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Diffstat (limited to 'vendor/bytes/src/lib.rs')
| -rw-r--r-- | vendor/bytes/src/lib.rs | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/vendor/bytes/src/lib.rs b/vendor/bytes/src/lib.rs new file mode 100644 index 00000000..08c42494 --- /dev/null +++ b/vendor/bytes/src/lib.rs @@ -0,0 +1,199 @@ +#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)] +#![doc(test( + no_crate_inject, + attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables)) +))] +#![no_std] +#![cfg_attr(docsrs, feature(doc_cfg))] + +//! Provides abstractions for working with bytes. +//! +//! The `bytes` crate provides an efficient byte buffer structure +//! ([`Bytes`]) and traits for working with buffer +//! implementations ([`Buf`], [`BufMut`]). +//! +//! # `Bytes` +//! +//! `Bytes` is an efficient container for storing and operating on contiguous +//! slices of memory. It is intended for use primarily in networking code, but +//! could have applications elsewhere as well. +//! +//! `Bytes` values facilitate zero-copy network programming by allowing multiple +//! `Bytes` objects to point to the same underlying memory. This is managed by +//! using a reference count to track when the memory is no longer needed and can +//! be freed. +//! +//! A `Bytes` handle can be created directly from an existing byte store (such as `&[u8]` +//! or `Vec<u8>`), but usually a `BytesMut` is used first and written to. For +//! example: +//! +//! ```rust +//! use bytes::{BytesMut, BufMut}; +//! +//! let mut buf = BytesMut::with_capacity(1024); +//! buf.put(&b"hello world"[..]); +//! buf.put_u16(1234); +//! +//! let a = buf.split(); +//! assert_eq!(a, b"hello world\x04\xD2"[..]); +//! +//! buf.put(&b"goodbye world"[..]); +//! +//! let b = buf.split(); +//! assert_eq!(b, b"goodbye world"[..]); +//! +//! assert_eq!(buf.capacity(), 998); +//! ``` +//! +//! In the above example, only a single buffer of 1024 is allocated. The handles +//! `a` and `b` will share the underlying buffer and maintain indices tracking +//! the view into the buffer represented by the handle. +//! +//! See the [struct docs](`Bytes`) for more details. +//! +//! # `Buf`, `BufMut` +//! +//! These two traits provide read and write access to buffers. The underlying +//! storage may or may not be in contiguous memory. For example, `Bytes` is a +//! buffer that guarantees contiguous memory, but a [rope] stores the bytes in +//! disjoint chunks. `Buf` and `BufMut` maintain cursors tracking the current +//! position in the underlying byte storage. When bytes are read or written, the +//! cursor is advanced. +//! +//! [rope]: https://en.wikipedia.org/wiki/Rope_(data_structure) +//! +//! ## Relation with `Read` and `Write` +//! +//! At first glance, it may seem that `Buf` and `BufMut` overlap in +//! functionality with [`std::io::Read`] and [`std::io::Write`]. However, they +//! serve different purposes. A buffer is the value that is provided as an +//! argument to `Read::read` and `Write::write`. `Read` and `Write` may then +//! perform a syscall, which has the potential of failing. Operations on `Buf` +//! and `BufMut` are infallible. + +extern crate alloc; + +#[cfg(feature = "std")] +extern crate std; + +pub mod buf; +pub use crate::buf::{Buf, BufMut}; + +mod bytes; +mod bytes_mut; +mod fmt; +mod loom; +pub use crate::bytes::Bytes; +pub use crate::bytes_mut::BytesMut; + +// Optional Serde support +#[cfg(feature = "serde")] +mod serde; + +#[inline(never)] +#[cold] +fn abort() -> ! { + #[cfg(feature = "std")] + { + std::process::abort(); + } + + #[cfg(not(feature = "std"))] + { + struct Abort; + impl Drop for Abort { + fn drop(&mut self) { + panic!(); + } + } + let _a = Abort; + panic!("abort"); + } +} + +#[inline(always)] +#[cfg(feature = "std")] +fn saturating_sub_usize_u64(a: usize, b: u64) -> usize { + use core::convert::TryFrom; + match usize::try_from(b) { + Ok(b) => a.saturating_sub(b), + Err(_) => 0, + } +} + +#[inline(always)] +#[cfg(feature = "std")] +fn min_u64_usize(a: u64, b: usize) -> usize { + use core::convert::TryFrom; + match usize::try_from(a) { + Ok(a) => usize::min(a, b), + Err(_) => b, + } +} + +/// Error type for the `try_get_` methods of [`Buf`]. +/// Indicates that there were not enough remaining +/// bytes in the buffer while attempting +/// to get a value from a [`Buf`] with one +/// of the `try_get_` methods. +#[derive(Debug, PartialEq, Eq)] +pub struct TryGetError { + /// The number of bytes necessary to get the value + pub requested: usize, + + /// The number of bytes available in the buffer + pub available: usize, +} + +impl core::fmt::Display for TryGetError { + fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> Result<(), core::fmt::Error> { + write!( + f, + "Not enough bytes remaining in buffer to read value (requested {} but only {} available)", + self.requested, + self.available + ) + } +} + +#[cfg(feature = "std")] +impl std::error::Error for TryGetError {} + +#[cfg(feature = "std")] +impl From<TryGetError> for std::io::Error { + fn from(error: TryGetError) -> Self { + std::io::Error::new(std::io::ErrorKind::Other, error) + } +} + +/// Panic with a nice error message. +#[cold] +fn panic_advance(error_info: &TryGetError) -> ! { + panic!( + "advance out of bounds: the len is {} but advancing by {}", + error_info.available, error_info.requested + ); +} + +#[cold] +fn panic_does_not_fit(size: usize, nbytes: usize) -> ! { + panic!( + "size too large: the integer type can fit {} bytes, but nbytes is {}", + size, nbytes + ); +} + +/// Precondition: dst >= original +/// +/// The following line is equivalent to: +/// +/// ```rust,ignore +/// self.ptr.as_ptr().offset_from(ptr) as usize; +/// ``` +/// +/// But due to min rust is 1.39 and it is only stabilized +/// in 1.47, we cannot use it. +#[inline] +fn offset_from(dst: *const u8, original: *const u8) -> usize { + dst as usize - original as usize +} |