summaryrefslogtreecommitdiffstats
path: root/tokio-util/src/io/poll_read_buf.rs
diff options
context:
space:
mode:
Diffstat (limited to 'tokio-util/src/io/poll_read_buf.rs')
-rw-r--r--tokio-util/src/io/poll_read_buf.rs90
1 files changed, 0 insertions, 90 deletions
diff --git a/tokio-util/src/io/poll_read_buf.rs b/tokio-util/src/io/poll_read_buf.rs
deleted file mode 100644
index efce7ced..00000000
--- a/tokio-util/src/io/poll_read_buf.rs
+++ /dev/null
@@ -1,90 +0,0 @@
-use bytes::BufMut;
-use futures_core::ready;
-use std::io;
-use std::pin::Pin;
-use std::task::{Context, Poll};
-use tokio::io::{AsyncRead, ReadBuf};
-
-/// Try to read data from an `AsyncRead` into an implementer of the [`Buf`] trait.
-///
-/// [`Buf`]: bytes::Buf
-///
-/// # Example
-///
-/// ```
-/// use bytes::{Bytes, BytesMut};
-/// use tokio::stream;
-/// use tokio::io::Result;
-/// use tokio_util::io::{StreamReader, poll_read_buf};
-/// use futures::future::poll_fn;
-/// use std::pin::Pin;
-/// # #[tokio::main]
-/// # async fn main() -> std::io::Result<()> {
-///
-/// // Create a reader from an iterator. This particular reader will always be
-/// // ready.
-/// let mut read = StreamReader::new(stream::iter(vec![Result::Ok(Bytes::from_static(&[0, 1, 2, 3]))]));
-///
-/// let mut buf = BytesMut::new();
-/// let mut reads = 0;
-///
-/// loop {
-/// reads += 1;
-/// let n = poll_fn(|cx| poll_read_buf(Pin::new(&mut read), cx, &mut buf)).await?;
-///
-/// if n == 0 {
-/// break;
-/// }
-/// }
-///
-/// // one or more reads might be necessary.
-/// assert!(reads >= 1);
-/// assert_eq!(&buf[..], &[0, 1, 2, 3]);
-/// # Ok(())
-/// # }
-/// ```
-pub fn poll_read_buf<R, B>(
- read: Pin<&mut R>,
- cx: &mut Context<'_>,
- buf: &mut B,
-) -> Poll<io::Result<usize>>
-where
- R: AsyncRead,
- B: BufMut,
-{
- if !buf.has_remaining_mut() {
- return Poll::Ready(Ok(0));
- }
-
- let n = {
- let mut buf = ReadBuf::uninit(buf.bytes_mut());
- let before = buf.filled().as_ptr();
-
- ready!(read.poll_read(cx, &mut buf)?);
-
- // This prevents a malicious read implementation from swapping out the
- // buffer being read, which would allow `filled` to be advanced without
- // actually initializing the provided buffer.
- //
- // We avoid this by asserting that the `ReadBuf` instance wraps the same
- // memory address both before and after the poll. Which will panic in
- // case its swapped.
- //
- // See https://github.com/tokio-rs/tokio/issues/2827 for more info.
- assert! {
- std::ptr::eq(before, buf.filled().as_ptr()),
- "Read buffer must not be changed during a read poll. \
- See https://github.com/tokio-rs/tokio/issues/2827 for more info."
- };
-
- buf.filled().len()
- };
-
- // Safety: This is guaranteed to be the number of initialized (and read)
- // bytes due to the invariants provided by `ReadBuf::filled`.
- unsafe {
- buf.advance_mut(n);
- }
-
- Poll::Ready(Ok(n))
-}