diff options
Diffstat (limited to 'tokio-util/src/io/poll_read_buf.rs')
-rw-r--r-- | tokio-util/src/io/poll_read_buf.rs | 90 |
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)) -} |