1 files changed, 55 insertions, 0 deletions
diff --git a/tokio/src/io/util/write_all.rs b/tokio/src/io/util/write_all.rs
new file mode 100644
index 00000000..d336e65d
--- /dev/null
+++ b/tokio/src/io/util/write_all.rs
@@ -0,0 +1,55 @@
+use crate::io::AsyncWrite;
+
+use std::future::Future;
+use std::io;
+use std::mem;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+#[derive(Debug)]
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct WriteAll<'a, W: ?Sized> {
+    writer: &'a mut W,
+    buf: &'a [u8],
+}
+
+pub(crate) fn write_all<'a, W>(writer: &'a mut W, buf: &'a [u8]) -> WriteAll<'a, W>
+where
+    W: AsyncWrite + Unpin + ?Sized,
+{
+    WriteAll { writer, buf }
+}
+
+impl<W> Future for WriteAll<'_, W>
+where
+    W: AsyncWrite + Unpin + ?Sized,
+{
+    type Output = io::Result<()>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        let me = &mut *self;
+        while !me.buf.is_empty() {
+            let n = ready!(Pin::new(&mut me.writer).poll_write(cx, me.buf))?;
+            {
+                let (_, rest) = mem::replace(&mut me.buf, &[]).split_at(n);
+                me.buf = rest;
+            }
+            if n == 0 {
+                return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
+            }
+        }
+
+        Poll::Ready(Ok(()))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn assert_unpin() {
+        use std::marker::PhantomPinned;
+        crate::is_unpin::<WriteAll<'_, PhantomPinned>>();
+    }
+}