blob: b21dc1c4ade45669eabc0afcfde670b6c9ab568d [file] [log] [blame]
use std::io;
use futures::{Future, Poll};
use {AsyncRead, AsyncWrite};
/// A future which will copy all data from a reader into a writer.
///
/// Created by the [`copy`] function, this future will resolve to the number of
/// bytes copied or an error if one happens.
///
/// [`copy`]: fn.copy.html
#[derive(Debug)]
pub struct Copy<R, W> {
reader: Option<R>,
read_done: bool,
writer: Option<W>,
pos: usize,
cap: usize,
amt: u64,
buf: Box<[u8]>,
}
/// Creates a future which represents copying all the bytes from one object to
/// another.
///
/// The returned future will copy all the bytes read from `reader` into the
/// `writer` specified. This future will only complete once the `reader` has hit
/// EOF and all bytes have been written to and flushed from the `writer`
/// provided.
///
/// On success the number of bytes is returned and the `reader` and `writer` are
/// consumed. On error the error is returned and the I/O objects are consumed as
/// well.
pub fn copy<R, W>(reader: R, writer: W) -> Copy<R, W>
where R: AsyncRead,
W: AsyncWrite,
{
Copy {
reader: Some(reader),
read_done: false,
writer: Some(writer),
amt: 0,
pos: 0,
cap: 0,
buf: Box::new([0; 2048]),
}
}
impl<R, W> Future for Copy<R, W>
where R: AsyncRead,
W: AsyncWrite,
{
type Item = (u64, R, W);
type Error = io::Error;
fn poll(&mut self) -> Poll<(u64, R, W), io::Error> {
loop {
// If our buffer is empty, then we need to read some data to
// continue.
if self.pos == self.cap && !self.read_done {
let reader = self.reader.as_mut().unwrap();
let n = try_ready!(reader.poll_read(&mut self.buf));
if n == 0 {
self.read_done = true;
} else {
self.pos = 0;
self.cap = n;
}
}
// If our buffer has some data, let's write it out!
while self.pos < self.cap {
let writer = self.writer.as_mut().unwrap();
let i = try_ready!(writer.poll_write(&self.buf[self.pos..self.cap]));
if i == 0 {
return Err(io::Error::new(io::ErrorKind::WriteZero,
"write zero byte into writer"));
} else {
self.pos += i;
self.amt += i as u64;
}
}
// If we've written al the data and we've seen EOF, flush out the
// data and finish the transfer.
// done with the entire transfer.
if self.pos == self.cap && self.read_done {
try_ready!(self.writer.as_mut().unwrap().poll_flush());
let reader = self.reader.take().unwrap();
let writer = self.writer.take().unwrap();
return Ok((self.amt, reader, writer).into())
}
}
}
}