189     pub fn alloc_fd(&mut self, file: File, fd: Option<i32>) -> Result<i32, SystemError> {  in alloc_fd()
206         if fd.is_some() {  in alloc_fd()
208             let new_fd = fd.unwrap();  in alloc_fd()
235     pub fn get_file_mut_by_fd(&self, fd: i32) -> Option<&mut File> {  in get_file_mut_by_fd()
236         if !FileDescriptorVec::validate_fd(fd) {  in get_file_mut_by_fd()
240         return r.fds[fd as usize].as_deref_mut();  in get_file_mut_by_fd()
249     pub fn get_file_ref_by_fd(&self, fd: i32) -> Option<&File> {  in get_file_ref_by_fd()
250         if !FileDescriptorVec::validate_fd(fd) {  in get_file_ref_by_fd()
254         return r.fds[fd as usize].as_deref();  in get_file_ref_by_fd()
260     pub fn drop_fd(&self, fd: i32) -> Result<(), SystemError> {  in drop_fd()
262         if !FileDescriptorVec::validate_fd(fd) {  in drop_fd()
267         let f: Option<&File> = r.fds[fd as usize].as_deref();  in drop_fd()
276         r.fds[fd as usize] = None;  in drop_fd()
304     pub fn get_socket(&self, fd: i32) -> Option<Arc<SocketInode>> {  in get_socket()
305         let f = self.get_file_mut_by_fd(fd)?;  in get_socket()