1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178

//! Simple CRC bindings backed by miniz.c

use std::io;
use std::io::prelude::*;

use crc32fast::Hasher;

/// The CRC calculated by a [`CrcReader`].
///
/// [`CrcReader`]: struct.CrcReader.html
#[derive(Debug)]
pub struct Crc {
    amt: u32,
    hasher: Hasher,
}

/// A wrapper around a [`Read`] that calculates the CRC.
///
/// [`Read`]: https://doc.rust-lang.org/std/io/trait.Read.html
#[derive(Debug)]
pub struct CrcReader<R> {
    inner: R,
    crc: Crc,
}

impl Crc {
    /// Create a new CRC.
    pub fn new() -> Crc {
        Crc {
            amt: 0,
            hasher: Hasher::new(),
        }
    }

    /// Returns the current crc32 checksum.
    pub fn sum(&self) -> u32 {
        self.hasher.clone().finalize()
    }

    /// The number of bytes that have been used to calculate the CRC.
    /// This value is only accurate if the amount is lower than 2<sup>32</sup>.
    pub fn amount(&self) -> u32 {
        self.amt
    }

    /// Update the CRC with the bytes in `data`.
    pub fn update(&mut self, data: &[u8]) {
        self.amt = self.amt.wrapping_add(data.len() as u32);
        self.hasher.update(data);
    }

    /// Reset the CRC.
    pub fn reset(&mut self) {
        self.amt = 0;
        self.hasher.reset();
    }

    /// Combine the CRC with the CRC for the subsequent block of bytes.
    pub fn combine(&mut self, additional_crc: &Crc) {
        self.amt += additional_crc.amt;
        self.hasher.combine(&additional_crc.hasher);
    }
}

impl<R: Read> CrcReader<R> {
    /// Create a new CrcReader.
    pub fn new(r: R) -> CrcReader<R> {
        CrcReader {
            inner: r,
            crc: Crc::new(),
        }
    }
}

impl<R> CrcReader<R> {
    /// Get the Crc for this CrcReader.
    pub fn crc(&self) -> &Crc {
        &self.crc
    }

    /// Get the reader that is wrapped by this CrcReader.
    pub fn into_inner(self) -> R {
        self.inner
    }

    /// Get the reader that is wrapped by this CrcReader by reference.
    pub fn get_ref(&self) -> &R {
        &self.inner
    }

    /// Get a mutable reference to the reader that is wrapped by this CrcReader.
    pub fn get_mut(&mut self) -> &mut R {
        &mut self.inner
    }

    /// Reset the Crc in this CrcReader.
    pub fn reset(&mut self) {
        self.crc.reset();
    }
}

impl<R: Read> Read for CrcReader<R> {
    fn read(&mut self, into: &mut [u8]) -> io::Result<usize> {
        let amt = self.inner.read(into)?;
        self.crc.update(&into[..amt]);
        Ok(amt)
    }
}

impl<R: BufRead> BufRead for CrcReader<R> {
    fn fill_buf(&mut self) -> io::Result<&[u8]> {
        self.inner.fill_buf()
    }
    fn consume(&mut self, amt: usize) {
        if let Ok(data) = self.inner.fill_buf() {
            self.crc.update(&data[..amt]);
        }
        self.inner.consume(amt);
    }
}

/// A wrapper around a [`Write`] that calculates the CRC.
///
/// [`Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
#[derive(Debug)]
pub struct CrcWriter<W> {
    inner: W,
    crc: Crc,
}

impl<W> CrcWriter<W> {
    /// Get the Crc for this CrcWriter.
    pub fn crc(&self) -> &Crc {
        &self.crc
    }

    /// Get the writer that is wrapped by this CrcWriter.
    pub fn into_inner(self) -> W {
        self.inner
    }

    /// Get the writer that is wrapped by this CrcWriter by reference.
    pub fn get_ref(&self) -> &W {
        &self.inner
    }

    /// Get a mutable reference to the writer that is wrapped by this CrcWriter.
    pub fn get_mut(&mut self) -> &mut W {
        &mut self.inner
    }

    /// Reset the Crc in this CrcWriter.
    pub fn reset(&mut self) {
        self.crc.reset();
    }
}

impl<W: Write> CrcWriter<W> {
    /// Create a new CrcWriter.
    pub fn new(w: W) -> CrcWriter<W> {
        CrcWriter {
            inner: w,
            crc: Crc::new(),
        }
    }
}

impl<W: Write> Write for CrcWriter<W> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        let amt = try!(self.inner.write(buf));
        self.crc.update(&buf[..amt]);
        Ok(amt)
    }

    fn flush(&mut self) -> io::Result<()> {
        self.inner.flush()
    }
}