diff options
Diffstat (limited to 'src/libcore/ptr/mod.rs')
| -rw-r--r-- | src/libcore/ptr/mod.rs | 1696 |
1 files changed, 5 insertions, 1691 deletions
diff --git a/src/libcore/ptr/mod.rs b/src/libcore/ptr/mod.rs index 776165e7bd7..a3a73ff6c6c 100644 --- a/src/libcore/ptr/mod.rs +++ b/src/libcore/ptr/mod.rs @@ -65,16 +65,15 @@ //! [`write_volatile`]: ./fn.write_volatile.html //! [`NonNull::dangling`]: ./struct.NonNull.html#method.dangling -// ignore-tidy-filelength // ignore-tidy-undocumented-unsafe #![stable(feature = "rust1", since = "1.0.0")] -use crate::cmp::Ordering::{self, Equal, Greater, Less}; +use crate::intrinsics; use crate::fmt; use crate::hash; -use crate::intrinsics; use crate::mem::{self, MaybeUninit}; +use crate::cmp::Ordering; #[stable(feature = "rust1", since = "1.0.0")] pub use crate::intrinsics::copy_nonoverlapping; @@ -93,6 +92,9 @@ mod unique; #[unstable(feature = "ptr_internals", issue = "0")] pub use unique::Unique; +mod const_ptr; +mod mut_ptr; + /// Executes the destructor (if any) of the pointed-to value. /// /// This is semantically equivalent to calling [`ptr::read`] and discarding @@ -1034,1586 +1036,6 @@ 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. - /// - /// Note that unsized types have many possible null pointers, as only the - /// raw data pointer is considered, not their length, vtable, etc. - /// Therefore, two pointers that are null may still not compare equal to - /// each other. - /// - /// # 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 { - // Compare via a cast to a thin pointer, so fat pointers are only - // considering their "data" part for null-ness. - (self as *const u8) == null() - } - - /// Casts to a pointer of another type. - #[stable(feature = "ptr_cast", since = "1.38.0")] - #[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")] - #[inline] - pub const fn cast<U>(self) -> *const U { - self as _ - } - - /// 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. - /// - /// When calling this method, you have to ensure that *either* the pointer is NULL *or* - /// all of the following is true: - /// - it is properly aligned - /// - it must point to an initialized instance of T; in particular, the pointer must be - /// "dereferencable" in the sense defined [here]. - /// - /// This applies even if the result of this method is unused! - /// (The part about being initialized is not yet fully decided, but until - /// it is, the only safe approach is to ensure that they are indeed initialized.) - /// - /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does - /// not necessarily reflect the actual lifetime of the data. *You* must enforce - /// Rust's aliasing rules. In particular, for the duration of this lifetime, - /// the memory the pointer points to must not get mutated (except inside `UnsafeCell`). - /// - /// [here]: crate::ptr#safety - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let ptr: *const u8 = &10u8 as *const u8; - /// - /// unsafe { - /// if let Some(val_back) = ptr.as_ref() { - /// println!("We got back the value: {}!", val_back); - /// } - /// } - /// ``` - /// - /// # Null-unchecked version - /// - /// If you are sure the pointer can never be null and are looking for some kind of - /// `as_ref_unchecked` that returns the `&T` instead of `Option<&T>`, know that you can - /// dereference the pointer directly. - /// - /// ``` - /// let ptr: *const u8 = &10u8 as *const u8; - /// - /// unsafe { - /// let val_back = &*ptr; - /// 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> { - 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 - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and resulting pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The computed offset, **in bytes**, cannot overflow an `isize`. - /// - /// * The offset being in bounds cannot rely on "wrapping around" the address - /// space. That is, the infinite-precision sum, **in bytes** must fit in a usize. - /// - /// The compiler and standard library generally tries to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `vec.as_ptr().add(vec.len())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_offset`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// [`wrapping_offset`]: #method.wrapping_offset - /// - /// # 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`). - /// - /// In particular, the resulting pointer remains attached to the same allocated - /// object that `self` points to. It may *not* be used to access a - /// different allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// In other words, `x.wrapping_offset(y.wrapping_offset_from(x))` is - /// *not* the same as `y`, and dereferencing it is undefined behavior - /// unless `x` and `y` point into the same allocated object. - /// - /// Compared to [`offset`], this method basically delays the requirement of staying - /// within the same allocated object: [`offset`] is immediate Undefined Behavior when - /// crossing object boundaries; `wrapping_offset` produces a pointer but still leads - /// to Undefined Behavior if that pointer is dereferenced. [`offset`] can be optimized - /// better and is thus preferrable in performance-sensitive code. - /// - /// If you need to cross object boundaries, cast the pointer to an integer and - /// do the arithmetic there. - /// - /// [`offset`]: #method.offset - /// - /// # 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>()`. - /// - /// This function is the inverse of [`offset`]. - /// - /// [`offset`]: #method.offset - /// [`wrapping_offset_from`]: #method.wrapping_offset_from - /// - /// # Safety - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and other pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The distance between the pointers, **in bytes**, cannot overflow an `isize`. - /// - /// * The distance between the pointers, in bytes, must be an exact multiple - /// of the size of `T`. - /// - /// * The distance being in bounds cannot rely on "wrapping around" the address space. - /// - /// The compiler and standard library generally try to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `ptr_into_vec.offset_from(vec.as_ptr())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_offset_from`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// # Panics - /// - /// This function panics if `T` is a Zero-Sized Type ("ZST"). - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// #![feature(ptr_offset_from)] - /// - /// let a = [0; 5]; - /// let ptr1: *const i32 = &a[1]; - /// let ptr2: *const i32 = &a[3]; - /// unsafe { - /// assert_eq!(ptr2.offset_from(ptr1), 2); - /// assert_eq!(ptr1.offset_from(ptr2), -2); - /// assert_eq!(ptr1.offset(2), ptr2); - /// assert_eq!(ptr2.offset(-2), ptr1); - /// } - /// ``` - #[unstable(feature = "ptr_offset_from", issue = "41079")] - #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "41079")] - #[inline] - pub const unsafe fn offset_from(self, origin: *const T) -> isize - where - T: Sized, - { - let pointee_size = mem::size_of::<T>(); - let ok = 0 < pointee_size && pointee_size <= isize::max_value() as usize; - // assert that the pointee size is valid in a const eval compatible way - // FIXME: do this with a real assert at some point - [()][(!ok) as usize]; - intrinsics::ptr_offset_from(self, origin) - } - - /// 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 is not a multiple of - /// `mem::size_of::<T>()` then the result of the division is rounded towards - /// zero. - /// - /// Though this method is safe for any two pointers, note that its result - /// will be mostly useless if the two pointers aren't into the same allocated - /// object, for example if they point to two different local variables. - /// - /// # Panics - /// - /// This function panics if `T` is a zero-sized type. - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// #![feature(ptr_wrapping_offset_from)] - /// - /// let a = [0; 5]; - /// let ptr1: *const i32 = &a[1]; - /// let ptr2: *const i32 = &a[3]; - /// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2); - /// assert_eq!(ptr1.wrapping_offset_from(ptr2), -2); - /// assert_eq!(ptr1.wrapping_offset(2), ptr2); - /// assert_eq!(ptr2.wrapping_offset(-2), ptr1); - /// - /// let ptr1: *const i32 = 3 as _; - /// let ptr2: *const i32 = 13 as _; - /// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2); - /// ``` - #[unstable(feature = "ptr_wrapping_offset_from", issue = "41079")] - #[inline] - pub fn wrapping_offset_from(self, origin: *const T) -> isize - where - T: Sized, - { - let pointee_size = mem::size_of::<T>(); - assert!(0 < pointee_size && pointee_size <= isize::max_value() as usize); - - let d = isize::wrapping_sub(self as _, origin as _); - d.wrapping_div(pointee_size as _) - } - - /// Calculates the offset from a pointer (convenience for `.offset(count as isize)`). - /// - /// `count` is in units of T; e.g., a `count` of 3 represents a pointer - /// offset of `3 * size_of::<T>()` bytes. - /// - /// # Safety - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and resulting pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The computed offset, **in bytes**, cannot overflow an `isize`. - /// - /// * The offset being in bounds cannot rely on "wrapping around" the address - /// space. That is, the infinite-precision sum must fit in a `usize`. - /// - /// The compiler and standard library generally tries to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `vec.as_ptr().add(vec.len())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_add`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// [`wrapping_add`]: #method.wrapping_add - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let s: &str = "123"; - /// let ptr: *const u8 = s.as_ptr(); - /// - /// unsafe { - /// println!("{}", *ptr.add(1) as char); - /// println!("{}", *ptr.add(2) as char); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn add(self, count: usize) -> Self - where - T: Sized, - { - self.offset(count as isize) - } - - /// Calculates the offset from a pointer (convenience for - /// `.offset((count as isize).wrapping_neg())`). - /// - /// `count` is in units of T; e.g., a `count` of 3 represents a pointer - /// offset of `3 * size_of::<T>()` bytes. - /// - /// # Safety - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and resulting pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The computed offset cannot exceed `isize::MAX` **bytes**. - /// - /// * The offset being in bounds cannot rely on "wrapping around" the address - /// space. That is, the infinite-precision sum must fit in a usize. - /// - /// The compiler and standard library generally tries to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_sub`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// [`wrapping_sub`]: #method.wrapping_sub - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let s: &str = "123"; - /// - /// unsafe { - /// let end: *const u8 = s.as_ptr().add(3); - /// println!("{}", *end.sub(1) as char); - /// println!("{}", *end.sub(2) as char); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn sub(self, count: usize) -> Self - where - T: Sized, - { - self.offset((count as isize).wrapping_neg()) - } - - /// Calculates the offset from a pointer using wrapping arithmetic. - /// (convenience for `.wrapping_offset(count as isize)`) - /// - /// `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`). - /// - /// In particular, the resulting pointer remains attached to the same allocated - /// object that `self` points to. It may *not* be used to access a - /// different allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// Compared to [`add`], this method basically delays the requirement of staying - /// within the same allocated object: [`add`] is immediate Undefined Behavior when - /// crossing object boundaries; `wrapping_add` produces a pointer but still leads - /// to Undefined Behavior if that pointer is dereferenced. [`add`] can be optimized - /// better and is thus preferrable in performance-sensitive code. - /// - /// If you need to cross object boundaries, cast the pointer to an integer and - /// do the arithmetic there. - /// - /// [`add`]: #method.add - /// - /// # 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_add(6); - /// - /// // This loop prints "1, 3, 5, " - /// while ptr != end_rounded_up { - /// unsafe { - /// print!("{}, ", *ptr); - /// } - /// ptr = ptr.wrapping_add(step); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub fn wrapping_add(self, count: usize) -> Self - where - T: Sized, - { - self.wrapping_offset(count as isize) - } - - /// Calculates the offset from a pointer using wrapping arithmetic. - /// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`) - /// - /// `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`). - /// - /// In particular, the resulting pointer remains attached to the same allocated - /// object that `self` points to. It may *not* be used to access a - /// different allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// Compared to [`sub`], this method basically delays the requirement of staying - /// within the same allocated object: [`sub`] is immediate Undefined Behavior when - /// crossing object boundaries; `wrapping_sub` produces a pointer but still leads - /// to Undefined Behavior if that pointer is dereferenced. [`sub`] can be optimized - /// better and is thus preferrable in performance-sensitive code. - /// - /// If you need to cross object boundaries, cast the pointer to an integer and - /// do the arithmetic there. - /// - /// [`sub`]: #method.sub - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// // Iterate using a raw pointer in increments of two elements (backwards) - /// let data = [1u8, 2, 3, 4, 5]; - /// let mut ptr: *const u8 = data.as_ptr(); - /// let start_rounded_down = ptr.wrapping_sub(2); - /// ptr = ptr.wrapping_add(4); - /// let step = 2; - /// // This loop prints "5, 3, 1, " - /// while ptr != start_rounded_down { - /// unsafe { - /// print!("{}, ", *ptr); - /// } - /// ptr = ptr.wrapping_sub(step); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub fn wrapping_sub(self, count: usize) -> Self - where - T: Sized, - { - self.wrapping_offset((count as isize).wrapping_neg()) - } - - /// Reads the value from `self` without moving it. This leaves the - /// memory in `self` unchanged. - /// - /// See [`ptr::read`] for safety concerns and examples. - /// - /// [`ptr::read`]: ./ptr/fn.read.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn read(self) -> T - where - T: Sized, - { - read(self) - } - - /// Performs a volatile read of the value from `self` without moving it. This - /// leaves the memory in `self` 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. - /// - /// See [`ptr::read_volatile`] for safety concerns and examples. - /// - /// [`ptr::read_volatile`]: ./ptr/fn.read_volatile.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn read_volatile(self) -> T - where - T: Sized, - { - read_volatile(self) - } - - /// Reads the value from `self` without moving it. This leaves the - /// memory in `self` unchanged. - /// - /// Unlike `read`, the pointer may be unaligned. - /// - /// See [`ptr::read_unaligned`] for safety concerns and examples. - /// - /// [`ptr::read_unaligned`]: ./ptr/fn.read_unaligned.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn read_unaligned(self) -> T - where - T: Sized, - { - read_unaligned(self) - } - - /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source - /// and destination may overlap. - /// - /// NOTE: this has the *same* argument order as [`ptr::copy`]. - /// - /// See [`ptr::copy`] for safety concerns and examples. - /// - /// [`ptr::copy`]: ./ptr/fn.copy.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn copy_to(self, dest: *mut T, count: usize) - where - T: Sized, - { - copy(self, dest, count) - } - - /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source - /// and destination may *not* overlap. - /// - /// NOTE: this has the *same* argument order as [`ptr::copy_nonoverlapping`]. - /// - /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples. - /// - /// [`ptr::copy_nonoverlapping`]: ./ptr/fn.copy_nonoverlapping.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize) - where - T: Sized, - { - copy_nonoverlapping(self, dest, count) - } - - /// Computes the offset that needs to be applied to the pointer in order to make it aligned to - /// `align`. - /// - /// If it is not possible to align the pointer, the implementation returns - /// `usize::max_value()`. It is permissible for the implementation to *always* - /// return `usize::max_value()`. Only your algorithm's performance can depend - /// on getting a usable offset here, not its correctness. - /// - /// The offset is expressed in number of `T` elements, and not bytes. The value returned can be - /// used with the `wrapping_add` method. - /// - /// There are no guarantees whatsoever that offsetting the pointer will not overflow or go - /// beyond the allocation that the pointer points into. It is up to the caller to ensure that - /// the returned offset is correct in all terms other than alignment. - /// - /// # Panics - /// - /// The function panics if `align` is not a power-of-two. - /// - /// # Examples - /// - /// Accessing adjacent `u8` as `u16` - /// - /// ``` - /// # fn foo(n: usize) { - /// # use std::mem::align_of; - /// # unsafe { - /// let x = [5u8, 6u8, 7u8, 8u8, 9u8]; - /// let ptr = &x[n] as *const u8; - /// let offset = ptr.align_offset(align_of::<u16>()); - /// if offset < x.len() - n - 1 { - /// let u16_ptr = ptr.add(offset) as *const u16; - /// assert_ne!(*u16_ptr, 500); - /// } else { - /// // while the pointer can be aligned via `offset`, it would point - /// // outside the allocation - /// } - /// # } } - /// ``` - #[stable(feature = "align_offset", since = "1.36.0")] - pub fn align_offset(self, align: usize) -> usize - where - T: Sized, - { - if !align.is_power_of_two() { - panic!("align_offset: align is not a power-of-two"); - } - unsafe { align_offset(self, align) } - } -} - -#[lang = "mut_ptr"] -impl<T: ?Sized> *mut T { - /// Returns `true` if the pointer is null. - /// - /// Note that unsized types have many possible null pointers, as only the - /// raw data pointer is considered, not their length, vtable, etc. - /// Therefore, two pointers that are null may still not compare equal to - /// each other. - /// - /// # 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 { - // Compare via a cast to a thin pointer, so fat pointers are only - // considering their "data" part for null-ness. - (self as *mut u8) == null_mut() - } - - /// Casts to a pointer of another type. - #[stable(feature = "ptr_cast", since = "1.38.0")] - #[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")] - #[inline] - pub const fn cast<U>(self) -> *mut U { - self as _ - } - - /// 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. - /// - /// When calling this method, you have to ensure that if the pointer is - /// non-NULL, then it is properly aligned, dereferencable (for the whole - /// size of `T`) and points to an initialized instance of `T`. This applies - /// even if the result of this method is unused! - /// (The part about being initialized is not yet fully decided, but until - /// it is, the only safe approach is to ensure that they are indeed initialized.) - /// - /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does - /// not necessarily reflect the actual lifetime of the data. It is up to the - /// caller to ensure that for the duration of this lifetime, the memory this - /// pointer points to does not get written to outside of `UnsafeCell<U>`. - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let ptr: *mut u8 = &mut 10u8 as *mut u8; - /// - /// unsafe { - /// if let Some(val_back) = ptr.as_ref() { - /// println!("We got back the value: {}!", val_back); - /// } - /// } - /// ``` - /// - /// # Null-unchecked version - /// - /// If you are sure the pointer can never be null and are looking for some kind of - /// `as_ref_unchecked` that returns the `&T` instead of `Option<&T>`, know that you can - /// dereference the pointer directly. - /// - /// ``` - /// let ptr: *mut u8 = &mut 10u8 as *mut u8; - /// - /// unsafe { - /// let val_back = &*ptr; - /// 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> { - 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 - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and resulting pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The computed offset, **in bytes**, cannot overflow an `isize`. - /// - /// * The offset being in bounds cannot rely on "wrapping around" the address - /// space. That is, the infinite-precision sum, **in bytes** must fit in a usize. - /// - /// The compiler and standard library generally tries to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `vec.as_ptr().add(vec.len())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_offset`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// [`wrapping_offset`]: #method.wrapping_offset - /// - /// # 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`). - /// - /// In particular, the resulting pointer remains attached to the same allocated - /// object that `self` points to. It may *not* be used to access a - /// different allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// In other words, `x.wrapping_offset(y.wrapping_offset_from(x))` is - /// *not* the same as `y`, and dereferencing it is undefined behavior - /// unless `x` and `y` point into the same allocated object. - /// - /// Compared to [`offset`], this method basically delays the requirement of staying - /// within the same allocated object: [`offset`] is immediate Undefined Behavior when - /// crossing object boundaries; `wrapping_offset` produces a pointer but still leads - /// to Undefined Behavior if that pointer is dereferenced. [`offset`] can be optimized - /// better and is thus preferrable in performance-sensitive code. - /// - /// If you need to cross object boundaries, cast the pointer to an integer and - /// do the arithmetic there. - /// - /// [`offset`]: #method.offset - /// - /// # 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. - /// - /// When calling this method, you have to ensure that *either* the pointer is NULL *or* - /// all of the following is true: - /// - it is properly aligned - /// - it must point to an initialized instance of T; in particular, the pointer must be - /// "dereferencable" in the sense defined [here]. - /// - /// This applies even if the result of this method is unused! - /// (The part about being initialized is not yet fully decided, but until - /// it is the only safe approach is to ensure that they are indeed initialized.) - /// - /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does - /// not necessarily reflect the actual lifetime of the data. *You* must enforce - /// Rust's aliasing rules. In particular, for the duration of this lifetime, - /// the memory this pointer points to must not get accessed (read or written) - /// through any other pointer. - /// - /// [here]: crate::ptr#safety - /// [`as_ref`]: #method.as_ref - /// - /// # 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> { - 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>()`. - /// - /// This function is the inverse of [`offset`]. - /// - /// [`offset`]: #method.offset-1 - /// [`wrapping_offset_from`]: #method.wrapping_offset_from-1 - /// - /// # Safety - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and other pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The distance between the pointers, **in bytes**, cannot overflow an `isize`. - /// - /// * The distance between the pointers, in bytes, must be an exact multiple - /// of the size of `T`. - /// - /// * The distance being in bounds cannot rely on "wrapping around" the address space. - /// - /// The compiler and standard library generally try to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `ptr_into_vec.offset_from(vec.as_ptr())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_offset_from`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// # Panics - /// - /// This function panics if `T` is a Zero-Sized Type ("ZST"). - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// #![feature(ptr_offset_from)] - /// - /// let mut a = [0; 5]; - /// let ptr1: *mut i32 = &mut a[1]; - /// let ptr2: *mut i32 = &mut a[3]; - /// unsafe { - /// assert_eq!(ptr2.offset_from(ptr1), 2); - /// assert_eq!(ptr1.offset_from(ptr2), -2); - /// assert_eq!(ptr1.offset(2), ptr2); - /// assert_eq!(ptr2.offset(-2), ptr1); - /// } - /// ``` - #[unstable(feature = "ptr_offset_from", issue = "41079")] - #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "41079")] - #[inline] - pub const unsafe fn offset_from(self, origin: *const T) -> isize - where - T: Sized, - { - (self as *const T).offset_from(origin) - } - - /// 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 is not a multiple of - /// `mem::size_of::<T>()` then the result of the division is rounded towards - /// zero. - /// - /// Though this method is safe for any two pointers, note that its result - /// will be mostly useless if the two pointers aren't into the same allocated - /// object, for example if they point to two different local variables. - /// - /// # Panics - /// - /// This function panics if `T` is a zero-sized type. - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// #![feature(ptr_wrapping_offset_from)] - /// - /// let mut a = [0; 5]; - /// let ptr1: *mut i32 = &mut a[1]; - /// let ptr2: *mut i32 = &mut a[3]; - /// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2); - /// assert_eq!(ptr1.wrapping_offset_from(ptr2), -2); - /// assert_eq!(ptr1.wrapping_offset(2), ptr2); - /// assert_eq!(ptr2.wrapping_offset(-2), ptr1); - /// - /// let ptr1: *mut i32 = 3 as _; - /// let ptr2: *mut i32 = 13 as _; - /// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2); - /// ``` - #[unstable(feature = "ptr_wrapping_offset_from", issue = "41079")] - #[inline] - pub fn wrapping_offset_from(self, origin: *const T) -> isize - where - T: Sized, - { - (self as *const T).wrapping_offset_from(origin) - } - - /// Calculates the offset from a pointer (convenience for `.offset(count as isize)`). - /// - /// `count` is in units of T; e.g., a `count` of 3 represents a pointer - /// offset of `3 * size_of::<T>()` bytes. - /// - /// # Safety - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and resulting pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The computed offset, **in bytes**, cannot overflow an `isize`. - /// - /// * The offset being in bounds cannot rely on "wrapping around" the address - /// space. That is, the infinite-precision sum must fit in a `usize`. - /// - /// The compiler and standard library generally tries to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `vec.as_ptr().add(vec.len())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_add`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// [`wrapping_add`]: #method.wrapping_add - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let s: &str = "123"; - /// let ptr: *const u8 = s.as_ptr(); - /// - /// unsafe { - /// println!("{}", *ptr.add(1) as char); - /// println!("{}", *ptr.add(2) as char); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn add(self, count: usize) -> Self - where - T: Sized, - { - self.offset(count as isize) - } - - /// Calculates the offset from a pointer (convenience for - /// `.offset((count as isize).wrapping_neg())`). - /// - /// `count` is in units of T; e.g., a `count` of 3 represents a pointer - /// offset of `3 * size_of::<T>()` bytes. - /// - /// # Safety - /// - /// If any of the following conditions are violated, the result is Undefined - /// Behavior: - /// - /// * Both the starting and resulting pointer must be either in bounds or one - /// byte past the end of the same allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// * The computed offset cannot exceed `isize::MAX` **bytes**. - /// - /// * The offset being in bounds cannot rely on "wrapping around" the address - /// space. That is, the infinite-precision sum must fit in a usize. - /// - /// The compiler and standard library generally tries to ensure allocations - /// never reach a size where an offset is a concern. For instance, `Vec` - /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so - /// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe. - /// - /// Most platforms fundamentally can't even construct such an allocation. - /// For instance, no known 64-bit platform can ever serve a request - /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space. - /// However, some 32-bit and 16-bit platforms may successfully serve a request for - /// more than `isize::MAX` bytes with things like Physical Address - /// Extension. As such, memory acquired directly from allocators or memory - /// mapped files *may* be too large to handle with this function. - /// - /// Consider using [`wrapping_sub`] instead if these constraints are - /// difficult to satisfy. The only advantage of this method is that it - /// enables more aggressive compiler optimizations. - /// - /// [`wrapping_sub`]: #method.wrapping_sub - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// let s: &str = "123"; - /// - /// unsafe { - /// let end: *const u8 = s.as_ptr().add(3); - /// println!("{}", *end.sub(1) as char); - /// println!("{}", *end.sub(2) as char); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn sub(self, count: usize) -> Self - where - T: Sized, - { - self.offset((count as isize).wrapping_neg()) - } - - /// Calculates the offset from a pointer using wrapping arithmetic. - /// (convenience for `.wrapping_offset(count as isize)`) - /// - /// `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`). - /// - /// In particular, the resulting pointer remains attached to the same allocated - /// object that `self` points to. It may *not* be used to access a - /// different allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// Compared to [`add`], this method basically delays the requirement of staying - /// within the same allocated object: [`add`] is immediate Undefined Behavior when - /// crossing object boundaries; `wrapping_add` produces a pointer but still leads - /// to Undefined Behavior if that pointer is dereferenced. [`add`] can be optimized - /// better and is thus preferrable in performance-sensitive code. - /// - /// If you need to cross object boundaries, cast the pointer to an integer and - /// do the arithmetic there. - /// - /// [`add`]: #method.add - /// - /// # 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_add(6); - /// - /// // This loop prints "1, 3, 5, " - /// while ptr != end_rounded_up { - /// unsafe { - /// print!("{}, ", *ptr); - /// } - /// ptr = ptr.wrapping_add(step); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub fn wrapping_add(self, count: usize) -> Self - where - T: Sized, - { - self.wrapping_offset(count as isize) - } - - /// Calculates the offset from a pointer using wrapping arithmetic. - /// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`) - /// - /// `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`). - /// - /// In particular, the resulting pointer remains attached to the same allocated - /// object that `self` points to. It may *not* be used to access a - /// different allocated object. Note that in Rust, - /// every (stack-allocated) variable is considered a separate allocated object. - /// - /// Compared to [`sub`], this method basically delays the requirement of staying - /// within the same allocated object: [`sub`] is immediate Undefined Behavior when - /// crossing object boundaries; `wrapping_sub` produces a pointer but still leads - /// to Undefined Behavior if that pointer is dereferenced. [`sub`] can be optimized - /// better and is thus preferrable in performance-sensitive code. - /// - /// If you need to cross object boundaries, cast the pointer to an integer and - /// do the arithmetic there. - /// - /// [`sub`]: #method.sub - /// - /// # Examples - /// - /// Basic usage: - /// - /// ``` - /// // Iterate using a raw pointer in increments of two elements (backwards) - /// let data = [1u8, 2, 3, 4, 5]; - /// let mut ptr: *const u8 = data.as_ptr(); - /// let start_rounded_down = ptr.wrapping_sub(2); - /// ptr = ptr.wrapping_add(4); - /// let step = 2; - /// // This loop prints "5, 3, 1, " - /// while ptr != start_rounded_down { - /// unsafe { - /// print!("{}, ", *ptr); - /// } - /// ptr = ptr.wrapping_sub(step); - /// } - /// ``` - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub fn wrapping_sub(self, count: usize) -> Self - where - T: Sized, - { - self.wrapping_offset((count as isize).wrapping_neg()) - } - - /// Reads the value from `self` without moving it. This leaves the - /// memory in `self` unchanged. - /// - /// See [`ptr::read`] for safety concerns and examples. - /// - /// [`ptr::read`]: ./ptr/fn.read.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn read(self) -> T - where - T: Sized, - { - read(self) - } - - /// Performs a volatile read of the value from `self` without moving it. This - /// leaves the memory in `self` 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. - /// - /// See [`ptr::read_volatile`] for safety concerns and examples. - /// - /// [`ptr::read_volatile`]: ./ptr/fn.read_volatile.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn read_volatile(self) -> T - where - T: Sized, - { - read_volatile(self) - } - - /// Reads the value from `self` without moving it. This leaves the - /// memory in `self` unchanged. - /// - /// Unlike `read`, the pointer may be unaligned. - /// - /// See [`ptr::read_unaligned`] for safety concerns and examples. - /// - /// [`ptr::read_unaligned`]: ./ptr/fn.read_unaligned.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn read_unaligned(self) -> T - where - T: Sized, - { - read_unaligned(self) - } - - /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source - /// and destination may overlap. - /// - /// NOTE: this has the *same* argument order as [`ptr::copy`]. - /// - /// See [`ptr::copy`] for safety concerns and examples. - /// - /// [`ptr::copy`]: ./ptr/fn.copy.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn copy_to(self, dest: *mut T, count: usize) - where - T: Sized, - { - copy(self, dest, count) - } - - /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source - /// and destination may *not* overlap. - /// - /// NOTE: this has the *same* argument order as [`ptr::copy_nonoverlapping`]. - /// - /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples. - /// - /// [`ptr::copy_nonoverlapping`]: ./ptr/fn.copy_nonoverlapping.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize) - where - T: Sized, - { - copy_nonoverlapping(self, dest, count) - } - - /// Copies `count * size_of<T>` bytes from `src` to `self`. The source - /// and destination may overlap. - /// - /// NOTE: this has the *opposite* argument order of [`ptr::copy`]. - /// - /// See [`ptr::copy`] for safety concerns and examples. - /// - /// [`ptr::copy`]: ./ptr/fn.copy.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn copy_from(self, src: *const T, count: usize) - where - T: Sized, - { - copy(src, self, count) - } - - /// Copies `count * size_of<T>` bytes from `src` to `self`. The source - /// and destination may *not* overlap. - /// - /// NOTE: this has the *opposite* argument order of [`ptr::copy_nonoverlapping`]. - /// - /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples. - /// - /// [`ptr::copy_nonoverlapping`]: ./ptr/fn.copy_nonoverlapping.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn copy_from_nonoverlapping(self, src: *const T, count: usize) - where - T: Sized, - { - copy_nonoverlapping(src, self, count) - } - - /// Executes the destructor (if any) of the pointed-to value. - /// - /// See [`ptr::drop_in_place`] for safety concerns and examples. - /// - /// [`ptr::drop_in_place`]: ./ptr/fn.drop_in_place.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn drop_in_place(self) { - drop_in_place(self) - } - - /// Overwrites a memory location with the given value without reading or - /// dropping the old value. - /// - /// See [`ptr::write`] for safety concerns and examples. - /// - /// [`ptr::write`]: ./ptr/fn.write.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn write(self, val: T) - where - T: Sized, - { - write(self, val) - } - - /// Invokes memset on the specified pointer, setting `count * size_of::<T>()` - /// bytes of memory starting at `self` to `val`. - /// - /// See [`ptr::write_bytes`] for safety concerns and examples. - /// - /// [`ptr::write_bytes`]: ./ptr/fn.write_bytes.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn write_bytes(self, val: u8, count: usize) - where - T: Sized, - { - write_bytes(self, val, count) - } - - /// 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. - /// - /// See [`ptr::write_volatile`] for safety concerns and examples. - /// - /// [`ptr::write_volatile`]: ./ptr/fn.write_volatile.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn write_volatile(self, val: T) - where - T: Sized, - { - write_volatile(self, val) - } - - /// Overwrites a memory location with the given value without reading or - /// dropping the old value. - /// - /// Unlike `write`, the pointer may be unaligned. - /// - /// See [`ptr::write_unaligned`] for safety concerns and examples. - /// - /// [`ptr::write_unaligned`]: ./ptr/fn.write_unaligned.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn write_unaligned(self, val: T) - where - T: Sized, - { - write_unaligned(self, val) - } - - /// Replaces the value at `self` with `src`, returning the old - /// value, without dropping either. - /// - /// See [`ptr::replace`] for safety concerns and examples. - /// - /// [`ptr::replace`]: ./ptr/fn.replace.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn replace(self, src: T) -> T - where - T: Sized, - { - replace(self, src) - } - - /// Swaps the values at two mutable locations of the same type, without - /// deinitializing either. They may overlap, unlike `mem::swap` which is - /// otherwise equivalent. - /// - /// See [`ptr::swap`] for safety concerns and examples. - /// - /// [`ptr::swap`]: ./ptr/fn.swap.html - #[stable(feature = "pointer_methods", since = "1.26.0")] - #[inline] - pub unsafe fn swap(self, with: *mut T) - where - T: Sized, - { - swap(self, with) - } - - /// Computes the offset that needs to be applied to the pointer in order to make it aligned to - /// `align`. - /// - /// If it is not possible to align the pointer, the implementation returns - /// `usize::max_value()`. It is permissible for the implementation to *always* - /// return `usize::max_value()`. Only your algorithm's performance can depend - /// on getting a usable offset here, not its correctness. - /// - /// The offset is expressed in number of `T` elements, and not bytes. The value returned can be - /// used with the `wrapping_add` method. - /// - /// There are no guarantees whatsoever that offsetting the pointer will not overflow or go - /// beyond the allocation that the pointer points into. It is up to the caller to ensure that - /// the returned offset is correct in all terms other than alignment. - /// - /// # Panics - /// - /// The function panics if `align` is not a power-of-two. - /// - /// # Examples - /// - /// Accessing adjacent `u8` as `u16` - /// - /// ``` - /// # fn foo(n: usize) { - /// # use std::mem::align_of; - /// # unsafe { - /// let x = [5u8, 6u8, 7u8, 8u8, 9u8]; - /// let ptr = &x[n] as *const u8; - /// let offset = ptr.align_offset(align_of::<u16>()); - /// if offset < x.len() - n - 1 { - /// let u16_ptr = ptr.add(offset) as *const u16; - /// assert_ne!(*u16_ptr, 500); - /// } else { - /// // while the pointer can be aligned via `offset`, it would point - /// // outside the allocation - /// } - /// # } } - /// ``` - #[stable(feature = "align_offset", since = "1.36.0")] - pub fn align_offset(self, align: usize) -> usize - where - T: Sized, - { - if !align.is_power_of_two() { - panic!("align_offset: align is not a power-of-two"); - } - unsafe { align_offset(self, align) } - } -} - /// Align pointer `p`. /// /// Calculate offset (in terms of elements of `stride` stride) that has to be applied @@ -2728,29 +1150,6 @@ pub(crate) unsafe fn align_offset<T: Sized>(p: *const T, a: usize) -> usize { usize::max_value() } -// 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 {} - /// Compares raw pointers for equality. /// /// This is the same as using the `==` operator, but less generic: @@ -2944,88 +1343,3 @@ 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 - } -} |