tee: improve stdout performance

Author: xtqqczze

src/uu/tee/src/tee.rs

@@ -80,7 +80,7 @@ fn tee(options: &Options) -> Result<()> {
         0,
         NamedWriter {
             name: translate!("tee-standard-output").into(),
-            inner: Writer::Stdout(stdout()),
+            inner: Writer::stdout_raw(),
         },
     );
 
@@ -197,21 +197,16 @@ impl MultiWriter {
 
     fn write_flush(&mut self, buf: &[u8]) -> Result<()> {
         let mode = self.output_error_mode;
-        self.writers.retain_mut(|writer| {
-            let res = (|| {
-                writer.inner.write_all(buf)?;
-                writer.inner.flush()
-            })();
-            match res {
+        self.writers
+            .retain_mut(|writer| match writer.inner.write_all(buf) {
                 Ok(()) => true,
                 Err(e) => {
                     if let Err(e) = process_error(mode, e, writer, &mut self.ignored_errors) {
                         self.aborted.get_or_insert(e);
                     }
                     false
                 }
-            }
-        });
+            });
         self.aborted.take().map_or(
             if self.writers.is_empty() {
                 // This error kind will never be raised by the standard
@@ -251,22 +246,37 @@ fn process_error(
 
 enum Writer {
     File(std::fs::File),
-    Stdout(std::io::Stdout),
+    StdoutRaw(core::mem::ManuallyDrop<std::fs::File>),
+}
+
+impl Writer {
+    #[cfg(not(windows))]
+    fn stdout_raw() -> Self {
+        let fd = std::os::fd::AsRawFd::as_raw_fd(&stdout());
+        Self::StdoutRaw(core::mem::ManuallyDrop::new(unsafe {
+            std::os::fd::FromRawFd::from_raw_fd(fd)
+        }))
+    }
+
+    #[cfg(windows)]
+    fn stdout_raw() -> Self {
+        let handle = std::os::windows::io::AsRawHandle::as_raw_handle(&stdout());
+        Self::StdoutRaw(core::mem::ManuallyDrop::new(unsafe {
+            std::os::windows::io::FromRawHandle::from_raw_handle(handle)
+        }))
+    }
 }
 
 impl Write for Writer {
     fn write(&mut self, buf: &[u8]) -> Result<usize> {
         match self {
             Self::File(f) => f.write(buf),
-            Self::Stdout(s) => s.write(buf),
+            Self::StdoutRaw(s) => s.write(buf),
         }
     }
 
     fn flush(&mut self) -> Result<()> {
-        match self {
-            Self::File(f) => f.flush(),
-            Self::Stdout(s) => s.flush(),
-        }
+        Ok(())
     }
 }