use std::cmp;
use std::io;
use std::io::prelude::*;
use std::mem;
use super::{corrupt, read_into, GzBuilder, GzHeader, GzHeaderParser};
use crate::crc::CrcReader;
use crate::deflate;
use crate::Compression;
fn copy(into: &mut [u8], from: &[u8], pos: &mut usize) -> usize {
let min = cmp::min(into.len(), from.len() - *pos);
for (slot, val) in into.iter_mut().zip(from[*pos..*pos + min].iter()) {
*slot = *val;
}
*pos += min;
min
}
/// A gzip streaming encoder
///
/// This structure implements a [`Read`] interface. When read from, it reads
/// uncompressed data from the underlying [`BufRead`] and provides the compressed data.
///
/// [`Read`]:
https://doc.rust-lang.org/std/io/trait.Read.html
/// [`BufRead`]:
https://doc.rust-lang.org/std/io/trait.BufRead.html
///
/// # Examples
///
/// ```
/// use std::io::prelude::*;
/// use std::io;
/// use flate2::Compression;
/// use flate2::bufread::GzEncoder;
/// use std::fs::File;
/// use std::io::BufReader;
///
/// // Opens sample file, compresses the contents and returns a Vector or error
/// // File wrapped in a BufReader implements BufRead
///
/// fn open_hello_world() -> io::Result<Vec<u8>> {
/// let f = File::open("examples/hello_world.txt")?;
/// let b = BufReader::new(f);
/// let mut gz = GzEncoder::new(b, Compression::fast());
/// let mut buffer = Vec::new();
/// gz.read_to_end(&mut buffer)?;
/// Ok(buffer)
/// }
/// ```
#[derive(Debug)]
pub struct GzEncoder<R> {
inner: deflate::bufread::DeflateEncoder<CrcReader<R>>,
header: Vec<u8>,
pos: usize,
eof: bool,
}
pub fn gz_encoder<R: BufRead>(header: Vec<u8>, r: R, lvl: Compression) -> GzEncoder<R> {
let crc = CrcReader::new(r);
GzEncoder {
inner: deflate::bufread::DeflateEncoder::new(crc, lvl),
header,
pos: 0,
eof: false,
}
}
impl<R: BufRead> GzEncoder<R> {
/// Creates a new encoder which will use the given compression level.
///
/// The encoder is not configured specially for the emitted header. For
/// header configuration, see the `GzBuilder` type.
///
/// The data read from the stream `r` will be compressed and available
/// through the returned reader.
pub fn new(r: R, level: Compression) -> GzEncoder<R> {
GzBuilder::new().buf_read(r, level)
}
fn read_footer(&mut self, into: &mut [u8]) -> io::Result<usize> {
if self.pos == 8 {
return Ok(0);
}
let crc = self.inner.get_ref().crc();
let ref arr = [
(crc.sum() >> 0) as u8,
(crc.sum() >> 8) as u8,
(crc.sum() >> 16) as u8,
(crc.sum() >> 24) as u8,
(crc.amount() >> 0) as u8,
(crc.amount() >> 8) as u8,
(crc.amount() >> 16) as u8,
(crc.amount() >> 24) as u8,
];
Ok(copy(into, arr, &mut self.pos))
}
}
impl<R> GzEncoder<R> {
/// Acquires a reference to the underlying reader.
pub fn get_ref(&self) -> &R {
self.inner.get_ref().get_ref()
}
/// Acquires a mutable reference to the underlying reader.
///
/// Note that mutation of the reader may result in surprising results if
/// this encoder is continued to be used.
pub fn get_mut(&mut self) -> &mut R {
self.inner.get_mut().get_mut()
}
/// Returns the underlying stream, consuming this encoder
pub fn into_inner(self) -> R {
self.inner.into_inner().into_inner()
}
}
#[inline]
fn finish(buf: &[u8; 8]) -> (u32, u32) {
let crc = ((buf[0] as u32) << 0)
| ((buf[1] as u32) << 8)
| ((buf[2] as u32) << 16)
| ((buf[3] as u32) << 24);
let amt = ((buf[4] as u32) << 0)
| ((buf[5] as u32) << 8)
| ((buf[6] as u32) << 16)
| ((buf[7] as u32) << 24);
(crc, amt)
}
impl<R: BufRead> Read for GzEncoder<R> {
fn read(&mut self, mut into: &mut [u8]) -> io::Result<usize> {
let mut amt = 0;
if self.eof {
return self.read_footer(into);
} else if self.pos < self.header.len() {
amt += copy(into, &self.header, &mut self.pos);
if amt == into.len() {
return Ok(amt);
}
let tmp = into;
into = &mut tmp[amt..];
}
match self.inner.read(into)? {
0 => {
self.eof = true;
self.pos = 0;
self.read_footer(into)
}
n => Ok(amt + n),
}
}
}
impl<R: BufRead + Write> Write for GzEncoder<R> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.get_mut().write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.get_mut().flush()
}
}
/// A decoder for a single member of a [gzip file].
///
/// This structure implements a [`Read`] interface. When read from, it reads
/// compressed data from the underlying [`BufRead`] and provides the uncompressed data.
///
/// After reading a single member of the gzip data this reader will return
/// Ok(0) even if there are more bytes available in the underlying reader.
/// If you need the following bytes, call `into_inner()` after Ok(0) to
/// recover the underlying reader.
///
/// To handle gzip files that may have multiple members, see [`MultiGzDecoder`]
/// or read more
/// [in the introduction](../index.html#about-multi-member-gzip-files).
///
/// [gzip file]:
https://www.rfc-editor.org/rfc/rfc1952#page-5
/// [`Read`]:
https://doc.rust-lang.org/std/io/trait.Read.html
/// [`BufRead`]:
https://doc.rust-lang.org/std/io/trait.BufRead.html
///
/// # Examples
///
/// ```
/// use std::io::prelude::*;
/// use std::io;
/// # use flate2::Compression;
/// # use flate2::write::GzEncoder;
/// use flate2::bufread::GzDecoder;
///
/// # fn main() {
/// # let mut e = GzEncoder::new(Vec::new(), Compression::default());
/// # e.write_all(b"Hello World").unwrap();
/// # let bytes = e.finish().unwrap();
/// # println!("{}", decode_reader(bytes).unwrap());
/// # }
/// #
/// // Uncompresses a Gz Encoded vector of bytes and returns a string or error
/// // Here &[u8] implements BufRead
///
/// fn decode_reader(bytes: Vec<u8>) -> io::Result<String> {
/// let mut gz = GzDecoder::new(&bytes[..]);
/// let mut s = String::new();
/// gz.read_to_string(&mut s)?;
/// Ok(s)
/// }
/// ```
#[derive(Debug)]
pub struct GzDecoder<R> {
state: GzState,
reader: CrcReader<deflate::bufread::DeflateDecoder<R>>,
multi: bool,
}
#[derive(Debug)]
enum GzState {
Header(GzHeaderParser),
Body(GzHeader),
Finished(GzHeader, usize, [u8; 8]),
Err(io::Error),
End(Option<GzHeader>),
}
impl<R: BufRead> GzDecoder<R> {
/// Creates a new decoder from the given reader, immediately parsing the
/// gzip header.
pub fn new(mut r: R) -> GzDecoder<R> {
let mut header_parser = GzHeaderParser::new();
let state = match header_parser.parse(&mut r) {
Ok(_) => GzState::Body(GzHeader::from(header_parser)),
Err(ref err) if io::ErrorKind::WouldBlock == err.kind() => {
GzState::Header(header_parser)
}
Err(err) => GzState::Err(err),
};
GzDecoder {
state,
reader: CrcReader::new(deflate::bufread::DeflateDecoder::new(r)),
multi: false,
}
}
fn multi(mut self, flag: bool) -> GzDecoder<R> {
self.multi = flag;
self
}
}
impl<R> GzDecoder<R> {
/// Returns the header associated with this stream, if it was valid
pub fn header(&self) -> Option<&GzHeader> {
match &self.state {
GzState::Body(header) | GzState::Finished(header, _, _) => Some(header),
GzState::End(header) => header.as_ref(),
_ => None,
}
}
/// Acquires a reference to the underlying reader.
pub fn get_ref(&self) -> &R {
self.reader.get_ref().get_ref()
}
/// Acquires a mutable reference to the underlying stream.
///
/// Note that mutation of the stream may result in surprising results if
/// this decoder is continued to be used.
pub fn get_mut(&mut self) -> &mut R {
self.reader.get_mut().get_mut()
}
/// Consumes this decoder, returning the underlying reader.
pub fn into_inner(self) -> R {
self.reader.into_inner().into_inner()
}
}
impl<R: BufRead> Read for GzDecoder<R> {
fn read(&mut self, into: &mut [u8]) -> io::Result<usize> {
loop {
match &mut self.state {
GzState::Header(parser) => {
parser.parse(self.reader.get_mut().get_mut())?;
self.state = GzState::Body(GzHeader::from(mem::take(parser)));
}
GzState::Body(header) => {
if into.is_empty() {
return Ok(0);
}
match self.reader.read(into)? {
0 => {
self.state = GzState::Finished(mem::take(header), 0, [0; 8]);
}
n => {
return Ok(n);
}
}
}
GzState::Finished(header, pos, buf) => {
if *pos < buf.len() {
*pos += read_into(self.reader.get_mut().get_mut(), &mut buf[*pos..])?;
} else {
let (crc, amt) = finish(&buf);
if crc != self.reader.crc().sum() || amt != self.reader.crc().amount() {
self.state = GzState::End(Some(mem::take(header)));
return Err(corrupt());
} else if self.multi {
let is_eof = self
.reader
.get_mut()
.get_mut()
.fill_buf()
.map(|buf| buf.is_empty())?;
if is_eof {
self.state = GzState::End(Some(mem::take(header)));
} else {
self.reader.reset();
self.reader.get_mut().reset_data();
self.state = GzState::Header(GzHeaderParser::new())
}
} else {
self.state = GzState::End(Some(mem::take(header)));
}
}
}
GzState::Err(err) => {
let result = Err(mem::replace(err, io::ErrorKind::Other.into()));
self.state = GzState::End(None);
return result;
}
GzState::End(_) => return Ok(0),
}
}
}
}
impl<R: BufRead + Write> Write for GzDecoder<R> {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
self.get_mut().write(buf)
}
fn flush(&mut self) -> io::Result<()> {
self.get_mut().flush()
}
}
/// A gzip streaming decoder that decodes a [gzip file] that may have multiple members.
///
/// This structure implements a [`Read`] interface. When read from, it reads
/// compressed data from the underlying [`BufRead`] and provides the uncompressed data.
///
/// A gzip file consists of a series of *members* concatenated one after another.
/// MultiGzDecoder decodes all members from the data and only returns Ok(0) when the
/// underlying reader does. For a file, this reads to the end of the file.
///
/// To handle members separately, see [GzDecoder] or read more
/// [in the introduction](../index.html#about-multi-member-gzip-files).
///
/// [gzip file]:
https://www.rfc-editor.org/rfc/rfc1952#page-5
/// [`Read`]:
https://doc.rust-lang.org/std/io/trait.Read.html
/// [`BufRead`]:
https://doc.rust-lang.org/std/io/trait.BufRead.html
///
/// # Examples
///
/// ```
/// use std::io::prelude::*;
/// use std::io;
/// # use flate2::Compression;
/// # use flate2::write::GzEncoder;
/// use flate2::bufread::MultiGzDecoder;
///
/// # fn main() {
/// # let mut e = GzEncoder::new(Vec::new(), Compression::default());
/// # e.write_all(b"Hello World").unwrap();
/// # let bytes = e.finish().unwrap();
/// # println!("{}", decode_reader(bytes).unwrap());
/// # }
/// #
/// // Uncompresses a Gz Encoded vector of bytes and returns a string or error
/// // Here &[u8] implements BufRead
///
/// fn decode_reader(bytes: Vec<u8>) -> io::Result<String> {
/// let mut gz = MultiGzDecoder::new(&bytes[..]);
/// let mut s = String::new();
/// gz.read_to_string(&mut s)?;
/// Ok(s)
/// }
/// ```
#[derive(Debug)]
pub struct MultiGzDecoder<R>(GzDecoder<R>);
impl<R: BufRead> MultiGzDecoder<R> {
/// Creates a new decoder from the given reader, immediately parsing the
/// (first) gzip header. If the gzip stream contains multiple members all will
/// be decoded.
pub fn new(r: R) -> MultiGzDecoder<R> {
MultiGzDecoder(GzDecoder::new(r).multi(true))
}
}
impl<R> MultiGzDecoder<R> {
/// Returns the current header associated with this stream, if it's valid
pub fn header(&self) -> Option<&GzHeader> {
self.0.header()
}
/// Acquires a reference to the underlying reader.
pub fn get_ref(&self) -> &R {
self.0.get_ref()
}
/// Acquires a mutable reference to the underlying stream.
///
/// Note that mutation of the stream may result in surprising results if
/// this decoder is continued to be used.
pub fn get_mut(&mut self) -> &mut R {
self.0.get_mut()
}
/// Consumes this decoder, returning the underlying reader.
pub fn into_inner(self) -> R {
self.0.into_inner()
}
}
impl<R: BufRead> Read for MultiGzDecoder<R> {
fn read(&mut self, into: &mut [u8]) -> io::Result<usize> {
self.0.read(into)
}
}
#[cfg(test)]
mod test {
use crate::bufread::GzDecoder;
use crate::gz::write;
use crate::Compression;
use std::io::{Read, Write};
// GzDecoder consumes one gzip member and then returns 0 for subsequent reads, allowing any
// additional data to be consumed by the caller.
#[test]
fn decode_extra_data() {
let expected = "Hello World";
let compressed = {
let mut e = write::GzEncoder::new(Vec::new(), Compression::default());
e.write(expected.as_ref()).unwrap();
let mut b = e.finish().unwrap();
b.push(b'x');
b
};
let mut output = Vec::new();
let mut decoder = GzDecoder::new(compressed.as_slice());
let decoded_bytes = decoder.read_to_end(&mut output).unwrap();
assert_eq!(decoded_bytes, output.len());
let actual = std::str::from_utf8(&output).expect("String parsing error");
assert_eq!(
actual, expected,
"after decompression we obtain the original input"
);
output.clear();
assert_eq!(
decoder.read(&mut output).unwrap(),
0,
"subsequent read of decoder returns 0, but inner reader can return additional data"
);
let mut reader = decoder.into_inner();
assert_eq!(
reader.read_to_end(&mut output).unwrap(),
1,
"extra data is accessible in underlying buf-read"
);
assert_eq!(output, b"x");
}
}
