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1 | // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
11 | // FIXME: talk about offset, copy_memory, copy_nonoverlapping_memory | |
12 | ||
54a0048b | 13 | //! Raw, unsafe pointers, `*const T`, and `*mut T`. |
1a4d82fc | 14 | //! |
54a0048b | 15 | //! *[See also the pointer primitive types](../../std/primitive.pointer.html).* |
1a4d82fc | 16 | |
85aaf69f | 17 | #![stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 18 | |
3b2f2976 | 19 | use convert::From; |
1a4d82fc | 20 | use intrinsics; |
7cac9316 | 21 | use ops::CoerceUnsized; |
c1a9b12d | 22 | use fmt; |
e9174d1e | 23 | use hash; |
9e0c209e | 24 | use marker::{PhantomData, Unsize}; |
e9174d1e | 25 | use mem; |
85aaf69f | 26 | use nonzero::NonZero; |
1a4d82fc | 27 | |
1a4d82fc JJ |
28 | use cmp::Ordering::{self, Less, Equal, Greater}; |
29 | ||
c34b1796 | 30 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 31 | pub use intrinsics::copy_nonoverlapping; |
1a4d82fc | 32 | |
c34b1796 | 33 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 34 | pub use intrinsics::copy; |
1a4d82fc | 35 | |
c34b1796 AL |
36 | #[stable(feature = "rust1", since = "1.0.0")] |
37 | pub use intrinsics::write_bytes; | |
1a4d82fc | 38 | |
cc61c64b XL |
39 | /// Executes the destructor (if any) of the pointed-to value. |
40 | /// | |
41 | /// This has two use cases: | |
42 | /// | |
43 | /// * It is *required* to use `drop_in_place` to drop unsized types like | |
44 | /// trait objects, because they can't be read out onto the stack and | |
45 | /// dropped normally. | |
46 | /// | |
47 | /// * It is friendlier to the optimizer to do this over `ptr::read` when | |
48 | /// dropping manually allocated memory (e.g. when writing Box/Rc/Vec), | |
49 | /// as the compiler doesn't need to prove that it's sound to elide the | |
50 | /// copy. | |
51 | /// | |
ea8adc8c | 52 | /// # Safety |
cc61c64b XL |
53 | /// |
54 | /// This has all the same safety problems as `ptr::read` with respect to | |
55 | /// invalid pointers, types, and double drops. | |
56 | #[stable(feature = "drop_in_place", since = "1.8.0")] | |
ea8adc8c | 57 | #[lang = "drop_in_place"] |
cc61c64b XL |
58 | #[allow(unconditional_recursion)] |
59 | pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) { | |
60 | // Code here does not matter - this is replaced by the | |
61 | // real drop glue by the compiler. | |
62 | drop_in_place(to_drop); | |
63 | } | |
64 | ||
1a4d82fc JJ |
65 | /// Creates a null raw pointer. |
66 | /// | |
67 | /// # Examples | |
68 | /// | |
69 | /// ``` | |
70 | /// use std::ptr; | |
71 | /// | |
85aaf69f | 72 | /// let p: *const i32 = ptr::null(); |
1a4d82fc JJ |
73 | /// assert!(p.is_null()); |
74 | /// ``` | |
75 | #[inline] | |
85aaf69f | 76 | #[stable(feature = "rust1", since = "1.0.0")] |
e9174d1e | 77 | pub const fn null<T>() -> *const T { 0 as *const T } |
1a4d82fc JJ |
78 | |
79 | /// Creates a null mutable raw pointer. | |
80 | /// | |
81 | /// # Examples | |
82 | /// | |
83 | /// ``` | |
84 | /// use std::ptr; | |
85 | /// | |
85aaf69f | 86 | /// let p: *mut i32 = ptr::null_mut(); |
1a4d82fc JJ |
87 | /// assert!(p.is_null()); |
88 | /// ``` | |
89 | #[inline] | |
85aaf69f | 90 | #[stable(feature = "rust1", since = "1.0.0")] |
e9174d1e | 91 | pub const fn null_mut<T>() -> *mut T { 0 as *mut T } |
1a4d82fc | 92 | |
1a4d82fc | 93 | /// Swaps the values at two mutable locations of the same type, without |
ff7c6d11 XL |
94 | /// deinitializing either. |
95 | /// | |
96 | /// The values pointed at by `x` and `y` may overlap, unlike `mem::swap` which | |
97 | /// is otherwise equivalent. If the values do overlap, then the overlapping | |
98 | /// region of memory from `x` will be used. This is demonstrated in the | |
99 | /// examples section below. | |
1a4d82fc JJ |
100 | /// |
101 | /// # Safety | |
102 | /// | |
32a655c1 SL |
103 | /// This function copies the memory through the raw pointers passed to it |
104 | /// as arguments. | |
105 | /// | |
106 | /// Ensure that these pointers are valid before calling `swap`. | |
ff7c6d11 XL |
107 | /// |
108 | /// # Examples | |
109 | /// | |
110 | /// Swapping two non-overlapping regions: | |
111 | /// | |
112 | /// ``` | |
113 | /// use std::ptr; | |
114 | /// | |
115 | /// let mut array = [0, 1, 2, 3]; | |
116 | /// | |
117 | /// let x = array[0..].as_mut_ptr() as *mut [u32; 2]; | |
118 | /// let y = array[2..].as_mut_ptr() as *mut [u32; 2]; | |
119 | /// | |
120 | /// unsafe { | |
121 | /// ptr::swap(x, y); | |
122 | /// assert_eq!([2, 3, 0, 1], array); | |
123 | /// } | |
124 | /// ``` | |
125 | /// | |
126 | /// Swapping two overlapping regions: | |
127 | /// | |
128 | /// ``` | |
129 | /// use std::ptr; | |
130 | /// | |
131 | /// let mut array = [0, 1, 2, 3]; | |
132 | /// | |
133 | /// let x = array[0..].as_mut_ptr() as *mut [u32; 3]; | |
134 | /// let y = array[1..].as_mut_ptr() as *mut [u32; 3]; | |
135 | /// | |
136 | /// unsafe { | |
137 | /// ptr::swap(x, y); | |
138 | /// assert_eq!([1, 0, 1, 2], array); | |
139 | /// } | |
140 | /// ``` | |
1a4d82fc | 141 | #[inline] |
85aaf69f | 142 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
143 | pub unsafe fn swap<T>(x: *mut T, y: *mut T) { |
144 | // Give ourselves some scratch space to work with | |
145 | let mut tmp: T = mem::uninitialized(); | |
1a4d82fc JJ |
146 | |
147 | // Perform the swap | |
c34b1796 AL |
148 | copy_nonoverlapping(x, &mut tmp, 1); |
149 | copy(y, x, 1); // `x` and `y` may overlap | |
150 | copy_nonoverlapping(&tmp, y, 1); | |
1a4d82fc JJ |
151 | |
152 | // y and t now point to the same thing, but we need to completely forget `tmp` | |
153 | // because it's no longer relevant. | |
154 | mem::forget(tmp); | |
155 | } | |
156 | ||
041b39d2 XL |
157 | /// Swaps a sequence of values at two mutable locations of the same type. |
158 | /// | |
159 | /// # Safety | |
160 | /// | |
161 | /// The two arguments must each point to the beginning of `count` locations | |
162 | /// of valid memory, and the two memory ranges must not overlap. | |
163 | /// | |
164 | /// # Examples | |
165 | /// | |
166 | /// Basic usage: | |
167 | /// | |
168 | /// ``` | |
169 | /// #![feature(swap_nonoverlapping)] | |
170 | /// | |
171 | /// use std::ptr; | |
172 | /// | |
173 | /// let mut x = [1, 2, 3, 4]; | |
174 | /// let mut y = [7, 8, 9]; | |
175 | /// | |
176 | /// unsafe { | |
177 | /// ptr::swap_nonoverlapping(x.as_mut_ptr(), y.as_mut_ptr(), 2); | |
178 | /// } | |
179 | /// | |
180 | /// assert_eq!(x, [7, 8, 3, 4]); | |
181 | /// assert_eq!(y, [1, 2, 9]); | |
182 | /// ``` | |
183 | #[inline] | |
184 | #[unstable(feature = "swap_nonoverlapping", issue = "42818")] | |
185 | pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) { | |
186 | let x = x as *mut u8; | |
187 | let y = y as *mut u8; | |
188 | let len = mem::size_of::<T>() * count; | |
189 | swap_nonoverlapping_bytes(x, y, len) | |
190 | } | |
191 | ||
192 | #[inline] | |
193 | unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) { | |
194 | // The approach here is to utilize simd to swap x & y efficiently. Testing reveals | |
195 | // that swapping either 32 bytes or 64 bytes at a time is most efficient for intel | |
196 | // Haswell E processors. LLVM is more able to optimize if we give a struct a | |
197 | // #[repr(simd)], even if we don't actually use this struct directly. | |
198 | // | |
199 | // FIXME repr(simd) broken on emscripten and redox | |
200 | // It's also broken on big-endian powerpc64 and s390x. #42778 | |
201 | #[cfg_attr(not(any(target_os = "emscripten", target_os = "redox", | |
202 | target_endian = "big")), | |
203 | repr(simd))] | |
204 | struct Block(u64, u64, u64, u64); | |
205 | struct UnalignedBlock(u64, u64, u64, u64); | |
206 | ||
207 | let block_size = mem::size_of::<Block>(); | |
208 | ||
209 | // Loop through x & y, copying them `Block` at a time | |
210 | // The optimizer should unroll the loop fully for most types | |
211 | // N.B. We can't use a for loop as the `range` impl calls `mem::swap` recursively | |
212 | let mut i = 0; | |
213 | while i + block_size <= len { | |
214 | // Create some uninitialized memory as scratch space | |
215 | // Declaring `t` here avoids aligning the stack when this loop is unused | |
216 | let mut t: Block = mem::uninitialized(); | |
217 | let t = &mut t as *mut _ as *mut u8; | |
218 | let x = x.offset(i as isize); | |
219 | let y = y.offset(i as isize); | |
220 | ||
221 | // Swap a block of bytes of x & y, using t as a temporary buffer | |
222 | // This should be optimized into efficient SIMD operations where available | |
223 | copy_nonoverlapping(x, t, block_size); | |
224 | copy_nonoverlapping(y, x, block_size); | |
225 | copy_nonoverlapping(t, y, block_size); | |
226 | i += block_size; | |
227 | } | |
228 | ||
229 | if i < len { | |
230 | // Swap any remaining bytes | |
231 | let mut t: UnalignedBlock = mem::uninitialized(); | |
232 | let rem = len - i; | |
233 | ||
234 | let t = &mut t as *mut _ as *mut u8; | |
235 | let x = x.offset(i as isize); | |
236 | let y = y.offset(i as isize); | |
237 | ||
238 | copy_nonoverlapping(x, t, rem); | |
239 | copy_nonoverlapping(y, x, rem); | |
240 | copy_nonoverlapping(t, y, rem); | |
241 | } | |
242 | } | |
243 | ||
1a4d82fc JJ |
244 | /// Replaces the value at `dest` with `src`, returning the old |
245 | /// value, without dropping either. | |
246 | /// | |
247 | /// # Safety | |
248 | /// | |
249 | /// This is only unsafe because it accepts a raw pointer. | |
250 | /// Otherwise, this operation is identical to `mem::replace`. | |
251 | #[inline] | |
85aaf69f | 252 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 253 | pub unsafe fn replace<T>(dest: *mut T, mut src: T) -> T { |
e9174d1e | 254 | mem::swap(&mut *dest, &mut src); // cannot overlap |
1a4d82fc JJ |
255 | src |
256 | } | |
257 | ||
85aaf69f | 258 | /// Reads the value from `src` without moving it. This leaves the |
1a4d82fc JJ |
259 | /// memory in `src` unchanged. |
260 | /// | |
261 | /// # Safety | |
262 | /// | |
263 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
264 | /// moves the value out of `src` without preventing further usage of `src`. | |
265 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
266 | /// `src` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 267 | /// `write_bytes`, or `copy`). Note that `*src = foo` counts as a use |
1a4d82fc | 268 | /// because it will attempt to drop the value previously at `*src`. |
a7813a04 | 269 | /// |
476ff2be SL |
270 | /// The pointer must be aligned; use `read_unaligned` if that is not the case. |
271 | /// | |
a7813a04 XL |
272 | /// # Examples |
273 | /// | |
274 | /// Basic usage: | |
275 | /// | |
276 | /// ``` | |
277 | /// let x = 12; | |
278 | /// let y = &x as *const i32; | |
279 | /// | |
9e0c209e SL |
280 | /// unsafe { |
281 | /// assert_eq!(std::ptr::read(y), 12); | |
282 | /// } | |
a7813a04 | 283 | /// ``` |
3b2f2976 | 284 | #[inline] |
85aaf69f | 285 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
286 | pub unsafe fn read<T>(src: *const T) -> T { |
287 | let mut tmp: T = mem::uninitialized(); | |
c34b1796 | 288 | copy_nonoverlapping(src, &mut tmp, 1); |
1a4d82fc JJ |
289 | tmp |
290 | } | |
291 | ||
476ff2be SL |
292 | /// Reads the value from `src` without moving it. This leaves the |
293 | /// memory in `src` unchanged. | |
294 | /// | |
295 | /// Unlike `read`, the pointer may be unaligned. | |
296 | /// | |
297 | /// # Safety | |
298 | /// | |
299 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
300 | /// moves the value out of `src` without preventing further usage of `src`. | |
301 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
302 | /// `src` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 303 | /// `write_bytes`, or `copy`). Note that `*src = foo` counts as a use |
476ff2be SL |
304 | /// because it will attempt to drop the value previously at `*src`. |
305 | /// | |
306 | /// # Examples | |
307 | /// | |
308 | /// Basic usage: | |
309 | /// | |
310 | /// ``` | |
476ff2be SL |
311 | /// let x = 12; |
312 | /// let y = &x as *const i32; | |
313 | /// | |
314 | /// unsafe { | |
315 | /// assert_eq!(std::ptr::read_unaligned(y), 12); | |
316 | /// } | |
317 | /// ``` | |
3b2f2976 | 318 | #[inline] |
8bb4bdeb | 319 | #[stable(feature = "ptr_unaligned", since = "1.17.0")] |
476ff2be SL |
320 | pub unsafe fn read_unaligned<T>(src: *const T) -> T { |
321 | let mut tmp: T = mem::uninitialized(); | |
322 | copy_nonoverlapping(src as *const u8, | |
323 | &mut tmp as *mut T as *mut u8, | |
324 | mem::size_of::<T>()); | |
325 | tmp | |
326 | } | |
327 | ||
1a4d82fc JJ |
328 | /// Overwrites a memory location with the given value without reading or |
329 | /// dropping the old value. | |
330 | /// | |
331 | /// # Safety | |
332 | /// | |
b039eaaf SL |
333 | /// This operation is marked unsafe because it accepts a raw pointer. |
334 | /// | |
335 | /// It does not drop the contents of `dst`. This is safe, but it could leak | |
336 | /// allocations or resources, so care must be taken not to overwrite an object | |
337 | /// that should be dropped. | |
1a4d82fc | 338 | /// |
cc61c64b XL |
339 | /// Additionally, it does not drop `src`. Semantically, `src` is moved into the |
340 | /// location pointed to by `dst`. | |
8bb4bdeb | 341 | /// |
1a4d82fc JJ |
342 | /// This is appropriate for initializing uninitialized memory, or overwriting |
343 | /// memory that has previously been `read` from. | |
a7813a04 | 344 | /// |
476ff2be SL |
345 | /// The pointer must be aligned; use `write_unaligned` if that is not the case. |
346 | /// | |
a7813a04 XL |
347 | /// # Examples |
348 | /// | |
349 | /// Basic usage: | |
350 | /// | |
351 | /// ``` | |
352 | /// let mut x = 0; | |
353 | /// let y = &mut x as *mut i32; | |
354 | /// let z = 12; | |
355 | /// | |
356 | /// unsafe { | |
357 | /// std::ptr::write(y, z); | |
9e0c209e | 358 | /// assert_eq!(std::ptr::read(y), 12); |
a7813a04 XL |
359 | /// } |
360 | /// ``` | |
1a4d82fc | 361 | #[inline] |
85aaf69f | 362 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
363 | pub unsafe fn write<T>(dst: *mut T, src: T) { |
364 | intrinsics::move_val_init(&mut *dst, src) | |
365 | } | |
366 | ||
476ff2be SL |
367 | /// Overwrites a memory location with the given value without reading or |
368 | /// dropping the old value. | |
369 | /// | |
370 | /// Unlike `write`, the pointer may be unaligned. | |
371 | /// | |
372 | /// # Safety | |
373 | /// | |
374 | /// This operation is marked unsafe because it accepts a raw pointer. | |
375 | /// | |
376 | /// It does not drop the contents of `dst`. This is safe, but it could leak | |
377 | /// allocations or resources, so care must be taken not to overwrite an object | |
378 | /// that should be dropped. | |
379 | /// | |
cc61c64b XL |
380 | /// Additionally, it does not drop `src`. Semantically, `src` is moved into the |
381 | /// location pointed to by `dst`. | |
382 | /// | |
476ff2be SL |
383 | /// This is appropriate for initializing uninitialized memory, or overwriting |
384 | /// memory that has previously been `read` from. | |
385 | /// | |
386 | /// # Examples | |
387 | /// | |
388 | /// Basic usage: | |
389 | /// | |
390 | /// ``` | |
476ff2be SL |
391 | /// let mut x = 0; |
392 | /// let y = &mut x as *mut i32; | |
393 | /// let z = 12; | |
394 | /// | |
395 | /// unsafe { | |
396 | /// std::ptr::write_unaligned(y, z); | |
397 | /// assert_eq!(std::ptr::read_unaligned(y), 12); | |
398 | /// } | |
399 | /// ``` | |
400 | #[inline] | |
8bb4bdeb | 401 | #[stable(feature = "ptr_unaligned", since = "1.17.0")] |
476ff2be SL |
402 | pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) { |
403 | copy_nonoverlapping(&src as *const T as *const u8, | |
404 | dst as *mut u8, | |
405 | mem::size_of::<T>()); | |
406 | mem::forget(src); | |
407 | } | |
408 | ||
7453a54e SL |
409 | /// Performs a volatile read of the value from `src` without moving it. This |
410 | /// leaves the memory in `src` unchanged. | |
411 | /// | |
412 | /// Volatile operations are intended to act on I/O memory, and are guaranteed | |
413 | /// to not be elided or reordered by the compiler across other volatile | |
54a0048b | 414 | /// operations. |
7453a54e | 415 | /// |
54a0048b SL |
416 | /// # Notes |
417 | /// | |
418 | /// Rust does not currently have a rigorously and formally defined memory model, | |
419 | /// so the precise semantics of what "volatile" means here is subject to change | |
420 | /// over time. That being said, the semantics will almost always end up pretty | |
421 | /// similar to [C11's definition of volatile][c11]. | |
422 | /// | |
3b2f2976 XL |
423 | /// The compiler shouldn't change the relative order or number of volatile |
424 | /// memory operations. However, volatile memory operations on zero-sized types | |
425 | /// (e.g. if a zero-sized type is passed to `read_volatile`) are no-ops | |
426 | /// and may be ignored. | |
427 | /// | |
54a0048b | 428 | /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf |
7453a54e SL |
429 | /// |
430 | /// # Safety | |
431 | /// | |
432 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
433 | /// moves the value out of `src` without preventing further usage of `src`. | |
434 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
435 | /// `src` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 436 | /// `write_bytes`, or `copy`). Note that `*src = foo` counts as a use |
7453a54e | 437 | /// because it will attempt to drop the value previously at `*src`. |
a7813a04 XL |
438 | /// |
439 | /// # Examples | |
440 | /// | |
441 | /// Basic usage: | |
442 | /// | |
443 | /// ``` | |
444 | /// let x = 12; | |
445 | /// let y = &x as *const i32; | |
446 | /// | |
9e0c209e SL |
447 | /// unsafe { |
448 | /// assert_eq!(std::ptr::read_volatile(y), 12); | |
449 | /// } | |
a7813a04 | 450 | /// ``` |
7453a54e | 451 | #[inline] |
54a0048b | 452 | #[stable(feature = "volatile", since = "1.9.0")] |
7453a54e SL |
453 | pub unsafe fn read_volatile<T>(src: *const T) -> T { |
454 | intrinsics::volatile_load(src) | |
455 | } | |
456 | ||
457 | /// Performs a volatile write of a memory location with the given value without | |
458 | /// reading or dropping the old value. | |
459 | /// | |
460 | /// Volatile operations are intended to act on I/O memory, and are guaranteed | |
461 | /// to not be elided or reordered by the compiler across other volatile | |
54a0048b SL |
462 | /// operations. |
463 | /// | |
464 | /// # Notes | |
465 | /// | |
466 | /// Rust does not currently have a rigorously and formally defined memory model, | |
467 | /// so the precise semantics of what "volatile" means here is subject to change | |
468 | /// over time. That being said, the semantics will almost always end up pretty | |
469 | /// similar to [C11's definition of volatile][c11]. | |
7453a54e | 470 | /// |
3b2f2976 XL |
471 | /// The compiler shouldn't change the relative order or number of volatile |
472 | /// memory operations. However, volatile memory operations on zero-sized types | |
473 | /// (e.g. if a zero-sized type is passed to `write_volatile`) are no-ops | |
474 | /// and may be ignored. | |
475 | /// | |
54a0048b | 476 | /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf |
7453a54e SL |
477 | /// |
478 | /// # Safety | |
479 | /// | |
480 | /// This operation is marked unsafe because it accepts a raw pointer. | |
481 | /// | |
482 | /// It does not drop the contents of `dst`. This is safe, but it could leak | |
483 | /// allocations or resources, so care must be taken not to overwrite an object | |
484 | /// that should be dropped. | |
485 | /// | |
486 | /// This is appropriate for initializing uninitialized memory, or overwriting | |
487 | /// memory that has previously been `read` from. | |
a7813a04 XL |
488 | /// |
489 | /// # Examples | |
490 | /// | |
491 | /// Basic usage: | |
492 | /// | |
493 | /// ``` | |
494 | /// let mut x = 0; | |
495 | /// let y = &mut x as *mut i32; | |
496 | /// let z = 12; | |
497 | /// | |
498 | /// unsafe { | |
499 | /// std::ptr::write_volatile(y, z); | |
9e0c209e | 500 | /// assert_eq!(std::ptr::read_volatile(y), 12); |
a7813a04 XL |
501 | /// } |
502 | /// ``` | |
7453a54e | 503 | #[inline] |
54a0048b | 504 | #[stable(feature = "volatile", since = "1.9.0")] |
7453a54e SL |
505 | pub unsafe fn write_volatile<T>(dst: *mut T, src: T) { |
506 | intrinsics::volatile_store(dst, src); | |
507 | } | |
508 | ||
c34b1796 AL |
509 | #[lang = "const_ptr"] |
510 | impl<T: ?Sized> *const T { | |
cc61c64b | 511 | /// Returns `true` if the pointer is null. |
54a0048b | 512 | /// |
ff7c6d11 XL |
513 | /// Note that unsized types have many possible null pointers, as only the |
514 | /// raw data pointer is considered, not their length, vtable, etc. | |
515 | /// Therefore, two pointers that are null may still not compare equal to | |
516 | /// each other. | |
517 | /// | |
54a0048b SL |
518 | /// # Examples |
519 | /// | |
520 | /// Basic usage: | |
521 | /// | |
522 | /// ``` | |
523 | /// let s: &str = "Follow the rabbit"; | |
524 | /// let ptr: *const u8 = s.as_ptr(); | |
525 | /// assert!(!ptr.is_null()); | |
526 | /// ``` | |
85aaf69f | 527 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 528 | #[inline] |
ff7c6d11 XL |
529 | pub fn is_null(self) -> bool { |
530 | // Compare via a cast to a thin pointer, so fat pointers are only | |
531 | // considering their "data" part for null-ness. | |
532 | (self as *const u8) == null() | |
c34b1796 | 533 | } |
1a4d82fc JJ |
534 | |
535 | /// Returns `None` if the pointer is null, or else returns a reference to | |
536 | /// the value wrapped in `Some`. | |
537 | /// | |
538 | /// # Safety | |
539 | /// | |
540 | /// While this method and its mutable counterpart are useful for | |
541 | /// null-safety, it is important to note that this is still an unsafe | |
542 | /// operation because the returned value could be pointing to invalid | |
543 | /// memory. | |
54a0048b SL |
544 | /// |
545 | /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does | |
546 | /// not necessarily reflect the actual lifetime of the data. | |
547 | /// | |
548 | /// # Examples | |
549 | /// | |
550 | /// Basic usage: | |
551 | /// | |
041b39d2 XL |
552 | /// ``` |
553 | /// let ptr: *const u8 = &10u8 as *const u8; | |
54a0048b SL |
554 | /// |
555 | /// unsafe { | |
041b39d2 | 556 | /// if let Some(val_back) = ptr.as_ref() { |
54a0048b SL |
557 | /// println!("We got back the value: {}!", val_back); |
558 | /// } | |
559 | /// } | |
560 | /// ``` | |
561 | #[stable(feature = "ptr_as_ref", since = "1.9.0")] | |
c34b1796 | 562 | #[inline] |
abe05a73 | 563 | pub unsafe fn as_ref<'a>(self) -> Option<&'a T> { |
ff7c6d11 | 564 | if self.is_null() { |
c34b1796 AL |
565 | None |
566 | } else { | |
54a0048b | 567 | Some(&*self) |
c34b1796 AL |
568 | } |
569 | } | |
1a4d82fc | 570 | |
ea8adc8c XL |
571 | /// Calculates the offset from a pointer. |
572 | /// | |
573 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
574 | /// offset of `3 * size_of::<T>()` bytes. | |
1a4d82fc JJ |
575 | /// |
576 | /// # Safety | |
577 | /// | |
ea8adc8c XL |
578 | /// If any of the following conditions are violated, the result is Undefined |
579 | /// Behavior: | |
580 | /// | |
581 | /// * Both the starting and resulting pointer must be either in bounds or one | |
582 | /// byte past the end of an allocated object. | |
583 | /// | |
ff7c6d11 | 584 | /// * The computed offset, **in bytes**, cannot overflow an `isize`. |
ea8adc8c XL |
585 | /// |
586 | /// * The offset being in bounds cannot rely on "wrapping around" the address | |
587 | /// space. That is, the infinite-precision sum, **in bytes** must fit in a usize. | |
588 | /// | |
589 | /// The compiler and standard library generally tries to ensure allocations | |
590 | /// never reach a size where an offset is a concern. For instance, `Vec` | |
591 | /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so | |
592 | /// `vec.as_ptr().offset(vec.len() as isize)` is always safe. | |
593 | /// | |
594 | /// Most platforms fundamentally can't even construct such an allocation. | |
595 | /// For instance, no known 64-bit platform can ever serve a request | |
abe05a73 | 596 | /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. |
ea8adc8c XL |
597 | /// However, some 32-bit and 16-bit platforms may successfully serve a request for |
598 | /// more than `isize::MAX` bytes with things like Physical Address | |
599 | /// Extension. As such, memory acquired directly from allocators or memory | |
600 | /// mapped files *may* be too large to handle with this function. | |
601 | /// | |
602 | /// Consider using `wrapping_offset` instead if these constraints are | |
603 | /// difficult to satisfy. The only advantage of this method is that it | |
604 | /// enables more aggressive compiler optimizations. | |
54a0048b SL |
605 | /// |
606 | /// # Examples | |
607 | /// | |
608 | /// Basic usage: | |
609 | /// | |
610 | /// ``` | |
611 | /// let s: &str = "123"; | |
612 | /// let ptr: *const u8 = s.as_ptr(); | |
613 | /// | |
614 | /// unsafe { | |
615 | /// println!("{}", *ptr.offset(1) as char); | |
616 | /// println!("{}", *ptr.offset(2) as char); | |
617 | /// } | |
618 | /// ``` | |
85aaf69f | 619 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 AL |
620 | #[inline] |
621 | pub unsafe fn offset(self, count: isize) -> *const T where T: Sized { | |
622 | intrinsics::offset(self, count) | |
623 | } | |
c30ab7b3 SL |
624 | |
625 | /// Calculates the offset from a pointer using wrapping arithmetic. | |
ea8adc8c | 626 | /// |
c30ab7b3 | 627 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer |
cc61c64b | 628 | /// offset of `3 * size_of::<T>()` bytes. |
c30ab7b3 SL |
629 | /// |
630 | /// # Safety | |
631 | /// | |
632 | /// The resulting pointer does not need to be in bounds, but it is | |
633 | /// potentially hazardous to dereference (which requires `unsafe`). | |
634 | /// | |
635 | /// Always use `.offset(count)` instead when possible, because `offset` | |
636 | /// allows the compiler to optimize better. | |
637 | /// | |
638 | /// # Examples | |
639 | /// | |
640 | /// Basic usage: | |
641 | /// | |
642 | /// ``` | |
c30ab7b3 SL |
643 | /// // Iterate using a raw pointer in increments of two elements |
644 | /// let data = [1u8, 2, 3, 4, 5]; | |
645 | /// let mut ptr: *const u8 = data.as_ptr(); | |
646 | /// let step = 2; | |
647 | /// let end_rounded_up = ptr.wrapping_offset(6); | |
648 | /// | |
649 | /// // This loop prints "1, 3, 5, " | |
650 | /// while ptr != end_rounded_up { | |
651 | /// unsafe { | |
652 | /// print!("{}, ", *ptr); | |
653 | /// } | |
654 | /// ptr = ptr.wrapping_offset(step); | |
655 | /// } | |
656 | /// ``` | |
32a655c1 | 657 | #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")] |
c30ab7b3 SL |
658 | #[inline] |
659 | pub fn wrapping_offset(self, count: isize) -> *const T where T: Sized { | |
660 | unsafe { | |
661 | intrinsics::arith_offset(self, count) | |
662 | } | |
663 | } | |
cc61c64b XL |
664 | |
665 | /// Calculates the distance between two pointers. The returned value is in | |
666 | /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`. | |
667 | /// | |
668 | /// If the address different between the two pointers ia not a multiple of | |
669 | /// `mem::size_of::<T>()` then the result of the division is rounded towards | |
670 | /// zero. | |
671 | /// | |
672 | /// This function returns `None` if `T` is a zero-sized typed. | |
673 | /// | |
674 | /// # Examples | |
675 | /// | |
676 | /// Basic usage: | |
677 | /// | |
678 | /// ``` | |
679 | /// #![feature(offset_to)] | |
680 | /// | |
681 | /// fn main() { | |
682 | /// let a = [0; 5]; | |
683 | /// let ptr1: *const i32 = &a[1]; | |
684 | /// let ptr2: *const i32 = &a[3]; | |
685 | /// assert_eq!(ptr1.offset_to(ptr2), Some(2)); | |
686 | /// assert_eq!(ptr2.offset_to(ptr1), Some(-2)); | |
687 | /// assert_eq!(unsafe { ptr1.offset(2) }, ptr2); | |
688 | /// assert_eq!(unsafe { ptr2.offset(-2) }, ptr1); | |
689 | /// } | |
690 | /// ``` | |
691 | #[unstable(feature = "offset_to", issue = "41079")] | |
692 | #[inline] | |
693 | pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized { | |
694 | let size = mem::size_of::<T>(); | |
695 | if size == 0 { | |
696 | None | |
697 | } else { | |
698 | let diff = (other as isize).wrapping_sub(self as isize); | |
699 | Some(diff / size as isize) | |
700 | } | |
701 | } | |
ea8adc8c XL |
702 | |
703 | /// Calculates the offset from a pointer (convenience for `.offset(count as isize)`). | |
704 | /// | |
705 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
706 | /// offset of `3 * size_of::<T>()` bytes. | |
707 | /// | |
708 | /// # Safety | |
709 | /// | |
710 | /// If any of the following conditions are violated, the result is Undefined | |
711 | /// Behavior: | |
712 | /// | |
713 | /// * Both the starting and resulting pointer must be either in bounds or one | |
714 | /// byte past the end of an allocated object. | |
715 | /// | |
ff7c6d11 | 716 | /// * The computed offset, **in bytes**, cannot overflow an `isize`. |
ea8adc8c XL |
717 | /// |
718 | /// * The offset being in bounds cannot rely on "wrapping around" the address | |
719 | /// space. That is, the infinite-precision sum must fit in a `usize`. | |
720 | /// | |
721 | /// The compiler and standard library generally tries to ensure allocations | |
722 | /// never reach a size where an offset is a concern. For instance, `Vec` | |
723 | /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so | |
724 | /// `vec.as_ptr().add(vec.len())` is always safe. | |
725 | /// | |
726 | /// Most platforms fundamentally can't even construct such an allocation. | |
727 | /// For instance, no known 64-bit platform can ever serve a request | |
abe05a73 | 728 | /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. |
ea8adc8c XL |
729 | /// However, some 32-bit and 16-bit platforms may successfully serve a request for |
730 | /// more than `isize::MAX` bytes with things like Physical Address | |
731 | /// Extension. As such, memory acquired directly from allocators or memory | |
732 | /// mapped files *may* be too large to handle with this function. | |
733 | /// | |
734 | /// Consider using `wrapping_offset` instead if these constraints are | |
735 | /// difficult to satisfy. The only advantage of this method is that it | |
736 | /// enables more aggressive compiler optimizations. | |
737 | /// | |
738 | /// # Examples | |
739 | /// | |
740 | /// Basic usage: | |
741 | /// | |
742 | /// ``` | |
743 | /// #![feature(pointer_methods)] | |
744 | /// | |
745 | /// let s: &str = "123"; | |
746 | /// let ptr: *const u8 = s.as_ptr(); | |
747 | /// | |
748 | /// unsafe { | |
749 | /// println!("{}", *ptr.add(1) as char); | |
750 | /// println!("{}", *ptr.add(2) as char); | |
751 | /// } | |
752 | /// ``` | |
753 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
754 | #[inline] | |
755 | pub unsafe fn add(self, count: usize) -> Self | |
756 | where T: Sized, | |
757 | { | |
758 | self.offset(count as isize) | |
759 | } | |
760 | ||
761 | /// Calculates the offset from a pointer (convenience for | |
762 | /// `.offset((count as isize).wrapping_neg())`). | |
763 | /// | |
764 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
765 | /// offset of `3 * size_of::<T>()` bytes. | |
766 | /// | |
767 | /// # Safety | |
768 | /// | |
769 | /// If any of the following conditions are violated, the result is Undefined | |
770 | /// Behavior: | |
771 | /// | |
772 | /// * Both the starting and resulting pointer must be either in bounds or one | |
773 | /// byte past the end of an allocated object. | |
774 | /// | |
775 | /// * The computed offset cannot exceed `isize::MAX` **bytes**. | |
776 | /// | |
777 | /// * The offset being in bounds cannot rely on "wrapping around" the address | |
778 | /// space. That is, the infinite-precision sum must fit in a usize. | |
779 | /// | |
780 | /// The compiler and standard library generally tries to ensure allocations | |
781 | /// never reach a size where an offset is a concern. For instance, `Vec` | |
782 | /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so | |
783 | /// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe. | |
784 | /// | |
785 | /// Most platforms fundamentally can't even construct such an allocation. | |
786 | /// For instance, no known 64-bit platform can ever serve a request | |
abe05a73 | 787 | /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. |
ea8adc8c XL |
788 | /// However, some 32-bit and 16-bit platforms may successfully serve a request for |
789 | /// more than `isize::MAX` bytes with things like Physical Address | |
790 | /// Extension. As such, memory acquired directly from allocators or memory | |
791 | /// mapped files *may* be too large to handle with this function. | |
792 | /// | |
793 | /// Consider using `wrapping_offset` instead if these constraints are | |
794 | /// difficult to satisfy. The only advantage of this method is that it | |
795 | /// enables more aggressive compiler optimizations. | |
796 | /// | |
797 | /// # Examples | |
798 | /// | |
799 | /// Basic usage: | |
800 | /// | |
801 | /// ``` | |
802 | /// #![feature(pointer_methods)] | |
803 | /// | |
804 | /// let s: &str = "123"; | |
805 | /// | |
806 | /// unsafe { | |
807 | /// let end: *const u8 = s.as_ptr().add(3); | |
808 | /// println!("{}", *end.sub(1) as char); | |
809 | /// println!("{}", *end.sub(2) as char); | |
810 | /// } | |
811 | /// ``` | |
812 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
813 | #[inline] | |
814 | pub unsafe fn sub(self, count: usize) -> Self | |
815 | where T: Sized, | |
816 | { | |
817 | self.offset((count as isize).wrapping_neg()) | |
818 | } | |
819 | ||
820 | /// Calculates the offset from a pointer using wrapping arithmetic. | |
821 | /// (convenience for `.wrapping_offset(count as isize)`) | |
822 | /// | |
823 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
824 | /// offset of `3 * size_of::<T>()` bytes. | |
825 | /// | |
826 | /// # Safety | |
827 | /// | |
828 | /// The resulting pointer does not need to be in bounds, but it is | |
829 | /// potentially hazardous to dereference (which requires `unsafe`). | |
830 | /// | |
831 | /// Always use `.add(count)` instead when possible, because `add` | |
832 | /// allows the compiler to optimize better. | |
833 | /// | |
834 | /// # Examples | |
835 | /// | |
836 | /// Basic usage: | |
837 | /// | |
838 | /// ``` | |
839 | /// #![feature(pointer_methods)] | |
840 | /// | |
841 | /// // Iterate using a raw pointer in increments of two elements | |
842 | /// let data = [1u8, 2, 3, 4, 5]; | |
843 | /// let mut ptr: *const u8 = data.as_ptr(); | |
844 | /// let step = 2; | |
845 | /// let end_rounded_up = ptr.wrapping_add(6); | |
846 | /// | |
847 | /// // This loop prints "1, 3, 5, " | |
848 | /// while ptr != end_rounded_up { | |
849 | /// unsafe { | |
850 | /// print!("{}, ", *ptr); | |
851 | /// } | |
852 | /// ptr = ptr.wrapping_add(step); | |
853 | /// } | |
854 | /// ``` | |
855 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
856 | #[inline] | |
857 | pub fn wrapping_add(self, count: usize) -> Self | |
858 | where T: Sized, | |
859 | { | |
860 | self.wrapping_offset(count as isize) | |
861 | } | |
862 | ||
863 | /// Calculates the offset from a pointer using wrapping arithmetic. | |
864 | /// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`) | |
865 | /// | |
866 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
867 | /// offset of `3 * size_of::<T>()` bytes. | |
868 | /// | |
869 | /// # Safety | |
870 | /// | |
871 | /// The resulting pointer does not need to be in bounds, but it is | |
872 | /// potentially hazardous to dereference (which requires `unsafe`). | |
873 | /// | |
874 | /// Always use `.sub(count)` instead when possible, because `sub` | |
875 | /// allows the compiler to optimize better. | |
876 | /// | |
877 | /// # Examples | |
878 | /// | |
879 | /// Basic usage: | |
880 | /// | |
881 | /// ``` | |
882 | /// #![feature(pointer_methods)] | |
883 | /// | |
884 | /// // Iterate using a raw pointer in increments of two elements (backwards) | |
885 | /// let data = [1u8, 2, 3, 4, 5]; | |
886 | /// let mut ptr: *const u8 = data.as_ptr(); | |
887 | /// let start_rounded_down = ptr.wrapping_sub(2); | |
888 | /// ptr = ptr.wrapping_add(4); | |
889 | /// let step = 2; | |
890 | /// // This loop prints "5, 3, 1, " | |
891 | /// while ptr != start_rounded_down { | |
892 | /// unsafe { | |
893 | /// print!("{}, ", *ptr); | |
894 | /// } | |
895 | /// ptr = ptr.wrapping_sub(step); | |
896 | /// } | |
897 | /// ``` | |
898 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
899 | #[inline] | |
900 | pub fn wrapping_sub(self, count: usize) -> Self | |
901 | where T: Sized, | |
902 | { | |
903 | self.wrapping_offset((count as isize).wrapping_neg()) | |
904 | } | |
905 | ||
906 | /// Reads the value from `self` without moving it. This leaves the | |
907 | /// memory in `self` unchanged. | |
908 | /// | |
909 | /// # Safety | |
910 | /// | |
911 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
912 | /// moves the value out of `self` without preventing further usage of `self`. | |
913 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
914 | /// `self` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 915 | /// `write_bytes`, or `copy`). Note that `*self = foo` counts as a use |
ea8adc8c XL |
916 | /// because it will attempt to drop the value previously at `*self`. |
917 | /// | |
918 | /// The pointer must be aligned; use `read_unaligned` if that is not the case. | |
919 | /// | |
920 | /// # Examples | |
921 | /// | |
922 | /// Basic usage: | |
923 | /// | |
924 | /// ``` | |
925 | /// #![feature(pointer_methods)] | |
926 | /// | |
927 | /// let x = 12; | |
928 | /// let y = &x as *const i32; | |
929 | /// | |
930 | /// unsafe { | |
931 | /// assert_eq!(y.read(), 12); | |
932 | /// } | |
933 | /// ``` | |
934 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
935 | #[inline] | |
936 | pub unsafe fn read(self) -> T | |
937 | where T: Sized, | |
938 | { | |
939 | read(self) | |
940 | } | |
941 | ||
942 | /// Performs a volatile read of the value from `self` without moving it. This | |
943 | /// leaves the memory in `self` unchanged. | |
944 | /// | |
945 | /// Volatile operations are intended to act on I/O memory, and are guaranteed | |
946 | /// to not be elided or reordered by the compiler across other volatile | |
947 | /// operations. | |
948 | /// | |
949 | /// # Notes | |
950 | /// | |
951 | /// Rust does not currently have a rigorously and formally defined memory model, | |
952 | /// so the precise semantics of what "volatile" means here is subject to change | |
953 | /// over time. That being said, the semantics will almost always end up pretty | |
954 | /// similar to [C11's definition of volatile][c11]. | |
955 | /// | |
956 | /// The compiler shouldn't change the relative order or number of volatile | |
957 | /// memory operations. However, volatile memory operations on zero-sized types | |
958 | /// (e.g. if a zero-sized type is passed to `read_volatile`) are no-ops | |
959 | /// and may be ignored. | |
960 | /// | |
961 | /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf | |
962 | /// | |
963 | /// # Safety | |
964 | /// | |
965 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
966 | /// moves the value out of `self` without preventing further usage of `self`. | |
967 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
968 | /// `self` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 969 | /// `write_bytes`, or `copy`). Note that `*self = foo` counts as a use |
ea8adc8c XL |
970 | /// because it will attempt to drop the value previously at `*self`. |
971 | /// | |
972 | /// # Examples | |
973 | /// | |
974 | /// Basic usage: | |
975 | /// | |
976 | /// ``` | |
977 | /// #![feature(pointer_methods)] | |
978 | /// | |
979 | /// let x = 12; | |
980 | /// let y = &x as *const i32; | |
981 | /// | |
982 | /// unsafe { | |
983 | /// assert_eq!(y.read_volatile(), 12); | |
984 | /// } | |
985 | /// ``` | |
986 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
987 | #[inline] | |
988 | pub unsafe fn read_volatile(self) -> T | |
989 | where T: Sized, | |
990 | { | |
991 | read_volatile(self) | |
992 | } | |
993 | ||
994 | /// Reads the value from `self` without moving it. This leaves the | |
995 | /// memory in `self` unchanged. | |
996 | /// | |
997 | /// Unlike `read`, the pointer may be unaligned. | |
998 | /// | |
999 | /// # Safety | |
1000 | /// | |
1001 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
1002 | /// moves the value out of `self` without preventing further usage of `self`. | |
1003 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
1004 | /// `self` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 1005 | /// `write_bytes`, or `copy`). Note that `*self = foo` counts as a use |
ea8adc8c XL |
1006 | /// because it will attempt to drop the value previously at `*self`. |
1007 | /// | |
1008 | /// # Examples | |
1009 | /// | |
1010 | /// Basic usage: | |
1011 | /// | |
1012 | /// ``` | |
1013 | /// #![feature(pointer_methods)] | |
1014 | /// | |
1015 | /// let x = 12; | |
1016 | /// let y = &x as *const i32; | |
1017 | /// | |
1018 | /// unsafe { | |
1019 | /// assert_eq!(y.read_unaligned(), 12); | |
1020 | /// } | |
1021 | /// ``` | |
1022 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1023 | #[inline] | |
1024 | pub unsafe fn read_unaligned(self) -> T | |
1025 | where T: Sized, | |
1026 | { | |
1027 | read_unaligned(self) | |
1028 | } | |
1029 | ||
1030 | /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source | |
1031 | /// and destination may overlap. | |
1032 | /// | |
1033 | /// NOTE: this has the *same* argument order as `ptr::copy`. | |
1034 | /// | |
1035 | /// This is semantically equivalent to C's `memmove`. | |
1036 | /// | |
1037 | /// # Safety | |
1038 | /// | |
1039 | /// Care must be taken with the ownership of `self` and `dest`. | |
1040 | /// This method semantically moves the values of `self` into `dest`. | |
1041 | /// However it does not drop the contents of `self`, or prevent the contents | |
1042 | /// of `dest` from being dropped or used. | |
1043 | /// | |
1044 | /// # Examples | |
1045 | /// | |
1046 | /// Efficiently create a Rust vector from an unsafe buffer: | |
1047 | /// | |
1048 | /// ``` | |
1049 | /// #![feature(pointer_methods)] | |
1050 | /// | |
1051 | /// # #[allow(dead_code)] | |
1052 | /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> { | |
1053 | /// let mut dst = Vec::with_capacity(elts); | |
1054 | /// dst.set_len(elts); | |
1055 | /// ptr.copy_to(dst.as_mut_ptr(), elts); | |
1056 | /// dst | |
1057 | /// } | |
1058 | /// ``` | |
1059 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1060 | #[inline] | |
1061 | pub unsafe fn copy_to(self, dest: *mut T, count: usize) | |
1062 | where T: Sized, | |
1063 | { | |
1064 | copy(self, dest, count) | |
1065 | } | |
1066 | ||
1067 | /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source | |
1068 | /// and destination may *not* overlap. | |
1069 | /// | |
1070 | /// NOTE: this has the *same* argument order as `ptr::copy_nonoverlapping`. | |
1071 | /// | |
1072 | /// `copy_nonoverlapping` is semantically equivalent to C's `memcpy`. | |
1073 | /// | |
1074 | /// # Safety | |
1075 | /// | |
1076 | /// Beyond requiring that the program must be allowed to access both regions | |
1077 | /// of memory, it is Undefined Behavior for source and destination to | |
1078 | /// overlap. Care must also be taken with the ownership of `self` and | |
1079 | /// `self`. This method semantically moves the values of `self` into `dest`. | |
1080 | /// However it does not drop the contents of `dest`, or prevent the contents | |
1081 | /// of `self` from being dropped or used. | |
1082 | /// | |
1083 | /// # Examples | |
1084 | /// | |
1085 | /// Efficiently create a Rust vector from an unsafe buffer: | |
1086 | /// | |
1087 | /// ``` | |
1088 | /// #![feature(pointer_methods)] | |
1089 | /// | |
1090 | /// # #[allow(dead_code)] | |
1091 | /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> { | |
1092 | /// let mut dst = Vec::with_capacity(elts); | |
1093 | /// dst.set_len(elts); | |
1094 | /// ptr.copy_to_nonoverlapping(dst.as_mut_ptr(), elts); | |
1095 | /// dst | |
1096 | /// } | |
1097 | /// ``` | |
1098 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1099 | #[inline] | |
1100 | pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize) | |
1101 | where T: Sized, | |
1102 | { | |
1103 | copy_nonoverlapping(self, dest, count) | |
1104 | } | |
1105 | ||
1106 | /// Computes the byte offset that needs to be applied in order to | |
1107 | /// make the pointer aligned to `align`. | |
1108 | /// If it is not possible to align the pointer, the implementation returns | |
1109 | /// `usize::max_value()`. | |
1110 | /// | |
1111 | /// There are no guarantees whatsover that offsetting the pointer will not | |
1112 | /// overflow or go beyond the allocation that the pointer points into. | |
1113 | /// It is up to the caller to ensure that the returned offset is correct | |
1114 | /// in all terms other than alignment. | |
1115 | /// | |
1116 | /// # Examples | |
1117 | /// | |
1118 | /// Accessing adjacent `u8` as `u16` | |
1119 | /// | |
1120 | /// ``` | |
1121 | /// # #![feature(align_offset)] | |
1122 | /// # fn foo(n: usize) { | |
1123 | /// # use std::mem::align_of; | |
1124 | /// # unsafe { | |
1125 | /// let x = [5u8, 6u8, 7u8, 8u8, 9u8]; | |
1126 | /// let ptr = &x[n] as *const u8; | |
1127 | /// let offset = ptr.align_offset(align_of::<u16>()); | |
1128 | /// if offset < x.len() - n - 1 { | |
1129 | /// let u16_ptr = ptr.offset(offset as isize) as *const u16; | |
1130 | /// assert_ne!(*u16_ptr, 500); | |
1131 | /// } else { | |
1132 | /// // while the pointer can be aligned via `offset`, it would point | |
1133 | /// // outside the allocation | |
1134 | /// } | |
1135 | /// # } } | |
1136 | /// ``` | |
1137 | #[unstable(feature = "align_offset", issue = "44488")] | |
1138 | pub fn align_offset(self, align: usize) -> usize { | |
1139 | unsafe { | |
1140 | intrinsics::align_offset(self as *const _, align) | |
1141 | } | |
1142 | } | |
1a4d82fc JJ |
1143 | } |
1144 | ||
c34b1796 AL |
1145 | #[lang = "mut_ptr"] |
1146 | impl<T: ?Sized> *mut T { | |
cc61c64b | 1147 | /// Returns `true` if the pointer is null. |
54a0048b | 1148 | /// |
ff7c6d11 XL |
1149 | /// Note that unsized types have many possible null pointers, as only the |
1150 | /// raw data pointer is considered, not their length, vtable, etc. | |
1151 | /// Therefore, two pointers that are null may still not compare equal to | |
1152 | /// each other. | |
1153 | /// | |
54a0048b SL |
1154 | /// # Examples |
1155 | /// | |
1156 | /// Basic usage: | |
1157 | /// | |
1158 | /// ``` | |
1159 | /// let mut s = [1, 2, 3]; | |
1160 | /// let ptr: *mut u32 = s.as_mut_ptr(); | |
1161 | /// assert!(!ptr.is_null()); | |
1162 | /// ``` | |
c34b1796 AL |
1163 | #[stable(feature = "rust1", since = "1.0.0")] |
1164 | #[inline] | |
ff7c6d11 XL |
1165 | pub fn is_null(self) -> bool { |
1166 | // Compare via a cast to a thin pointer, so fat pointers are only | |
1167 | // considering their "data" part for null-ness. | |
1168 | (self as *mut u8) == null_mut() | |
c34b1796 | 1169 | } |
1a4d82fc | 1170 | |
c34b1796 AL |
1171 | /// Returns `None` if the pointer is null, or else returns a reference to |
1172 | /// the value wrapped in `Some`. | |
1a4d82fc JJ |
1173 | /// |
1174 | /// # Safety | |
1175 | /// | |
c34b1796 AL |
1176 | /// While this method and its mutable counterpart are useful for |
1177 | /// null-safety, it is important to note that this is still an unsafe | |
1178 | /// operation because the returned value could be pointing to invalid | |
1179 | /// memory. | |
54a0048b SL |
1180 | /// |
1181 | /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does | |
1182 | /// not necessarily reflect the actual lifetime of the data. | |
1183 | /// | |
1184 | /// # Examples | |
1185 | /// | |
1186 | /// Basic usage: | |
1187 | /// | |
041b39d2 XL |
1188 | /// ``` |
1189 | /// let ptr: *mut u8 = &mut 10u8 as *mut u8; | |
54a0048b SL |
1190 | /// |
1191 | /// unsafe { | |
041b39d2 | 1192 | /// if let Some(val_back) = ptr.as_ref() { |
54a0048b SL |
1193 | /// println!("We got back the value: {}!", val_back); |
1194 | /// } | |
1195 | /// } | |
1196 | /// ``` | |
1197 | #[stable(feature = "ptr_as_ref", since = "1.9.0")] | |
1a4d82fc | 1198 | #[inline] |
abe05a73 | 1199 | pub unsafe fn as_ref<'a>(self) -> Option<&'a T> { |
ff7c6d11 | 1200 | if self.is_null() { |
1a4d82fc JJ |
1201 | None |
1202 | } else { | |
54a0048b | 1203 | Some(&*self) |
1a4d82fc JJ |
1204 | } |
1205 | } | |
1a4d82fc | 1206 | |
ea8adc8c XL |
1207 | /// Calculates the offset from a pointer. |
1208 | /// | |
1209 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
1210 | /// offset of `3 * size_of::<T>()` bytes. | |
c34b1796 AL |
1211 | /// |
1212 | /// # Safety | |
1213 | /// | |
ea8adc8c XL |
1214 | /// If any of the following conditions are violated, the result is Undefined |
1215 | /// Behavior: | |
1216 | /// | |
1217 | /// * Both the starting and resulting pointer must be either in bounds or one | |
1218 | /// byte past the end of an allocated object. | |
1219 | /// | |
ff7c6d11 | 1220 | /// * The computed offset, **in bytes**, cannot overflow an `isize`. |
ea8adc8c XL |
1221 | /// |
1222 | /// * The offset being in bounds cannot rely on "wrapping around" the address | |
1223 | /// space. That is, the infinite-precision sum, **in bytes** must fit in a usize. | |
1224 | /// | |
1225 | /// The compiler and standard library generally tries to ensure allocations | |
1226 | /// never reach a size where an offset is a concern. For instance, `Vec` | |
1227 | /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so | |
1228 | /// `vec.as_ptr().offset(vec.len() as isize)` is always safe. | |
1229 | /// | |
1230 | /// Most platforms fundamentally can't even construct such an allocation. | |
1231 | /// For instance, no known 64-bit platform can ever serve a request | |
abe05a73 | 1232 | /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. |
ea8adc8c XL |
1233 | /// However, some 32-bit and 16-bit platforms may successfully serve a request for |
1234 | /// more than `isize::MAX` bytes with things like Physical Address | |
1235 | /// Extension. As such, memory acquired directly from allocators or memory | |
1236 | /// mapped files *may* be too large to handle with this function. | |
1237 | /// | |
1238 | /// Consider using `wrapping_offset` instead if these constraints are | |
1239 | /// difficult to satisfy. The only advantage of this method is that it | |
1240 | /// enables more aggressive compiler optimizations. | |
54a0048b SL |
1241 | /// |
1242 | /// # Examples | |
1243 | /// | |
1244 | /// Basic usage: | |
1245 | /// | |
1246 | /// ``` | |
1247 | /// let mut s = [1, 2, 3]; | |
1248 | /// let ptr: *mut u32 = s.as_mut_ptr(); | |
1249 | /// | |
1250 | /// unsafe { | |
1251 | /// println!("{}", *ptr.offset(1)); | |
1252 | /// println!("{}", *ptr.offset(2)); | |
1253 | /// } | |
1254 | /// ``` | |
85aaf69f | 1255 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1256 | #[inline] |
c34b1796 | 1257 | pub unsafe fn offset(self, count: isize) -> *mut T where T: Sized { |
85aaf69f | 1258 | intrinsics::offset(self, count) as *mut T |
1a4d82fc JJ |
1259 | } |
1260 | ||
c30ab7b3 SL |
1261 | /// Calculates the offset from a pointer using wrapping arithmetic. |
1262 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
cc61c64b | 1263 | /// offset of `3 * size_of::<T>()` bytes. |
c30ab7b3 SL |
1264 | /// |
1265 | /// # Safety | |
1266 | /// | |
1267 | /// The resulting pointer does not need to be in bounds, but it is | |
1268 | /// potentially hazardous to dereference (which requires `unsafe`). | |
1269 | /// | |
1270 | /// Always use `.offset(count)` instead when possible, because `offset` | |
1271 | /// allows the compiler to optimize better. | |
1272 | /// | |
1273 | /// # Examples | |
1274 | /// | |
1275 | /// Basic usage: | |
1276 | /// | |
1277 | /// ``` | |
c30ab7b3 SL |
1278 | /// // Iterate using a raw pointer in increments of two elements |
1279 | /// let mut data = [1u8, 2, 3, 4, 5]; | |
1280 | /// let mut ptr: *mut u8 = data.as_mut_ptr(); | |
1281 | /// let step = 2; | |
1282 | /// let end_rounded_up = ptr.wrapping_offset(6); | |
1283 | /// | |
1284 | /// while ptr != end_rounded_up { | |
1285 | /// unsafe { | |
1286 | /// *ptr = 0; | |
1287 | /// } | |
1288 | /// ptr = ptr.wrapping_offset(step); | |
1289 | /// } | |
1290 | /// assert_eq!(&data, &[0, 2, 0, 4, 0]); | |
1291 | /// ``` | |
32a655c1 | 1292 | #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")] |
c30ab7b3 SL |
1293 | #[inline] |
1294 | pub fn wrapping_offset(self, count: isize) -> *mut T where T: Sized { | |
1295 | unsafe { | |
1296 | intrinsics::arith_offset(self, count) as *mut T | |
1297 | } | |
1298 | } | |
1299 | ||
c34b1796 AL |
1300 | /// Returns `None` if the pointer is null, or else returns a mutable |
1301 | /// reference to the value wrapped in `Some`. | |
1302 | /// | |
1303 | /// # Safety | |
1304 | /// | |
1305 | /// As with `as_ref`, this is unsafe because it cannot verify the validity | |
54a0048b SL |
1306 | /// of the returned pointer, nor can it ensure that the lifetime `'a` |
1307 | /// returned is indeed a valid lifetime for the contained data. | |
1308 | /// | |
1309 | /// # Examples | |
1310 | /// | |
1311 | /// Basic usage: | |
1312 | /// | |
1313 | /// ``` | |
1314 | /// let mut s = [1, 2, 3]; | |
1315 | /// let ptr: *mut u32 = s.as_mut_ptr(); | |
a7813a04 XL |
1316 | /// let first_value = unsafe { ptr.as_mut().unwrap() }; |
1317 | /// *first_value = 4; | |
1318 | /// println!("{:?}", s); // It'll print: "[4, 2, 3]". | |
54a0048b SL |
1319 | /// ``` |
1320 | #[stable(feature = "ptr_as_ref", since = "1.9.0")] | |
1a4d82fc | 1321 | #[inline] |
abe05a73 | 1322 | pub unsafe fn as_mut<'a>(self) -> Option<&'a mut T> { |
ff7c6d11 | 1323 | if self.is_null() { |
1a4d82fc JJ |
1324 | None |
1325 | } else { | |
54a0048b | 1326 | Some(&mut *self) |
1a4d82fc JJ |
1327 | } |
1328 | } | |
cc61c64b XL |
1329 | |
1330 | /// Calculates the distance between two pointers. The returned value is in | |
1331 | /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`. | |
1332 | /// | |
1333 | /// If the address different between the two pointers ia not a multiple of | |
1334 | /// `mem::size_of::<T>()` then the result of the division is rounded towards | |
1335 | /// zero. | |
1336 | /// | |
1337 | /// This function returns `None` if `T` is a zero-sized typed. | |
1338 | /// | |
1339 | /// # Examples | |
1340 | /// | |
1341 | /// Basic usage: | |
1342 | /// | |
1343 | /// ``` | |
1344 | /// #![feature(offset_to)] | |
1345 | /// | |
1346 | /// fn main() { | |
1347 | /// let mut a = [0; 5]; | |
1348 | /// let ptr1: *mut i32 = &mut a[1]; | |
1349 | /// let ptr2: *mut i32 = &mut a[3]; | |
1350 | /// assert_eq!(ptr1.offset_to(ptr2), Some(2)); | |
1351 | /// assert_eq!(ptr2.offset_to(ptr1), Some(-2)); | |
1352 | /// assert_eq!(unsafe { ptr1.offset(2) }, ptr2); | |
1353 | /// assert_eq!(unsafe { ptr2.offset(-2) }, ptr1); | |
1354 | /// } | |
1355 | /// ``` | |
1356 | #[unstable(feature = "offset_to", issue = "41079")] | |
1357 | #[inline] | |
1358 | pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized { | |
1359 | let size = mem::size_of::<T>(); | |
1360 | if size == 0 { | |
1361 | None | |
1362 | } else { | |
1363 | let diff = (other as isize).wrapping_sub(self as isize); | |
1364 | Some(diff / size as isize) | |
1365 | } | |
1366 | } | |
1a4d82fc | 1367 | |
ea8adc8c XL |
1368 | /// Computes the byte offset that needs to be applied in order to |
1369 | /// make the pointer aligned to `align`. | |
1370 | /// If it is not possible to align the pointer, the implementation returns | |
1371 | /// `usize::max_value()`. | |
1372 | /// | |
1373 | /// There are no guarantees whatsover that offsetting the pointer will not | |
1374 | /// overflow or go beyond the allocation that the pointer points into. | |
1375 | /// It is up to the caller to ensure that the returned offset is correct | |
1376 | /// in all terms other than alignment. | |
1377 | /// | |
1378 | /// # Examples | |
1379 | /// | |
1380 | /// Accessing adjacent `u8` as `u16` | |
1381 | /// | |
1382 | /// ``` | |
1383 | /// # #![feature(align_offset)] | |
1384 | /// # fn foo(n: usize) { | |
1385 | /// # use std::mem::align_of; | |
1386 | /// # unsafe { | |
1387 | /// let x = [5u8, 6u8, 7u8, 8u8, 9u8]; | |
1388 | /// let ptr = &x[n] as *const u8; | |
1389 | /// let offset = ptr.align_offset(align_of::<u16>()); | |
1390 | /// if offset < x.len() - n - 1 { | |
1391 | /// let u16_ptr = ptr.offset(offset as isize) as *const u16; | |
1392 | /// assert_ne!(*u16_ptr, 500); | |
1393 | /// } else { | |
1394 | /// // while the pointer can be aligned via `offset`, it would point | |
1395 | /// // outside the allocation | |
1396 | /// } | |
1397 | /// # } } | |
1398 | /// ``` | |
1399 | #[unstable(feature = "align_offset", issue = "44488")] | |
1400 | pub fn align_offset(self, align: usize) -> usize { | |
1401 | unsafe { | |
1402 | intrinsics::align_offset(self as *const _, align) | |
1403 | } | |
1404 | } | |
1405 | ||
1406 | /// Calculates the offset from a pointer (convenience for `.offset(count as isize)`). | |
1407 | /// | |
1408 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
1409 | /// offset of `3 * size_of::<T>()` bytes. | |
1410 | /// | |
1411 | /// # Safety | |
1412 | /// | |
1413 | /// If any of the following conditions are violated, the result is Undefined | |
1414 | /// Behavior: | |
1415 | /// | |
1416 | /// * Both the starting and resulting pointer must be either in bounds or one | |
1417 | /// byte past the end of an allocated object. | |
1418 | /// | |
ff7c6d11 | 1419 | /// * The computed offset, **in bytes**, cannot overflow an `isize`. |
ea8adc8c XL |
1420 | /// |
1421 | /// * The offset being in bounds cannot rely on "wrapping around" the address | |
1422 | /// space. That is, the infinite-precision sum must fit in a `usize`. | |
1423 | /// | |
1424 | /// The compiler and standard library generally tries to ensure allocations | |
1425 | /// never reach a size where an offset is a concern. For instance, `Vec` | |
1426 | /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so | |
1427 | /// `vec.as_ptr().add(vec.len())` is always safe. | |
1428 | /// | |
1429 | /// Most platforms fundamentally can't even construct such an allocation. | |
1430 | /// For instance, no known 64-bit platform can ever serve a request | |
abe05a73 | 1431 | /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. |
ea8adc8c XL |
1432 | /// However, some 32-bit and 16-bit platforms may successfully serve a request for |
1433 | /// more than `isize::MAX` bytes with things like Physical Address | |
1434 | /// Extension. As such, memory acquired directly from allocators or memory | |
1435 | /// mapped files *may* be too large to handle with this function. | |
1436 | /// | |
1437 | /// Consider using `wrapping_offset` instead if these constraints are | |
1438 | /// difficult to satisfy. The only advantage of this method is that it | |
1439 | /// enables more aggressive compiler optimizations. | |
1440 | /// | |
1441 | /// # Examples | |
1442 | /// | |
1443 | /// Basic usage: | |
1444 | /// | |
1445 | /// ``` | |
1446 | /// #![feature(pointer_methods)] | |
1447 | /// | |
1448 | /// let s: &str = "123"; | |
1449 | /// let ptr: *const u8 = s.as_ptr(); | |
1450 | /// | |
1451 | /// unsafe { | |
1452 | /// println!("{}", *ptr.add(1) as char); | |
1453 | /// println!("{}", *ptr.add(2) as char); | |
1454 | /// } | |
1455 | /// ``` | |
1456 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1457 | #[inline] | |
1458 | pub unsafe fn add(self, count: usize) -> Self | |
1459 | where T: Sized, | |
1460 | { | |
1461 | self.offset(count as isize) | |
1462 | } | |
1463 | ||
1464 | /// Calculates the offset from a pointer (convenience for | |
1465 | /// `.offset((count as isize).wrapping_neg())`). | |
1466 | /// | |
1467 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
1468 | /// offset of `3 * size_of::<T>()` bytes. | |
1469 | /// | |
1470 | /// # Safety | |
1471 | /// | |
1472 | /// If any of the following conditions are violated, the result is Undefined | |
1473 | /// Behavior: | |
1474 | /// | |
1475 | /// * Both the starting and resulting pointer must be either in bounds or one | |
1476 | /// byte past the end of an allocated object. | |
1477 | /// | |
1478 | /// * The computed offset cannot exceed `isize::MAX` **bytes**. | |
1479 | /// | |
1480 | /// * The offset being in bounds cannot rely on "wrapping around" the address | |
1481 | /// space. That is, the infinite-precision sum must fit in a usize. | |
1482 | /// | |
1483 | /// The compiler and standard library generally tries to ensure allocations | |
1484 | /// never reach a size where an offset is a concern. For instance, `Vec` | |
1485 | /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so | |
1486 | /// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe. | |
1487 | /// | |
1488 | /// Most platforms fundamentally can't even construct such an allocation. | |
1489 | /// For instance, no known 64-bit platform can ever serve a request | |
abe05a73 | 1490 | /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. |
ea8adc8c XL |
1491 | /// However, some 32-bit and 16-bit platforms may successfully serve a request for |
1492 | /// more than `isize::MAX` bytes with things like Physical Address | |
1493 | /// Extension. As such, memory acquired directly from allocators or memory | |
1494 | /// mapped files *may* be too large to handle with this function. | |
1495 | /// | |
1496 | /// Consider using `wrapping_offset` instead if these constraints are | |
1497 | /// difficult to satisfy. The only advantage of this method is that it | |
1498 | /// enables more aggressive compiler optimizations. | |
1499 | /// | |
1500 | /// # Examples | |
1501 | /// | |
1502 | /// Basic usage: | |
1503 | /// | |
1504 | /// ``` | |
1505 | /// #![feature(pointer_methods)] | |
1506 | /// | |
1507 | /// let s: &str = "123"; | |
1508 | /// | |
1509 | /// unsafe { | |
1510 | /// let end: *const u8 = s.as_ptr().add(3); | |
1511 | /// println!("{}", *end.sub(1) as char); | |
1512 | /// println!("{}", *end.sub(2) as char); | |
1513 | /// } | |
1514 | /// ``` | |
1515 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1516 | #[inline] | |
1517 | pub unsafe fn sub(self, count: usize) -> Self | |
1518 | where T: Sized, | |
1519 | { | |
1520 | self.offset((count as isize).wrapping_neg()) | |
1521 | } | |
1522 | ||
1523 | /// Calculates the offset from a pointer using wrapping arithmetic. | |
1524 | /// (convenience for `.wrapping_offset(count as isize)`) | |
1525 | /// | |
1526 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
1527 | /// offset of `3 * size_of::<T>()` bytes. | |
1528 | /// | |
1529 | /// # Safety | |
1530 | /// | |
1531 | /// The resulting pointer does not need to be in bounds, but it is | |
1532 | /// potentially hazardous to dereference (which requires `unsafe`). | |
1533 | /// | |
1534 | /// Always use `.add(count)` instead when possible, because `add` | |
1535 | /// allows the compiler to optimize better. | |
1536 | /// | |
1537 | /// # Examples | |
1538 | /// | |
1539 | /// Basic usage: | |
1540 | /// | |
1541 | /// ``` | |
1542 | /// #![feature(pointer_methods)] | |
1543 | /// | |
1544 | /// // Iterate using a raw pointer in increments of two elements | |
1545 | /// let data = [1u8, 2, 3, 4, 5]; | |
1546 | /// let mut ptr: *const u8 = data.as_ptr(); | |
1547 | /// let step = 2; | |
1548 | /// let end_rounded_up = ptr.wrapping_add(6); | |
1549 | /// | |
1550 | /// // This loop prints "1, 3, 5, " | |
1551 | /// while ptr != end_rounded_up { | |
1552 | /// unsafe { | |
1553 | /// print!("{}, ", *ptr); | |
1554 | /// } | |
1555 | /// ptr = ptr.wrapping_add(step); | |
1556 | /// } | |
1557 | /// ``` | |
1558 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1559 | #[inline] | |
1560 | pub fn wrapping_add(self, count: usize) -> Self | |
1561 | where T: Sized, | |
1562 | { | |
1563 | self.wrapping_offset(count as isize) | |
1564 | } | |
1565 | ||
1566 | /// Calculates the offset from a pointer using wrapping arithmetic. | |
1567 | /// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`) | |
1568 | /// | |
1569 | /// `count` is in units of T; e.g. a `count` of 3 represents a pointer | |
1570 | /// offset of `3 * size_of::<T>()` bytes. | |
1571 | /// | |
1572 | /// # Safety | |
1573 | /// | |
1574 | /// The resulting pointer does not need to be in bounds, but it is | |
1575 | /// potentially hazardous to dereference (which requires `unsafe`). | |
1576 | /// | |
1577 | /// Always use `.sub(count)` instead when possible, because `sub` | |
1578 | /// allows the compiler to optimize better. | |
1579 | /// | |
1580 | /// # Examples | |
1581 | /// | |
1582 | /// Basic usage: | |
1583 | /// | |
1584 | /// ``` | |
1585 | /// #![feature(pointer_methods)] | |
1586 | /// | |
1587 | /// // Iterate using a raw pointer in increments of two elements (backwards) | |
1588 | /// let data = [1u8, 2, 3, 4, 5]; | |
1589 | /// let mut ptr: *const u8 = data.as_ptr(); | |
1590 | /// let start_rounded_down = ptr.wrapping_sub(2); | |
1591 | /// ptr = ptr.wrapping_add(4); | |
1592 | /// let step = 2; | |
1593 | /// // This loop prints "5, 3, 1, " | |
1594 | /// while ptr != start_rounded_down { | |
1595 | /// unsafe { | |
1596 | /// print!("{}, ", *ptr); | |
1597 | /// } | |
1598 | /// ptr = ptr.wrapping_sub(step); | |
1599 | /// } | |
1600 | /// ``` | |
1601 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1602 | #[inline] | |
1603 | pub fn wrapping_sub(self, count: usize) -> Self | |
1604 | where T: Sized, | |
1605 | { | |
1606 | self.wrapping_offset((count as isize).wrapping_neg()) | |
1607 | } | |
1608 | ||
1609 | /// Reads the value from `self` without moving it. This leaves the | |
1610 | /// memory in `self` unchanged. | |
1611 | /// | |
1612 | /// # Safety | |
1613 | /// | |
1614 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
1615 | /// moves the value out of `self` without preventing further usage of `self`. | |
1616 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
1617 | /// `self` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 1618 | /// `write_bytes`, or `copy`). Note that `*self = foo` counts as a use |
ea8adc8c XL |
1619 | /// because it will attempt to drop the value previously at `*self`. |
1620 | /// | |
1621 | /// The pointer must be aligned; use `read_unaligned` if that is not the case. | |
1622 | /// | |
1623 | /// # Examples | |
1624 | /// | |
1625 | /// Basic usage: | |
1626 | /// | |
1627 | /// ``` | |
1628 | /// #![feature(pointer_methods)] | |
1629 | /// | |
1630 | /// let x = 12; | |
1631 | /// let y = &x as *const i32; | |
1632 | /// | |
1633 | /// unsafe { | |
1634 | /// assert_eq!(y.read(), 12); | |
1635 | /// } | |
1636 | /// ``` | |
1637 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1638 | #[inline] | |
1639 | pub unsafe fn read(self) -> T | |
1640 | where T: Sized, | |
1641 | { | |
1642 | read(self) | |
1643 | } | |
1644 | ||
1645 | /// Performs a volatile read of the value from `self` without moving it. This | |
1646 | /// leaves the memory in `self` unchanged. | |
1647 | /// | |
1648 | /// Volatile operations are intended to act on I/O memory, and are guaranteed | |
1649 | /// to not be elided or reordered by the compiler across other volatile | |
1650 | /// operations. | |
1651 | /// | |
1652 | /// # Notes | |
1653 | /// | |
1654 | /// Rust does not currently have a rigorously and formally defined memory model, | |
1655 | /// so the precise semantics of what "volatile" means here is subject to change | |
1656 | /// over time. That being said, the semantics will almost always end up pretty | |
1657 | /// similar to [C11's definition of volatile][c11]. | |
1658 | /// | |
1659 | /// The compiler shouldn't change the relative order or number of volatile | |
1660 | /// memory operations. However, volatile memory operations on zero-sized types | |
1661 | /// (e.g. if a zero-sized type is passed to `read_volatile`) are no-ops | |
1662 | /// and may be ignored. | |
1663 | /// | |
1664 | /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf | |
1665 | /// | |
1666 | /// # Safety | |
1667 | /// | |
1668 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
1669 | /// moves the value out of `self` without preventing further usage of `self`. | |
1670 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
1671 | /// `src` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 1672 | /// `write_bytes`, or `copy`). Note that `*self = foo` counts as a use |
ea8adc8c XL |
1673 | /// because it will attempt to drop the value previously at `*self`. |
1674 | /// | |
1675 | /// # Examples | |
1676 | /// | |
1677 | /// Basic usage: | |
1678 | /// | |
1679 | /// ``` | |
1680 | /// #![feature(pointer_methods)] | |
1681 | /// | |
1682 | /// let x = 12; | |
1683 | /// let y = &x as *const i32; | |
1684 | /// | |
1685 | /// unsafe { | |
1686 | /// assert_eq!(y.read_volatile(), 12); | |
1687 | /// } | |
1688 | /// ``` | |
1689 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1690 | #[inline] | |
1691 | pub unsafe fn read_volatile(self) -> T | |
1692 | where T: Sized, | |
1693 | { | |
1694 | read_volatile(self) | |
1695 | } | |
1696 | ||
1697 | /// Reads the value from `self` without moving it. This leaves the | |
1698 | /// memory in `self` unchanged. | |
1699 | /// | |
1700 | /// Unlike `read`, the pointer may be unaligned. | |
1701 | /// | |
1702 | /// # Safety | |
1703 | /// | |
1704 | /// Beyond accepting a raw pointer, this is unsafe because it semantically | |
1705 | /// moves the value out of `self` without preventing further usage of `self`. | |
1706 | /// If `T` is not `Copy`, then care must be taken to ensure that the value at | |
1707 | /// `self` is not used before the data is overwritten again (e.g. with `write`, | |
abe05a73 | 1708 | /// `write_bytes`, or `copy`). Note that `*self = foo` counts as a use |
ea8adc8c XL |
1709 | /// because it will attempt to drop the value previously at `*self`. |
1710 | /// | |
1711 | /// # Examples | |
1712 | /// | |
1713 | /// Basic usage: | |
1714 | /// | |
1715 | /// ``` | |
1716 | /// #![feature(pointer_methods)] | |
1717 | /// | |
1718 | /// let x = 12; | |
1719 | /// let y = &x as *const i32; | |
1720 | /// | |
1721 | /// unsafe { | |
1722 | /// assert_eq!(y.read_unaligned(), 12); | |
1723 | /// } | |
1724 | /// ``` | |
1725 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1726 | #[inline] | |
1727 | pub unsafe fn read_unaligned(self) -> T | |
1728 | where T: Sized, | |
1729 | { | |
1730 | read_unaligned(self) | |
1731 | } | |
1732 | ||
1733 | /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source | |
1734 | /// and destination may overlap. | |
1735 | /// | |
1736 | /// NOTE: this has the *same* argument order as `ptr::copy`. | |
1737 | /// | |
1738 | /// This is semantically equivalent to C's `memmove`. | |
1739 | /// | |
1740 | /// # Safety | |
1741 | /// | |
1742 | /// Care must be taken with the ownership of `self` and `dest`. | |
1743 | /// This method semantically moves the values of `self` into `dest`. | |
1744 | /// However it does not drop the contents of `self`, or prevent the contents | |
1745 | /// of `dest` from being dropped or used. | |
1746 | /// | |
1747 | /// # Examples | |
1748 | /// | |
1749 | /// Efficiently create a Rust vector from an unsafe buffer: | |
1750 | /// | |
1751 | /// ``` | |
1752 | /// #![feature(pointer_methods)] | |
1753 | /// | |
1754 | /// # #[allow(dead_code)] | |
1755 | /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> { | |
1756 | /// let mut dst = Vec::with_capacity(elts); | |
1757 | /// dst.set_len(elts); | |
1758 | /// ptr.copy_to(dst.as_mut_ptr(), elts); | |
1759 | /// dst | |
1760 | /// } | |
1761 | /// ``` | |
1762 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1763 | #[inline] | |
1764 | pub unsafe fn copy_to(self, dest: *mut T, count: usize) | |
1765 | where T: Sized, | |
1766 | { | |
1767 | copy(self, dest, count) | |
1768 | } | |
1769 | ||
1770 | /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source | |
1771 | /// and destination may *not* overlap. | |
1772 | /// | |
1773 | /// NOTE: this has the *same* argument order as `ptr::copy_nonoverlapping`. | |
1774 | /// | |
1775 | /// `copy_nonoverlapping` is semantically equivalent to C's `memcpy`. | |
1776 | /// | |
1777 | /// # Safety | |
1778 | /// | |
1779 | /// Beyond requiring that the program must be allowed to access both regions | |
1780 | /// of memory, it is Undefined Behavior for source and destination to | |
1781 | /// overlap. Care must also be taken with the ownership of `self` and | |
1782 | /// `self`. This method semantically moves the values of `self` into `dest`. | |
1783 | /// However it does not drop the contents of `dest`, or prevent the contents | |
1784 | /// of `self` from being dropped or used. | |
1785 | /// | |
1786 | /// # Examples | |
1787 | /// | |
1788 | /// Efficiently create a Rust vector from an unsafe buffer: | |
1789 | /// | |
1790 | /// ``` | |
1791 | /// #![feature(pointer_methods)] | |
1792 | /// | |
1793 | /// # #[allow(dead_code)] | |
1794 | /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> { | |
1795 | /// let mut dst = Vec::with_capacity(elts); | |
1796 | /// dst.set_len(elts); | |
1797 | /// ptr.copy_to_nonoverlapping(dst.as_mut_ptr(), elts); | |
1798 | /// dst | |
1799 | /// } | |
1800 | /// ``` | |
1801 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1802 | #[inline] | |
1803 | pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize) | |
1804 | where T: Sized, | |
1805 | { | |
1806 | copy_nonoverlapping(self, dest, count) | |
1807 | } | |
1808 | ||
1809 | /// Copies `count * size_of<T>` bytes from `src` to `self`. The source | |
1810 | /// and destination may overlap. | |
1811 | /// | |
1812 | /// NOTE: this has the *opposite* argument order of `ptr::copy`. | |
1813 | /// | |
1814 | /// This is semantically equivalent to C's `memmove`. | |
1815 | /// | |
1816 | /// # Safety | |
1817 | /// | |
1818 | /// Care must be taken with the ownership of `src` and `self`. | |
1819 | /// This method semantically moves the values of `src` into `self`. | |
1820 | /// However it does not drop the contents of `self`, or prevent the contents | |
1821 | /// of `src` from being dropped or used. | |
1822 | /// | |
1823 | /// # Examples | |
1824 | /// | |
1825 | /// Efficiently create a Rust vector from an unsafe buffer: | |
1826 | /// | |
1827 | /// ``` | |
1828 | /// #![feature(pointer_methods)] | |
1829 | /// | |
1830 | /// # #[allow(dead_code)] | |
1831 | /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> { | |
ff7c6d11 | 1832 | /// let mut dst: Vec<T> = Vec::with_capacity(elts); |
ea8adc8c XL |
1833 | /// dst.set_len(elts); |
1834 | /// dst.as_mut_ptr().copy_from(ptr, elts); | |
1835 | /// dst | |
1836 | /// } | |
1837 | /// ``` | |
1838 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1839 | #[inline] | |
1840 | pub unsafe fn copy_from(self, src: *const T, count: usize) | |
1841 | where T: Sized, | |
1842 | { | |
1843 | copy(src, self, count) | |
1844 | } | |
1845 | ||
1846 | /// Copies `count * size_of<T>` bytes from `src` to `self`. The source | |
1847 | /// and destination may *not* overlap. | |
1848 | /// | |
1849 | /// NOTE: this has the *opposite* argument order of `ptr::copy_nonoverlapping`. | |
1850 | /// | |
1851 | /// `copy_nonoverlapping` is semantically equivalent to C's `memcpy`. | |
1852 | /// | |
1853 | /// # Safety | |
1854 | /// | |
1855 | /// Beyond requiring that the program must be allowed to access both regions | |
1856 | /// of memory, it is Undefined Behavior for source and destination to | |
1857 | /// overlap. Care must also be taken with the ownership of `src` and | |
1858 | /// `self`. This method semantically moves the values of `src` into `self`. | |
1859 | /// However it does not drop the contents of `self`, or prevent the contents | |
1860 | /// of `src` from being dropped or used. | |
1861 | /// | |
1862 | /// # Examples | |
1863 | /// | |
1864 | /// Efficiently create a Rust vector from an unsafe buffer: | |
1865 | /// | |
1866 | /// ``` | |
1867 | /// #![feature(pointer_methods)] | |
1868 | /// | |
1869 | /// # #[allow(dead_code)] | |
1870 | /// unsafe fn from_buf_raw<T: Copy>(ptr: *const T, elts: usize) -> Vec<T> { | |
ff7c6d11 | 1871 | /// let mut dst: Vec<T> = Vec::with_capacity(elts); |
ea8adc8c XL |
1872 | /// dst.set_len(elts); |
1873 | /// dst.as_mut_ptr().copy_from_nonoverlapping(ptr, elts); | |
1874 | /// dst | |
1875 | /// } | |
1876 | /// ``` | |
1877 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1878 | #[inline] | |
1879 | pub unsafe fn copy_from_nonoverlapping(self, src: *const T, count: usize) | |
1880 | where T: Sized, | |
1881 | { | |
1882 | copy_nonoverlapping(src, self, count) | |
1883 | } | |
1884 | ||
1885 | /// Executes the destructor (if any) of the pointed-to value. | |
1886 | /// | |
1887 | /// This has two use cases: | |
1888 | /// | |
1889 | /// * It is *required* to use `drop_in_place` to drop unsized types like | |
1890 | /// trait objects, because they can't be read out onto the stack and | |
1891 | /// dropped normally. | |
1892 | /// | |
1893 | /// * It is friendlier to the optimizer to do this over `ptr::read` when | |
1894 | /// dropping manually allocated memory (e.g. when writing Box/Rc/Vec), | |
1895 | /// as the compiler doesn't need to prove that it's sound to elide the | |
1896 | /// copy. | |
1897 | /// | |
1898 | /// # Safety | |
1899 | /// | |
1900 | /// This has all the same safety problems as `ptr::read` with respect to | |
1901 | /// invalid pointers, types, and double drops. | |
1902 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1903 | #[inline] | |
1904 | pub unsafe fn drop_in_place(self) { | |
1905 | drop_in_place(self) | |
1906 | } | |
1907 | ||
1908 | /// Overwrites a memory location with the given value without reading or | |
1909 | /// dropping the old value. | |
1910 | /// | |
1911 | /// # Safety | |
1912 | /// | |
1913 | /// This operation is marked unsafe because it writes through a raw pointer. | |
1914 | /// | |
1915 | /// It does not drop the contents of `self`. This is safe, but it could leak | |
1916 | /// allocations or resources, so care must be taken not to overwrite an object | |
1917 | /// that should be dropped. | |
1918 | /// | |
1919 | /// Additionally, it does not drop `val`. Semantically, `val` is moved into the | |
1920 | /// location pointed to by `self`. | |
1921 | /// | |
1922 | /// This is appropriate for initializing uninitialized memory, or overwriting | |
1923 | /// memory that has previously been `read` from. | |
1924 | /// | |
1925 | /// The pointer must be aligned; use `write_unaligned` if that is not the case. | |
1926 | /// | |
1927 | /// # Examples | |
1928 | /// | |
1929 | /// Basic usage: | |
1930 | /// | |
1931 | /// ``` | |
1932 | /// #![feature(pointer_methods)] | |
1933 | /// | |
1934 | /// let mut x = 0; | |
1935 | /// let y = &mut x as *mut i32; | |
1936 | /// let z = 12; | |
1937 | /// | |
1938 | /// unsafe { | |
1939 | /// y.write(z); | |
1940 | /// assert_eq!(y.read(), 12); | |
1941 | /// } | |
1942 | /// ``` | |
1943 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1944 | #[inline] | |
1945 | pub unsafe fn write(self, val: T) | |
1946 | where T: Sized, | |
1947 | { | |
1948 | write(self, val) | |
1949 | } | |
1950 | ||
1951 | /// Invokes memset on the specified pointer, setting `count * size_of::<T>()` | |
1952 | /// bytes of memory starting at `self` to `val`. | |
1953 | /// | |
1954 | /// # Examples | |
1955 | /// | |
1956 | /// ``` | |
1957 | /// #![feature(pointer_methods)] | |
1958 | /// | |
1959 | /// let mut vec = vec![0; 4]; | |
1960 | /// unsafe { | |
1961 | /// let vec_ptr = vec.as_mut_ptr(); | |
1962 | /// vec_ptr.write_bytes(b'a', 2); | |
1963 | /// } | |
1964 | /// assert_eq!(vec, [b'a', b'a', 0, 0]); | |
1965 | /// ``` | |
1966 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
1967 | #[inline] | |
1968 | pub unsafe fn write_bytes(self, val: u8, count: usize) | |
1969 | where T: Sized, | |
1970 | { | |
1971 | write_bytes(self, val, count) | |
1972 | } | |
1973 | ||
1974 | /// Performs a volatile write of a memory location with the given value without | |
1975 | /// reading or dropping the old value. | |
1976 | /// | |
1977 | /// Volatile operations are intended to act on I/O memory, and are guaranteed | |
1978 | /// to not be elided or reordered by the compiler across other volatile | |
1979 | /// operations. | |
1980 | /// | |
1981 | /// # Notes | |
1982 | /// | |
1983 | /// Rust does not currently have a rigorously and formally defined memory model, | |
1984 | /// so the precise semantics of what "volatile" means here is subject to change | |
1985 | /// over time. That being said, the semantics will almost always end up pretty | |
1986 | /// similar to [C11's definition of volatile][c11]. | |
1987 | /// | |
1988 | /// The compiler shouldn't change the relative order or number of volatile | |
1989 | /// memory operations. However, volatile memory operations on zero-sized types | |
1990 | /// (e.g. if a zero-sized type is passed to `write_volatile`) are no-ops | |
1991 | /// and may be ignored. | |
1992 | /// | |
1993 | /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf | |
1994 | /// | |
1995 | /// # Safety | |
1996 | /// | |
1997 | /// This operation is marked unsafe because it accepts a raw pointer. | |
1998 | /// | |
1999 | /// It does not drop the contents of `self`. This is safe, but it could leak | |
2000 | /// allocations or resources, so care must be taken not to overwrite an object | |
2001 | /// that should be dropped. | |
2002 | /// | |
2003 | /// This is appropriate for initializing uninitialized memory, or overwriting | |
2004 | /// memory that has previously been `read` from. | |
2005 | /// | |
2006 | /// # Examples | |
2007 | /// | |
2008 | /// Basic usage: | |
2009 | /// | |
2010 | /// ``` | |
2011 | /// #![feature(pointer_methods)] | |
2012 | /// | |
2013 | /// let mut x = 0; | |
2014 | /// let y = &mut x as *mut i32; | |
2015 | /// let z = 12; | |
2016 | /// | |
2017 | /// unsafe { | |
2018 | /// y.write_volatile(z); | |
2019 | /// assert_eq!(y.read_volatile(), 12); | |
2020 | /// } | |
2021 | /// ``` | |
2022 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
2023 | #[inline] | |
2024 | pub unsafe fn write_volatile(self, val: T) | |
2025 | where T: Sized, | |
2026 | { | |
2027 | write_volatile(self, val) | |
2028 | } | |
2029 | ||
2030 | /// Overwrites a memory location with the given value without reading or | |
2031 | /// dropping the old value. | |
2032 | /// | |
2033 | /// Unlike `write`, the pointer may be unaligned. | |
2034 | /// | |
2035 | /// # Safety | |
2036 | /// | |
2037 | /// This operation is marked unsafe because it writes through a raw pointer. | |
2038 | /// | |
2039 | /// It does not drop the contents of `self`. This is safe, but it could leak | |
2040 | /// allocations or resources, so care must be taken not to overwrite an object | |
2041 | /// that should be dropped. | |
2042 | /// | |
2043 | /// Additionally, it does not drop `src`. Semantically, `src` is moved into the | |
2044 | /// location pointed to by `dst`. | |
2045 | /// | |
2046 | /// This is appropriate for initializing uninitialized memory, or overwriting | |
2047 | /// memory that has previously been `read` from. | |
2048 | /// | |
2049 | /// # Examples | |
2050 | /// | |
2051 | /// Basic usage: | |
2052 | /// | |
2053 | /// ``` | |
2054 | /// #![feature(pointer_methods)] | |
2055 | /// | |
2056 | /// let mut x = 0; | |
2057 | /// let y = &mut x as *mut i32; | |
2058 | /// let z = 12; | |
2059 | /// | |
2060 | /// unsafe { | |
2061 | /// y.write_unaligned(z); | |
2062 | /// assert_eq!(y.read_unaligned(), 12); | |
2063 | /// } | |
2064 | /// ``` | |
2065 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
2066 | #[inline] | |
2067 | pub unsafe fn write_unaligned(self, val: T) | |
2068 | where T: Sized, | |
2069 | { | |
2070 | write_unaligned(self, val) | |
2071 | } | |
2072 | ||
2073 | /// Replaces the value at `self` with `src`, returning the old | |
2074 | /// value, without dropping either. | |
2075 | /// | |
2076 | /// # Safety | |
2077 | /// | |
2078 | /// This is only unsafe because it accepts a raw pointer. | |
2079 | /// Otherwise, this operation is identical to `mem::replace`. | |
2080 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
2081 | #[inline] | |
2082 | pub unsafe fn replace(self, src: T) -> T | |
2083 | where T: Sized, | |
2084 | { | |
2085 | replace(self, src) | |
2086 | } | |
2087 | ||
2088 | /// Swaps the values at two mutable locations of the same type, without | |
2089 | /// deinitializing either. They may overlap, unlike `mem::swap` which is | |
2090 | /// otherwise equivalent. | |
2091 | /// | |
2092 | /// # Safety | |
2093 | /// | |
2094 | /// This function copies the memory through the raw pointers passed to it | |
2095 | /// as arguments. | |
2096 | /// | |
2097 | /// Ensure that these pointers are valid before calling `swap`. | |
2098 | #[unstable(feature = "pointer_methods", issue = "43941")] | |
2099 | #[inline] | |
2100 | pub unsafe fn swap(self, with: *mut T) | |
2101 | where T: Sized, | |
2102 | { | |
2103 | swap(self, with) | |
2104 | } | |
2105 | } | |
2106 | ||
2107 | // Equality for pointers | |
2108 | #[stable(feature = "rust1", since = "1.0.0")] | |
2109 | impl<T: ?Sized> PartialEq for *const T { | |
2110 | #[inline] | |
2111 | fn eq(&self, other: &*const T) -> bool { *self == *other } | |
2112 | } | |
1a4d82fc | 2113 | |
85aaf69f | 2114 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2115 | impl<T: ?Sized> Eq for *const T {} |
1a4d82fc | 2116 | |
85aaf69f | 2117 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2118 | impl<T: ?Sized> PartialEq for *mut T { |
1a4d82fc | 2119 | #[inline] |
c34b1796 | 2120 | fn eq(&self, other: &*mut T) -> bool { *self == *other } |
1a4d82fc JJ |
2121 | } |
2122 | ||
85aaf69f | 2123 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2124 | impl<T: ?Sized> Eq for *mut T {} |
1a4d82fc | 2125 | |
9e0c209e SL |
2126 | /// Compare raw pointers for equality. |
2127 | /// | |
2128 | /// This is the same as using the `==` operator, but less generic: | |
2129 | /// the arguments have to be `*const T` raw pointers, | |
2130 | /// not anything that implements `PartialEq`. | |
2131 | /// | |
2132 | /// This can be used to compare `&T` references (which coerce to `*const T` implicitly) | |
2133 | /// by their address rather than comparing the values they point to | |
2134 | /// (which is what the `PartialEq for &T` implementation does). | |
2135 | /// | |
2136 | /// # Examples | |
2137 | /// | |
2138 | /// ``` | |
9e0c209e SL |
2139 | /// use std::ptr; |
2140 | /// | |
2141 | /// let five = 5; | |
2142 | /// let other_five = 5; | |
2143 | /// let five_ref = &five; | |
2144 | /// let same_five_ref = &five; | |
2145 | /// let other_five_ref = &other_five; | |
2146 | /// | |
2147 | /// assert!(five_ref == same_five_ref); | |
2148 | /// assert!(five_ref == other_five_ref); | |
2149 | /// | |
2150 | /// assert!(ptr::eq(five_ref, same_five_ref)); | |
2151 | /// assert!(!ptr::eq(five_ref, other_five_ref)); | |
2152 | /// ``` | |
8bb4bdeb | 2153 | #[stable(feature = "ptr_eq", since = "1.17.0")] |
9e0c209e SL |
2154 | #[inline] |
2155 | pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool { | |
2156 | a == b | |
2157 | } | |
2158 | ||
e9174d1e SL |
2159 | // Impls for function pointers |
2160 | macro_rules! fnptr_impls_safety_abi { | |
2161 | ($FnTy: ty, $($Arg: ident),*) => { | |
e9174d1e SL |
2162 | #[stable(feature = "fnptr_impls", since = "1.4.0")] |
2163 | impl<Ret, $($Arg),*> PartialEq for $FnTy { | |
2164 | #[inline] | |
2165 | fn eq(&self, other: &Self) -> bool { | |
2166 | *self as usize == *other as usize | |
2167 | } | |
1a4d82fc | 2168 | } |
e9174d1e SL |
2169 | |
2170 | #[stable(feature = "fnptr_impls", since = "1.4.0")] | |
2171 | impl<Ret, $($Arg),*> Eq for $FnTy {} | |
2172 | ||
2173 | #[stable(feature = "fnptr_impls", since = "1.4.0")] | |
2174 | impl<Ret, $($Arg),*> PartialOrd for $FnTy { | |
2175 | #[inline] | |
2176 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { | |
2177 | (*self as usize).partial_cmp(&(*other as usize)) | |
2178 | } | |
2179 | } | |
2180 | ||
2181 | #[stable(feature = "fnptr_impls", since = "1.4.0")] | |
2182 | impl<Ret, $($Arg),*> Ord for $FnTy { | |
2183 | #[inline] | |
2184 | fn cmp(&self, other: &Self) -> Ordering { | |
2185 | (*self as usize).cmp(&(*other as usize)) | |
2186 | } | |
2187 | } | |
2188 | ||
2189 | #[stable(feature = "fnptr_impls", since = "1.4.0")] | |
2190 | impl<Ret, $($Arg),*> hash::Hash for $FnTy { | |
2191 | fn hash<HH: hash::Hasher>(&self, state: &mut HH) { | |
2192 | state.write_usize(*self as usize) | |
2193 | } | |
2194 | } | |
2195 | ||
2196 | #[stable(feature = "fnptr_impls", since = "1.4.0")] | |
2197 | impl<Ret, $($Arg),*> fmt::Pointer for $FnTy { | |
2198 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2199 | fmt::Pointer::fmt(&(*self as *const ()), f) | |
2200 | } | |
2201 | } | |
2202 | ||
2203 | #[stable(feature = "fnptr_impls", since = "1.4.0")] | |
2204 | impl<Ret, $($Arg),*> fmt::Debug for $FnTy { | |
2205 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2206 | fmt::Pointer::fmt(&(*self as *const ()), f) | |
1a4d82fc JJ |
2207 | } |
2208 | } | |
2209 | } | |
1a4d82fc JJ |
2210 | } |
2211 | ||
e9174d1e | 2212 | macro_rules! fnptr_impls_args { |
5bcae85e | 2213 | ($($Arg: ident),+) => { |
e9174d1e SL |
2214 | fnptr_impls_safety_abi! { extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* } |
2215 | fnptr_impls_safety_abi! { extern "C" fn($($Arg),*) -> Ret, $($Arg),* } | |
5bcae85e | 2216 | fnptr_impls_safety_abi! { extern "C" fn($($Arg),* , ...) -> Ret, $($Arg),* } |
e9174d1e SL |
2217 | fnptr_impls_safety_abi! { unsafe extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* } |
2218 | fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),*) -> Ret, $($Arg),* } | |
5bcae85e SL |
2219 | fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),* , ...) -> Ret, $($Arg),* } |
2220 | }; | |
2221 | () => { | |
2222 | // No variadic functions with 0 parameters | |
2223 | fnptr_impls_safety_abi! { extern "Rust" fn() -> Ret, } | |
2224 | fnptr_impls_safety_abi! { extern "C" fn() -> Ret, } | |
2225 | fnptr_impls_safety_abi! { unsafe extern "Rust" fn() -> Ret, } | |
2226 | fnptr_impls_safety_abi! { unsafe extern "C" fn() -> Ret, } | |
2227 | }; | |
e9174d1e SL |
2228 | } |
2229 | ||
2230 | fnptr_impls_args! { } | |
2231 | fnptr_impls_args! { A } | |
2232 | fnptr_impls_args! { A, B } | |
2233 | fnptr_impls_args! { A, B, C } | |
2234 | fnptr_impls_args! { A, B, C, D } | |
2235 | fnptr_impls_args! { A, B, C, D, E } | |
2236 | fnptr_impls_args! { A, B, C, D, E, F } | |
2237 | fnptr_impls_args! { A, B, C, D, E, F, G } | |
2238 | fnptr_impls_args! { A, B, C, D, E, F, G, H } | |
2239 | fnptr_impls_args! { A, B, C, D, E, F, G, H, I } | |
2240 | fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J } | |
2241 | fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K } | |
2242 | fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K, L } | |
2243 | ||
1a4d82fc | 2244 | // Comparison for pointers |
85aaf69f | 2245 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2246 | impl<T: ?Sized> Ord for *const T { |
1a4d82fc JJ |
2247 | #[inline] |
2248 | fn cmp(&self, other: &*const T) -> Ordering { | |
2249 | if self < other { | |
2250 | Less | |
2251 | } else if self == other { | |
2252 | Equal | |
2253 | } else { | |
2254 | Greater | |
2255 | } | |
2256 | } | |
2257 | } | |
2258 | ||
85aaf69f | 2259 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2260 | impl<T: ?Sized> PartialOrd for *const T { |
1a4d82fc JJ |
2261 | #[inline] |
2262 | fn partial_cmp(&self, other: &*const T) -> Option<Ordering> { | |
2263 | Some(self.cmp(other)) | |
2264 | } | |
2265 | ||
2266 | #[inline] | |
2267 | fn lt(&self, other: &*const T) -> bool { *self < *other } | |
2268 | ||
2269 | #[inline] | |
2270 | fn le(&self, other: &*const T) -> bool { *self <= *other } | |
2271 | ||
2272 | #[inline] | |
2273 | fn gt(&self, other: &*const T) -> bool { *self > *other } | |
2274 | ||
2275 | #[inline] | |
2276 | fn ge(&self, other: &*const T) -> bool { *self >= *other } | |
2277 | } | |
2278 | ||
85aaf69f | 2279 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2280 | impl<T: ?Sized> Ord for *mut T { |
1a4d82fc JJ |
2281 | #[inline] |
2282 | fn cmp(&self, other: &*mut T) -> Ordering { | |
2283 | if self < other { | |
2284 | Less | |
2285 | } else if self == other { | |
2286 | Equal | |
2287 | } else { | |
2288 | Greater | |
2289 | } | |
2290 | } | |
2291 | } | |
2292 | ||
85aaf69f | 2293 | #[stable(feature = "rust1", since = "1.0.0")] |
c34b1796 | 2294 | impl<T: ?Sized> PartialOrd for *mut T { |
1a4d82fc JJ |
2295 | #[inline] |
2296 | fn partial_cmp(&self, other: &*mut T) -> Option<Ordering> { | |
2297 | Some(self.cmp(other)) | |
2298 | } | |
2299 | ||
2300 | #[inline] | |
2301 | fn lt(&self, other: &*mut T) -> bool { *self < *other } | |
2302 | ||
2303 | #[inline] | |
2304 | fn le(&self, other: &*mut T) -> bool { *self <= *other } | |
2305 | ||
2306 | #[inline] | |
2307 | fn gt(&self, other: &*mut T) -> bool { *self > *other } | |
2308 | ||
2309 | #[inline] | |
2310 | fn ge(&self, other: &*mut T) -> bool { *self >= *other } | |
2311 | } | |
2312 | ||
7453a54e | 2313 | /// A wrapper around a raw non-null `*mut T` that indicates that the possessor |
7cac9316 XL |
2314 | /// of this wrapper owns the referent. Useful for building abstractions like |
2315 | /// `Box<T>`, `Vec<T>`, `String`, and `HashMap<K, V>`. | |
2316 | /// | |
2317 | /// Unlike `*mut T`, `Unique<T>` behaves "as if" it were an instance of `T`. | |
2318 | /// It implements `Send`/`Sync` if `T` is `Send`/`Sync`. It also implies | |
2319 | /// the kind of strong aliasing guarantees an instance of `T` can expect: | |
2320 | /// the referent of the pointer should not be modified without a unique path to | |
2321 | /// its owning Unique. | |
2322 | /// | |
2323 | /// If you're uncertain of whether it's correct to use `Unique` for your purposes, | |
2c00a5a8 | 2324 | /// consider using `NonNull`, which has weaker semantics. |
7cac9316 XL |
2325 | /// |
2326 | /// Unlike `*mut T`, the pointer must always be non-null, even if the pointer | |
2327 | /// is never dereferenced. This is so that enums may use this forbidden value | |
2328 | /// as a discriminant -- `Option<Unique<T>>` has the same size as `Unique<T>`. | |
2329 | /// However the pointer may still dangle if it isn't dereferenced. | |
2330 | /// | |
2331 | /// Unlike `*mut T`, `Unique<T>` is covariant over `T`. This should always be correct | |
2332 | /// for any type which upholds Unique's aliasing requirements. | |
2c00a5a8 XL |
2333 | #[unstable(feature = "ptr_internals", issue = "0", |
2334 | reason = "use NonNull instead and consider PhantomData<T> \ | |
2335 | (if you also use #[may_dangle]), Send, and/or Sync")] | |
c34b1796 | 2336 | pub struct Unique<T: ?Sized> { |
85aaf69f | 2337 | pointer: NonZero<*const T>, |
62682a34 SL |
2338 | // NOTE: this marker has no consequences for variance, but is necessary |
2339 | // for dropck to understand that we logically own a `T`. | |
2340 | // | |
2341 | // For details, see: | |
2342 | // https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md#phantom-data | |
85aaf69f SL |
2343 | _marker: PhantomData<T>, |
2344 | } | |
1a4d82fc | 2345 | |
2c00a5a8 XL |
2346 | #[unstable(feature = "ptr_internals", issue = "0")] |
2347 | impl<T: ?Sized> fmt::Debug for Unique<T> { | |
2348 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2349 | fmt::Pointer::fmt(&self.as_ptr(), f) | |
2350 | } | |
2351 | } | |
2352 | ||
1a4d82fc JJ |
2353 | /// `Unique` pointers are `Send` if `T` is `Send` because the data they |
2354 | /// reference is unaliased. Note that this aliasing invariant is | |
2355 | /// unenforced by the type system; the abstraction using the | |
2356 | /// `Unique` must enforce it. | |
2c00a5a8 | 2357 | #[unstable(feature = "ptr_internals", issue = "0")] |
85aaf69f | 2358 | unsafe impl<T: Send + ?Sized> Send for Unique<T> { } |
1a4d82fc JJ |
2359 | |
2360 | /// `Unique` pointers are `Sync` if `T` is `Sync` because the data they | |
2361 | /// reference is unaliased. Note that this aliasing invariant is | |
2362 | /// unenforced by the type system; the abstraction using the | |
2363 | /// `Unique` must enforce it. | |
2c00a5a8 | 2364 | #[unstable(feature = "ptr_internals", issue = "0")] |
85aaf69f SL |
2365 | unsafe impl<T: Sync + ?Sized> Sync for Unique<T> { } |
2366 | ||
2c00a5a8 | 2367 | #[unstable(feature = "ptr_internals", issue = "0")] |
7cac9316 XL |
2368 | impl<T: Sized> Unique<T> { |
2369 | /// Creates a new `Unique` that is dangling, but well-aligned. | |
2370 | /// | |
2371 | /// This is useful for initializing types which lazily allocate, like | |
2372 | /// `Vec::new` does. | |
2c00a5a8 | 2373 | // FIXME: rename to dangling() to match NonNull? |
7cac9316 XL |
2374 | pub fn empty() -> Self { |
2375 | unsafe { | |
2376 | let ptr = mem::align_of::<T>() as *mut T; | |
3b2f2976 | 2377 | Unique::new_unchecked(ptr) |
7cac9316 XL |
2378 | } |
2379 | } | |
2380 | } | |
2381 | ||
2c00a5a8 | 2382 | #[unstable(feature = "ptr_internals", issue = "0")] |
c34b1796 | 2383 | impl<T: ?Sized> Unique<T> { |
9cc50fc6 | 2384 | /// Creates a new `Unique`. |
7453a54e SL |
2385 | /// |
2386 | /// # Safety | |
2387 | /// | |
2388 | /// `ptr` must be non-null. | |
3b2f2976 XL |
2389 | pub const unsafe fn new_unchecked(ptr: *mut T) -> Self { |
2390 | Unique { pointer: NonZero::new_unchecked(ptr), _marker: PhantomData } | |
2391 | } | |
2392 | ||
2393 | /// Creates a new `Unique` if `ptr` is non-null. | |
2394 | pub fn new(ptr: *mut T) -> Option<Self> { | |
2395 | NonZero::new(ptr as *const T).map(|nz| Unique { pointer: nz, _marker: PhantomData }) | |
9cc50fc6 | 2396 | } |
85aaf69f | 2397 | |
7cac9316 XL |
2398 | /// Acquires the underlying `*mut` pointer. |
2399 | pub fn as_ptr(self) -> *mut T { | |
2400 | self.pointer.get() as *mut T | |
2401 | } | |
2402 | ||
9346a6ac | 2403 | /// Dereferences the content. |
7cac9316 XL |
2404 | /// |
2405 | /// The resulting lifetime is bound to self so this behaves "as if" | |
2406 | /// it were actually an instance of T that is getting borrowed. If a longer | |
2c00a5a8 | 2407 | /// (unbound) lifetime is needed, use `&*my_ptr.as_ptr()`. |
7cac9316 XL |
2408 | pub unsafe fn as_ref(&self) -> &T { |
2409 | &*self.as_ptr() | |
85aaf69f SL |
2410 | } |
2411 | ||
9346a6ac | 2412 | /// Mutably dereferences the content. |
7cac9316 XL |
2413 | /// |
2414 | /// The resulting lifetime is bound to self so this behaves "as if" | |
2415 | /// it were actually an instance of T that is getting borrowed. If a longer | |
2c00a5a8 | 2416 | /// (unbound) lifetime is needed, use `&mut *my_ptr.as_ptr()`. |
7cac9316 XL |
2417 | pub unsafe fn as_mut(&mut self) -> &mut T { |
2418 | &mut *self.as_ptr() | |
1a4d82fc | 2419 | } |
85aaf69f | 2420 | } |
1a4d82fc | 2421 | |
2c00a5a8 | 2422 | #[unstable(feature = "ptr_internals", issue = "0")] |
7cac9316 XL |
2423 | impl<T: ?Sized> Clone for Unique<T> { |
2424 | fn clone(&self) -> Self { | |
2425 | *self | |
1a4d82fc JJ |
2426 | } |
2427 | } | |
9346a6ac | 2428 | |
2c00a5a8 | 2429 | #[unstable(feature = "ptr_internals", issue = "0")] |
7cac9316 XL |
2430 | impl<T: ?Sized> Copy for Unique<T> { } |
2431 | ||
2c00a5a8 | 2432 | #[unstable(feature = "ptr_internals", issue = "0")] |
7cac9316 XL |
2433 | impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where T: Unsize<U> { } |
2434 | ||
2c00a5a8 | 2435 | #[unstable(feature = "ptr_internals", issue = "0")] |
7cac9316 | 2436 | impl<T: ?Sized> fmt::Pointer for Unique<T> { |
9346a6ac | 2437 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
7cac9316 | 2438 | fmt::Pointer::fmt(&self.as_ptr(), f) |
9346a6ac AL |
2439 | } |
2440 | } | |
b039eaaf | 2441 | |
2c00a5a8 | 2442 | #[unstable(feature = "ptr_internals", issue = "0")] |
3b2f2976 XL |
2443 | impl<'a, T: ?Sized> From<&'a mut T> for Unique<T> { |
2444 | fn from(reference: &'a mut T) -> Self { | |
2445 | Unique { pointer: NonZero::from(reference), _marker: PhantomData } | |
2446 | } | |
2447 | } | |
2448 | ||
2c00a5a8 | 2449 | #[unstable(feature = "ptr_internals", issue = "0")] |
3b2f2976 XL |
2450 | impl<'a, T: ?Sized> From<&'a T> for Unique<T> { |
2451 | fn from(reference: &'a T) -> Self { | |
2452 | Unique { pointer: NonZero::from(reference), _marker: PhantomData } | |
2453 | } | |
2454 | } | |
2455 | ||
2c00a5a8 XL |
2456 | #[unstable(feature = "ptr_internals", issue = "0")] |
2457 | impl<'a, T: ?Sized> From<NonNull<T>> for Unique<T> { | |
2458 | fn from(p: NonNull<T>) -> Self { | |
2459 | Unique { pointer: p.pointer, _marker: PhantomData } | |
2460 | } | |
2461 | } | |
2462 | ||
2463 | /// Previous name of `NonNull`. | |
2464 | #[rustc_deprecated(since = "1.25.0", reason = "renamed to `NonNull`")] | |
2465 | #[unstable(feature = "shared", issue = "27730")] | |
2466 | pub type Shared<T> = NonNull<T>; | |
2467 | ||
ff7c6d11 | 2468 | /// `*mut T` but non-zero and covariant. |
7cac9316 | 2469 | /// |
ff7c6d11 XL |
2470 | /// This is often the correct thing to use when building data structures using |
2471 | /// raw pointers, but is ultimately more dangerous to use because of its additional | |
2c00a5a8 | 2472 | /// properties. If you're not sure if you should use `NonNull<T>`, just use `*mut T`! |
7cac9316 XL |
2473 | /// |
2474 | /// Unlike `*mut T`, the pointer must always be non-null, even if the pointer | |
2475 | /// is never dereferenced. This is so that enums may use this forbidden value | |
2c00a5a8 | 2476 | /// as a discriminant -- `Option<NonNull<T>>` has the same size as `NonNull<T>`. |
7cac9316 XL |
2477 | /// However the pointer may still dangle if it isn't dereferenced. |
2478 | /// | |
2c00a5a8 | 2479 | /// Unlike `*mut T`, `NonNull<T>` is covariant over `T`. If this is incorrect |
7cac9316 XL |
2480 | /// for your use case, you should include some PhantomData in your type to |
2481 | /// provide invariance, such as `PhantomData<Cell<T>>` or `PhantomData<&'a mut T>`. | |
ff7c6d11 XL |
2482 | /// Usually this won't be necessary; covariance is correct for most safe abstractions, |
2483 | /// such as Box, Rc, Arc, Vec, and LinkedList. This is the case because they | |
2484 | /// provide a public API that follows the normal shared XOR mutable rules of Rust. | |
2c00a5a8 XL |
2485 | #[stable(feature = "nonnull", since = "1.25.0")] |
2486 | pub struct NonNull<T: ?Sized> { | |
b039eaaf | 2487 | pointer: NonZero<*const T>, |
b039eaaf SL |
2488 | } |
2489 | ||
2c00a5a8 | 2490 | /// `NonNull` pointers are not `Send` because the data they reference may be aliased. |
b039eaaf | 2491 | // NB: This impl is unnecessary, but should provide better error messages. |
2c00a5a8 XL |
2492 | #[stable(feature = "nonnull", since = "1.25.0")] |
2493 | impl<T: ?Sized> !Send for NonNull<T> { } | |
b039eaaf | 2494 | |
2c00a5a8 | 2495 | /// `NonNull` pointers are not `Sync` because the data they reference may be aliased. |
b039eaaf | 2496 | // NB: This impl is unnecessary, but should provide better error messages. |
2c00a5a8 XL |
2497 | #[stable(feature = "nonnull", since = "1.25.0")] |
2498 | impl<T: ?Sized> !Sync for NonNull<T> { } | |
b039eaaf | 2499 | |
2c00a5a8 XL |
2500 | impl<T: Sized> NonNull<T> { |
2501 | /// Creates a new `NonNull` that is dangling, but well-aligned. | |
7cac9316 XL |
2502 | /// |
2503 | /// This is useful for initializing types which lazily allocate, like | |
2504 | /// `Vec::new` does. | |
2c00a5a8 XL |
2505 | #[stable(feature = "nonnull", since = "1.25.0")] |
2506 | pub fn dangling() -> Self { | |
7cac9316 XL |
2507 | unsafe { |
2508 | let ptr = mem::align_of::<T>() as *mut T; | |
2c00a5a8 | 2509 | NonNull::new_unchecked(ptr) |
7cac9316 XL |
2510 | } |
2511 | } | |
2512 | } | |
2513 | ||
2c00a5a8 XL |
2514 | impl<T: ?Sized> NonNull<T> { |
2515 | /// Creates a new `NonNull`. | |
7453a54e SL |
2516 | /// |
2517 | /// # Safety | |
2518 | /// | |
2519 | /// `ptr` must be non-null. | |
2c00a5a8 | 2520 | #[stable(feature = "nonnull", since = "1.25.0")] |
3b2f2976 | 2521 | pub const unsafe fn new_unchecked(ptr: *mut T) -> Self { |
2c00a5a8 | 2522 | NonNull { pointer: NonZero::new_unchecked(ptr) } |
3b2f2976 XL |
2523 | } |
2524 | ||
2c00a5a8 XL |
2525 | /// Creates a new `NonNull` if `ptr` is non-null. |
2526 | #[stable(feature = "nonnull", since = "1.25.0")] | |
3b2f2976 | 2527 | pub fn new(ptr: *mut T) -> Option<Self> { |
2c00a5a8 | 2528 | NonZero::new(ptr as *const T).map(|nz| NonNull { pointer: nz }) |
b039eaaf | 2529 | } |
b039eaaf | 2530 | |
7cac9316 | 2531 | /// Acquires the underlying `*mut` pointer. |
2c00a5a8 | 2532 | #[stable(feature = "nonnull", since = "1.25.0")] |
7cac9316 XL |
2533 | pub fn as_ptr(self) -> *mut T { |
2534 | self.pointer.get() as *mut T | |
2535 | } | |
2536 | ||
2537 | /// Dereferences the content. | |
2538 | /// | |
2539 | /// The resulting lifetime is bound to self so this behaves "as if" | |
2540 | /// it were actually an instance of T that is getting borrowed. If a longer | |
2c00a5a8 XL |
2541 | /// (unbound) lifetime is needed, use `&*my_ptr.as_ptr()`. |
2542 | #[stable(feature = "nonnull", since = "1.25.0")] | |
7cac9316 XL |
2543 | pub unsafe fn as_ref(&self) -> &T { |
2544 | &*self.as_ptr() | |
2545 | } | |
2546 | ||
2547 | /// Mutably dereferences the content. | |
2548 | /// | |
2549 | /// The resulting lifetime is bound to self so this behaves "as if" | |
2550 | /// it were actually an instance of T that is getting borrowed. If a longer | |
2c00a5a8 XL |
2551 | /// (unbound) lifetime is needed, use `&mut *my_ptr.as_ptr()`. |
2552 | #[stable(feature = "nonnull", since = "1.25.0")] | |
7cac9316 XL |
2553 | pub unsafe fn as_mut(&mut self) -> &mut T { |
2554 | &mut *self.as_ptr() | |
2555 | } | |
2556 | ||
2c00a5a8 XL |
2557 | /// Cast to a pointer of another type |
2558 | #[unstable(feature = "nonnull_cast", issue = "47653")] | |
2559 | pub fn cast<U>(self) -> NonNull<U> { | |
2560 | unsafe { | |
2561 | NonNull::new_unchecked(self.as_ptr() as *mut U) | |
2562 | } | |
8bb4bdeb XL |
2563 | } |
2564 | } | |
2565 | ||
2c00a5a8 XL |
2566 | #[stable(feature = "nonnull", since = "1.25.0")] |
2567 | impl<T: ?Sized> Clone for NonNull<T> { | |
b039eaaf SL |
2568 | fn clone(&self) -> Self { |
2569 | *self | |
2570 | } | |
2571 | } | |
2572 | ||
2c00a5a8 XL |
2573 | #[stable(feature = "nonnull", since = "1.25.0")] |
2574 | impl<T: ?Sized> Copy for NonNull<T> { } | |
b039eaaf | 2575 | |
2c00a5a8 XL |
2576 | #[stable(feature = "nonnull", since = "1.25.0")] |
2577 | impl<T: ?Sized, U: ?Sized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> { } | |
b039eaaf | 2578 | |
2c00a5a8 XL |
2579 | #[stable(feature = "nonnull", since = "1.25.0")] |
2580 | impl<T: ?Sized> fmt::Debug for NonNull<T> { | |
b039eaaf | 2581 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
7cac9316 | 2582 | fmt::Pointer::fmt(&self.as_ptr(), f) |
b039eaaf SL |
2583 | } |
2584 | } | |
3b2f2976 | 2585 | |
2c00a5a8 XL |
2586 | #[stable(feature = "nonnull", since = "1.25.0")] |
2587 | impl<T: ?Sized> fmt::Pointer for NonNull<T> { | |
2588 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2589 | fmt::Pointer::fmt(&self.as_ptr(), f) | |
2590 | } | |
2591 | } | |
2592 | ||
2593 | #[stable(feature = "nonnull", since = "1.25.0")] | |
2594 | impl<T: ?Sized> Eq for NonNull<T> {} | |
2595 | ||
2596 | #[stable(feature = "nonnull", since = "1.25.0")] | |
2597 | impl<T: ?Sized> PartialEq for NonNull<T> { | |
2598 | fn eq(&self, other: &Self) -> bool { | |
2599 | self.as_ptr() == other.as_ptr() | |
2600 | } | |
2601 | } | |
2602 | ||
2603 | #[stable(feature = "nonnull", since = "1.25.0")] | |
2604 | impl<T: ?Sized> Ord for NonNull<T> { | |
2605 | fn cmp(&self, other: &Self) -> Ordering { | |
2606 | self.as_ptr().cmp(&other.as_ptr()) | |
2607 | } | |
2608 | } | |
2609 | ||
2610 | #[stable(feature = "nonnull", since = "1.25.0")] | |
2611 | impl<T: ?Sized> PartialOrd for NonNull<T> { | |
2612 | fn partial_cmp(&self, other: &Self) -> Option<Ordering> { | |
2613 | self.as_ptr().partial_cmp(&other.as_ptr()) | |
2614 | } | |
2615 | } | |
2616 | ||
2617 | #[stable(feature = "nonnull", since = "1.25.0")] | |
2618 | impl<T: ?Sized> hash::Hash for NonNull<T> { | |
2619 | fn hash<H: hash::Hasher>(&self, state: &mut H) { | |
2620 | self.as_ptr().hash(state) | |
2621 | } | |
2622 | } | |
2623 | ||
2624 | #[stable(feature = "nonnull", since = "1.25.0")] | |
2625 | impl<T: ?Sized> From<Unique<T>> for NonNull<T> { | |
3b2f2976 | 2626 | fn from(unique: Unique<T>) -> Self { |
2c00a5a8 | 2627 | NonNull { pointer: unique.pointer } |
3b2f2976 XL |
2628 | } |
2629 | } | |
2630 | ||
2c00a5a8 XL |
2631 | #[stable(feature = "nonnull", since = "1.25.0")] |
2632 | impl<'a, T: ?Sized> From<&'a mut T> for NonNull<T> { | |
3b2f2976 | 2633 | fn from(reference: &'a mut T) -> Self { |
2c00a5a8 | 2634 | NonNull { pointer: NonZero::from(reference) } |
3b2f2976 XL |
2635 | } |
2636 | } | |
2637 | ||
2c00a5a8 XL |
2638 | #[stable(feature = "nonnull", since = "1.25.0")] |
2639 | impl<'a, T: ?Sized> From<&'a T> for NonNull<T> { | |
3b2f2976 | 2640 | fn from(reference: &'a T) -> Self { |
2c00a5a8 | 2641 | NonNull { pointer: NonZero::from(reference) } |
3b2f2976 XL |
2642 | } |
2643 | } |