libcoreinst/io/
xz.rs

1// Copyright 2021 Red Hat
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// Implementation of an API similar to xz2::bufread::XzDecoder using
16// xz2::write::XzDecoder.  We need this because bufread::XzDecoder returns
17// io::ErrorKind::InvalidData if there's trailing data after an xz stream
18// (which can't be disambiguated from an actual error) but write::XzDecoder
19// returns Ok(0).  Return Ok(0) in this case and allow the caller to decide
20// what it wants to do about trailing data.
21//
22// https://github.com/alexcrichton/xz2-rs/pull/86
23
24use bytes::{Buf, BufMut, BytesMut};
25use std::io::{self, BufRead, Read};
26use xz2::write::XzDecoder;
27
28use crate::io::*;
29
30pub struct XzStreamDecoder<R: BufRead> {
31    source: R,
32    decompressor: XzDecoder<bytes::buf::Writer<BytesMut>>,
33}
34
35impl<R: BufRead> XzStreamDecoder<R> {
36    pub fn new(source: R) -> Self {
37        Self {
38            source,
39            decompressor: XzDecoder::new(BytesMut::new().writer()),
40        }
41    }
42
43    pub fn get_mut(&mut self) -> &mut R {
44        &mut self.source
45    }
46
47    pub fn into_inner(self) -> R {
48        self.source
49    }
50}
51
52impl<R: BufRead> Read for XzStreamDecoder<R> {
53    fn read(&mut self, out: &mut [u8]) -> io::Result<usize> {
54        if out.is_empty() {
55            return Ok(0);
56        }
57        loop {
58            let buf = self.decompressor.get_mut().get_mut();
59            if !buf.is_empty() {
60                let count = buf.len().min(out.len());
61                buf.copy_to_slice(&mut out[..count]);
62                return Ok(count);
63            }
64            let in_ = self.source.fill_buf()?;
65            if in_.is_empty() {
66                // EOF
67                self.decompressor.finish()?;
68                return Ok(0);
69            }
70            let count = self.decompressor.write(in_)?;
71            if count == 0 {
72                // end of compressed data
73                return Ok(0);
74            }
75            self.source.consume(count);
76            // decompressor normally wouldn't fill buf until the next
77            // write call
78            self.decompressor.flush()?;
79        }
80    }
81}
82
83#[cfg(test)]
84mod tests {
85    use super::*;
86    use std::io::BufReader;
87    use xz2::read::XzDecoder;
88
89    #[test]
90    fn small_decode() {
91        let mut compressed = Vec::new();
92        compressed.extend(include_bytes!("../../fixtures/verify/1M.xz"));
93        let mut uncompressed = Vec::new();
94        XzDecoder::new(&*compressed)
95            .read_to_end(&mut uncompressed)
96            .unwrap();
97        compressed.extend(b"abcdefg");
98
99        let mut d = XzStreamDecoder::new(BufReader::with_capacity(1, &*compressed));
100        let mut out = Vec::new();
101        let mut buf = [0u8];
102        loop {
103            match d.read(&mut buf).unwrap() {
104                0 => break,
105                1 => out.push(buf[0]),
106                _ => unreachable!(),
107            }
108        }
109        assert_eq!(&out, &uncompressed);
110        let mut remainder = Vec::new();
111        d.into_inner().read_to_end(&mut remainder).unwrap();
112        assert_eq!(&remainder, b"abcdefg");
113    }
114}
libcoreinst/io/xz.rs

libcoreinst/io/
xz.rs
