Implement Clone for File.

Implement `Clone` for `File` so that `File`s can be passed into closures for use in `spawn_blocking`. `File`'s contents are already wrapped in `Arc`s, so the implementation of `clone` is straightforward. This also aligns with `TcpStream` which already implements `Clone` using its internal `Arc`.

Author: sunfishcode

src/fs/file.rs

@@ -58,6 +58,7 @@ use crate::utils::Context as _;
 /// #
 /// # Ok(()) }) }
 /// ```
+#[derive(Clone)]
 pub struct File {
  /// A reference to the inner file.
  file: Arc<std::fs::File>,
@@ -470,6 +471,13 @@ struct Lock<T>(Arc<LockState<T>>);
 unsafe impl<T: Send> Send for Lock<T> {}
 unsafe impl<T: Send> Sync for Lock<T> {}
 
+impl<T> Clone for Lock<T> {
+ #[inline]
+ fn clone(&self) -> Self {
+ Self(Arc::clone(&self.0))
+ }
+}
+
 /// The state of a lock.
 struct LockState<T> {
  /// Set to `true` when locked.
@@ -878,4 +886,21 @@ mod tests {
  File::open(file!()).await.unwrap();
  });
  }
+
+ #[test]
+ fn async_file_clone() {
+ crate::task::block_on(async move {
+ let file = File::open(file!()).await.unwrap();
+ let mut clone = file.clone();
+ let len = crate::task::spawn_blocking(move || {
+ let mut buf = Vec::new();
+ crate::task::block_on(async move {
+ clone.read_to_end(&mut buf).await.unwrap();
+ drop(clone);
+ buf.len()
+ })
+ }).await;
+ assert_eq!(len as u64, file.metadata().await.unwrap().len());
+ });
+ }
 }