T, E>,
1089 { 1024 {
1090 let init = move |slot: *mut [T; N]| { 1025 let init = move |slot: *mut [T; N]| {
1091 let slot = slot.cast::<T>(); 1026 let slot = slot.cast::<T>();
1092 // Counts the number of initialized e 1027 // Counts the number of initialized elements and when dropped drops that many elements from
1093 // `slot`. 1028 // `slot`.
1094 let mut init_count = ScopeGuard::new_ 1029 let mut init_count = ScopeGuard::new_with_data(0, |i| {
1095 // We now free every element that 1030 // We now free every element that has been initialized before.
1096 // SAFETY: The loop initialized e 1031 // SAFETY: The loop initialized exactly the values from 0..i and since we
1097 // return `Err` below, the caller 1032 // return `Err` below, the caller will consider the memory at `slot` as
1098 // uninitialized. 1033 // uninitialized.
1099 unsafe { ptr::drop_in_place(ptr:: 1034 unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(slot, i)) };
1100 }); 1035 });
1101 for i in 0..N { 1036 for i in 0..N {
1102 let init = make_init(i); 1037 let init = make_init(i);
1103 // SAFETY: Since 0 <= `i` < N, it 1038 // SAFETY: Since 0 <= `i` < N, it is still in bounds of `[T; N]`.
1104 let ptr = unsafe { slot.add(i) }; 1039 let ptr = unsafe { slot.add(i) };
1105 // SAFETY: The pointer is derived 1040 // SAFETY: The pointer is derived from `slot` and thus satisfies the `__init`
1106 // requirements. 1041 // requirements.
1107 unsafe { init.__init(ptr) }?; 1042 unsafe { init.__init(ptr) }?;
1108 *init_count += 1; 1043 *init_count += 1;
1109 } 1044 }
1110 init_count.dismiss(); 1045 init_count.dismiss();
1111 Ok(()) 1046 Ok(())
1112 }; 1047 };
1113 // SAFETY: The initializer above initiali 1048 // SAFETY: The initializer above initializes every element of the array. On failure it drops
1114 // any initialized elements and returns ` 1049 // any initialized elements and returns `Err`.
1115 unsafe { init_from_closure(init) } 1050 unsafe { init_from_closure(init) }
1116 } 1051 }
1117 1052
1118 /// Initializes an array by initializing each 1053 /// Initializes an array by initializing each element via the provided initializer.
1119 /// 1054 ///
1120 /// # Examples 1055 /// # Examples
1121 /// 1056 ///
1122 /// ```rust 1057 /// ```rust
1123 /// use kernel::{sync::{Arc, Mutex}, init::pi 1058 /// use kernel::{sync::{Arc, Mutex}, init::pin_init_array_from_fn, new_mutex};
1124 /// let array: Arc<[Mutex<usize>; 1_000]> = 1059 /// let array: Arc<[Mutex<usize>; 1_000]> =
1125 /// Arc::pin_init(pin_init_array_from_fn( !! 1060 /// Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i))).unwrap();
1126 /// assert_eq!(array.len(), 1_000); 1061 /// assert_eq!(array.len(), 1_000);
1127 /// ``` 1062 /// ```
1128 pub fn pin_init_array_from_fn<I, const N: usi 1063 pub fn pin_init_array_from_fn<I, const N: usize, T, E>(
1129 mut make_init: impl FnMut(usize) -> I, 1064 mut make_init: impl FnMut(usize) -> I,
1130 ) -> impl PinInit<[T; N], E> 1065 ) -> impl PinInit<[T; N], E>
1131 where 1066 where
1132 I: PinInit<T, E>, 1067 I: PinInit<T, E>,
1133 { 1068 {
1134 let init = move |slot: *mut [T; N]| { 1069 let init = move |slot: *mut [T; N]| {
1135 let slot = slot.cast::<T>(); 1070 let slot = slot.cast::<T>();
1136 // Counts the number of initialized e 1071 // Counts the number of initialized elements and when dropped drops that many elements from
1137 // `slot`. 1072 // `slot`.
1138 let mut init_count = ScopeGuard::new_ 1073 let mut init_count = ScopeGuard::new_with_data(0, |i| {
1139 // We now free every element that 1074 // We now free every element that has been initialized before.
1140 // SAFETY: The loop initialized e 1075 // SAFETY: The loop initialized exactly the values from 0..i and since we
1141 // return `Err` below, the caller 1076 // return `Err` below, the caller will consider the memory at `slot` as
1142 // uninitialized. 1077 // uninitialized.
1143 unsafe { ptr::drop_in_place(ptr:: 1078 unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(slot, i)) };
1144 }); 1079 });
1145 for i in 0..N { 1080 for i in 0..N {
1146 let init = make_init(i); 1081 let init = make_init(i);
1147 // SAFETY: Since 0 <= `i` < N, it 1082 // SAFETY: Since 0 <= `i` < N, it is still in bounds of `[T; N]`.
1148 let ptr = unsafe { slot.add(i) }; 1083 let ptr = unsafe { slot.add(i) };
1149 // SAFETY: The pointer is derived 1084 // SAFETY: The pointer is derived from `slot` and thus satisfies the `__init`
1150 // requirements. 1085 // requirements.
1151 unsafe { init.__pinned_init(ptr) 1086 unsafe { init.__pinned_init(ptr) }?;
1152 *init_count += 1; 1087 *init_count += 1;
1153 } 1088 }
1154 init_count.dismiss(); 1089 init_count.dismiss();
1155 Ok(()) 1090 Ok(())
1156 }; 1091 };
1157 // SAFETY: The initializer above initiali 1092 // SAFETY: The initializer above initializes every element of the array. On failure it drops
1158 // any initialized elements and returns ` 1093 // any initialized elements and returns `Err`.
1159 unsafe { pin_init_from_closure(init) } 1094 unsafe { pin_init_from_closure(init) }
1160 } 1095 }
1161 1096
1162 // SAFETY: Every type can be initialized by-v 1097 // SAFETY: Every type can be initialized by-value.
1163 unsafe impl<T, E> Init<T, E> for T { 1098 unsafe impl<T, E> Init<T, E> for T {
1164 unsafe fn __init(self, slot: *mut T) -> R 1099 unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
1165 unsafe { slot.write(self) }; 1100 unsafe { slot.write(self) };
1166 Ok(()) 1101 Ok(())
1167 } 1102 }
1168 } 1103 }
1169 1104
1170 // SAFETY: Every type can be initialized by-v 1105 // SAFETY: Every type can be initialized by-value. `__pinned_init` calls `__init`.
1171 unsafe impl<T, E> PinInit<T, E> for T { 1106 unsafe impl<T, E> PinInit<T, E> for T {
1172 unsafe fn __pinned_init(self, slot: *mut 1107 unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
1173 unsafe { self.__init(slot) } 1108 unsafe { self.__init(slot) }
1174 } 1109 }
1175 } 1110 }
1176 1111
1177 /// Smart pointer that can initialize memory 1112 /// Smart pointer that can initialize memory in-place.
1178 pub trait InPlaceInit<T>: Sized { 1113 pub trait InPlaceInit<T>: Sized {
1179 /// Pinned version of `Self`. <<
1180 /// <<
1181 /// If a type already implicitly pins its <<
1182 /// `Self`, otherwise just use `Pin<Self> <<
1183 type PinnedSelf; <<
1184 <<
1185 /// Use the given pin-initializer to pin- 1114 /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this
1186 /// type. 1115 /// type.
1187 /// 1116 ///
1188 /// If `T: !Unpin` it will not be able to 1117 /// If `T: !Unpin` it will not be able to move afterwards.
1189 fn try_pin_init<E>(init: impl PinInit<T, !! 1118 fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
1190 where 1119 where
1191 E: From<AllocError>; 1120 E: From<AllocError>;
1192 1121
1193 /// Use the given pin-initializer to pin- 1122 /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this
1194 /// type. 1123 /// type.
1195 /// 1124 ///
1196 /// If `T: !Unpin` it will not be able to 1125 /// If `T: !Unpin` it will not be able to move afterwards.
1197 fn pin_init<E>(init: impl PinInit<T, E>, !! 1126 fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Pin<Self>>
1198 where 1127 where
1199 Error: From<E>, 1128 Error: From<E>,
1200 { 1129 {
1201 // SAFETY: We delegate to `init` and 1130 // SAFETY: We delegate to `init` and only change the error type.
1202 let init = unsafe { 1131 let init = unsafe {
1203 pin_init_from_closure(|slot| init 1132 pin_init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
1204 }; 1133 };
1205 Self::try_pin_init(init, flags) !! 1134 Self::try_pin_init(init)
1206 } 1135 }
1207 1136
1208 /// Use the given initializer to in-place 1137 /// Use the given initializer to in-place initialize a `T`.
1209 fn try_init<E>(init: impl Init<T, E>, fla !! 1138 fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
1210 where 1139 where
1211 E: From<AllocError>; 1140 E: From<AllocError>;
1212 1141
1213 /// Use the given initializer to in-place 1142 /// Use the given initializer to in-place initialize a `T`.
1214 fn init<E>(init: impl Init<T, E>, flags: !! 1143 fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
1215 where 1144 where
1216 Error: From<E>, 1145 Error: From<E>,
1217 { 1146 {
1218 // SAFETY: We delegate to `init` and 1147 // SAFETY: We delegate to `init` and only change the error type.
1219 let init = unsafe { 1148 let init = unsafe {
1220 init_from_closure(|slot| init.__p 1149 init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
1221 }; 1150 };
1222 Self::try_init(init, flags) !! 1151 Self::try_init(init)
1223 } <<
1224 } <<
1225 <<
1226 impl<T> InPlaceInit<T> for Arc<T> { <<
1227 type PinnedSelf = Self; <<
1228 <<
1229 #[inline] <<
1230 fn try_pin_init<E>(init: impl PinInit<T, <<
1231 where <<
1232 E: From<AllocError>, <<
1233 { <<
1234 UniqueArc::try_pin_init(init, flags). <<
1235 } <<
1236 <<
1237 #[inline] <<
1238 fn try_init<E>(init: impl Init<T, E>, fla <<
1239 where <<
1240 E: From<AllocError>, <<
1241 { <<
1242 UniqueArc::try_init(init, flags).map( <<
1243 } 1152 }
1244 } 1153 }
1245 1154
1246 impl<T> InPlaceInit<T> for Box<T> { 1155 impl<T> InPlaceInit<T> for Box<T> {
1247 type PinnedSelf = Pin<Self>; <<
1248 <<
1249 #[inline] 1156 #[inline]
1250 fn try_pin_init<E>(init: impl PinInit<T, !! 1157 fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
1251 where 1158 where
1252 E: From<AllocError>, 1159 E: From<AllocError>,
1253 { 1160 {
1254 <Box<_> as BoxExt<_>>::new_uninit(fla !! 1161 let mut this = Box::try_new_uninit()?;
>> 1162 let slot = this.as_mut_ptr();
>> 1163 // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
>> 1164 // slot is valid and will not be moved, because we pin it later.
>> 1165 unsafe { init.__pinned_init(slot)? };
>> 1166 // SAFETY: All fields have been initialized.
>> 1167 Ok(unsafe { this.assume_init() }.into())
1255 } 1168 }
1256 1169
1257 #[inline] 1170 #[inline]
1258 fn try_init<E>(init: impl Init<T, E>, fla !! 1171 fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
1259 where 1172 where
1260 E: From<AllocError>, 1173 E: From<AllocError>,
1261 { 1174 {
1262 <Box<_> as BoxExt<_>>::new_uninit(fla !! 1175 let mut this = Box::try_new_uninit()?;
>> 1176 let slot = this.as_mut_ptr();
>> 1177 // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
>> 1178 // slot is valid.
>> 1179 unsafe { init.__init(slot)? };
>> 1180 // SAFETY: All fields have been initialized.
>> 1181 Ok(unsafe { this.assume_init() })
1263 } 1182 }
1264 } 1183 }
1265 1184
1266 impl<T> InPlaceInit<T> for UniqueArc<T> { 1185 impl<T> InPlaceInit<T> for UniqueArc<T> {
1267 type PinnedSelf = Pin<Self>; <<
1268 <<
1269 #[inline] 1186 #[inline]
1270 fn try_pin_init<E>(init: impl PinInit<T, !! 1187 fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
1271 where 1188 where
1272 E: From<AllocError>, 1189 E: From<AllocError>,
1273 { 1190 {
1274 UniqueArc::new_uninit(flags)?.write_p !! 1191 let mut this = UniqueArc::try_new_uninit()?;
1275 } !! 1192 let slot = this.as_mut_ptr();
1276 <<
1277 #[inline] <<
1278 fn try_init<E>(init: impl Init<T, E>, fla <<
1279 where <<
1280 E: From<AllocError>, <<
1281 { <<
1282 UniqueArc::new_uninit(flags)?.write_i <<
1283 } <<
1284 } <<
1285 <<
1286 /// Smart pointer containing uninitialized me <<
1287 pub trait InPlaceWrite<T> { <<
1288 /// The type `Self` turns into when the c <<
1289 type Initialized; <<
1290 <<
1291 /// Use the given initializer to write a <<
1292 /// <<
1293 /// Does not drop the current value and c <<
1294 fn write_init<E>(self, init: impl Init<T, <<
1295 <<
1296 /// Use the given pin-initializer to writ <<
1297 /// <<
1298 /// Does not drop the current value and c <<
1299 fn write_pin_init<E>(self, init: impl Pin <<
1300 } <<
1301 <<
1302 impl<T> InPlaceWrite<T> for Box<MaybeUninit<T <<
1303 type Initialized = Box<T>; <<
1304 <<
1305 fn write_init<E>(mut self, init: impl Ini <<
1306 let slot = self.as_mut_ptr(); <<
1307 // SAFETY: When init errors/panics, s <<
1308 // slot is valid. <<
1309 unsafe { init.__init(slot)? }; <<
1310 // SAFETY: All fields have been initi <<
1311 Ok(unsafe { self.assume_init() }) <<
1312 } <<
1313 <<
1314 fn write_pin_init<E>(mut self, init: impl <<
1315 let slot = self.as_mut_ptr(); <<
1316 // SAFETY: When init errors/panics, s 1193 // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
1317 // slot is valid and will not be move 1194 // slot is valid and will not be moved, because we pin it later.
1318 unsafe { init.__pinned_init(slot)? }; 1195 unsafe { init.__pinned_init(slot)? };
1319 // SAFETY: All fields have been initi 1196 // SAFETY: All fields have been initialized.
1320 Ok(unsafe { self.assume_init() }.into !! 1197 Ok(unsafe { this.assume_init() }.into())
1321 } 1198 }
1322 } <<
1323 1199
1324 impl<T> InPlaceWrite<T> for UniqueArc<MaybeUn !! 1200 #[inline]
1325 type Initialized = UniqueArc<T>; !! 1201 fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
1326 !! 1202 where
1327 fn write_init<E>(mut self, init: impl Ini !! 1203 E: From<AllocError>,
1328 let slot = self.as_mut_ptr(); !! 1204 {
>> 1205 let mut this = UniqueArc::try_new_uninit()?;
>> 1206 let slot = this.as_mut_ptr();
1329 // SAFETY: When init errors/panics, s 1207 // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
1330 // slot is valid. 1208 // slot is valid.
1331 unsafe { init.__init(slot)? }; 1209 unsafe { init.__init(slot)? };
1332 // SAFETY: All fields have been initi 1210 // SAFETY: All fields have been initialized.
1333 Ok(unsafe { self.assume_init() }) !! 1211 Ok(unsafe { this.assume_init() })
1334 } <<
1335 <<
1336 fn write_pin_init<E>(mut self, init: impl <<
1337 let slot = self.as_mut_ptr(); <<
1338 // SAFETY: When init errors/panics, s <<
1339 // slot is valid and will not be move <<
1340 unsafe { init.__pinned_init(slot)? }; <<
1341 // SAFETY: All fields have been initi <<
1342 Ok(unsafe { self.assume_init() }.into <<
1343 } 1212 }
1344 } 1213 }
1345 1214
1346 /// Trait facilitating pinned destruction. 1215 /// Trait facilitating pinned destruction.
1347 /// 1216 ///
1348 /// Use [`pinned_drop`] to implement this tra 1217 /// Use [`pinned_drop`] to implement this trait safely:
1349 /// 1218 ///
1350 /// ```rust 1219 /// ```rust
1351 /// # use kernel::sync::Mutex; 1220 /// # use kernel::sync::Mutex;
1352 /// use kernel::macros::pinned_drop; 1221 /// use kernel::macros::pinned_drop;
1353 /// use core::pin::Pin; 1222 /// use core::pin::Pin;
1354 /// #[pin_data(PinnedDrop)] 1223 /// #[pin_data(PinnedDrop)]
1355 /// struct Foo { 1224 /// struct Foo {
1356 /// #[pin] 1225 /// #[pin]
1357 /// mtx: Mutex<usize>, 1226 /// mtx: Mutex<usize>,
1358 /// } 1227 /// }
1359 /// 1228 ///
1360 /// #[pinned_drop] 1229 /// #[pinned_drop]
1361 /// impl PinnedDrop for Foo { 1230 /// impl PinnedDrop for Foo {
1362 /// fn drop(self: Pin<&mut Self>) { 1231 /// fn drop(self: Pin<&mut Self>) {
1363 /// pr_info!("Foo is being dropped!") 1232 /// pr_info!("Foo is being dropped!");
1364 /// } 1233 /// }
1365 /// } 1234 /// }
1366 /// ``` 1235 /// ```
1367 /// 1236 ///
1368 /// # Safety 1237 /// # Safety
1369 /// 1238 ///
1370 /// This trait must be implemented via the [` 1239 /// This trait must be implemented via the [`pinned_drop`] proc-macro attribute on the impl.
1371 /// 1240 ///
1372 /// [`pinned_drop`]: kernel::macros::pinned_d 1241 /// [`pinned_drop`]: kernel::macros::pinned_drop
1373 pub unsafe trait PinnedDrop: __internal::HasP 1242 pub unsafe trait PinnedDrop: __internal::HasPinData {
1374 /// Executes the pinned destructor of thi 1243 /// Executes the pinned destructor of this type.
1375 /// 1244 ///
1376 /// While this function is marked safe, i 1245 /// While this function is marked safe, it is actually unsafe to call it manually. For this
1377 /// reason it takes an additional paramet 1246 /// reason it takes an additional parameter. This type can only be constructed by `unsafe` code
1378 /// and thus prevents this function from 1247 /// and thus prevents this function from being called where it should not.
1379 /// 1248 ///
1380 /// This extra parameter will be generate 1249 /// This extra parameter will be generated by the `#[pinned_drop]` proc-macro attribute
1381 /// automatically. 1250 /// automatically.
1382 fn drop(self: Pin<&mut Self>, only_call_f 1251 fn drop(self: Pin<&mut Self>, only_call_from_drop: __internal::OnlyCallFromDrop);
1383 } 1252 }
1384 1253
1385 /// Marker trait for types that can be initia 1254 /// Marker trait for types that can be initialized by writing just zeroes.
1386 /// 1255 ///
1387 /// # Safety 1256 /// # Safety
1388 /// 1257 ///
1389 /// The bit pattern consisting of only zeroes 1258 /// The bit pattern consisting of only zeroes is a valid bit pattern for this type. In other words,
1390 /// this is not UB: 1259 /// this is not UB:
1391 /// 1260 ///
1392 /// ```rust,ignore 1261 /// ```rust,ignore
1393 /// let val: Self = unsafe { core::mem::zeroe 1262 /// let val: Self = unsafe { core::mem::zeroed() };
1394 /// ``` 1263 /// ```
1395 pub unsafe trait Zeroable {} 1264 pub unsafe trait Zeroable {}
1396 1265
1397 /// Create a new zeroed T. 1266 /// Create a new zeroed T.
1398 /// 1267 ///
1399 /// The returned initializer will write `0x00 1268 /// The returned initializer will write `0x00` to every byte of the given `slot`.
1400 #[inline] 1269 #[inline]
1401 pub fn zeroed<T: Zeroable>() -> impl Init<T> 1270 pub fn zeroed<T: Zeroable>() -> impl Init<T> {
1402 // SAFETY: Because `T: Zeroable`, all byt 1271 // SAFETY: Because `T: Zeroable`, all bytes zero is a valid bit pattern for `T`
1403 // and because we write all zeroes, the m 1272 // and because we write all zeroes, the memory is initialized.
1404 unsafe { 1273 unsafe {
1405 init_from_closure(|slot: *mut T| { 1274 init_from_closure(|slot: *mut T| {
1406 slot.write_bytes(0, 1); 1275 slot.write_bytes(0, 1);
1407 Ok(()) 1276 Ok(())
1408 }) 1277 })
1409 } 1278 }
1410 } 1279 }
1411 1280
1412 macro_rules! impl_zeroable { 1281 macro_rules! impl_zeroable {
1413 ($($({$($generics:tt)*})? $t:ty, )*) => { 1282 ($($({$($generics:tt)*})? $t:ty, )*) => {
1414 $(unsafe impl$($($generics)*)? Zeroab 1283 $(unsafe impl$($($generics)*)? Zeroable for $t {})*
1415 }; 1284 };
1416 } 1285 }
1417 1286
1418 impl_zeroable! { 1287 impl_zeroable! {
1419 // SAFETY: All primitives that are allowe 1288 // SAFETY: All primitives that are allowed to be zero.
1420 bool, 1289 bool,
1421 char, 1290 char,
1422 u8, u16, u32, u64, u128, usize, 1291 u8, u16, u32, u64, u128, usize,
1423 i8, i16, i32, i64, i128, isize, 1292 i8, i16, i32, i64, i128, isize,
1424 f32, f64, 1293 f32, f64,
1425 1294
1426 // Note: do not add uninhabited types (su 1295 // Note: do not add uninhabited types (such as `!` or `core::convert::Infallible`) to this list;
1427 // creating an instance of an uninhabited 1296 // creating an instance of an uninhabited type is immediate undefined behavior. For more on
1428 // uninhabited/empty types, consult The R 1297 // uninhabited/empty types, consult The Rustonomicon:
1429 // <https://doc.rust-lang.org/stable/nomi 1298 // <https://doc.rust-lang.org/stable/nomicon/exotic-sizes.html#empty-types>. The Rust Reference
1430 // also has information on undefined beha 1299 // also has information on undefined behavior:
1431 // <https://doc.rust-lang.org/stable/refe 1300 // <https://doc.rust-lang.org/stable/reference/behavior-considered-undefined.html>.
1432 // 1301 //
1433 // SAFETY: These are inhabited ZSTs; ther 1302 // SAFETY: These are inhabited ZSTs; there is nothing to zero and a valid value exists.
1434 {<T: ?Sized>} PhantomData<T>, core::marke 1303 {<T: ?Sized>} PhantomData<T>, core::marker::PhantomPinned, (),
1435 1304
1436 // SAFETY: Type is allowed to take any va 1305 // SAFETY: Type is allowed to take any value, including all zeros.
1437 {<T>} MaybeUninit<T>, 1306 {<T>} MaybeUninit<T>,
1438 // SAFETY: Type is allowed to take any va 1307 // SAFETY: Type is allowed to take any value, including all zeros.
1439 {<T>} Opaque<T>, 1308 {<T>} Opaque<T>,
1440 1309
1441 // SAFETY: `T: Zeroable` and `UnsafeCell` 1310 // SAFETY: `T: Zeroable` and `UnsafeCell` is `repr(transparent)`.
1442 {<T: ?Sized + Zeroable>} UnsafeCell<T>, 1311 {<T: ?Sized + Zeroable>} UnsafeCell<T>,
1443 1312
1444 // SAFETY: All zeros is equivalent to `No 1313 // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
1445 Option<NonZeroU8>, Option<NonZeroU16>, Op 1314 Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,
1446 Option<NonZeroU128>, Option<NonZeroUsize> 1315 Option<NonZeroU128>, Option<NonZeroUsize>,
1447 Option<NonZeroI8>, Option<NonZeroI16>, Op 1316 Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>,
1448 Option<NonZeroI128>, Option<NonZeroIsize> 1317 Option<NonZeroI128>, Option<NonZeroIsize>,
1449 1318
1450 // SAFETY: All zeros is equivalent to `No 1319 // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
1451 // 1320 //
1452 // In this case we are allowed to use `T: 1321 // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant.
1453 {<T: ?Sized>} Option<NonNull<T>>, 1322 {<T: ?Sized>} Option<NonNull<T>>,
1454 {<T: ?Sized>} Option<Box<T>>, 1323 {<T: ?Sized>} Option<Box<T>>,
1455 1324
1456 // SAFETY: `null` pointer is valid. 1325 // SAFETY: `null` pointer is valid.
1457 // 1326 //
1458 // We cannot use `T: ?Sized`, since the V 1327 // We cannot use `T: ?Sized`, since the VTABLE pointer part of fat pointers is not allowed to be
1459 // null. 1328 // null.
1460 // 1329 //
1461 // When `Pointee` gets stabilized, we cou 1330 // When `Pointee` gets stabilized, we could use
1462 // `T: ?Sized where <T as Pointee>::Metad 1331 // `T: ?Sized where <T as Pointee>::Metadata: Zeroable`
1463 {<T>} *mut T, {<T>} *const T, 1332 {<T>} *mut T, {<T>} *const T,
1464 1333
1465 // SAFETY: `null` pointer is valid and th 1334 // SAFETY: `null` pointer is valid and the metadata part of these fat pointers is allowed to be
1466 // zero. 1335 // zero.
1467 {<T>} *mut [T], {<T>} *const [T], *mut st 1336 {<T>} *mut [T], {<T>} *const [T], *mut str, *const str,
1468 1337
1469 // SAFETY: `T` is `Zeroable`. 1338 // SAFETY: `T` is `Zeroable`.
1470 {<const N: usize, T: Zeroable>} [T; N], { 1339 {<const N: usize, T: Zeroable>} [T; N], {<T: Zeroable>} Wrapping<T>,
1471 } 1340 }
1472 1341
1473 macro_rules! impl_tuple_zeroable { 1342 macro_rules! impl_tuple_zeroable {
1474 ($(,)?) => {}; 1343 ($(,)?) => {};
1475 ($first:ident, $($t:ident),* $(,)?) => { 1344 ($first:ident, $($t:ident),* $(,)?) => {
1476 // SAFETY: All elements are zeroable 1345 // SAFETY: All elements are zeroable and padding can be zero.
1477 unsafe impl<$first: Zeroable, $($t: Z 1346 unsafe impl<$first: Zeroable, $($t: Zeroable),*> Zeroable for ($first, $($t),*) {}
1478 impl_tuple_zeroable!($($t),* ,); 1347 impl_tuple_zeroable!($($t),* ,);
1479 } 1348 }
1480 } 1349 }
1481 1350
1482 impl_tuple_zeroable!(A, B, C, D, E, F, G, H, 1351 impl_tuple_zeroable!(A, B, C, D, E, F, G, H, I, J);
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