diff --git a/src/buf/buf_mut.rs b/src/buf/buf_mut.rs
index ecf4720ba656b506a04c47c294df28d16f664ee7..d976ec4191cd7b321a3b80e824c041998a7d105f 100644
--- a/src/buf/buf_mut.rs
+++ b/src/buf/buf_mut.rs
@@ -1,10 +1,10 @@
#[cfg(feature = "std")]
use super::Writer;
-use core::{mem, cmp, ptr, usize};
+use core::{cmp, mem::{self, MaybeUninit}, ptr, usize};
#[cfg(feature = "std")]
-use std::io::IoSliceMut;
+use std::fmt;
use alloc::{vec::Vec, boxed::Box};
@@ -72,13 +72,15 @@ pub trait BufMut {
/// let mut buf = Vec::with_capacity(16);
///
/// unsafe {
- /// buf.bytes_mut()[0] = b'h';
- /// buf.bytes_mut()[1] = b'e';
+ /// // MaybeUninit::as_mut_ptr
+ /// buf.bytes_mut()[0].as_mut_ptr().write(b'h');
+ /// buf.bytes_mut()[1].as_mut_ptr().write(b'e');
///
/// buf.advance_mut(2);
///
- /// buf.bytes_mut()[0] = b'l';
- /// buf.bytes_mut()[1..3].copy_from_slice(b"lo");
+ /// buf.bytes_mut()[0].as_mut_ptr().write(b'l');
+ /// buf.bytes_mut()[1].as_mut_ptr().write(b'l');
+ /// buf.bytes_mut()[2].as_mut_ptr().write(b'o');
///
/// buf.advance_mut(3);
/// }
@@ -139,13 +141,15 @@ pub trait BufMut {
/// let mut buf = Vec::with_capacity(16);
///
/// unsafe {
- /// buf.bytes_mut()[0] = b'h';
- /// buf.bytes_mut()[1] = b'e';
+ /// // MaybeUninit::as_mut_ptr
+ /// buf.bytes_mut()[0].as_mut_ptr().write(b'h');
+ /// buf.bytes_mut()[1].as_mut_ptr().write(b'e');
///
/// buf.advance_mut(2);
///
- /// buf.bytes_mut()[0] = b'l';
- /// buf.bytes_mut()[1..3].copy_from_slice(b"lo");
+ /// buf.bytes_mut()[0].as_mut_ptr().write(b'l');
+ /// buf.bytes_mut()[1].as_mut_ptr().write(b'l');
+ /// buf.bytes_mut()[2].as_mut_ptr().write(b'o');
///
/// buf.advance_mut(3);
/// }
@@ -161,7 +165,7 @@ pub trait BufMut {
/// `bytes_mut` returning an empty slice implies that `remaining_mut` will
/// return 0 and `remaining_mut` returning 0 implies that `bytes_mut` will
/// return an empty slice.
- unsafe fn bytes_mut(&mut self) -> &mut [u8];
+ fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>];
/// Fills `dst` with potentially multiple mutable slices starting at `self`'s
/// current position.
@@ -192,13 +196,13 @@ pub trait BufMut {
///
/// [`readv`]: http://man7.org/linux/man-pages/man2/readv.2.html
#[cfg(feature = "std")]
- unsafe fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize {
+ fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize {
if dst.is_empty() {
return 0;
}
if self.has_remaining_mut() {
- dst[0] = IoSliceMut::new(self.bytes_mut());
+ dst[0] = IoSliceMut::from(self.bytes_mut());
1
} else {
0
@@ -238,7 +242,7 @@ pub trait BufMut {
ptr::copy_nonoverlapping(
s.as_ptr(),
- d.as_mut_ptr(),
+ d.as_mut_ptr() as *mut u8,
l);
}
@@ -280,7 +284,7 @@ pub trait BufMut {
ptr::copy_nonoverlapping(
src[off..].as_ptr(),
- dst.as_mut_ptr(),
+ dst.as_mut_ptr() as *mut u8,
cnt);
off += cnt;
@@ -931,12 +935,12 @@ impl<T: BufMut + ?Sized> BufMut for &mut T {
(**self).remaining_mut()
}
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
+ fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>] {
(**self).bytes_mut()
}
#[cfg(feature = "std")]
- unsafe fn bytes_vectored_mut<'b>(&'b mut self, dst: &mut [IoSliceMut<'b>]) -> usize {
+ fn bytes_vectored_mut<'b>(&'b mut self, dst: &mut [IoSliceMut<'b>]) -> usize {
(**self).bytes_vectored_mut(dst)
}
@@ -950,12 +954,12 @@ impl<T: BufMut + ?Sized> BufMut for Box<T> {
(**self).remaining_mut()
}
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
+ fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>] {
(**self).bytes_mut()
}
#[cfg(feature = "std")]
- unsafe fn bytes_vectored_mut<'b>(&'b mut self, dst: &mut [IoSliceMut<'b>]) -> usize {
+ fn bytes_vectored_mut<'b>(&'b mut self, dst: &mut [IoSliceMut<'b>]) -> usize {
(**self).bytes_vectored_mut(dst)
}
@@ -971,8 +975,9 @@ impl BufMut for &mut [u8] {
}
#[inline]
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
- self
+ fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>] {
+ // MaybeUninit is repr(transparent), so safe to transmute
+ unsafe { mem::transmute(&mut **self) }
}
#[inline]
@@ -1003,7 +1008,7 @@ impl BufMut for Vec<u8> {
}
#[inline]
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
+ fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>] {
use core::slice;
if self.capacity() == self.len() {
@@ -1013,11 +1018,54 @@ impl BufMut for Vec<u8> {
let cap = self.capacity();
let len = self.len();
- let ptr = self.as_mut_ptr();
- &mut slice::from_raw_parts_mut(ptr, cap)[len..]
+ let ptr = self.as_mut_ptr() as *mut MaybeUninit<u8>;
+ unsafe {
+ &mut slice::from_raw_parts_mut(ptr, cap)[len..]
+ }
}
}
// The existence of this function makes the compiler catch if the BufMut
// trait is "object-safe" or not.
fn _assert_trait_object(_b: &dyn BufMut) {}
+
+// ===== impl IoSliceMut =====
+
+/// A buffer type used for `readv`.
+///
+/// This is a wrapper around an `std::io::IoSliceMut`, but does not expose
+/// the inner bytes in a safe API, as they may point at uninitialized memory.
+///
+/// This is `repr(transparent)` of the `std::io::IoSliceMut`, so it is valid to
+/// transmute them. However, as the memory might be uninitialized, care must be
+/// taken to not *read* the internal bytes, only *write* to them.
+#[repr(transparent)]
+#[cfg(feature = "std")]
+pub struct IoSliceMut<'a>(std::io::IoSliceMut<'a>);
+
+#[cfg(feature = "std")]
+impl fmt::Debug for IoSliceMut<'_> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_struct("IoSliceMut")
+ .field("len", &self.0.len())
+ .finish()
+ }
+}
+
+#[cfg(feature = "std")]
+impl<'a> From<&'a mut [u8]> for IoSliceMut<'a> {
+ fn from(buf: &'a mut [u8]) -> IoSliceMut<'a> {
+ IoSliceMut(std::io::IoSliceMut::new(buf))
+ }
+}
+
+#[cfg(feature = "std")]
+impl<'a> From<&'a mut [MaybeUninit<u8>]> for IoSliceMut<'a> {
+ fn from(buf: &'a mut [MaybeUninit<u8>]) -> IoSliceMut<'a> {
+ IoSliceMut(std::io::IoSliceMut::new(unsafe {
+ // We don't look at the contents, and `std::io::IoSliceMut`
+ // doesn't either.
+ mem::transmute::<&'a mut [MaybeUninit<u8>], &'a mut [u8]>(buf)
+ }))
+ }
+}
diff --git a/src/buf/chain.rs b/src/buf/chain.rs
index 7090ac49f9dd53e250a7df5a05236b1136264ffe..2805bf3654ae087b20db661a8a3399a8a8831a92 100644
--- a/src/buf/chain.rs
+++ b/src/buf/chain.rs
@@ -1,8 +1,12 @@
use crate::{Buf, BufMut};
use crate::buf::IntoIter;
+use core::mem::MaybeUninit;
+
+#[cfg(feature = "std")]
+use std::io::{IoSlice};
#[cfg(feature = "std")]
-use std::io::{IoSlice, IoSliceMut};
+use crate::buf::IoSliceMut;
/// A `Chain` sequences two buffers.
///
@@ -196,7 +200,7 @@ impl<T, U> BufMut for Chain<T, U>
self.a.remaining_mut() + self.b.remaining_mut()
}
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
+ fn bytes_mut(&mut self) -> &mut [MaybeUninit<u8>] {
if self.a.has_remaining_mut() {
self.a.bytes_mut()
} else {
@@ -223,7 +227,7 @@ impl<T, U> BufMut for Chain<T, U>
}
#[cfg(feature = "std")]
- unsafe fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize {
+ fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize {
let mut n = self.a.bytes_vectored_mut(dst);
n += self.b.bytes_vectored_mut(&mut dst[n..]);
n
diff --git a/src/buf/mod.rs b/src/buf/mod.rs
index 15e032de00c046c007bb4e180125494994fccf13..1448abdea5555bc461c94ce4a354dbcebf4e6f26 100644
--- a/src/buf/mod.rs
+++ b/src/buf/mod.rs
@@ -31,6 +31,8 @@ mod writer;
pub use self::buf_impl::Buf;
pub use self::buf_mut::BufMut;
+#[cfg(feature = "std")]
+pub use self::buf_mut::IoSliceMut;
pub use self::chain::Chain;
pub use self::iter::IntoIter;
#[cfg(feature = "std")]
diff --git a/src/bytes_mut.rs b/src/bytes_mut.rs
index 6777929c686a11cbdabe9031e2c389173acebcff..8895602f7ced87bd537c104e978e66f6a7b8b514 100644
--- a/src/bytes_mut.rs
+++ b/src/bytes_mut.rs
@@ -926,19 +926,9 @@ impl BufMut for BytesMut {
}
#[inline]
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
- slice::from_raw_parts_mut(self.ptr.as_ptr().offset(self.len as isize), self.cap)
- }
-
- #[inline]
- fn put_slice(&mut self, src: &[u8]) {
- assert!(self.remaining_mut() >= src.len());
-
- let len = src.len();
-
+ fn bytes_mut(&mut self) -> &mut [mem::MaybeUninit<u8>] {
unsafe {
- self.bytes_mut()[..len].copy_from_slice(src);
- self.advance_mut(len);
+ slice::from_raw_parts_mut(self.ptr.as_ptr().offset(self.len as isize) as *mut mem::MaybeUninit<u8>, self.cap)
}
}
}
@@ -1085,11 +1075,12 @@ impl Extend<u8> for BytesMut {
let (lower, _) = iter.size_hint();
self.reserve(lower);
+ // TODO: optimize
+ // 1. If self.kind() == KIND_VEC, use Vec::extend
+ // 2. Make `reserve` inline-able
for b in iter {
- unsafe {
- self.bytes_mut()[0] = b;
- self.advance_mut(1);
- }
+ self.reserve(1);
+ self.put_u8(b);
}
}
}
diff --git a/src/either.rs b/src/either.rs
index 76bee808fa452ca26a1bbf0d2c91b28a798c5e41..9a0fd396f8ef17697ead606bc7a90df84ac5a789 100644
--- a/src/either.rs
+++ b/src/either.rs
@@ -4,7 +4,9 @@ use either::Either;
use either::Either::*;
#[cfg(feature = "std")]
-use std::io::{IoSlice, IoSliceMut};
+use std::io::IoSlice;
+#[cfg(feature = "std")]
+use crate::buf::IoSliceMut;
impl<L, R> Buf for Either<L, R>
where
@@ -60,7 +62,7 @@ where
}
}
- unsafe fn bytes_mut(&mut self) -> &mut [u8] {
+ fn bytes_mut(&mut self) -> &mut [core::mem::MaybeUninit<u8>] {
match *self {
Left(ref mut b) => b.bytes_mut(),
Right(ref mut b) => b.bytes_mut(),
@@ -68,7 +70,7 @@ where
}
#[cfg(feature = "std")]
- unsafe fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize {
+ fn bytes_vectored_mut<'a>(&'a mut self, dst: &mut [IoSliceMut<'a>]) -> usize {
match *self {
Left(ref mut b) => b.bytes_vectored_mut(dst),
Right(ref mut b) => b.bytes_vectored_mut(dst),
diff --git a/tests/test_buf_mut.rs b/tests/test_buf_mut.rs
index 94654b7d2c498f2ecfc20c46871be8bbe4b27cca..0d372d1ec53962857a577d005ef50474931841fa 100644
--- a/tests/test_buf_mut.rs
+++ b/tests/test_buf_mut.rs
@@ -1,9 +1,8 @@
#![deny(warnings, rust_2018_idioms)]
-use bytes::{BufMut, BytesMut};
+use bytes::{buf::IoSliceMut, BufMut, BytesMut};
use std::usize;
use std::fmt::Write;
-use std::io::IoSliceMut;
#[test]
fn test_vec_as_mut_buf() {
@@ -11,9 +10,7 @@ fn test_vec_as_mut_buf() {
assert_eq!(buf.remaining_mut(), usize::MAX);
- unsafe {
- assert!(buf.bytes_mut().len() >= 64);
- }
+ assert!(buf.bytes_mut().len() >= 64);
buf.put(&b"zomg"[..]);
@@ -72,20 +69,16 @@ fn test_clone() {
fn test_bufs_vec_mut() {
let b1: &mut [u8] = &mut [];
let b2: &mut [u8] = &mut [];
- let mut dst = [IoSliceMut::new(b1), IoSliceMut::new(b2)];
+ let mut dst = [IoSliceMut::from(b1), IoSliceMut::from(b2)];
// with no capacity
let mut buf = BytesMut::new();
assert_eq!(buf.capacity(), 0);
- unsafe {
- assert_eq!(0, buf.bytes_vectored_mut(&mut dst[..]));
- }
+ assert_eq!(0, buf.bytes_vectored_mut(&mut dst[..]));
// with capacity
let mut buf = BytesMut::with_capacity(64);
- unsafe {
- assert_eq!(1, buf.bytes_vectored_mut(&mut dst[..]));
- }
+ assert_eq!(1, buf.bytes_vectored_mut(&mut dst[..]));
}
#[test]
diff --git a/tests/test_bytes.rs b/tests/test_bytes.rs
index 212189eeaf24d2faad8b6993ac56c50274b78d6f..9fa8019eef3a4d7800a58e99eac992e8fee97ed4 100644
--- a/tests/test_bytes.rs
+++ b/tests/test_bytes.rs
@@ -464,6 +464,16 @@ fn extend_from_slice_mut() {
}
}
+#[test]
+fn extend_mut_without_size_hint() {
+ let mut bytes = BytesMut::with_capacity(0);
+ let mut long_iter = LONG.iter();
+
+ // Use iter::from_fn since it doesn't know a size_hint
+ bytes.extend(std::iter::from_fn(|| long_iter.next()));
+ assert_eq!(*bytes, LONG[..]);
+}
+
#[test]
fn from_static() {
let mut a = Bytes::from_static(b"ab");