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use std::pin::Pin;
use std::task::{Context, Poll};
use std::path::Path;
use std::io::{self, Cursor};
use tokio::fs::File;
use tokio::io::{AsyncRead, AsyncWrite, AsyncReadExt, ReadBuf, Take};
use futures::stream::Stream;
use futures::ready;
use yansi::Paint;
use crate::http::hyper;
use crate::ext::{PollExt, Chain};
use crate::data::{Capped, N};
/// Raw data stream of a request body.
///
/// This stream can only be obtained by calling
/// [`Data::open()`](crate::data::Data::open()) with a data limit. The stream
/// contains all of the data in the body of the request.
///
/// Reading from a `DataStream` is accomplished via the various methods on the
/// structure. In general, methods exists in two variants: those that _check_
/// whether the entire stream was read and those that don't. The former either
/// directly or indirectly (via [`Capped`]) return an [`N`] which allows
/// checking if the stream was read to completion while the latter do not.
///
/// | Read Into | Method | Notes |
/// |-----------|--------------------------------------|----------------------------------|
/// | `String` | [`DataStream::into_string()`] | Completeness checked. Preferred. |
/// | `String` | [`AsyncReadExt::read_to_string()`] | Unchecked w/existing `String`. |
/// | `Vec<u8>` | [`DataStream::into_bytes()`] | Checked. Preferred. |
/// | `Vec<u8>` | [`DataStream::stream_to(&mut vec)`] | Checked w/existing `Vec`. |
/// | `Vec<u8>` | [`DataStream::stream_precise_to()`] | Unchecked w/existing `Vec`. |
/// | `File` | [`DataStream::into_file()`] | Checked. Preferred. |
/// | `File` | [`DataStream::stream_to(&mut file)`] | Checked w/ existing `File`. |
/// | `File` | [`DataStream::stream_precise_to()`] | Unchecked w/ existing `File`. |
/// | `T` | [`DataStream::stream_to()`] | Checked. Any `T: AsyncWrite`. |
/// | `T` | [`DataStream::stream_precise_to()`] | Unchecked. Any `T: AsyncWrite`. |
///
/// [`DataStream::stream_to(&mut vec)`]: DataStream::stream_to()
/// [`DataStream::stream_to(&mut file)`]: DataStream::stream_to()
pub struct DataStream<'r> {
pub(crate) chain: Take<Chain<Cursor<Vec<u8>>, StreamReader<'r>>>,
}
/// An adapter: turns a `T: Stream` (in `StreamKind`) into a `tokio::AsyncRead`.
pub struct StreamReader<'r> {
state: State,
inner: StreamKind<'r>,
}
/// The current state of `StreamReader` `AsyncRead` adapter.
enum State {
Pending,
Partial(Cursor<hyper::body::Bytes>),
Done,
}
/// The kinds of streams we accept as `Data`.
enum StreamKind<'r> {
Empty,
Body(&'r mut hyper::Body),
Multipart(multer::Field<'r>)
}
impl<'r> DataStream<'r> {
pub(crate) fn new(buf: Vec<u8>, stream: StreamReader<'r>, limit: u64) -> Self {
let chain = Chain::new(Cursor::new(buf), stream).take(limit).into();
Self { chain }
}
/// Whether a previous read exhausted the set limit _and then some_.
async fn limit_exceeded(&mut self) -> io::Result<bool> {
#[cold]
async fn _limit_exceeded(stream: &mut DataStream<'_>) -> io::Result<bool> {
// Read one more byte after reaching limit to see if we cut early.
stream.chain.set_limit(1);
let mut buf = [0u8; 1];
Ok(stream.read(&mut buf).await? != 0)
}
Ok(self.chain.limit() == 0 && _limit_exceeded(self).await?)
}
/// Number of bytes a full read from `self` will _definitely_ read.
///
/// # Example
///
/// ```rust
/// use rocket::data::{Data, ToByteUnit};
///
/// async fn f(data: Data<'_>) {
/// let definitely_have_n_bytes = data.open(1.kibibytes()).hint();
/// }
/// ```
pub fn hint(&self) -> usize {
let buf_len = self.chain.get_ref().get_ref().0.get_ref().len();
std::cmp::min(buf_len, self.chain.limit() as usize)
}
/// A helper method to write the body of the request to any `AsyncWrite`
/// type. Returns an [`N`] which indicates how many bytes were written and
/// whether the entire stream was read. An additional read from `self` may
/// be required to check if all of the stream has been read. If that
/// information is not needed, use [`DataStream::stream_precise_to()`].
///
/// This method is identical to `tokio::io::copy(&mut self, &mut writer)`
/// except in that it returns an `N` to check for completeness.
///
/// # Example
///
/// ```rust
/// use std::io;
/// use rocket::data::{Data, ToByteUnit};
///
/// async fn data_guard(mut data: Data<'_>) -> io::Result<String> {
/// // write all of the data to stdout
/// let written = data.open(512.kibibytes())
/// .stream_to(tokio::io::stdout()).await?;
///
/// Ok(format!("Wrote {} bytes.", written))
/// }
/// ```
#[inline(always)]
pub async fn stream_to<W>(mut self, mut writer: W) -> io::Result<N>
where W: AsyncWrite + Unpin
{
let written = tokio::io::copy(&mut self, &mut writer).await?;
Ok(N { written, complete: !self.limit_exceeded().await? })
}
/// Like [`DataStream::stream_to()`] except that no end-of-stream check is
/// conducted and thus read/write completeness is unknown.
///
/// # Example
///
/// ```rust
/// use std::io;
/// use rocket::data::{Data, ToByteUnit};
///
/// async fn data_guard(mut data: Data<'_>) -> io::Result<String> {
/// // write all of the data to stdout
/// let written = data.open(512.kibibytes())
/// .stream_precise_to(tokio::io::stdout()).await?;
///
/// Ok(format!("Wrote {} bytes.", written))
/// }
/// ```
#[inline(always)]
pub async fn stream_precise_to<W>(mut self, mut writer: W) -> io::Result<u64>
where W: AsyncWrite + Unpin
{
tokio::io::copy(&mut self, &mut writer).await
}
/// A helper method to write the body of the request to a `Vec<u8>`.
///
/// # Example
///
/// ```rust
/// use std::io;
/// use rocket::data::{Data, ToByteUnit};
///
/// async fn data_guard(data: Data<'_>) -> io::Result<Vec<u8>> {
/// let bytes = data.open(4.kibibytes()).into_bytes().await?;
/// if !bytes.is_complete() {
/// println!("there are bytes remaining in the stream");
/// }
///
/// Ok(bytes.into_inner())
/// }
/// ```
pub async fn into_bytes(self) -> io::Result<Capped<Vec<u8>>> {
let mut vec = Vec::with_capacity(self.hint());
let n = self.stream_to(&mut vec).await?;
Ok(Capped { value: vec, n })
}
/// A helper method to write the body of the request to a `String`.
///
/// # Example
///
/// ```rust
/// use std::io;
/// use rocket::data::{Data, ToByteUnit};
///
/// async fn data_guard(data: Data<'_>) -> io::Result<String> {
/// let string = data.open(10.bytes()).into_string().await?;
/// if !string.is_complete() {
/// println!("there are bytes remaining in the stream");
/// }
///
/// Ok(string.into_inner())
/// }
/// ```
pub async fn into_string(mut self) -> io::Result<Capped<String>> {
let mut string = String::with_capacity(self.hint());
let written = self.read_to_string(&mut string).await?;
let n = N { written: written as u64, complete: !self.limit_exceeded().await? };
Ok(Capped { value: string, n })
}
/// A helper method to write the body of the request to a file at the path
/// determined by `path`. If a file at the path already exists, it is
/// overwritten. The opened file is returned.
///
/// # Example
///
/// ```rust
/// use std::io;
/// use rocket::data::{Data, ToByteUnit};
///
/// async fn data_guard(mut data: Data<'_>) -> io::Result<String> {
/// let file = data.open(1.megabytes()).into_file("/static/file").await?;
/// if !file.is_complete() {
/// println!("there are bytes remaining in the stream");
/// }
///
/// Ok(format!("Wrote {} bytes to /static/file", file.n))
/// }
/// ```
pub async fn into_file<P: AsRef<Path>>(self, path: P) -> io::Result<Capped<File>> {
let mut file = File::create(path).await?;
let n = self.stream_to(&mut tokio::io::BufWriter::new(&mut file)).await?;
Ok(Capped { value: file, n })
}
}
// TODO.async: Consider implementing `AsyncBufRead`.
impl StreamReader<'_> {
pub fn empty() -> Self {
Self { inner: StreamKind::Empty, state: State::Done }
}
}
impl<'r> From<&'r mut hyper::Body> for StreamReader<'r> {
fn from(body: &'r mut hyper::Body) -> Self {
Self { inner: StreamKind::Body(body), state: State::Pending }
}
}
impl<'r> From<multer::Field<'r>> for StreamReader<'r> {
fn from(field: multer::Field<'r>) -> Self {
Self { inner: StreamKind::Multipart(field), state: State::Pending }
}
}
impl AsyncRead for DataStream<'_> {
#[inline(always)]
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
if self.chain.limit() == 0 {
let stream: &StreamReader<'_> = &self.chain.get_ref().get_ref().1;
let kind = match stream.inner {
StreamKind::Empty => "an empty stream (vacuous)",
StreamKind::Body(_) => "the request body",
StreamKind::Multipart(_) => "a multipart form field",
};
warn_!("Data limit reached while reading {}.", kind.primary().bold());
}
Pin::new(&mut self.chain).poll_read(cx, buf)
}
}
impl Stream for StreamKind<'_> {
type Item = io::Result<hyper::body::Bytes>;
fn poll_next(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<Self::Item>> {
match self.get_mut() {
StreamKind::Body(body) => Pin::new(body).poll_next(cx)
.map_err_ext(|e| io::Error::new(io::ErrorKind::Other, e)),
StreamKind::Multipart(mp) => Pin::new(mp).poll_next(cx)
.map_err_ext(|e| io::Error::new(io::ErrorKind::Other, e)),
StreamKind::Empty => Poll::Ready(None),
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
match self {
StreamKind::Body(body) => body.size_hint(),
StreamKind::Multipart(mp) => mp.size_hint(),
StreamKind::Empty => (0, Some(0)),
}
}
}
impl AsyncRead for StreamReader<'_> {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
loop {
self.state = match self.state {
State::Pending => {
match ready!(Pin::new(&mut self.inner).poll_next(cx)) {
Some(Err(e)) => return Poll::Ready(Err(e)),
Some(Ok(bytes)) => State::Partial(Cursor::new(bytes)),
None => State::Done,
}
},
State::Partial(ref mut cursor) => {
let rem = buf.remaining();
match ready!(Pin::new(cursor).poll_read(cx, buf)) {
Ok(()) if rem == buf.remaining() => State::Pending,
result => return Poll::Ready(result),
}
}
State::Done => return Poll::Ready(Ok(())),
}
}
}
}