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-rw-r--r--vendor/bytes/src/buf/uninit_slice.rs257
1 files changed, 257 insertions, 0 deletions
diff --git a/vendor/bytes/src/buf/uninit_slice.rs b/vendor/bytes/src/buf/uninit_slice.rs
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+++ b/vendor/bytes/src/buf/uninit_slice.rs
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+use core::fmt;
+use core::mem::MaybeUninit;
+use core::ops::{
+ Index, IndexMut, Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive,
+};
+
+/// Uninitialized byte slice.
+///
+/// Returned by `BufMut::chunk_mut()`, the referenced byte slice may be
+/// uninitialized. The wrapper provides safe access without introducing
+/// undefined behavior.
+///
+/// The safety invariants of this wrapper are:
+///
+/// 1. Reading from an `UninitSlice` is undefined behavior.
+/// 2. Writing uninitialized bytes to an `UninitSlice` is undefined behavior.
+///
+/// The difference between `&mut UninitSlice` and `&mut [MaybeUninit<u8>]` is
+/// that it is possible in safe code to write uninitialized bytes to an
+/// `&mut [MaybeUninit<u8>]`, which this type prohibits.
+#[repr(transparent)]
+pub struct UninitSlice([MaybeUninit<u8>]);
+
+impl UninitSlice {
+ /// Creates a `&mut UninitSlice` wrapping a slice of initialised memory.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::buf::UninitSlice;
+ ///
+ /// let mut buffer = [0u8; 64];
+ /// let slice = UninitSlice::new(&mut buffer[..]);
+ /// ```
+ #[inline]
+ pub fn new(slice: &mut [u8]) -> &mut UninitSlice {
+ unsafe { &mut *(slice as *mut [u8] as *mut [MaybeUninit<u8>] as *mut UninitSlice) }
+ }
+
+ /// Creates a `&mut UninitSlice` wrapping a slice of uninitialised memory.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::buf::UninitSlice;
+ /// use core::mem::MaybeUninit;
+ ///
+ /// let mut buffer = [MaybeUninit::uninit(); 64];
+ /// let slice = UninitSlice::uninit(&mut buffer[..]);
+ ///
+ /// let mut vec = Vec::with_capacity(1024);
+ /// let spare: &mut UninitSlice = vec.spare_capacity_mut().into();
+ /// ```
+ #[inline]
+ pub fn uninit(slice: &mut [MaybeUninit<u8>]) -> &mut UninitSlice {
+ unsafe { &mut *(slice as *mut [MaybeUninit<u8>] as *mut UninitSlice) }
+ }
+
+ fn uninit_ref(slice: &[MaybeUninit<u8>]) -> &UninitSlice {
+ unsafe { &*(slice as *const [MaybeUninit<u8>] as *const UninitSlice) }
+ }
+
+ /// Create a `&mut UninitSlice` from a pointer and a length.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` references a valid memory region owned
+ /// by the caller representing a byte slice for the duration of `'a`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::buf::UninitSlice;
+ ///
+ /// let bytes = b"hello world".to_vec();
+ /// let ptr = bytes.as_ptr() as *mut _;
+ /// let len = bytes.len();
+ ///
+ /// let slice = unsafe { UninitSlice::from_raw_parts_mut(ptr, len) };
+ /// ```
+ #[inline]
+ pub unsafe fn from_raw_parts_mut<'a>(ptr: *mut u8, len: usize) -> &'a mut UninitSlice {
+ let maybe_init: &mut [MaybeUninit<u8>] =
+ core::slice::from_raw_parts_mut(ptr as *mut _, len);
+ Self::uninit(maybe_init)
+ }
+
+ /// Write a single byte at the specified offset.
+ ///
+ /// # Panics
+ ///
+ /// The function panics if `index` is out of bounds.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::buf::UninitSlice;
+ ///
+ /// let mut data = [b'f', b'o', b'o'];
+ /// let slice = unsafe { UninitSlice::from_raw_parts_mut(data.as_mut_ptr(), 3) };
+ ///
+ /// slice.write_byte(0, b'b');
+ ///
+ /// assert_eq!(b"boo", &data[..]);
+ /// ```
+ #[inline]
+ pub fn write_byte(&mut self, index: usize, byte: u8) {
+ assert!(index < self.len());
+
+ unsafe { self[index..].as_mut_ptr().write(byte) }
+ }
+
+ /// Copies bytes from `src` into `self`.
+ ///
+ /// The length of `src` must be the same as `self`.
+ ///
+ /// # Panics
+ ///
+ /// The function panics if `src` has a different length than `self`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::buf::UninitSlice;
+ ///
+ /// let mut data = [b'f', b'o', b'o'];
+ /// let slice = unsafe { UninitSlice::from_raw_parts_mut(data.as_mut_ptr(), 3) };
+ ///
+ /// slice.copy_from_slice(b"bar");
+ ///
+ /// assert_eq!(b"bar", &data[..]);
+ /// ```
+ #[inline]
+ pub fn copy_from_slice(&mut self, src: &[u8]) {
+ use core::ptr;
+
+ assert_eq!(self.len(), src.len());
+
+ unsafe {
+ ptr::copy_nonoverlapping(src.as_ptr(), self.as_mut_ptr(), self.len());
+ }
+ }
+
+ /// Return a raw pointer to the slice's buffer.
+ ///
+ /// # Safety
+ ///
+ /// The caller **must not** read from the referenced memory and **must not**
+ /// write **uninitialized** bytes to the slice either.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::BufMut;
+ ///
+ /// let mut data = [0, 1, 2];
+ /// let mut slice = &mut data[..];
+ /// let ptr = BufMut::chunk_mut(&mut slice).as_mut_ptr();
+ /// ```
+ #[inline]
+ pub fn as_mut_ptr(&mut self) -> *mut u8 {
+ self.0.as_mut_ptr() as *mut _
+ }
+
+ /// Return a `&mut [MaybeUninit<u8>]` to this slice's buffer.
+ ///
+ /// # Safety
+ ///
+ /// The caller **must not** read from the referenced memory and **must not** write
+ /// **uninitialized** bytes to the slice either. This is because `BufMut` implementation
+ /// that created the `UninitSlice` knows which parts are initialized. Writing uninitialized
+ /// bytes to the slice may cause the `BufMut` to read those bytes and trigger undefined
+ /// behavior.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::BufMut;
+ ///
+ /// let mut data = [0, 1, 2];
+ /// let mut slice = &mut data[..];
+ /// unsafe {
+ /// let uninit_slice = BufMut::chunk_mut(&mut slice).as_uninit_slice_mut();
+ /// };
+ /// ```
+ #[inline]
+ pub unsafe fn as_uninit_slice_mut(&mut self) -> &mut [MaybeUninit<u8>] {
+ &mut self.0
+ }
+
+ /// Returns the number of bytes in the slice.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use bytes::BufMut;
+ ///
+ /// let mut data = [0, 1, 2];
+ /// let mut slice = &mut data[..];
+ /// let len = BufMut::chunk_mut(&mut slice).len();
+ ///
+ /// assert_eq!(len, 3);
+ /// ```
+ #[inline]
+ pub fn len(&self) -> usize {
+ self.0.len()
+ }
+}
+
+impl fmt::Debug for UninitSlice {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ fmt.debug_struct("UninitSlice[...]").finish()
+ }
+}
+
+impl<'a> From<&'a mut [u8]> for &'a mut UninitSlice {
+ fn from(slice: &'a mut [u8]) -> Self {
+ UninitSlice::new(slice)
+ }
+}
+
+impl<'a> From<&'a mut [MaybeUninit<u8>]> for &'a mut UninitSlice {
+ fn from(slice: &'a mut [MaybeUninit<u8>]) -> Self {
+ UninitSlice::uninit(slice)
+ }
+}
+
+macro_rules! impl_index {
+ ($($t:ty),*) => {
+ $(
+ impl Index<$t> for UninitSlice {
+ type Output = UninitSlice;
+
+ #[inline]
+ fn index(&self, index: $t) -> &UninitSlice {
+ UninitSlice::uninit_ref(&self.0[index])
+ }
+ }
+
+ impl IndexMut<$t> for UninitSlice {
+ #[inline]
+ fn index_mut(&mut self, index: $t) -> &mut UninitSlice {
+ UninitSlice::uninit(&mut self.0[index])
+ }
+ }
+ )*
+ };
+}
+
+impl_index!(
+ Range<usize>,
+ RangeFrom<usize>,
+ RangeFull,
+ RangeInclusive<usize>,
+ RangeTo<usize>,
+ RangeToInclusive<usize>
+);
generated by cgit v1.2.3 (git 2.39.1) at 2026-02-03 07:46:48 +0000