async_compression/generic/bufread/
decoder.rs

1use crate::{
2    codecs::DecodeV2,
3    core::util::{PartialBuffer, WriteBuffer},
4};
5use std::{io::Result, ops::ControlFlow, panic::AssertUnwindSafe};
6
7#[derive(Debug)]
8enum State {
9    Decoding,
10    Flushing,
11    Done,
12    Next,
13    Error(AssertUnwindSafe<std::io::Error>),
14}
15
16#[derive(Debug)]
17pub struct Decoder {
18    state: State,
19    multiple_members: bool,
20}
21
22impl Default for Decoder {
23    fn default() -> Self {
24        Self {
25            state: State::Decoding,
26            multiple_members: false,
27        }
28    }
29}
30
31impl Decoder {
32    pub fn multiple_members(&mut self, enabled: bool) {
33        self.multiple_members = enabled;
34    }
35
36    pub fn do_poll_read(
37        &mut self,
38        output: &mut WriteBuffer<'_>,
39        decoder: &mut dyn DecodeV2,
40        input: &mut PartialBuffer<&[u8]>,
41        mut first: bool,
42    ) -> ControlFlow<Result<()>> {
43        loop {
44            self.state = match self.state {
45                State::Decoding => {
46                    if input.unwritten().is_empty() && !first {
47                        // Avoid attempting to reinitialise the decoder if the
48                        // reader has returned EOF.
49                        self.multiple_members = false;
50
51                        State::Flushing
52                    } else {
53                        match decoder.decode(input, output) {
54                            Ok(true) => State::Flushing,
55                            // ignore the first error, occurs when input is empty
56                            // but we need to run decode to flush
57                            Err(err) if !first => {
58                                self.state = State::Error(AssertUnwindSafe(err));
59                                if output.written_len() > 0 {
60                                    return ControlFlow::Break(Ok(()));
61                                } else {
62                                    continue;
63                                }
64                            }
65                            // poll for more data for the next decode
66                            _ => break,
67                        }
68                    }
69                }
70
71                State::Flushing => {
72                    match decoder.finish(output) {
73                        Ok(true) => {
74                            if self.multiple_members {
75                                if let Err(err) = decoder.reinit() {
76                                    self.state = State::Error(AssertUnwindSafe(err));
77                                    if output.written_len() > 0 {
78                                        return ControlFlow::Break(Ok(()));
79                                    } else {
80                                        continue;
81                                    }
82                                }
83
84                                // Poll again only if the decode stage consumed all the input.
85                                first = input.unwritten().is_empty();
86                                State::Next
87                            } else {
88                                State::Done
89                            }
90                        }
91                        Ok(false) => State::Flushing,
92                        Err(err) => {
93                            self.state = State::Error(AssertUnwindSafe(err));
94                            if output.written_len() > 0 {
95                                return ControlFlow::Break(Ok(()));
96                            } else {
97                                continue;
98                            }
99                        }
100                    }
101                }
102
103                State::Done => return ControlFlow::Break(Ok(())),
104
105                State::Next => {
106                    if input.unwritten().is_empty() {
107                        if first {
108                            // poll for more data to check if there's another stream
109                            break;
110                        }
111                        State::Done
112                    } else {
113                        State::Decoding
114                    }
115                }
116
117                State::Error(_) => {
118                    let State::Error(err) = std::mem::replace(&mut self.state, State::Done) else {
119                        unreachable!()
120                    };
121                    return ControlFlow::Break(Err(err.0));
122                }
123            };
124
125            if output.has_no_spare_space() {
126                return ControlFlow::Break(Ok(()));
127            }
128        }
129
130        if output.has_no_spare_space() {
131            ControlFlow::Break(Ok(()))
132        } else {
133            ControlFlow::Continue(())
134        }
135    }
136}
137
138macro_rules! impl_decoder {
139    () => {
140        use crate::generic::bufread::Decoder as GenericDecoder;
141
142        use std::{ops::ControlFlow, task::ready};
143
144        use pin_project_lite::pin_project;
145
146        pin_project! {
147            #[derive(Debug)]
148            pub struct Decoder<R, D> {
149                #[pin]
150                reader: R,
151                decoder: D,
152                inner: GenericDecoder,
153            }
154        }
155
156        impl<R: AsyncBufRead, D: DecodeV2> Decoder<R, D> {
157            pub fn new(reader: R, decoder: D) -> Self {
158                Self {
159                    reader,
160                    decoder,
161                    inner: GenericDecoder::default(),
162                }
163            }
164        }
165
166        impl<R, D> Decoder<R, D> {
167            pub fn get_ref(&self) -> &R {
168                &self.reader
169            }
170
171            pub fn get_mut(&mut self) -> &mut R {
172                &mut self.reader
173            }
174
175            pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R> {
176                self.project().reader
177            }
178
179            pub fn into_inner(self) -> R {
180                self.reader
181            }
182
183            pub fn multiple_members(&mut self, enabled: bool) {
184                self.inner.multiple_members(enabled);
185            }
186        }
187
188        fn do_poll_read(
189            inner: &mut GenericDecoder,
190            decoder: &mut dyn DecodeV2,
191            mut reader: Pin<&mut dyn AsyncBufRead>,
192            cx: &mut Context<'_>,
193            output: &mut WriteBuffer<'_>,
194        ) -> Poll<Result<()>> {
195            if let ControlFlow::Break(res) =
196                inner.do_poll_read(output, decoder, &mut PartialBuffer::new(&[][..]), true)
197            {
198                return Poll::Ready(res);
199            }
200
201            loop {
202                let mut input = PartialBuffer::new(match reader.as_mut().poll_fill_buf(cx)? {
203                    Poll::Ready(input) => input,
204                    Poll::Pending if output.written().is_empty() => return Poll::Pending,
205                    _ => return Poll::Ready(Ok(())),
206                });
207
208                let control_flow = inner.do_poll_read(output, decoder, &mut input, false);
209
210                let bytes_read = input.written().len();
211                reader.as_mut().consume(bytes_read);
212
213                if let ControlFlow::Break(res) = control_flow {
214                    break Poll::Ready(res);
215                }
216            }
217        }
218
219        impl<R: AsyncBufRead, D: DecodeV2> Decoder<R, D> {
220            fn do_poll_read(
221                self: Pin<&mut Self>,
222                cx: &mut Context<'_>,
223                output: &mut WriteBuffer<'_>,
224            ) -> Poll<Result<()>> {
225                let this = self.project();
226
227                do_poll_read(this.inner, this.decoder, this.reader, cx, output)
228            }
229        }
230    };
231}
232pub(crate) use impl_decoder;
async_compression/generic/bufread/decoder.rs

async_compression/generic/bufread/
decoder.rs
