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Rollup merge of #130042 - lolbinarycat:bufreaker_peek_eof, r=Amanieu

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properly handle EOF in BufReader::peek

previously this would cause an infinite loop due to it being unable to read `n` bytes.
This commit is contained in:
Stuart Cook 2024-09-15 12:14:55 +10:00 committed by GitHub
commit e02e6bf0e9
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2 changed files with 12 additions and 4 deletions
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12
library/std/src/io/buffered/bufreader.rs
View File

@ -99,7 +99,10 @@ impl<R: Read> BufReader<R> {
impl<R: Read + ?Sized> BufReader<R> { impl<R: Read + ?Sized> BufReader<R> {
/// Attempt to look ahead `n` bytes. /// Attempt to look ahead `n` bytes.
/// ///
/// `n` must be less than `capacity`. /// `n` must be less than or equal to `capacity`.
///
/// the returned slice may be less than `n` bytes long if
/// end of file is reached.
/// ///
/// ## Examples /// ## Examples
/// ///
@ -117,6 +120,7 @@ impl<R: Read + ?Sized> BufReader<R> {
/// let mut s = String::new(); /// let mut s = String::new();
/// rdr.read_to_string(&mut s).unwrap(); /// rdr.read_to_string(&mut s).unwrap();
/// assert_eq!(&s, "hello"); /// assert_eq!(&s, "hello");
/// assert_eq!(rdr.peek(1).unwrap().len(), 0);
/// ``` /// ```
#[unstable(feature = "bufreader_peek", issue = "128405")] #[unstable(feature = "bufreader_peek", issue = "128405")]
pub fn peek(&mut self, n: usize) -> io::Result<&[u8]> { pub fn peek(&mut self, n: usize) -> io::Result<&[u8]> {
@ -125,7 +129,11 @@ impl<R: Read + ?Sized> BufReader<R> {
if self.buf.pos() > 0 { if self.buf.pos() > 0 {
self.buf.backshift(); self.buf.backshift();
} }
self.buf.read_more(&mut self.inner)?; let new = self.buf.read_more(&mut self.inner)?;
if new == 0 {
// end of file, no more bytes to read
return Ok(&self.buf.buffer()[..]);
}
debug_assert_eq!(self.buf.pos(), 0); debug_assert_eq!(self.buf.pos(), 0);
} }
Ok(&self.buf.buffer()[..n]) Ok(&self.buf.buffer()[..n])

4
library/std/src/io/buffered/bufreader/buffer.rs
View File

@ -98,7 +98,7 @@ impl Buffer {
} }
/// Read more bytes into the buffer without discarding any of its contents /// Read more bytes into the buffer without discarding any of its contents
pub fn read_more(&mut self, mut reader: impl Read) -> io::Result<()> { pub fn read_more(&mut self, mut reader: impl Read) -> io::Result<usize> {
let mut buf = BorrowedBuf::from(&mut self.buf[self.pos..]); let mut buf = BorrowedBuf::from(&mut self.buf[self.pos..]);
let old_init = self.initialized - self.pos; let old_init = self.initialized - self.pos;
unsafe { unsafe {
@ -107,7 +107,7 @@ impl Buffer {
reader.read_buf(buf.unfilled())?; reader.read_buf(buf.unfilled())?;
self.filled += buf.len(); self.filled += buf.len();
self.initialized += buf.init_len() - old_init; self.initialized += buf.init_len() - old_init;
Ok(()) Ok(buf.len())
} }
/// Remove bytes that have already been read from the buffer. /// Remove bytes that have already been read from the buffer.