read_write_ext_tokio/lib.rs
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//! [](https://crates.io/crates/read-write-ext-tokio)
//! [](http://www.apache.org/licenses/LICENSE-2.0)
//! [](https://github.com/rust-secure-code/safety-dance/)
//! [](https://gitlab.com/leonhard-llc/fixed-buffer-rs/-/pipelines)
//!
//! `AsyncReadWriteExt` trait with `chain_after` and `take_rw` for `tokio::io::Read + Write` structs.
//!
//! # Features
//! - `forbid(unsafe_code)`
//! - Good test coverage (100%)
//! - Like [`tokio::io::AsyncReadExt::chain`](https://docs.rs/tokio/latest/tokio/io/trait.AsyncReadExt.html#method.chain)
//! and [`tokio::io::AsyncReadExt::take`](https://docs.rs/tokio/latest/tokio/io/trait.AsyncReadExt.html#method.take)
//! but also passes through writes.
//! - Useful with `Read + Write` objects like
//! [`tokio::net::TcpStream`](https://docs.rs/tokio/latest/tokio/net/struct.TcpStream.html)
//! and [`tokio_rustls::TlsStream`](https://docs.rs/tokio-rustls/latest/tokio_rustls/enum.TlsStream.html).
//!
//! # Changelog
//! - v0.1.0 - Initial release. Moved code from `fixed-buffer-tokio`.
//!
//! # TO DO
//!
//! # Release Process
//! 1. Edit `Cargo.toml` and bump version number.
//! 1. Run `../release.sh`
#![forbid(unsafe_code)]
use std::pin::Pin;
use std::task::{Context, Poll};
use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
/// A wrapper for a pair of structs, R and RW.
///
/// Implements `tokio::io::AsyncRead`. Reads from `R` until it is empty, then reads from `RW`.
///
/// Implements `tokio::io::AsyncWrite`. Passes all writes through to `RW`.
///
/// This is like the struct returned by
/// [`tokio::io::AsyncReadExt::chain`](https://docs.rs/tokio/latest/tokio/io/trait.AsyncReadExt.html#method.chain)
/// that also passes through writes.
pub struct AsyncReadWriteChain<R: AsyncRead, RW: AsyncRead + AsyncWrite> {
reader: Option<R>,
read_writer: RW,
}
impl<R: AsyncRead, RW: AsyncRead + AsyncWrite> AsyncReadWriteChain<R, RW> {
/// See [`AsyncReadWriteChain`](struct.AsyncReadWriteChain.html).
pub fn new(reader: R, read_writer: RW) -> AsyncReadWriteChain<R, RW> {
Self {
reader: Some(reader),
read_writer,
}
}
}
impl<R: AsyncRead + Unpin, RW: AsyncRead + AsyncWrite + Unpin> AsyncRead
for AsyncReadWriteChain<R, RW>
{
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<Result<(), std::io::Error>> {
if let Some(ref mut reader) = self.reader {
let before_len = buf.filled().len();
match Pin::new(&mut *reader).poll_read(cx, buf) {
Poll::Pending => return Poll::Pending,
Poll::Ready(Err(e)) => return Poll::Ready(Err(e)),
Poll::Ready(Ok(())) => {
let num_read = buf.filled().len() - before_len;
if num_read > 0 {
return Poll::Ready(Ok(()));
}
// EOF
self.reader = None;
// Fall through.
}
}
}
Pin::new(&mut self.read_writer).poll_read(cx, buf)
}
}
impl<R: AsyncRead + Unpin, RW: AsyncRead + AsyncWrite + Unpin> AsyncWrite
for AsyncReadWriteChain<R, RW>
{
fn poll_write(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<Result<usize, std::io::Error>> {
Pin::new(&mut self.read_writer).poll_write(cx, buf)
}
fn poll_flush(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), std::io::Error>> {
Pin::new(&mut self.read_writer).poll_flush(cx)
}
fn poll_shutdown(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), std::io::Error>> {
Pin::new(&mut self.read_writer).poll_shutdown(cx)
}
}
/// Wraps a `tokio::io::AsyncRead + tokio::io::AsyncWrite` struct.
/// Passes through reads and writes to the struct.
/// Limits the number of bytes that can be read.
///
/// This is like [`tokio::io::Take`](https://docs.rs/tokio/latest/tokio/io/struct.Take.html)
/// that also passes through writes.
pub struct AsyncReadWriteTake<RW: AsyncRead + AsyncWrite> {
read_writer: RW,
remaining_bytes: u64,
}
impl<RW: AsyncRead + AsyncWrite + Unpin> AsyncReadWriteTake<RW> {
/// See [`AsyncReadWriteTake`](struct.AsyncReadWriteTake.html).
pub fn new(read_writer: RW, len: u64) -> AsyncReadWriteTake<RW> {
Self {
read_writer,
remaining_bytes: len,
}
}
}
impl<RW: AsyncRead + AsyncWrite + Unpin> AsyncRead for AsyncReadWriteTake<RW> {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<Result<(), std::io::Error>> {
if self.remaining_bytes == 0 {
return Poll::Ready(Ok(()));
}
let num_to_read =
usize::try_from(self.remaining_bytes.min(buf.remaining() as u64)).unwrap_or(usize::MAX);
let dest = &mut buf.initialize_unfilled()[0..num_to_read];
let mut buf2 = ReadBuf::new(dest);
match Pin::new(&mut self.read_writer).poll_read(cx, &mut buf2) {
Poll::Ready(Ok(())) => {
let num_read = buf2.filled().len();
buf.advance(num_read);
self.remaining_bytes -= num_read as u64;
Poll::Ready(Ok(()))
}
Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
Poll::Pending => Poll::Pending,
}
}
}
impl<RW: AsyncRead + AsyncWrite + Unpin> AsyncWrite for AsyncReadWriteTake<RW> {
fn poll_write(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<Result<usize, std::io::Error>> {
Pin::new(&mut self.read_writer).poll_write(cx, buf)
}
fn poll_flush(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), std::io::Error>> {
Pin::new(&mut self.read_writer).poll_flush(cx)
}
fn poll_shutdown(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), std::io::Error>> {
Pin::new(&mut self.read_writer).poll_shutdown(cx)
}
}
pub trait AsyncReadWriteExt: tokio::io::AsyncRead + tokio::io::AsyncWrite + Unpin {
/// Returns a struct that implements `tokio::io::AsyncRead` and `tokio::io::AsyncWrite`.
///
/// It reads from `reader` until it is empty, then reads from `self`.
///
/// It passes all writes through to `self`.
///
/// This is like [`tokio::io::AsyncReadExt::chain`](https://docs.rs/tokio/latest/tokio/io/trait.AsyncReadExt.html#method.chain)
/// that also passes through writes.
fn chain_after<R: tokio::io::AsyncRead>(
&mut self,
reader: R,
) -> AsyncReadWriteChain<R, &mut Self> {
AsyncReadWriteChain::new(reader, self)
}
/// Wraps a struct that implements `tokio::io::AsyncRead` and `tokio::io::AsyncWrite`.
///
/// The returned struct passes through reads and writes to the struct.
///
/// It limits the number of bytes that can be read.
///
/// This is like [`tokio::io::AsyncReadExt::take`](https://docs.rs/tokio/latest/tokio/io/trait.AsyncReadExt.html#method.take)
/// that also passes through writes.
fn take_rw(&mut self, len: u64) -> AsyncReadWriteTake<&mut Self> {
AsyncReadWriteTake::new(self, len)
}
}
impl<RW: tokio::io::AsyncRead + tokio::io::AsyncWrite + ?Sized + Unpin> AsyncReadWriteExt for RW {}