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use futures_core::future::Future;
use futures_core::task::{LocalWaker, Poll};
use futures_io::AsyncRead;
use std::io;
use std::marker::Unpin;
use std::pin::Pin;
use std::vec::Vec;
#[derive(Debug)]
pub struct ReadToEnd<'a, R: ?Sized> {
reader: &'a mut R,
buf: &'a mut Vec<u8>,
}
impl<R: ?Sized> Unpin for ReadToEnd<'_, R> {}
impl<'a, R: AsyncRead + ?Sized> ReadToEnd<'a, R> {
pub(super) fn new(reader: &'a mut R, buf: &'a mut Vec<u8>) -> Self {
ReadToEnd { reader, buf }
}
}
struct Guard<'a> { buf: &'a mut Vec<u8>, len: usize }
impl Drop for Guard<'_> {
fn drop(&mut self) {
unsafe { self.buf.set_len(self.len); }
}
}
fn read_to_end_internal<R: AsyncRead + ?Sized>(
rd: &mut R,
lw: &LocalWaker,
buf: &mut Vec<u8>,
) -> Poll<io::Result<()>> {
let mut g = Guard { len: buf.len(), buf };
let ret;
loop {
if g.len == g.buf.len() {
unsafe {
g.buf.reserve(32);
let capacity = g.buf.capacity();
g.buf.set_len(capacity);
rd.initializer().initialize(&mut g.buf[g.len..]);
}
}
match rd.poll_read(lw, &mut g.buf[g.len..]) {
Poll::Ready(Ok(0)) => {
ret = Poll::Ready(Ok(()));
break;
}
Poll::Ready(Ok(n)) => g.len += n,
Poll::Pending => return Poll::Pending,
Poll::Ready(Err(e)) => {
ret = Poll::Ready(Err(e));
break;
}
}
}
ret
}
impl<A> Future for ReadToEnd<'_, A>
where A: AsyncRead + ?Sized,
{
type Output = io::Result<()>;
fn poll(mut self: Pin<&mut Self>, lw: &LocalWaker) -> Poll<Self::Output> {
let this = &mut *self;
read_to_end_internal(this.reader, lw, this.buf)
}
}