util: add more get_{ref,mut,pin_mut} methods (#3364)

This commit adds:

- Framed::get_pin_mut
- FramedRead::get_pin_mut
- FramedWrite::get_pin_mut
- StreamReader::get_ref
- StreamReader::get_mut
- StreamReader::get_pin_mut
- StreamReader::into_inner

tokio-util/src/codec/framed.rs

@@ -170,6 +170,16 @@ impl<T, U> Framed<T, U> {
         &mut self.inner.inner
     }
 
+    /// Returns a pinned mutable reference to the underlying I/O stream wrapped by
+    /// `Framed`.
+    ///
+    /// Note that care should be taken to not tamper with the underlying stream
+    /// of data coming in as it may corrupt the stream of frames otherwise
+    /// being worked with.
+    pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
+        self.project().inner.project().inner
+    }
+
     /// Returns a reference to the underlying codec wrapped by
     /// `Framed`.
     ///

tokio-util/src/codec/framed_read.rs

@@ -78,6 +78,16 @@ impl<T, D> FramedRead<T, D> {
         &mut self.inner.inner
     }
 
+    /// Returns a pinned mutable reference to the underlying I/O stream wrapped by
+    /// `FramedRead`.
+    ///
+    /// Note that care should be taken to not tamper with the underlying stream
+    /// of data coming in as it may corrupt the stream of frames otherwise
+    /// being worked with.
+    pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
+        self.project().inner.project().inner
+    }
+
     /// Consumes the `FramedRead`, returning its underlying I/O stream.
     ///
     /// Note that care should be taken to not tamper with the underlying stream

tokio-util/src/codec/framed_write.rs

@@ -58,6 +58,16 @@ impl<T, E> FramedWrite<T, E> {
         &mut self.inner.inner
     }
 
+    /// Returns a pinned mutable reference to the underlying I/O stream wrapped by
+    /// `FramedWrite`.
+    ///
+    /// Note that care should be taken to not tamper with the underlying stream
+    /// of data coming in as it may corrupt the stream of frames otherwise
+    /// being worked with.
+    pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
+        self.project().inner.project().inner
+    }
+
     /// Consumes the `FramedWrite`, returning its underlying I/O stream.
     ///
     /// Note that care should be taken to not tamper with the underlying stream