From 246f239d9f40f633160f0c18f87a20922d4e77bb Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:06:37 +0200 Subject: Merging debian version 1.65.0+dfsg1-2. Signed-off-by: Daniel Baumann --- library/std/src/io/mod.rs | 93 +++++++++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 44 deletions(-) (limited to 'library/std/src/io/mod.rs') diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs index 96addbd1a..eeace2c43 100644 --- a/library/std/src/io/mod.rs +++ b/library/std/src/io/mod.rs @@ -278,7 +278,7 @@ pub use self::{ }; #[unstable(feature = "read_buf", issue = "78485")] -pub use self::readbuf::ReadBuf; +pub use self::readbuf::{BorrowedBuf, BorrowedCursor}; pub(crate) use error::const_io_error; mod buffered; @@ -362,29 +362,30 @@ pub(crate) fn default_read_to_end(r: &mut R, buf: &mut Vec buf.reserve(32); // buf is full, need more space } - let mut read_buf = ReadBuf::uninit(buf.spare_capacity_mut()); + let mut read_buf: BorrowedBuf<'_> = buf.spare_capacity_mut().into(); // SAFETY: These bytes were initialized but not filled in the previous loop unsafe { - read_buf.assume_init(initialized); + read_buf.set_init(initialized); } - match r.read_buf(&mut read_buf) { + let mut cursor = read_buf.unfilled(); + match r.read_buf(cursor.reborrow()) { Ok(()) => {} Err(e) if e.kind() == ErrorKind::Interrupted => continue, Err(e) => return Err(e), } - if read_buf.filled_len() == 0 { + if cursor.written() == 0 { return Ok(buf.len() - start_len); } // store how much was initialized but not filled - initialized = read_buf.initialized_len() - read_buf.filled_len(); - let new_len = read_buf.filled_len() + buf.len(); + initialized = cursor.init_ref().len(); - // SAFETY: ReadBuf's invariants mean this much memory is init + // SAFETY: BorrowedBuf's invariants mean this much memory is initialized. unsafe { + let new_len = read_buf.filled().len() + buf.len(); buf.set_len(new_len); } @@ -461,12 +462,15 @@ pub(crate) fn default_read_exact(this: &mut R, mut buf: &mut [ } } -pub(crate) fn default_read_buf(read: F, buf: &mut ReadBuf<'_>) -> Result<()> +pub(crate) fn default_read_buf(read: F, mut cursor: BorrowedCursor<'_>) -> Result<()> where F: FnOnce(&mut [u8]) -> Result, { - let n = read(buf.initialize_unfilled())?; - buf.add_filled(n); + let n = read(cursor.ensure_init().init_mut())?; + unsafe { + // SAFETY: we initialised using `ensure_init` so there is no uninit data to advance to. + cursor.advance(n); + } Ok(()) } @@ -803,30 +807,30 @@ pub trait Read { /// Pull some bytes from this source into the specified buffer. /// - /// This is equivalent to the [`read`](Read::read) method, except that it is passed a [`ReadBuf`] rather than `[u8]` to allow use + /// This is equivalent to the [`read`](Read::read) method, except that it is passed a [`BorrowedCursor`] rather than `[u8]` to allow use /// with uninitialized buffers. The new data will be appended to any existing contents of `buf`. /// /// The default implementation delegates to `read`. #[unstable(feature = "read_buf", issue = "78485")] - fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> Result<()> { + fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<()> { default_read_buf(|b| self.read(b), buf) } - /// Read the exact number of bytes required to fill `buf`. + /// Read the exact number of bytes required to fill `cursor`. /// - /// This is equivalent to the [`read_exact`](Read::read_exact) method, except that it is passed a [`ReadBuf`] rather than `[u8]` to + /// This is equivalent to the [`read_exact`](Read::read_exact) method, except that it is passed a [`BorrowedCursor`] rather than `[u8]` to /// allow use with uninitialized buffers. #[unstable(feature = "read_buf", issue = "78485")] - fn read_buf_exact(&mut self, buf: &mut ReadBuf<'_>) -> Result<()> { - while buf.remaining() > 0 { - let prev_filled = buf.filled().len(); - match self.read_buf(buf) { + fn read_buf_exact(&mut self, mut cursor: BorrowedCursor<'_>) -> Result<()> { + while cursor.capacity() > 0 { + let prev_written = cursor.written(); + match self.read_buf(cursor.reborrow()) { Ok(()) => {} Err(e) if e.kind() == ErrorKind::Interrupted => continue, Err(e) => return Err(e), } - if buf.filled().len() == prev_filled { + if cursor.written() == prev_written { return Err(Error::new(ErrorKind::UnexpectedEof, "failed to fill buffer")); } } @@ -883,6 +887,10 @@ pub trait Read { /// The yielded item is [`Ok`] if a byte was successfully read and [`Err`] /// otherwise. EOF is mapped to returning [`None`] from this iterator. /// + /// The default implementation calls `read` for each byte, + /// which can be very inefficient for data that's not in memory, + /// such as [`File`]. Consider using a [`BufReader`] in such cases. + /// /// # Examples /// /// [`File`]s implement `Read`: @@ -895,10 +903,11 @@ pub trait Read { /// ```no_run /// use std::io; /// use std::io::prelude::*; + /// use std::io::BufReader; /// use std::fs::File; /// /// fn main() -> io::Result<()> { - /// let f = File::open("foo.txt")?; + /// let f = BufReader::new(File::open("foo.txt")?); /// /// for byte in f.bytes() { /// println!("{}", byte.unwrap()); @@ -1028,8 +1037,6 @@ pub trait Read { /// # Examples /// /// ```no_run -/// #![feature(io_read_to_string)] -/// /// # use std::io; /// fn main() -> io::Result<()> { /// let stdin = io::read_to_string(io::stdin())?; @@ -1038,7 +1045,7 @@ pub trait Read { /// Ok(()) /// } /// ``` -#[unstable(feature = "io_read_to_string", issue = "80218")] +#[stable(feature = "io_read_to_string", since = "1.65.0")] pub fn read_to_string(mut reader: R) -> Result { let mut buf = String::new(); reader.read_to_string(&mut buf)?; @@ -2582,50 +2589,48 @@ impl Read for Take { Ok(n) } - fn read_buf(&mut self, buf: &mut ReadBuf<'_>) -> Result<()> { + fn read_buf(&mut self, mut buf: BorrowedCursor<'_>) -> Result<()> { // Don't call into inner reader at all at EOF because it may still block if self.limit == 0 { return Ok(()); } - let prev_filled = buf.filled_len(); - - if self.limit <= buf.remaining() as u64 { + if self.limit <= buf.capacity() as u64 { // if we just use an as cast to convert, limit may wrap around on a 32 bit target let limit = cmp::min(self.limit, usize::MAX as u64) as usize; - let extra_init = cmp::min(limit as usize, buf.initialized_len() - buf.filled_len()); + let extra_init = cmp::min(limit as usize, buf.init_ref().len()); // SAFETY: no uninit data is written to ibuf - let ibuf = unsafe { &mut buf.unfilled_mut()[..limit] }; + let ibuf = unsafe { &mut buf.as_mut()[..limit] }; - let mut sliced_buf = ReadBuf::uninit(ibuf); + let mut sliced_buf: BorrowedBuf<'_> = ibuf.into(); // SAFETY: extra_init bytes of ibuf are known to be initialized unsafe { - sliced_buf.assume_init(extra_init); + sliced_buf.set_init(extra_init); } - self.inner.read_buf(&mut sliced_buf)?; + let mut cursor = sliced_buf.unfilled(); + self.inner.read_buf(cursor.reborrow())?; - let new_init = sliced_buf.initialized_len(); - let filled = sliced_buf.filled_len(); + let new_init = cursor.init_ref().len(); + let filled = sliced_buf.len(); - // sliced_buf / ibuf must drop here + // cursor / sliced_buf / ibuf must drop here - // SAFETY: new_init bytes of buf's unfilled buffer have been initialized unsafe { - buf.assume_init(new_init); + // SAFETY: filled bytes have been filled and therefore initialized + buf.advance(filled); + // SAFETY: new_init bytes of buf's unfilled buffer have been initialized + buf.set_init(new_init); } - buf.add_filled(filled); - self.limit -= filled as u64; } else { - self.inner.read_buf(buf)?; - - //inner may unfill - self.limit -= buf.filled_len().saturating_sub(prev_filled) as u64; + let written = buf.written(); + self.inner.read_buf(buf.reborrow())?; + self.limit -= (buf.written() - written) as u64; } Ok(()) -- cgit v1.2.3