impl AsyncReadRentAt and AsyncWriteRentAt for File (#309)

* impl ReadRentAt

* impl AsyncWriteRentAt for File

* fmt

* back to &mut

monoio/src/fs/file/mod.rs

@@ -1,10 +1,11 @@
-use std::{io, path::Path};
+use std::{future::Future, io, path::Path};
 
 use crate::{
     buf::{IoBuf, IoBufMut, IoVecBuf, IoVecBufMut},
     driver::{op::Op, shared_fd::SharedFd},
     fs::OpenOptions,
     io::{AsyncReadRent, AsyncWriteRent},
+    BufResult,
 };
 
 #[cfg(unix)]
@@ -16,6 +17,8 @@ mod windows;
 #[cfg(windows)]
 use windows as file_impl;
 
+use crate::io::{AsyncReadRentAt, AsyncWriteRentAt};
+
 /// A reference to an open file on the filesystem.
 ///
 /// An instance of a `File` can be read and/or written depending on what options
@@ -635,6 +638,16 @@ impl AsyncWriteRent for File {
     }
 }
 
+impl AsyncWriteRentAt for File {
+    fn write_at<T: IoBuf>(
+        &mut self,
+        buf: T,
+        pos: usize,
+    ) -> impl Future<Output = BufResult<usize, T>> {
+        File::write_at(self, buf, pos as u64)
+    }
+}
+
 impl AsyncReadRent for File {
     /// Reads bytes from the file at the current file pointer into the specified buffer, returning
     /// the number of bytes read.
@@ -753,3 +766,13 @@ impl AsyncReadRent for File {
         self.read_vectored(buf).await
     }
 }
+
+impl AsyncReadRentAt for File {
+    fn read_at<T: IoBufMut>(
+        &mut self,
+        buf: T,
+        pos: usize,
+    ) -> impl Future<Output = BufResult<usize, T>> {
+        File::read_at(self, buf, pos as u64)
+    }
+}