From 2c9db0d682b37c931ffdd011d1c81cf2ebcc1976 Mon Sep 17 00:00:00 2001
From: Dario Nieuwenhuis <dirbaio@dirbaio.net>
Date: Fri, 25 Aug 2023 01:11:15 +0200
Subject: [PATCH] io-adapters: add support for BufRead for `futures` and
 `tokio`.

---
 embedded-io-adapters/CHANGELOG.md      |  4 ++++
 embedded-io-adapters/Cargo.toml        |  2 +-
 embedded-io-adapters/src/futures_03.rs | 12 ++++++++++++
 embedded-io-adapters/src/tokio_1.rs    | 12 ++++++++++++
 4 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/embedded-io-adapters/CHANGELOG.md b/embedded-io-adapters/CHANGELOG.md
index 978a92d8b..bf9f2d391 100644
--- a/embedded-io-adapters/CHANGELOG.md
+++ b/embedded-io-adapters/CHANGELOG.md
@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+- Add support for adapting `BufRead` from `futures` and `tokio`.
+
 ## 0.5.0 - 2023-08-06
 
 - First release
\ No newline at end of file
diff --git a/embedded-io-adapters/Cargo.toml b/embedded-io-adapters/Cargo.toml
index 5dbcf4354..a849b1f12 100644
--- a/embedded-io-adapters/Cargo.toml
+++ b/embedded-io-adapters/Cargo.toml
@@ -21,7 +21,7 @@ embedded-io = { version = "0.5", path = "../embedded-io" }
 embedded-io-async = { version = "0.5", path = "../embedded-io-async", optional = true }
 
 futures = { version = "0.3.21", features = ["std"], default-features = false, optional = true }
-tokio = { version = "1", default-features = false, optional = true }
+tokio = { version = "1", features = ["io-util"], default-features = false, optional = true }
 
 [package.metadata.docs.rs]
 features = ["std", "tokio-1", "futures-03"]
diff --git a/embedded-io-adapters/src/futures_03.rs b/embedded-io-adapters/src/futures_03.rs
index b672215ed..a3402cbb9 100644
--- a/embedded-io-adapters/src/futures_03.rs
+++ b/embedded-io-adapters/src/futures_03.rs
@@ -3,6 +3,8 @@
 use core::future::poll_fn;
 use core::pin::Pin;
 
+use futures::AsyncBufReadExt;
+
 /// Adapter from `futures::io` traits.
 #[derive(Clone)]
 pub struct FromFutures<T: ?Sized> {
@@ -43,6 +45,16 @@ impl<T: futures::io::AsyncRead + Unpin + ?Sized> embedded_io_async::Read for Fro
     }
 }
 
+impl<T: futures::io::AsyncBufRead + Unpin + ?Sized> embedded_io_async::BufRead for FromFutures<T> {
+    async fn fill_buf(&mut self) -> Result<&[u8], Self::Error> {
+        self.inner.fill_buf().await
+    }
+
+    fn consume(&mut self, amt: usize) {
+        Pin::new(&mut self.inner).consume(amt)
+    }
+}
+
 impl<T: futures::io::AsyncWrite + Unpin + ?Sized> embedded_io_async::Write for FromFutures<T> {
     async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
         poll_fn(|cx| Pin::new(&mut self.inner).poll_write(cx, buf)).await
diff --git a/embedded-io-adapters/src/tokio_1.rs b/embedded-io-adapters/src/tokio_1.rs
index 04e1cf1aa..92060a4fe 100644
--- a/embedded-io-adapters/src/tokio_1.rs
+++ b/embedded-io-adapters/src/tokio_1.rs
@@ -4,6 +4,8 @@ use core::future::poll_fn;
 use core::pin::Pin;
 use core::task::Poll;
 
+use tokio::io::AsyncBufReadExt;
+
 /// Adapter from `tokio::io` traits.
 #[derive(Clone)]
 pub struct FromTokio<T: ?Sized> {
@@ -54,6 +56,16 @@ impl<T: tokio::io::AsyncRead + Unpin + ?Sized> embedded_io_async::Read for FromT
     }
 }
 
+impl<T: tokio::io::AsyncBufRead + Unpin + ?Sized> embedded_io_async::BufRead for FromTokio<T> {
+    async fn fill_buf(&mut self) -> Result<&[u8], Self::Error> {
+        self.inner.fill_buf().await
+    }
+
+    fn consume(&mut self, amt: usize) {
+        Pin::new(&mut self.inner).consume(amt)
+    }
+}
+
 impl<T: tokio::io::AsyncWrite + Unpin + ?Sized> embedded_io_async::Write for FromTokio<T> {
     async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
         poll_fn(|cx| Pin::new(&mut self.inner).poll_write(cx, buf)).await