cargo/util/
io.rs

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1use std::io::{self, Read, Take};
2
3#[derive(Debug)]
4pub struct LimitErrorReader<R> {
5    inner: Take<R>,
6}
7
8impl<R: Read> LimitErrorReader<R> {
9    pub fn new(r: R, limit: u64) -> LimitErrorReader<R> {
10        LimitErrorReader {
11            inner: r.take(limit),
12        }
13    }
14}
15
16impl<R: Read> Read for LimitErrorReader<R> {
17    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
18        match self.inner.read(buf) {
19            Ok(0) if self.inner.limit() == 0 => Err(io::Error::new(
20                io::ErrorKind::Other,
21                "maximum limit reached when reading",
22            )),
23            e => e,
24        }
25    }
26}
27
28#[cfg(test)]
29mod tests {
30    use super::LimitErrorReader;
31
32    use std::io::Read;
33
34    #[test]
35    fn under_the_limit() {
36        let buf = &[1; 7][..];
37        let mut r = LimitErrorReader::new(buf, 8);
38        let mut out = Vec::new();
39        assert!(matches!(r.read_to_end(&mut out), Ok(7)));
40        assert_eq!(buf, out.as_slice());
41    }
42
43    #[test]
44    #[should_panic = "maximum limit reached when reading"]
45    fn over_the_limit() {
46        let buf = &[1; 8][..];
47        let mut r = LimitErrorReader::new(buf, 8);
48        let mut out = Vec::new();
49        r.read_to_end(&mut out).unwrap();
50    }
51}
cargo/util/io.rs

cargo/util/
io.rs
