1 files changed, 109 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/io/stderr.rs b/third_party/rust/tokio/src/io/stderr.rs
new file mode 100644
index 0000000000..2f624fba9d
--- /dev/null
+++ b/third_party/rust/tokio/src/io/stderr.rs
@@ -0,0 +1,109 @@
+use crate::io::blocking::Blocking;
+use crate::io::stdio_common::SplitByUtf8BoundaryIfWindows;
+use crate::io::AsyncWrite;
+
+use std::io;
+use std::pin::Pin;
+use std::task::Context;
+use std::task::Poll;
+
+cfg_io_std! {
+    /// A handle to the standard error stream of a process.
+    ///
+    /// Concurrent writes to stderr must be executed with care: Only individual
+    /// writes to this [`AsyncWrite`] are guaranteed to be intact. In particular
+    /// you should be aware that writes using [`write_all`] are not guaranteed
+    /// to occur as a single write, so multiple threads writing data with
+    /// [`write_all`] may result in interleaved output.
+    ///
+    /// Created by the [`stderr`] function.
+    ///
+    /// [`stderr`]: stderr()
+    /// [`AsyncWrite`]: AsyncWrite
+    /// [`write_all`]: crate::io::AsyncWriteExt::write_all()
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::io::{self, AsyncWriteExt};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let mut stderr = io::stdout();
+    ///     stderr.write_all(b"Print some error here.").await?;
+    ///     Ok(())
+    /// }
+    /// ```
+    #[derive(Debug)]
+    pub struct Stderr {
+        std: SplitByUtf8BoundaryIfWindows<Blocking<std::io::Stderr>>,
+    }
+
+    /// Constructs a new handle to the standard error of the current process.
+    ///
+    /// The returned handle allows writing to standard error from the within the
+    /// Tokio runtime.
+    ///
+    /// Concurrent writes to stderr must be executed with care: Only individual
+    /// writes to this [`AsyncWrite`] are guaranteed to be intact. In particular
+    /// you should be aware that writes using [`write_all`] are not guaranteed
+    /// to occur as a single write, so multiple threads writing data with
+    /// [`write_all`] may result in interleaved output.
+    ///
+    /// [`AsyncWrite`]: AsyncWrite
+    /// [`write_all`]: crate::io::AsyncWriteExt::write_all()
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::io::{self, AsyncWriteExt};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let mut stderr = io::stderr();
+    ///     stderr.write_all(b"Print some error here.").await?;
+    ///     Ok(())
+    /// }
+    /// ```
+    pub fn stderr() -> Stderr {
+        let std = io::stderr();
+        Stderr {
+            std: SplitByUtf8BoundaryIfWindows::new(Blocking::new(std)),
+        }
+    }
+}
+
+#[cfg(unix)]
+impl std::os::unix::io::AsRawFd for Stderr {
+    fn as_raw_fd(&self) -> std::os::unix::io::RawFd {
+        std::io::stderr().as_raw_fd()
+    }
+}
+
+#[cfg(windows)]
+impl std::os::windows::io::AsRawHandle for Stderr {
+    fn as_raw_handle(&self) -> std::os::windows::io::RawHandle {
+        std::io::stderr().as_raw_handle()
+    }
+}
+
+impl AsyncWrite for Stderr {
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        Pin::new(&mut self.std).poll_write(cx, buf)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.std).poll_flush(cx)
+    }
+
+    fn poll_shutdown(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        Pin::new(&mut self.std).poll_shutdown(cx)
+    }
+}