| // 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](../primitive.pointer.html).* |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| use clone::Clone; |
| use intrinsics; |
| use ops::{CoerceUnsized, Deref}; |
| use fmt; |
| use hash; |
| use option::Option::{self, Some, None}; |
| use marker::{Copy, PhantomData, Send, Sized, Sync, Unsize}; |
| use mem; |
| use nonzero::NonZero; |
| |
| use cmp::{PartialEq, Eq, Ord, PartialOrd}; |
| 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; |
| |
| #[unstable(feature = "drop_in_place", reason = "just exposed, needs FCP", issue = "27908")] |
| pub use intrinsics::drop_in_place; |
| |
| /// 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 is only unsafe because it accepts a raw pointer. |
| #[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`. |
| #[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 |
| } |
| |
| /// Variant of read_and_zero that writes the specific drop-flag byte |
| /// (which may be more appropriate than zero). |
| #[inline(always)] |
| #[unstable(feature = "filling_drop", |
| reason = "may play a larger role in std::ptr future extensions", |
| issue = "5016")] |
| pub unsafe fn read_and_drop<T>(dest: *mut T) -> T { |
| // Copy the data out from `dest`: |
| let tmp = read(&*dest); |
| |
| // Now mark `dest` as dropped: |
| write_bytes(dest, mem::POST_DROP_U8, 1); |
| |
| 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. |
| /// |
| /// This is appropriate for initializing uninitialized memory, or overwriting |
| /// memory that has previously been `read` from. |
| #[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) |
| } |
| |
| #[lang = "const_ptr"] |
| impl<T: ?Sized> *const T { |
| /// Returns true if the pointer 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. |
| #[unstable(feature = "ptr_as_ref", |
| reason = "Option is not clearly the right return type, and we \ |
| may want to tie the return lifetime to a borrow of \ |
| the raw pointer", |
| issue = "27780")] |
| #[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 * sizeof::<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. |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub unsafe fn offset(self, count: isize) -> *const T where T: Sized { |
| intrinsics::offset(self, count) |
| } |
| } |
| |
| #[lang = "mut_ptr"] |
| impl<T: ?Sized> *mut T { |
| /// Returns true if the pointer 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. |
| #[unstable(feature = "ptr_as_ref", |
| reason = "Option is not clearly the right return type, and we \ |
| may want to tie the return lifetime to a borrow of \ |
| the raw pointer", |
| issue = "27780")] |
| #[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 * sizeof::<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. |
| #[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 |
| } |
| |
| /// 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. |
| #[unstable(feature = "ptr_as_ref", |
| reason = "return value does not necessarily convey all possible \ |
| information", |
| issue = "27780")] |
| #[inline] |
| pub unsafe fn as_mut<'a>(&self) -> Option<&'a mut T> where T: Sized { |
| if self.is_null() { |
| None |
| } else { |
| Some(&mut **self) |
| } |
| } |
| } |
| |
| // 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 {} |
| |
| #[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! { unsafe extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* } |
| fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),*) -> Ret, $($Arg),* } |
| } |
| } |
| |
| 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 `*mut T` that indicates that the possessor |
| /// of this wrapper owns the referent. This in turn implies that the |
| /// `Unique<T>` is `Send`/`Sync` if `T` is `Send`/`Sync`, unlike a raw |
| /// `*mut T` (which conveys no particular ownership semantics). It |
| /// also implies that the referent of the pointer should not be |
| /// modified without a unique path to the `Unique` reference. Useful |
| /// for building abstractions like `Vec<T>` or `Box<T>`, which |
| /// internally use raw pointers to manage the memory that they own. |
| #[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`. |
| pub const unsafe fn new(ptr: *mut T) -> Unique<T> { |
| Unique { pointer: NonZero::new(ptr), _marker: PhantomData } |
| } |
| |
| /// Dereferences the content. |
| pub unsafe fn get(&self) -> &T { |
| &**self.pointer |
| } |
| |
| /// Mutably dereferences the content. |
| pub unsafe fn get_mut(&mut self) -> &mut T { |
| &mut ***self |
| } |
| } |
| |
| #[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> Deref for Unique<T> { |
| type Target = *mut T; |
| |
| #[inline] |
| fn deref(&self) -> &*mut T { |
| unsafe { mem::transmute(&*self.pointer) } |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> fmt::Pointer for Unique<T> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| fmt::Pointer::fmt(&*self.pointer, 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>` or `Arc<T>`, which internally |
| /// use raw pointers to manage the memory that they own. |
| #[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`. |
| pub unsafe fn new(ptr: *mut T) -> Self { |
| Shared { pointer: NonZero::new(ptr), _marker: PhantomData } |
| } |
| } |
| |
| #[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> Deref for Shared<T> { |
| type Target = *mut T; |
| |
| #[inline] |
| fn deref(&self) -> &*mut T { |
| unsafe { mem::transmute(&*self.pointer) } |
| } |
| } |
| |
| #[unstable(feature = "shared", issue = "27730")] |
| impl<T> fmt::Pointer for Shared<T> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| fmt::Pointer::fmt(&*self.pointer, f) |
| } |
| } |