Implement WriteVolatile for std::io::Stdout

This is needed for vm-virtio/virtio-console, to be able to wire up the
console to stdout.

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Author: roypat

src/io.rs

@@ -6,7 +6,7 @@
 use crate::bitmap::BitmapSlice;
 use crate::volatile_memory::copy_slice_impl::{copy_from_volatile_slice, copy_to_volatile_slice};
 use crate::{VolatileMemoryError, VolatileSlice};
-use std::io::ErrorKind;
+use std::io::{ErrorKind, Stdout};
 use std::os::fd::AsRawFd;
 
 /// A version of the standard library's [`Read`] trait that operates on volatile memory instead of
@@ -134,6 +134,15 @@ macro_rules! impl_read_write_volatile_for_raw_fd {
     };
 }
 
+impl WriteVolatile for Stdout {
+    fn write_volatile<B: BitmapSlice>(
+        &mut self,
+        buf: &VolatileSlice<B>,
+    ) -> Result<usize, VolatileMemoryError> {
+        write_volatile_raw_fd(self, buf)
+    }
+}
+
 impl_read_write_volatile_for_raw_fd!(std::fs::File);
 impl_read_write_volatile_for_raw_fd!(std::os::unix::net::UnixStream);
 impl_read_write_volatile_for_raw_fd!(std::os::fd::OwnedFd);