use std::{
io::{self, IoSlice, SeekFrom},
iter,
pin::Pin,
task::{Context, Poll},
};
use tokio::io::{AsyncRead, AsyncSeek, AsyncWrite};
use crate::VirtualFile;
#[derive(Debug, Default)]
pub struct ZeroFile {}
impl AsyncSeek for ZeroFile {
fn start_seek(self: Pin<&mut Self>, _position: SeekFrom) -> io::Result<()> {
Ok(())
}
fn poll_complete(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<u64>> {
Poll::Ready(Ok(0))
}
}
impl AsyncWrite for ZeroFile {
fn poll_write(
self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &[u8],
) -> Poll<io::Result<usize>> {
Poll::Ready(Ok(buf.len()))
}
fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
Poll::Ready(Ok(()))
}
fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
Poll::Ready(Ok(()))
}
fn poll_write_vectored(
self: Pin<&mut Self>,
_cx: &mut Context<'_>,
bufs: &[IoSlice<'_>],
) -> Poll<io::Result<usize>> {
Poll::Ready(Ok(bufs.len()))
}
fn is_write_vectored(&self) -> bool {
false
}
}
impl AsyncRead for ZeroFile {
fn poll_read(
self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &mut tokio::io::ReadBuf<'_>,
) -> Poll<io::Result<()>> {
let zeros: Vec<u8> = iter::repeat(0).take(buf.remaining()).collect();
buf.put_slice(&zeros[..]);
Poll::Ready(Ok(()))
}
}
impl VirtualFile for ZeroFile {
fn last_accessed(&self) -> u64 {
0
}
fn last_modified(&self) -> u64 {
0
}
fn created_time(&self) -> u64 {
0
}
fn size(&self) -> u64 {
0
}
fn set_len(&mut self, _new_size: u64) -> crate::Result<()> {
Ok(())
}
fn unlink(&mut self) -> crate::Result<()> {
Ok(())
}
fn poll_read_ready(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<usize>> {
Poll::Ready(Ok(0))
}
fn poll_write_ready(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<usize>> {
Poll::Ready(Ok(0))
}
}