inflate/reader.rs
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use std::io::{self, BufRead, Read, BufReader, Error, ErrorKind, Write};
use std::{cmp,mem};
use super::InflateStream;
/// Workaround for lack of copy_from_slice on pre-1.9 rust.
#[inline]
fn copy_from_slice(mut to: &mut [u8], from: &[u8]) {
assert_eq!(to.len(), from.len());
to.write_all(from).unwrap();
}
/// A DEFLATE decoder/decompressor.
///
/// This structure implements a `Read` interface and takes a stream
/// of compressed data that implements the `BufRead` trait as input,
/// providing the decompressed data when read from.
///
/// # Example
/// ```
/// use std::io::Read;
/// use inflate::DeflateDecoderBuf;
///
/// const TEST_STRING: &'static str = "Hello, world";
/// let encoded = vec![243, 72, 205, 201, 201, 215, 81, 40, 207, 47, 202, 73, 1, 0];
/// let mut decoder = DeflateDecoderBuf::new(&encoded[..]);
/// let mut output = Vec::new();
/// let status = decoder.read_to_end(&mut output);
/// # let _ = status;
/// assert_eq!(String::from_utf8(output).unwrap(), TEST_STRING);
/// ```
pub struct DeflateDecoderBuf<R> {
/// The inner reader instance
reader: R,
/// The raw decompressor
decompressor: InflateStream,
/// How many bytes of the decompressor's output buffer still need to be output.
pending_output_bytes: usize,
/// Total number of bytes read from the underlying reader.
total_in: u64,
/// Total number of bytes written in `read` calls.
total_out: u64,
}
impl<R: BufRead> DeflateDecoderBuf<R> {
/// Create a new `Deflatedecoderbuf` to read from a raw deflate stream.
pub fn new(reader: R) -> DeflateDecoderBuf<R> {
DeflateDecoderBuf {
reader: reader,
decompressor: InflateStream::new(),
pending_output_bytes: 0,
total_in: 0,
total_out: 0,
}
}
/// Create a new `DeflateDecoderbuf` that reads from a zlib wrapped deflate stream.
pub fn from_zlib(reader: R) -> DeflateDecoderBuf<R> {
DeflateDecoderBuf {
reader: reader,
decompressor: InflateStream::from_zlib(),
pending_output_bytes: 0,
total_in: 0,
total_out: 0,
}
}
/// Create a new `DeflateDecoderbuf` that reads from a zlib wrapped deflate stream.
/// without calculating and validating the checksum.
pub fn from_zlib_no_checksum(reader: R) -> DeflateDecoderBuf<R> {
DeflateDecoderBuf {
reader: reader,
decompressor: InflateStream::from_zlib_no_checksum(),
pending_output_bytes: 0,
total_in: 0,
total_out: 0,
}
}
}
impl<R> DeflateDecoderBuf<R> {
/// Resets the decompressor, and replaces the current inner `BufRead` instance by `r`.
/// without doing any extra reallocations.
///
/// Note that this function doesn't ensure that all data has been output.
#[inline]
pub fn reset(&mut self, r: R) -> R {
self.decompressor.reset();
mem::replace(&mut self.reader, r)
}
/// Resets the decoder, but continue to read from the same reader.
///
/// Note that this function doesn't ensure that all data has been output.
#[inline]
pub fn reset_data(&mut self) {
self.decompressor.reset()
}
/// Returns a reference to the underlying `BufRead` instance.
#[inline]
pub fn get_ref(&self) -> &R {
&self.reader
}
/// Returns a mutable reference to the underlying `BufRead` instance.
///
/// Note that mutation of the reader may cause surprising results if the decoder is going to
/// keep being used.
#[inline]
pub fn get_mut(&mut self) -> &mut R {
&mut self.reader
}
/// Drops the decoder and return the inner `BufRead` instance.
///
/// Note that this function doesn't ensure that all data has been output.
#[inline]
pub fn into_inner(self) -> R {
self.reader
}
/// Returns the total bytes read from the underlying `BufRead` instance.
#[inline]
pub fn total_in(&self) -> u64 {
self.total_in
}
/// Returns the total number of bytes output from this decoder.
#[inline]
pub fn total_out(&self) -> u64 {
self.total_out
}
/// Returns the calculated checksum value of the currently decoded data.
///
/// Will return 0 for cases where the checksum is not validated.
#[inline]
pub fn current_checksum(&self) -> u32 {
self.decompressor.current_checksum()
}
}
impl<R: BufRead> Read for DeflateDecoderBuf<R> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let mut bytes_out = 0;
// If there is still data left to ouput from the last call to `update()`, that needs to be
// output first
if self.pending_output_bytes != 0 {
// Get the part of the buffer that has not been output yet.
// The decompressor sets `pos` to 0 when it reaches the end of it's internal buffer,
// so we have to check for that.
let start = if self.decompressor.pos != 0 {
self.decompressor.pos as usize - self.pending_output_bytes
} else {
self.decompressor.buffer.len() - self.pending_output_bytes
};
// Copy as much decompressed as possible to buf.
let bytes_to_copy = cmp::min(buf.len(), self.pending_output_bytes);
let pending_data =
&self.decompressor.buffer[start..
start + bytes_to_copy];
copy_from_slice(&mut buf[..bytes_to_copy],pending_data);
bytes_out += bytes_to_copy;
// This won't underflow since `bytes_to_copy` will be at most
// the same value as `pending_output_bytes`.
self.pending_output_bytes -= bytes_to_copy;
if self.pending_output_bytes != 0 {
self.total_out += bytes_out as u64;
// If there is still decompressed data left that didn't
// fit in `buf`, return what we read.
return Ok(bytes_out);
}
}
// There is space in `buf` for more data, so try to read more.
let (input_bytes_read, remaining_bytes) = {
self.pending_output_bytes = 0;
let input = try!(self.reader.fill_buf());
if input.len() == 0 {
self.total_out += bytes_out as u64;
//If there is nothing more to read, return.
return Ok(bytes_out);
}
let (input_bytes_read, data) =
match self.decompressor.update(&input) {
Ok(res) => res,
Err(m) => return Err(Error::new(ErrorKind::Other, m))
};
// Space left in `buf`
let space_left = buf.len() - bytes_out;
let bytes_to_copy = cmp::min(space_left, data.len());
copy_from_slice(&mut buf[bytes_out..bytes_out + bytes_to_copy], &data[..bytes_to_copy]);
bytes_out += bytes_to_copy;
// Can't underflow as bytes_to_copy is bounded by data.len().
(input_bytes_read, data.len() - bytes_to_copy)
};
self.pending_output_bytes += remaining_bytes;
self.total_in += input_bytes_read as u64;
self.total_out += bytes_out as u64;
self.reader.consume(input_bytes_read);
Ok(bytes_out)
}
}
/// A DEFLATE decoder/decompressor.
///
/// This structure implements a `Read` interface and takes a stream of compressed data that
/// implements the `Read` trait as input,
/// provoding the decompressed data when read from.
/// # Example
/// ```
/// use std::io::Read;
/// use inflate::DeflateDecoder;
/// const TEST_STRING: &'static str = "Hello, world";
/// let encoded = vec![243, 72, 205, 201, 201, 215, 81, 40, 207, 47, 202, 73, 1, 0];
/// let mut decoder = DeflateDecoder::new(&encoded[..]);
/// let mut output = Vec::new();
/// let status = decoder.read_to_end(&mut output);
/// # let _ = status;
/// assert_eq!(String::from_utf8(output).unwrap(), TEST_STRING);
/// ```
pub struct DeflateDecoder<R> {
/// Inner DeflateDecoderBuf, with R wrapped in a `BufReader`.
inner: DeflateDecoderBuf<BufReader<R>>
}
impl<R: Read> DeflateDecoder<R> {
/// Create a new `Deflatedecoderbuf` to read from a raw deflate stream.
pub fn new(reader: R) -> DeflateDecoder<R> {
DeflateDecoder {
inner: DeflateDecoderBuf::new(BufReader::new(reader))
}
}
/// Create a new `DeflateDecoderbuf` that reads from a zlib wrapped deflate stream.
pub fn from_zlib(reader: R) -> DeflateDecoder<R> {
DeflateDecoder {
inner: DeflateDecoderBuf::from_zlib(BufReader::new(reader))
}
}
/// Create a new `DeflateDecoderbuf` that reads from a zlib wrapped deflate stream.
/// without calculating and validating the checksum.
pub fn from_zlib_no_checksum(reader: R) -> DeflateDecoder<R> {
DeflateDecoder {
inner: DeflateDecoderBuf::from_zlib_no_checksum(BufReader::new(reader))
}
}
/// Resets the decompressor, and replaces the current inner `BufRead` instance by `r`.
/// without doing any extra reallocations.
///
/// Note that this function doesn't ensure that all data has been output.
#[inline]
pub fn reset(&mut self, r: R) -> R {
self.inner.reset(BufReader::new(r)).into_inner()
}
/// Returns a reference to the underlying reader.
#[inline]
pub fn get_ref(&self) -> &R {
self.inner.get_ref().get_ref()
}
/// Returns a mutable reference to the underlying reader.
///
/// Note that mutation of the reader may cause surprising results if the decoder is going to
/// keep being used.
#[inline]
pub fn get_mut(&mut self) -> &mut R {
self.inner.get_mut().get_mut()
}
/// Returns the total number of bytes output from this decoder.
#[inline]
pub fn into_inner(self) -> R {
self.inner.into_inner().into_inner()
}
}
impl<R> DeflateDecoder<R> {
/// Resets the decoder, but continue to read from the same reader.
///
/// Note that this function doesn't ensure that all data has been output.
#[inline]
pub fn reset_data(&mut self) {
self.inner.reset_data()
}
/// Returns the total bytes read from the underlying reader.
#[inline]
pub fn total_in(&self) -> u64 {
self.inner.total_in
}
/// Returns the total number of bytes output from this decoder.
#[inline]
pub fn total_out(&self) -> u64 {
self.inner.total_out
}
/// Returns the calculated checksum value of the currently decoded data.
///
/// Will return 0 for cases where the checksum is not validated.
#[inline]
pub fn current_checksum(&self) -> u32 {
self.inner.current_checksum()
}
}
impl<R: Read> Read for DeflateDecoder<R> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
self.inner.read(buf)
}
}
#[cfg(test)]
mod test {
use super::{DeflateDecoder};
use std::io::Read;
#[test]
fn deflate_reader() {
const TEST_STRING: &'static str = "Hello, world";
let encoded = vec![243, 72, 205, 201, 201, 215, 81, 40, 207, 47, 202, 73, 1, 0];
let mut decoder = DeflateDecoder::new(&encoded[..]);
let mut output = Vec::new();
decoder.read_to_end(&mut output).unwrap();
assert_eq!(String::from_utf8(output).unwrap(), TEST_STRING);
assert_eq!(decoder.total_in(), encoded.len() as u64);
assert_eq!(decoder.total_out(), TEST_STRING.len() as u64);
}
#[test]
fn zlib_reader() {
const TEST_STRING: &'static str = "Hello, zlib!";
let encoded = vec![120, 156, 243, 72, 205, 201, 201, 215, 81, 168, 202, 201,
76, 82, 4, 0, 27, 101, 4, 19];
let mut decoder = DeflateDecoder::from_zlib(&encoded[..]);
let mut output = Vec::new();
decoder.read_to_end(&mut output).unwrap();
assert_eq!(String::from_utf8(output).unwrap(), TEST_STRING);
assert_eq!(decoder.total_in(), encoded.len() as u64);
assert_eq!(decoder.total_out(), TEST_STRING.len() as u64);
}
}