| use std::mem; |
| use std::pin::Pin; |
| use std::future::Future; |
| |
| use crate::io::{self, Read}; |
| use crate::task::{Context, Poll}; |
| |
| #[doc(hidden)] |
| #[allow(missing_debug_implementations)] |
| pub struct ReadExactFuture<'a, T: Unpin + ?Sized> { |
| pub(crate) reader: &'a mut T, |
| pub(crate) buf: &'a mut [u8], |
| } |
| |
| impl<T: Read + Unpin + ?Sized> Future for ReadExactFuture<'_, T> { |
| type Output = io::Result<()>; |
| |
| fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { |
| let Self { reader, buf } = &mut *self; |
| |
| while !buf.is_empty() { |
| let n = futures_core::ready!(Pin::new(&mut *reader).poll_read(cx, buf))?; |
| let (_, rest) = mem::replace(buf, &mut []).split_at_mut(n); |
| *buf = rest; |
| |
| if n == 0 { |
| return Poll::Ready(Err(io::ErrorKind::UnexpectedEof.into())); |
| } |
| } |
| |
| Poll::Ready(Ok(())) |
| } |
| } |