Impl io::Write for helpers::FileLock

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

src/helpers/flock.rs

@@ -43,3 +43,16 @@ impl ops::DerefMut for FileLock {
         &mut self.0
     }
 }
+
+impl io::Write for FileLock {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.0.write(buf)
+    }
+    fn flush(&mut self) -> io::Result<()> {
+        self.0.flush()
+    }
+
+    fn write_vectored(&mut self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+        self.0.write_vectored(bufs)
+    }
+}