Remove wrapper type handling absent raw standard streams

Raw standard streams are always available.  Remove unused wrapper type
that was supposed to be responsible for handling their absence.

Author: tmiasko

library/std/src/io/stdio.rs

@@ -83,11 +83,11 @@ const fn stderr_raw() -> StderrRaw {
 
 impl Read for StdinRaw {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        self.0.read(buf)
+        handle_ebadf(self.0.read(buf), 0)
     }
 
     fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        self.0.read_vectored(bufs)
+        handle_ebadf(self.0.read_vectored(bufs), 0)
     }
 
     #[inline]
@@ -101,25 +101,22 @@ impl Read for StdinRaw {
     }
 
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        self.0.read_to_end(buf)
+        handle_ebadf(self.0.read_to_end(buf), 0)
     }
 
     fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
-        self.0.read_to_string(buf)
-    }
-
-    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
-        self.0.read_exact(buf)
+        handle_ebadf(self.0.read_to_string(buf), 0)
     }
 }
 
 impl Write for StdoutRaw {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        self.0.write(buf)
+        handle_ebadf(self.0.write(buf), buf.len())
     }
 
     fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        self.0.write_vectored(bufs)
+        let total = bufs.iter().map(|b| b.len()).sum();
+        handle_ebadf(self.0.write_vectored(bufs), total)
     }
 
     #[inline]
@@ -128,29 +125,30 @@ impl Write for StdoutRaw {
     }
 
     fn flush(&mut self) -> io::Result<()> {
-        self.0.flush()
+        handle_ebadf(self.0.flush(), ())
     }
 
     fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
-        self.0.write_all(buf)
+        handle_ebadf(self.0.write_all(buf), ())
     }
 
     fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
-        self.0.write_all_vectored(bufs)
+        handle_ebadf(self.0.write_all_vectored(bufs), ())
     }
 
     fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
-        self.0.write_fmt(fmt)
+        handle_ebadf(self.0.write_fmt(fmt), ())
     }
 }
 
 impl Write for StderrRaw {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        self.0.write(buf)
+        handle_ebadf(self.0.write(buf), buf.len())
     }
 
     fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        self.0.write_vectored(bufs)
+        let total = bufs.iter().map(|b| b.len()).sum();
+        handle_ebadf(self.0.write_vectored(bufs), total)
     }
 
     #[inline]
@@ -159,80 +157,19 @@ impl Write for StderrRaw {
     }
 
     fn flush(&mut self) -> io::Result<()> {
-        self.0.flush()
+        handle_ebadf(self.0.flush(), ())
     }
 
     fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
-        self.0.write_all(buf)
+        handle_ebadf(self.0.write_all(buf), ())
     }
 
     fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
-        self.0.write_all_vectored(bufs)
+        handle_ebadf(self.0.write_all_vectored(bufs), ())
     }
 
     fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
-        self.0.write_fmt(fmt)
-    }
-}
-
-enum Maybe<T> {
-    Real(T),
-    Fake,
-}
-
-impl<W: io::Write> io::Write for Maybe<W> {
-    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        match *self {
-            Maybe::Real(ref mut w) => handle_ebadf(w.write(buf), buf.len()),
-            Maybe::Fake => Ok(buf.len()),
-        }
-    }
-
-    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
-        let total = bufs.iter().map(|b| b.len()).sum();
-        match self {
-            Maybe::Real(w) => handle_ebadf(w.write_vectored(bufs), total),
-            Maybe::Fake => Ok(total),
-        }
-    }
-
-    #[inline]
-    fn is_write_vectored(&self) -> bool {
-        match self {
-            Maybe::Real(w) => w.is_write_vectored(),
-            Maybe::Fake => true,
-        }
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        match *self {
-            Maybe::Real(ref mut w) => handle_ebadf(w.flush(), ()),
-            Maybe::Fake => Ok(()),
-        }
-    }
-}
-
-impl<R: io::Read> io::Read for Maybe<R> {
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        match *self {
-            Maybe::Real(ref mut r) => handle_ebadf(r.read(buf), 0),
-            Maybe::Fake => Ok(0),
-        }
-    }
-
-    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        match self {
-            Maybe::Real(r) => handle_ebadf(r.read_vectored(bufs), 0),
-            Maybe::Fake => Ok(0),
-        }
-    }
-
-    #[inline]
-    fn is_read_vectored(&self) -> bool {
-        match self {
-            Maybe::Real(w) => w.is_read_vectored(),
-            Maybe::Fake => true,
-        }
+        handle_ebadf(self.0.write_fmt(fmt), ())
     }
 }
 
@@ -277,7 +214,7 @@ fn handle_ebadf<T>(r: io::Result<T>, default: T) -> io::Result<T> {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Stdin {
-    inner: Arc<Mutex<BufReader<Maybe<StdinRaw>>>>,
+    inner: Arc<Mutex<BufReader<StdinRaw>>>,
 }
 
 /// A locked reference to the `Stdin` handle.
@@ -308,7 +245,7 @@ pub struct Stdin {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct StdinLock<'a> {
-    inner: MutexGuard<'a, BufReader<Maybe<StdinRaw>>>,
+    inner: MutexGuard<'a, BufReader<StdinRaw>>,
 }
 
 /// Constructs a new handle to the standard input of the current process.
@@ -352,14 +289,14 @@ pub struct StdinLock<'a> {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn stdin() -> Stdin {
-    static INSTANCE: Lazy<Mutex<BufReader<Maybe<StdinRaw>>>> = Lazy::new();
+    static INSTANCE: Lazy<Mutex<BufReader<StdinRaw>>> = Lazy::new();
     return Stdin {
         inner: unsafe { INSTANCE.get(stdin_init).expect("cannot access stdin during shutdown") },
     };
 
-    fn stdin_init() -> Arc<Mutex<BufReader<Maybe<StdinRaw>>>> {
+    fn stdin_init() -> Arc<Mutex<BufReader<StdinRaw>>> {
         // This must not reentrantly access `INSTANCE`
-        let stdin = Maybe::Real(stdin_raw());
+        let stdin = stdin_raw();
         Arc::new(Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin)))
     }
 }
@@ -536,7 +473,7 @@ pub struct Stdout {
     // FIXME: this should be LineWriter or BufWriter depending on the state of
     //        stdout (tty or not). Note that if this is not line buffered it
     //        should also flush-on-panic or some form of flush-on-abort.
-    inner: Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>>,
+    inner: Arc<ReentrantMutex<RefCell<LineWriter<StdoutRaw>>>>,
 }
 
 /// A locked reference to the `Stdout` handle.
@@ -550,7 +487,7 @@ pub struct Stdout {
 /// an error.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct StdoutLock<'a> {
-    inner: ReentrantMutexGuard<'a, RefCell<LineWriter<Maybe<StdoutRaw>>>>,
+    inner: ReentrantMutexGuard<'a, RefCell<LineWriter<StdoutRaw>>>,
 }
 
 /// Constructs a new handle to the standard output of the current process.
@@ -594,14 +531,14 @@ pub struct StdoutLock<'a> {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn stdout() -> Stdout {
-    static INSTANCE: Lazy<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>> = Lazy::new();
+    static INSTANCE: Lazy<ReentrantMutex<RefCell<LineWriter<StdoutRaw>>>> = Lazy::new();
     return Stdout {
         inner: unsafe { INSTANCE.get(stdout_init).expect("cannot access stdout during shutdown") },
     };
 
-    fn stdout_init() -> Arc<ReentrantMutex<RefCell<LineWriter<Maybe<StdoutRaw>>>>> {
+    fn stdout_init() -> Arc<ReentrantMutex<RefCell<LineWriter<StdoutRaw>>>> {
         // This must not reentrantly access `INSTANCE`
-        let stdout = Maybe::Real(stdout_raw());
+        let stdout = stdout_raw();
         unsafe {
             let ret = Arc::new(ReentrantMutex::new(RefCell::new(LineWriter::new(stdout))));
             ret.init();
@@ -711,7 +648,7 @@ impl fmt::Debug for StdoutLock<'_> {
 /// an error.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Stderr {
-    inner: &'static ReentrantMutex<RefCell<Maybe<StderrRaw>>>,
+    inner: &'static ReentrantMutex<RefCell<StderrRaw>>,
 }
 
 /// A locked reference to the `Stderr` handle.
@@ -725,7 +662,7 @@ pub struct Stderr {
 /// an error.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct StderrLock<'a> {
-    inner: ReentrantMutexGuard<'a, RefCell<Maybe<StderrRaw>>>,
+    inner: ReentrantMutexGuard<'a, RefCell<StderrRaw>>,
 }
 
 /// Constructs a new handle to the standard error of the current process.
@@ -774,18 +711,14 @@ pub fn stderr() -> Stderr {
     //
     // This has the added benefit of allowing `stderr` to be usable during
     // process shutdown as well!
-    static INSTANCE: ReentrantMutex<RefCell<Maybe<StderrRaw>>> =
-        unsafe { ReentrantMutex::new(RefCell::new(Maybe::Fake)) };
+    static INSTANCE: ReentrantMutex<RefCell<StderrRaw>> =
+        unsafe { ReentrantMutex::new(RefCell::new(stderr_raw())) };
 
     // When accessing stderr we need one-time initialization of the reentrant
-    // mutex, followed by one-time detection of whether we actually have a
-    // stderr handle or not. Afterwards we can just always use the now-filled-in
-    // `INSTANCE` value.
+    // mutex. Afterwards we can just always use the now-filled-in `INSTANCE` value.
     static INIT: Once = Once::new();
     INIT.call_once(|| unsafe {
         INSTANCE.init();
-        let stderr = stderr_raw();
-        *INSTANCE.lock().borrow_mut() = Maybe::Real(stderr);
     });
     Stderr { inner: &INSTANCE }
 }