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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. // FIXME: talk about offset, copy_memory, copy_nonoverlapping_memory //! Raw, unsafe pointers, `*const T`, and `*mut T`. //! //! *[See also the pointer primitive types](../../std/primitive.pointer.html).* #![stable(feature = "rust1", since = "1.0.0")] use intrinsics; use ops::CoerceUnsized; use fmt; use hash; use marker::{PhantomData, Unsize}; use mem; use nonzero::NonZero; use cmp::Ordering::{self, Less, Equal, Greater}; // FIXME #19649: intrinsic docs don't render, so these have no docs :( #[stable(feature = "rust1", since = "1.0.0")] pub use intrinsics::copy_nonoverlapping; #[stable(feature = "rust1", since = "1.0.0")] pub use intrinsics::copy; #[stable(feature = "rust1", since = "1.0.0")] pub use intrinsics::write_bytes; /// Executes the destructor (if any) of the pointed-to value. /// /// This has two use cases: /// /// * It is *required* to use `drop_in_place` to drop unsized types like /// trait objects, because they can't be read out onto the stack and /// dropped normally. /// /// * It is friendlier to the optimizer to do this over `ptr::read` when /// dropping manually allocated memory (e.g. when writing Box/Rc/Vec), /// as the compiler doesn't need to prove that it's sound to elide the /// copy. /// /// # Undefined Behavior /// /// This has all the same safety problems as `ptr::read` with respect to /// invalid pointers, types, and double drops. #[stable(feature = "drop_in_place", since = "1.8.0")] #[lang="drop_in_place"] #[allow(unconditional_recursion)] pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) { // Code here does not matter - this is replaced by the // real drop glue by the compiler. drop_in_place(to_drop); } /// Creates a null raw pointer. /// /// # Examples /// /// ``` /// use std::ptr; /// /// let p: *const i32 = ptr::null(); /// assert!(p.is_null()); /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub const fn null<T>() -> *const T { 0 as *const T } /// Creates a null mutable raw pointer. /// /// # Examples /// /// ``` /// use std::ptr; /// /// let p: *mut i32 = ptr::null_mut(); /// assert!(p.is_null()); /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub const fn null_mut<T>() -> *mut T { 0 as *mut T } /// Swaps the values at two mutable locations of the same type, without /// deinitializing either. They may overlap, unlike `mem::swap` which is /// otherwise equivalent. /// /// # Safety /// /// This function copies the memory through the raw pointers passed to it /// as arguments. /// /// Ensure that these pointers are valid before calling `swap`. #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn swap<T>(x: *mut T, y: *mut T) { // Give ourselves some scratch space to work with let mut tmp: T = mem::uninitialized(); // Perform the swap copy_nonoverlapping(x, &mut tmp, 1); copy(y, x, 1); // `x` and `y` may overlap copy_nonoverlapping(&tmp, y, 1); // y and t now point to the same thing, but we need to completely forget `tmp` // because it's no longer relevant. mem::forget(tmp); } /// Replaces the value at `dest` with `src`, returning the old /// value, without dropping either. /// /// # Safety /// /// This is only unsafe because it accepts a raw pointer. /// Otherwise, this operation is identical to `mem::replace`. #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn replace<T>(dest: *mut T, mut src: T) -> T { mem::swap(&mut *dest, &mut src); // cannot overlap src } /// Reads the value from `src` without moving it. This leaves the /// memory in `src` unchanged. /// /// # Safety /// /// Beyond accepting a raw pointer, this is unsafe because it semantically /// moves the value out of `src` without preventing further usage of `src`. /// If `T` is not `Copy`, then care must be taken to ensure that the value at /// `src` is not used before the data is overwritten again (e.g. with `write`, /// `zero_memory`, or `copy_memory`). Note that `*src = foo` counts as a use /// because it will attempt to drop the value previously at `*src`. /// /// The pointer must be aligned; use `read_unaligned` if that is not the case. /// /// # Examples /// /// Basic usage: /// /// ``` /// let x = 12; /// let y = &x as *const i32; /// /// unsafe { /// assert_eq!(std::ptr::read(y), 12); /// } /// ``` #[inline(always)] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn read<T>(src: *const T) -> T { let mut tmp: T = mem::uninitialized(); copy_nonoverlapping(src, &mut tmp, 1); tmp } /// Reads the value from `src` without moving it. This leaves the /// memory in `src` unchanged. /// /// Unlike `read`, the pointer may be unaligned. /// /// # Safety /// /// Beyond accepting a raw pointer, this is unsafe because it semantically /// moves the value out of `src` without preventing further usage of `src`. /// If `T` is not `Copy`, then care must be taken to ensure that the value at /// `src` is not used before the data is overwritten again (e.g. with `write`, /// `zero_memory`, or `copy_memory`). Note that `*src = foo` counts as a use /// because it will attempt to drop the value previously at `*src`. /// /// # Examples /// /// Basic usage: /// /// ``` /// let x = 12; /// let y = &x as *const i32; /// /// unsafe { /// assert_eq!(std::ptr::read_unaligned(y), 12); /// } /// ``` #[inline(always)] #[stable(feature = "ptr_unaligned", since = "1.17.0")] pub unsafe fn read_unaligned<T>(src: *const T) -> T { let mut tmp: T = mem::uninitialized(); copy_nonoverlapping(src as *const u8, &mut tmp as *mut T as *mut u8, mem::size_of::<T>()); tmp } /// Overwrites a memory location with the given value without reading or /// dropping the old value. /// /// # Safety /// /// This operation is marked unsafe because it accepts a raw pointer. /// /// It does not drop the contents of `dst`. This is safe, but it could leak /// allocations or resources, so care must be taken not to overwrite an object /// that should be dropped. /// /// Additionally, it does not drop `src`. Semantically, `src` is moved into the /// location pointed to by `dst`. /// /// This is appropriate for initializing uninitialized memory, or overwriting /// memory that has previously been `read` from. /// /// The pointer must be aligned; use `write_unaligned` if that is not the case. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut x = 0; /// let y = &mut x as *mut i32; /// let z = 12; /// /// unsafe { /// std::ptr::write(y, z); /// assert_eq!(std::ptr::read(y), 12); /// } /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn write<T>(dst: *mut T, src: T) { intrinsics::move_val_init(&mut *dst, src) } /// Overwrites a memory location with the given value without reading or /// dropping the old value. /// /// Unlike `write`, the pointer may be unaligned. /// /// # Safety /// /// This operation is marked unsafe because it accepts a raw pointer. /// /// It does not drop the contents of `dst`. This is safe, but it could leak /// allocations or resources, so care must be taken not to overwrite an object /// that should be dropped. /// /// Additionally, it does not drop `src`. Semantically, `src` is moved into the /// location pointed to by `dst`. /// /// This is appropriate for initializing uninitialized memory, or overwriting /// memory that has previously been `read` from. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut x = 0; /// let y = &mut x as *mut i32; /// let z = 12; /// /// unsafe { /// std::ptr::write_unaligned(y, z); /// assert_eq!(std::ptr::read_unaligned(y), 12); /// } /// ``` #[inline] #[stable(feature = "ptr_unaligned", since = "1.17.0")] pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) { copy_nonoverlapping(&src as *const T as *const u8, dst as *mut u8, mem::size_of::<T>()); mem::forget(src); } /// Performs a volatile read of the value from `src` without moving it. This /// leaves the memory in `src` unchanged. /// /// Volatile operations are intended to act on I/O memory, and are guaranteed /// to not be elided or reordered by the compiler across other volatile /// operations. /// /// # Notes /// /// Rust does not currently have a rigorously and formally defined memory model, /// so the precise semantics of what "volatile" means here is subject to change /// over time. That being said, the semantics will almost always end up pretty /// similar to [C11's definition of volatile][c11]. /// /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf /// /// # Safety /// /// Beyond accepting a raw pointer, this is unsafe because it semantically /// moves the value out of `src` without preventing further usage of `src`. /// If `T` is not `Copy`, then care must be taken to ensure that the value at /// `src` is not used before the data is overwritten again (e.g. with `write`, /// `zero_memory`, or `copy_memory`). Note that `*src = foo` counts as a use /// because it will attempt to drop the value previously at `*src`. /// /// # Examples /// /// Basic usage: /// /// ``` /// let x = 12; /// let y = &x as *const i32; /// /// unsafe { /// assert_eq!(std::ptr::read_volatile(y), 12); /// } /// ``` #[inline] #[stable(feature = "volatile", since = "1.9.0")] pub unsafe fn read_volatile<T>(src: *const T) -> T { intrinsics::volatile_load(src) } /// Performs a volatile write of a memory location with the given value without /// reading or dropping the old value. /// /// Volatile operations are intended to act on I/O memory, and are guaranteed /// to not be elided or reordered by the compiler across other volatile /// operations. /// /// # Notes /// /// Rust does not currently have a rigorously and formally defined memory model, /// so the precise semantics of what "volatile" means here is subject to change /// over time. That being said, the semantics will almost always end up pretty /// similar to [C11's definition of volatile][c11]. /// /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf /// /// # Safety /// /// This operation is marked unsafe because it accepts a raw pointer. /// /// It does not drop the contents of `dst`. This is safe, but it could leak /// allocations or resources, so care must be taken not to overwrite an object /// that should be dropped. /// /// This is appropriate for initializing uninitialized memory, or overwriting /// memory that has previously been `read` from. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut x = 0; /// let y = &mut x as *mut i32; /// let z = 12; /// /// unsafe { /// std::ptr::write_volatile(y, z); /// assert_eq!(std::ptr::read_volatile(y), 12); /// } /// ``` #[inline] #[stable(feature = "volatile", since = "1.9.0")] pub unsafe fn write_volatile<T>(dst: *mut T, src: T) { intrinsics::volatile_store(dst, src); } #[lang = "const_ptr"] impl<T: ?Sized> *const T { /// Returns `true` if the pointer is null. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s: &str = "Follow the rabbit"; /// let ptr: *const u8 = s.as_ptr(); /// assert!(!ptr.is_null()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_null(self) -> bool where T: Sized { self == null() } /// Returns `None` if the pointer is null, or else returns a reference to /// the value wrapped in `Some`. /// /// # Safety /// /// While this method and its mutable counterpart are useful for /// null-safety, it is important to note that this is still an unsafe /// operation because the returned value could be pointing to invalid /// memory. /// /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does /// not necessarily reflect the actual lifetime of the data. /// /// # Examples /// /// Basic usage: /// /// ```ignore /// let val: *const u8 = &10u8 as *const u8; /// /// unsafe { /// if let Some(val_back) = val.as_ref() { /// println!("We got back the value: {}!", val_back); /// } /// } /// ``` #[stable(feature = "ptr_as_ref", since = "1.9.0")] #[inline] pub unsafe fn as_ref<'a>(self) -> Option<&'a T> where T: Sized { if self.is_null() { None } else { Some(&*self) } } /// Calculates the offset from a pointer. `count` is in units of T; e.g. a /// `count` of 3 represents a pointer offset of `3 * size_of::<T>()` bytes. /// /// # Safety /// /// Both the starting and resulting pointer must be either in bounds or one /// byte past the end of an allocated object. If either pointer is out of /// bounds or arithmetic overflow occurs then /// any further use of the returned value will result in undefined behavior. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s: &str = "123"; /// let ptr: *const u8 = s.as_ptr(); /// /// unsafe { /// println!("{}", *ptr.offset(1) as char); /// println!("{}", *ptr.offset(2) as char); /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub unsafe fn offset(self, count: isize) -> *const T where T: Sized { intrinsics::offset(self, count) } /// Calculates the offset from a pointer using wrapping arithmetic. /// `count` is in units of T; e.g. a `count` of 3 represents a pointer /// offset of `3 * size_of::<T>()` bytes. /// /// # Safety /// /// The resulting pointer does not need to be in bounds, but it is /// potentially hazardous to dereference (which requires `unsafe`). /// /// Always use `.offset(count)` instead when possible, because `offset` /// allows the compiler to optimize better. /// /// # Examples /// /// Basic usage: /// /// ``` /// // Iterate using a raw pointer in increments of two elements /// let data = [1u8, 2, 3, 4, 5]; /// let mut ptr: *const u8 = data.as_ptr(); /// let step = 2; /// let end_rounded_up = ptr.wrapping_offset(6); /// /// // This loop prints "1, 3, 5, " /// while ptr != end_rounded_up { /// unsafe { /// print!("{}, ", *ptr); /// } /// ptr = ptr.wrapping_offset(step); /// } /// ``` #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")] #[inline] pub fn wrapping_offset(self, count: isize) -> *const T where T: Sized { unsafe { intrinsics::arith_offset(self, count) } } /// Calculates the distance between two pointers. The returned value is in /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`. /// /// If the address different between the two pointers ia not a multiple of /// `mem::size_of::<T>()` then the result of the division is rounded towards /// zero. /// /// This function returns `None` if `T` is a zero-sized typed. /// /// # Examples /// /// Basic usage: /// /// ``` /// #![feature(offset_to)] /// /// fn main() { /// let a = [0; 5]; /// let ptr1: *const i32 = &a[1]; /// let ptr2: *const i32 = &a[3]; /// assert_eq!(ptr1.offset_to(ptr2), Some(2)); /// assert_eq!(ptr2.offset_to(ptr1), Some(-2)); /// assert_eq!(unsafe { ptr1.offset(2) }, ptr2); /// assert_eq!(unsafe { ptr2.offset(-2) }, ptr1); /// } /// ``` #[unstable(feature = "offset_to", issue = "41079")] #[inline] pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized { let size = mem::size_of::<T>(); if size == 0 { None } else { let diff = (other as isize).wrapping_sub(self as isize); Some(diff / size as isize) } } } #[lang = "mut_ptr"] impl<T: ?Sized> *mut T { /// Returns `true` if the pointer is null. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut s = [1, 2, 3]; /// let ptr: *mut u32 = s.as_mut_ptr(); /// assert!(!ptr.is_null()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_null(self) -> bool where T: Sized { self == null_mut() } /// Returns `None` if the pointer is null, or else returns a reference to /// the value wrapped in `Some`. /// /// # Safety /// /// While this method and its mutable counterpart are useful for /// null-safety, it is important to note that this is still an unsafe /// operation because the returned value could be pointing to invalid /// memory. /// /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does /// not necessarily reflect the actual lifetime of the data. /// /// # Examples /// /// Basic usage: /// /// ```ignore /// let val: *mut u8 = &mut 10u8 as *mut u8; /// /// unsafe { /// if let Some(val_back) = val.as_ref() { /// println!("We got back the value: {}!", val_back); /// } /// } /// ``` #[stable(feature = "ptr_as_ref", since = "1.9.0")] #[inline] pub unsafe fn as_ref<'a>(self) -> Option<&'a T> where T: Sized { if self.is_null() { None } else { Some(&*self) } } /// Calculates the offset from a pointer. `count` is in units of T; e.g. a /// `count` of 3 represents a pointer offset of `3 * size_of::<T>()` bytes. /// /// # Safety /// /// The offset must be in-bounds of the object, or one-byte-past-the-end. /// Otherwise `offset` invokes Undefined Behavior, regardless of whether /// the pointer is used. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut s = [1, 2, 3]; /// let ptr: *mut u32 = s.as_mut_ptr(); /// /// unsafe { /// println!("{}", *ptr.offset(1)); /// println!("{}", *ptr.offset(2)); /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub unsafe fn offset(self, count: isize) -> *mut T where T: Sized { intrinsics::offset(self, count) as *mut T } /// Calculates the offset from a pointer using wrapping arithmetic. /// `count` is in units of T; e.g. a `count` of 3 represents a pointer /// offset of `3 * size_of::<T>()` bytes. /// /// # Safety /// /// The resulting pointer does not need to be in bounds, but it is /// potentially hazardous to dereference (which requires `unsafe`). /// /// Always use `.offset(count)` instead when possible, because `offset` /// allows the compiler to optimize better. /// /// # Examples /// /// Basic usage: /// /// ``` /// // Iterate using a raw pointer in increments of two elements /// let mut data = [1u8, 2, 3, 4, 5]; /// let mut ptr: *mut u8 = data.as_mut_ptr(); /// let step = 2; /// let end_rounded_up = ptr.wrapping_offset(6); /// /// while ptr != end_rounded_up { /// unsafe { /// *ptr = 0; /// } /// ptr = ptr.wrapping_offset(step); /// } /// assert_eq!(&data, &[0, 2, 0, 4, 0]); /// ``` #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")] #[inline] pub fn wrapping_offset(self, count: isize) -> *mut T where T: Sized { unsafe { intrinsics::arith_offset(self, count) as *mut T } } /// Returns `None` if the pointer is null, or else returns a mutable /// reference to the value wrapped in `Some`. /// /// # Safety /// /// As with `as_ref`, this is unsafe because it cannot verify the validity /// of the returned pointer, nor can it ensure that the lifetime `'a` /// returned is indeed a valid lifetime for the contained data. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut s = [1, 2, 3]; /// let ptr: *mut u32 = s.as_mut_ptr(); /// let first_value = unsafe { ptr.as_mut().unwrap() }; /// *first_value = 4; /// println!("{:?}", s); // It'll print: "[4, 2, 3]". /// ``` #[stable(feature = "ptr_as_ref", since = "1.9.0")] #[inline] pub unsafe fn as_mut<'a>(self) -> Option<&'a mut T> where T: Sized { if self.is_null() { None } else { Some(&mut *self) } } /// Calculates the distance between two pointers. The returned value is in /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`. /// /// If the address different between the two pointers ia not a multiple of /// `mem::size_of::<T>()` then the result of the division is rounded towards /// zero. /// /// This function returns `None` if `T` is a zero-sized typed. /// /// # Examples /// /// Basic usage: /// /// ``` /// #![feature(offset_to)] /// /// fn main() { /// let mut a = [0; 5]; /// let ptr1: *mut i32 = &mut a[1]; /// let ptr2: *mut i32 = &mut a[3]; /// assert_eq!(ptr1.offset_to(ptr2), Some(2)); /// assert_eq!(ptr2.offset_to(ptr1), Some(-2)); /// assert_eq!(unsafe { ptr1.offset(2) }, ptr2); /// assert_eq!(unsafe { ptr2.offset(-2) }, ptr1); /// } /// ``` #[unstable(feature = "offset_to", issue = "41079")] #[inline] pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized { let size = mem::size_of::<T>(); if size == 0 { None } else { let diff = (other as isize).wrapping_sub(self as isize); Some(diff / size as isize) } } } // Equality for pointers #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> PartialEq for *const T { #[inline] fn eq(&self, other: &*const T) -> bool { *self == *other } } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> Eq for *const T {} #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> PartialEq for *mut T { #[inline] fn eq(&self, other: &*mut T) -> bool { *self == *other } } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> Eq for *mut T {} /// Compare raw pointers for equality. /// /// This is the same as using the `==` operator, but less generic: /// the arguments have to be `*const T` raw pointers, /// not anything that implements `PartialEq`. /// /// This can be used to compare `&T` references (which coerce to `*const T` implicitly) /// by their address rather than comparing the values they point to /// (which is what the `PartialEq for &T` implementation does). /// /// # Examples /// /// ``` /// use std::ptr; /// /// let five = 5; /// let other_five = 5; /// let five_ref = &five; /// let same_five_ref = &five; /// let other_five_ref = &other_five; /// /// assert!(five_ref == same_five_ref); /// assert!(five_ref == other_five_ref); /// /// assert!(ptr::eq(five_ref, same_five_ref)); /// assert!(!ptr::eq(five_ref, other_five_ref)); /// ``` #[stable(feature = "ptr_eq", since = "1.17.0")] #[inline] pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool { a == b } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> Clone for *const T { #[inline] fn clone(&self) -> *const T { *self } } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> Clone for *mut T { #[inline] fn clone(&self) -> *mut T { *self } } // Impls for function pointers macro_rules! fnptr_impls_safety_abi { ($FnTy: ty, $($Arg: ident),*) => { #[stable(feature = "rust1", since = "1.0.0")] impl<Ret, $($Arg),*> Clone for $FnTy { #[inline] fn clone(&self) -> Self { *self } } #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> PartialEq for $FnTy { #[inline] fn eq(&self, other: &Self) -> bool { *self as usize == *other as usize } } #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> Eq for $FnTy {} #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> PartialOrd for $FnTy { #[inline] fn partial_cmp(&self, other: &Self) -> Option<Ordering> { (*self as usize).partial_cmp(&(*other as usize)) } } #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> Ord for $FnTy { #[inline] fn cmp(&self, other: &Self) -> Ordering { (*self as usize).cmp(&(*other as usize)) } } #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> hash::Hash for $FnTy { fn hash<HH: hash::Hasher>(&self, state: &mut HH) { state.write_usize(*self as usize) } } #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> fmt::Pointer for $FnTy { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Pointer::fmt(&(*self as *const ()), f) } } #[stable(feature = "fnptr_impls", since = "1.4.0")] impl<Ret, $($Arg),*> fmt::Debug for $FnTy { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Pointer::fmt(&(*self as *const ()), f) } } } } macro_rules! fnptr_impls_args { ($($Arg: ident),+) => { fnptr_impls_safety_abi! { extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* } fnptr_impls_safety_abi! { extern "C" fn($($Arg),*) -> Ret, $($Arg),* } fnptr_impls_safety_abi! { extern "C" fn($($Arg),* , ...) -> Ret, $($Arg),* } fnptr_impls_safety_abi! { unsafe extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* } fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),*) -> Ret, $($Arg),* } fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),* , ...) -> Ret, $($Arg),* } }; () => { // No variadic functions with 0 parameters fnptr_impls_safety_abi! { extern "Rust" fn() -> Ret, } fnptr_impls_safety_abi! { extern "C" fn() -> Ret, } fnptr_impls_safety_abi! { unsafe extern "Rust" fn() -> Ret, } fnptr_impls_safety_abi! { unsafe extern "C" fn() -> Ret, } }; } fnptr_impls_args! { } fnptr_impls_args! { A } fnptr_impls_args! { A, B } fnptr_impls_args! { A, B, C } fnptr_impls_args! { A, B, C, D } fnptr_impls_args! { A, B, C, D, E } fnptr_impls_args! { A, B, C, D, E, F } fnptr_impls_args! { A, B, C, D, E, F, G } fnptr_impls_args! { A, B, C, D, E, F, G, H } fnptr_impls_args! { A, B, C, D, E, F, G, H, I } fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J } fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K } fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K, L } // Comparison for pointers #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> Ord for *const T { #[inline] fn cmp(&self, other: &*const T) -> Ordering { if self < other { Less } else if self == other { Equal } else { Greater } } } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> PartialOrd for *const T { #[inline] fn partial_cmp(&self, other: &*const T) -> Option<Ordering> { Some(self.cmp(other)) } #[inline] fn lt(&self, other: &*const T) -> bool { *self < *other } #[inline] fn le(&self, other: &*const T) -> bool { *self <= *other } #[inline] fn gt(&self, other: &*const T) -> bool { *self > *other } #[inline] fn ge(&self, other: &*const T) -> bool { *self >= *other } } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> Ord for *mut T { #[inline] fn cmp(&self, other: &*mut T) -> Ordering { if self < other { Less } else if self == other { Equal } else { Greater } } } #[stable(feature = "rust1", since = "1.0.0")] impl<T: ?Sized> PartialOrd for *mut T { #[inline] fn partial_cmp(&self, other: &*mut T) -> Option<Ordering> { Some(self.cmp(other)) } #[inline] fn lt(&self, other: &*mut T) -> bool { *self < *other } #[inline] fn le(&self, other: &*mut T) -> bool { *self <= *other } #[inline] fn gt(&self, other: &*mut T) -> bool { *self > *other } #[inline] fn ge(&self, other: &*mut T) -> bool { *self >= *other } } /// A wrapper around a raw non-null `*mut T` that indicates that the possessor /// of this wrapper owns the referent. Useful for building abstractions like /// `Box<T>`, `Vec<T>`, `String`, and `HashMap<K, V>`. /// /// Unlike `*mut T`, `Unique<T>` behaves "as if" it were an instance of `T`. /// It implements `Send`/`Sync` if `T` is `Send`/`Sync`. It also implies /// the kind of strong aliasing guarantees an instance of `T` can expect: /// the referent of the pointer should not be modified without a unique path to /// its owning Unique. /// /// If you're uncertain of whether it's correct to use `Unique` for your purposes, /// consider using `Shared`, which has weaker semantics. /// /// Unlike `*mut T`, the pointer must always be non-null, even if the pointer /// is never dereferenced. This is so that enums may use this forbidden value /// as a discriminant -- `Option<Unique<T>>` has the same size as `Unique<T>`. /// However the pointer may still dangle if it isn't dereferenced. /// /// Unlike `*mut T`, `Unique<T>` is covariant over `T`. This should always be correct /// for any type which upholds Unique's aliasing requirements. #[allow(missing_debug_implementations)] #[unstable(feature = "unique", reason = "needs an RFC to flesh out design", issue = "27730")] pub struct Unique<T: ?Sized> { pointer: NonZero<*const T>, // NOTE: this marker has no consequences for variance, but is necessary // for dropck to understand that we logically own a `T`. // // For details, see: // https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md#phantom-data _marker: PhantomData<T>, } /// `Unique` pointers are `Send` if `T` is `Send` because the data they /// reference is unaliased. Note that this aliasing invariant is /// unenforced by the type system; the abstraction using the /// `Unique` must enforce it. #[unstable(feature = "unique", issue = "27730")] unsafe impl<T: Send + ?Sized> Send for Unique<T> { } /// `Unique` pointers are `Sync` if `T` is `Sync` because the data they /// reference is unaliased. Note that this aliasing invariant is /// unenforced by the type system; the abstraction using the /// `Unique` must enforce it. #[unstable(feature = "unique", issue = "27730")] unsafe impl<T: Sync + ?Sized> Sync for Unique<T> { } #[unstable(feature = "unique", issue = "27730")] impl<T: Sized> Unique<T> { /// Creates a new `Unique` that is dangling, but well-aligned. /// /// This is useful for initializing types which lazily allocate, like /// `Vec::new` does. pub fn empty() -> Self { unsafe { let ptr = mem::align_of::<T>() as *mut T; Unique::new(ptr) } } } #[unstable(feature = "unique", issue = "27730")] impl<T: ?Sized> Unique<T> { /// Creates a new `Unique`. /// /// # Safety /// /// `ptr` must be non-null. pub const unsafe fn new(ptr: *mut T) -> Unique<T> { Unique { pointer: NonZero::new(ptr), _marker: PhantomData } } /// Acquires the underlying `*mut` pointer. pub fn as_ptr(self) -> *mut T { self.pointer.get() as *mut T } /// Dereferences the content. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use `&*my_ptr.ptr()`. pub unsafe fn as_ref(&self) -> &T { &*self.as_ptr() } /// Mutably dereferences the content. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use `&mut *my_ptr.ptr()`. pub unsafe fn as_mut(&mut self) -> &mut T { &mut *self.as_ptr() } } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> Clone for Unique<T> { fn clone(&self) -> Self { *self } } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> Copy for Unique<T> { } #[unstable(feature = "unique", issue = "27730")] impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where T: Unsize<U> { } #[unstable(feature = "unique", issue = "27730")] impl<T: ?Sized> fmt::Pointer for Unique<T> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Pointer::fmt(&self.as_ptr(), f) } } /// A wrapper around a raw `*mut T` that indicates that the possessor /// of this wrapper has shared ownership of the referent. Useful for /// building abstractions like `Rc<T>`, `Arc<T>`, or doubly-linked lists, which /// internally use aliased raw pointers to manage the memory that they own. /// /// This is similar to `Unique`, except that it doesn't make any aliasing /// guarantees, and doesn't derive Send and Sync. Note that unlike `&T`, /// Shared has no special mutability requirements. Shared may mutate data /// aliased by other Shared pointers. More precise rules require Rust to /// develop an actual aliasing model. /// /// Unlike `*mut T`, the pointer must always be non-null, even if the pointer /// is never dereferenced. This is so that enums may use this forbidden value /// as a discriminant -- `Option<Shared<T>>` has the same size as `Shared<T>`. /// However the pointer may still dangle if it isn't dereferenced. /// /// Unlike `*mut T`, `Shared<T>` is covariant over `T`. If this is incorrect /// for your use case, you should include some PhantomData in your type to /// provide invariance, such as `PhantomData<Cell<T>>` or `PhantomData<&'a mut T>`. /// Usually this won't be necessary; covariance is correct for Rc, Arc, and LinkedList /// because they provide a public API that follows the normal shared XOR mutable /// rules of Rust. #[allow(missing_debug_implementations)] #[unstable(feature = "shared", reason = "needs an RFC to flesh out design", issue = "27730")] pub struct Shared<T: ?Sized> { pointer: NonZero<*const T>, // NOTE: this marker has no consequences for variance, but is necessary // for dropck to understand that we logically own a `T`. // // For details, see: // https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md#phantom-data _marker: PhantomData<T>, } /// `Shared` pointers are not `Send` because the data they reference may be aliased. // NB: This impl is unnecessary, but should provide better error messages. #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> !Send for Shared<T> { } /// `Shared` pointers are not `Sync` because the data they reference may be aliased. // NB: This impl is unnecessary, but should provide better error messages. #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> !Sync for Shared<T> { } #[unstable(feature = "shared", issue = "27730")] impl<T: Sized> Shared<T> { /// Creates a new `Shared` that is dangling, but well-aligned. /// /// This is useful for initializing types which lazily allocate, like /// `Vec::new` does. pub fn empty() -> Self { unsafe { let ptr = mem::align_of::<T>() as *mut T; Shared::new(ptr) } } } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> Shared<T> { /// Creates a new `Shared`. /// /// # Safety /// /// `ptr` must be non-null. pub unsafe fn new(ptr: *mut T) -> Self { Shared { pointer: NonZero::new(ptr), _marker: PhantomData } } /// Acquires the underlying `*mut` pointer. pub fn as_ptr(self) -> *mut T { self.pointer.get() as *mut T } /// Dereferences the content. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use `&*my_ptr.ptr()`. pub unsafe fn as_ref(&self) -> &T { &*self.as_ptr() } /// Mutably dereferences the content. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use `&mut *my_ptr.ptr_mut()`. pub unsafe fn as_mut(&mut self) -> &mut T { &mut *self.as_ptr() } /// Acquires the underlying pointer as a `*mut` pointer. #[rustc_deprecated(since = "1.19", reason = "renamed to `as_ptr` for ergonomics/consistency")] #[unstable(feature = "shared", issue = "27730")] pub unsafe fn as_mut_ptr(&self) -> *mut T { self.as_ptr() } } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> Clone for Shared<T> { fn clone(&self) -> Self { *self } } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> Copy for Shared<T> { } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized, U: ?Sized> CoerceUnsized<Shared<U>> for Shared<T> where T: Unsize<U> { } #[unstable(feature = "shared", issue = "27730")] impl<T: ?Sized> fmt::Pointer for Shared<T> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Pointer::fmt(&self.as_ptr(), f) } }