From b3cf116c4f721af1c6894098888be85b1c7f46c8 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 15 Apr 2021 01:59:58 +0100
Subject: [PATCH] packetframe: Introduce Fuse::with

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/packetframe.rs | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/packetframe.rs b/src/packetframe.rs
index 95b5d18e..920916a8 100644
--- a/src/packetframe.rs
+++ b/src/packetframe.rs
@@ -49,13 +49,13 @@ impl<RW> Fuse<RW> {
   fn get(&mut self) -> &mut RW {
     self.0.as_mut().map_err(|broken| broken.clone())?
   }
-}
 
-impl<R:Read> Read for Fuse<R> {
   #[throws(io::Error)]
-  fn read(&mut self, buf: &mut [u8]) -> usize {
+  fn with<F,T>(&mut self, f: F) -> T
+    where F: FnOnce(&mut RW) -> Result<T, io::Error>
+  {
     let inner = self.get()?;
-    let r = inner.read(buf);
+    let r = f(inner);
     if let Err(e) = &r {
       self.0 = Err(Broken {
         msg: e.to_string(),
@@ -66,6 +66,13 @@ impl<R:Read> Read for Fuse<R> {
   }
 }
 
+impl<R:Read> Read for Fuse<R> {
+  #[throws(io::Error)]
+  fn read(&mut self, buf: &mut [u8]) -> usize {
+    self.with(|inner| inner.read(buf))?
+  }
+}
+
 impl From<Broken> for io::Error {
   fn from(broken: Broken) -> io::Error {
     io::Error::new(broken.kind, broken)
-- 
2.30.2