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slice::from_raw_parts: mention no-wrap-around condition

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Ralf Jung 2023-06-16 14:56:31 +02:00
parent de1ff0a8b5
commit 18b86468b8
1 changed files with 14 additions and 10 deletions
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24
library/core/src/slice/raw.rs
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@ -32,7 +32,8 @@ use crate::ptr;
/// * The memory referenced by the returned slice must not be mutated for the duration
/// of lifetime `'a`, except inside an `UnsafeCell`.
///
/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`.
/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`,
/// and adding that size to `data` must not "wrap around" the address space.
/// See the safety documentation of [`pointer::offset`].
///
/// # Caveat
@ -125,7 +126,8 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
/// (not derived from the return value) for the duration of lifetime `'a`.
/// Both read and write accesses are forbidden.
///
/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`.
/// * The total size `len * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`,
/// and adding that size to `data` must not "wrap around" the address space.
/// See the safety documentation of [`pointer::offset`].
///
/// [valid]: ptr#safety
@ -179,15 +181,16 @@ pub const fn from_mut<T>(s: &mut T) -> &mut [T] {
/// the last element, such that the offset from the end to the start pointer is
/// the length of the slice.
///
/// * The range must contain `N` consecutive properly initialized values of type `T`:
/// * The entire memory range of this slice must be contained within a single allocated object!
/// Slices can never span across multiple allocated objects.
///
/// * The entire memory range of this slice must be contained within a single allocated object!
/// Slices can never span across multiple allocated objects.
/// * The range must contain `N` consecutive properly initialized values of type `T`.
///
/// * The memory referenced by the returned slice must not be mutated for the duration
/// of lifetime `'a`, except inside an `UnsafeCell`.
///
/// * The total length of the range must be no larger than `isize::MAX`.
/// * The total length of the range must be no larger than `isize::MAX`,
/// and adding that size to `data` must not "wrap around" the address space.
/// See the safety documentation of [`pointer::offset`].
///
/// Note that a range created from [`slice::as_ptr_range`] fulfills these requirements.
@ -247,16 +250,17 @@ pub const unsafe fn from_ptr_range<'a, T>(range: Range<*const T>) -> &'a [T] {
/// the last element, such that the offset from the end to the start pointer is
/// the length of the slice.
///
/// * The range must contain `N` consecutive properly initialized values of type `T`:
/// * The entire memory range of this slice must be contained within a single allocated object!
/// Slices can never span across multiple allocated objects.
///
/// * The entire memory range of this slice must be contained within a single allocated object!
/// Slices can never span across multiple allocated objects.
/// * The range must contain `N` consecutive properly initialized values of type `T`.
///
/// * The memory referenced by the returned slice must not be accessed through any other pointer
/// (not derived from the return value) for the duration of lifetime `'a`.
/// Both read and write accesses are forbidden.
///
/// * The total length of the range must be no larger than `isize::MAX`.
/// * The total length of the range must be no larger than `isize::MAX`,
/// and adding that size to `data` must not "wrap around" the address space.
/// See the safety documentation of [`pointer::offset`].
///
/// Note that a range created from [`slice::as_mut_ptr_range`] fulfills these requirements.