150 lines
4.5 KiB
Rust
150 lines
4.5 KiB
Rust
use bytes::{Buf, BufMut, Bytes, BytesMut};
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use futures::Async;
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use futures3::stream::{Stream, StreamExt, TryStream};
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use std::task::{Context, Poll};
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use crate::ebml::FromEbml;
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use crate::error::WebmetroError;
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pub struct EbmlStreamingParser<S> {
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stream: S,
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buffer: BytesMut,
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buffer_size_limit: Option<usize>,
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borrowed: Bytes,
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}
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impl<S> EbmlStreamingParser<S> {
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/// add a "soft" buffer size limit; if the input buffer exceeds this size,
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/// error the stream instead of resuming. It's still possible for the buffer
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/// to exceed this size *after* a fill, so ensure input sizes are reasonable.
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pub fn with_soft_limit(mut self, limit: usize) -> Self {
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self.buffer_size_limit = Some(limit);
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self
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}
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}
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pub trait StreamEbml: Sized + TryStream + Unpin
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where
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Self: Sized + TryStream + Unpin,
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Self::Ok: Buf,
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{
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fn parse_ebml(self) -> EbmlStreamingParser<Self> {
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EbmlStreamingParser {
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stream: self,
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buffer: BytesMut::new(),
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buffer_size_limit: None,
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borrowed: Bytes::new(),
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}
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}
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}
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impl<I: Buf, S: Stream<Item = Result<I, WebmetroError>> + Unpin> StreamEbml for S {}
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impl<I: Buf, S: Stream<Item = Result<I, WebmetroError>> + Unpin> EbmlStreamingParser<S> {
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pub fn poll_event<'a, T: FromEbml<'a>>(
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&'a mut self,
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cx: &mut Context,
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) -> Result<Async<Option<T>>, WebmetroError> {
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loop {
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match T::check_space(&self.buffer)? {
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None => {
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// need to refill buffer, below
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}
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Some(info) => {
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let mut bytes = self.buffer.split_to(info.element_len).freeze();
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bytes.advance(info.body_offset);
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self.borrowed = bytes;
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return Ok(Async::Ready(Some(T::decode(
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info.element_id,
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&self.borrowed,
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)?)));
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}
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}
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if let Some(limit) = self.buffer_size_limit {
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if limit <= self.buffer.len() {
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return Err(WebmetroError::ResourcesExceeded);
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}
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}
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match self.stream.poll_next_unpin(cx)? {
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Poll::Ready(Some(buf)) => {
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self.buffer.reserve(buf.remaining());
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self.buffer.put(buf);
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// ok can retry decoding now
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}
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Poll::Ready(None) => return Ok(Async::Ready(None)),
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Poll::Pending => return Ok(Async::NotReady),
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}
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use bytes::IntoBuf;
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use futures::Async::*;
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use futures3::{
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future::poll_fn,
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stream::StreamExt,
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FutureExt,
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};
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use matches::assert_matches;
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use crate::stream_parser::*;
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use crate::tests::ENCODE_WEBM_TEST_FILE;
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use crate::webm::*;
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#[test]
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fn stream_webm_test() {
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poll_fn(|cx| {
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let pieces = vec![
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&ENCODE_WEBM_TEST_FILE[0..20],
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&ENCODE_WEBM_TEST_FILE[20..40],
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&ENCODE_WEBM_TEST_FILE[40..],
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];
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let mut stream_parser = futures3::stream::iter(pieces.iter())
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.map(|bytes| Ok(bytes.into_buf()))
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.parse_ebml();
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::EbmlHead)))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::Segment)))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::Tracks(_))))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::Cluster)))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::Timecode(0))))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::SimpleBlock(_))))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::Cluster)))
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);
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assert_matches!(
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stream_parser.poll_event(cx),
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Ok(Ready(Some(WebmElement::Timecode(1000))))
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);
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std::task::Poll::Ready(())
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})
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.now_or_never()
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.expect("Test succeeded without blocking");
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}
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}
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