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//! 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.
///
#[derive(Debug)]
pub struct CrcReader<R> {
inner: R,
crc: Crc,
}
impl Default for Crc {
fn default() -> Self {
Self::new()
}
}
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 = self.amt.wrapping_add(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.
///
#[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 = self.inner.write(buf)?;
self.crc.update(&buf[..amt]);
Ok(amt)
}
fn flush(&mut self) -> io::Result<()> {
self.inner.flush()
}
}