bzip2/write.rs
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//! Writer-based compression/decompression streams
use std::io;
use std::io::prelude::*;
use crate::{Action, Compress, Compression, Decompress, Status};
/// A compression stream which will have uncompressed data written to it and
/// will write compressed data to an output stream.
pub struct BzEncoder<W: Write> {
data: Compress,
obj: Option<W>,
buf: Vec<u8>,
done: bool,
panicked: bool,
}
/// A compression stream which will have compressed data written to it and
/// will write uncompressed data to an output stream.
pub struct BzDecoder<W: Write> {
data: Decompress,
obj: Option<W>,
buf: Vec<u8>,
done: bool,
panicked: bool,
}
impl<W: Write> BzEncoder<W> {
/// Create a new compression stream which will compress at the given level
/// to write compress output to the give output stream.
pub fn new(obj: W, level: Compression) -> BzEncoder<W> {
BzEncoder {
data: Compress::new(level, 30),
obj: Some(obj),
buf: Vec::with_capacity(32 * 1024),
done: false,
panicked: false,
}
}
fn dump(&mut self) -> io::Result<()> {
while !self.buf.is_empty() {
self.panicked = true;
let r = self.obj.as_mut().unwrap().write(&self.buf);
self.panicked = false;
match r {
Ok(n) => self.buf.drain(..n),
Err(ref err) if err.kind() == io::ErrorKind::Interrupted => continue,
Err(err) => return Err(err),
};
}
Ok(())
}
/// Acquires a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.obj.as_ref().unwrap()
}
/// Acquires a mutable reference to the underlying writer.
///
/// Note that mutating the output/input state of the stream may corrupt this
/// object, so care must be taken when using this method.
pub fn get_mut(&mut self) -> &mut W {
self.obj.as_mut().unwrap()
}
/// Attempt to finish this output stream, writing out final chunks of data.
///
/// Note that this function can only be used once data has finished being
/// written to the output stream. After this function is called then further
/// calls to [`write`] may result in a panic.
///
/// # Panics
///
/// Attempts to write data to this stream may result in a panic after this
/// function is called.
///
/// [`write`]: Self::write
pub fn try_finish(&mut self) -> io::Result<()> {
while !self.done {
self.dump()?;
let res = self.data.compress_vec(&[], &mut self.buf, Action::Finish);
if res == Ok(Status::StreamEnd) {
self.done = true;
break;
}
}
self.dump()
}
/// Consumes this encoder, flushing the output stream.
///
/// This will flush the underlying data stream and then return the contained
/// writer if the flush succeeded.
///
/// Note that this function may not be suitable to call in a situation where
/// the underlying stream is an asynchronous I/O stream. To finish a stream
/// the [`try_finish`] (or `shutdown`) method should be used instead. To
/// re-acquire ownership of a stream it is safe to call this method after
/// [`try_finish`] or `shutdown` has returned `Ok`.
///
/// [`try_finish`]: Self::try_finish
pub fn finish(mut self) -> io::Result<W> {
self.try_finish()?;
Ok(self.obj.take().unwrap())
}
/// Returns the number of bytes produced by the compressor
///
/// Note that, due to buffering, this only bears any relation to
/// [`total_in`] after a call to [`flush`]. At that point,
/// `total_out() / total_in()` is the compression ratio.
///
/// [`flush`]: Self::flush
/// [`total_in`]: Self::total_in
pub fn total_out(&self) -> u64 {
self.data.total_out()
}
/// Returns the number of bytes consumed by the compressor
/// (e.g. the number of bytes written to this stream.)
pub fn total_in(&self) -> u64 {
self.data.total_in()
}
}
impl<W: Write> Write for BzEncoder<W> {
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
loop {
self.dump()?;
let total_in = self.total_in();
self.data
.compress_vec(data, &mut self.buf, Action::Run)
.unwrap();
let written = (self.total_in() - total_in) as usize;
if written > 0 || data.is_empty() {
return Ok(written);
}
}
}
fn flush(&mut self) -> io::Result<()> {
loop {
self.dump()?;
let before = self.total_out();
self.data
.compress_vec(&[], &mut self.buf, Action::Flush)
.unwrap();
if before == self.total_out() {
break;
}
}
self.obj.as_mut().unwrap().flush()
}
}
impl<W: Write> BzDecoder<W> {
/// Create a new decoding stream which will decompress all data written
/// to it into `obj`.
pub fn new(obj: W) -> BzDecoder<W> {
BzDecoder {
data: Decompress::new(false),
obj: Some(obj),
buf: Vec::with_capacity(32 * 1024),
done: false,
panicked: false,
}
}
/// Acquires a reference to the underlying writer.
pub fn get_ref(&self) -> &W {
self.obj.as_ref().unwrap()
}
/// Acquires a mutable reference to the underlying writer.
///
/// Note that mutating the output/input state of the stream may corrupt this
/// object, so care must be taken when using this method.
pub fn get_mut(&mut self) -> &mut W {
self.obj.as_mut().unwrap()
}
fn dump(&mut self) -> io::Result<()> {
while !self.buf.is_empty() {
self.panicked = true;
let r = self.obj.as_mut().unwrap().write(&self.buf);
self.panicked = false;
match r {
Ok(n) => self.buf.drain(..n),
Err(ref err) if err.kind() == io::ErrorKind::Interrupted => continue,
Err(err) => return Err(err),
};
}
Ok(())
}
/// Attempt to finish this output stream, writing out final chunks of data.
///
/// Note that this function can only be used once data has finished being
/// written to the output stream. After this function is called then further
/// calls to [`write`] may result in a panic.
///
/// # Panics
///
/// Attempts to write data to this stream may result in a panic after this
/// function is called.
///
/// [`write`]: Self::write
pub fn try_finish(&mut self) -> io::Result<()> {
while !self.done {
// The write is effectively a `self.flush()`, but we want to know how many
// bytes were written. exit if no input was read and no output was written
if self.write(&[])? == 0 {
// finishing the output stream is effectively EOF of the input
let msg = "Input EOF reached before logical stream end";
return Err(io::Error::new(io::ErrorKind::UnexpectedEof, msg));
}
}
self.dump()
}
/// Unwrap the underlying writer, finishing the compression stream.
///
/// Note that this function may not be suitable to call in a situation where
/// the underlying stream is an asynchronous I/O stream. To finish a stream
/// the [`try_finish`] (or `shutdown`) method should be used instead. To
/// re-acquire ownership of a stream it is safe to call this method after
/// [`try_finish`] or `shutdown` has returned `Ok`.
///
/// [`try_finish`]: Self::try_finish
pub fn finish(&mut self) -> io::Result<W> {
self.try_finish()?;
Ok(self.obj.take().unwrap())
}
/// Returns the number of bytes produced by the decompressor
///
/// Note that, due to buffering, this only bears any relation to
/// [`total_in`] after a call to [`flush`]. At that point,
/// `total_in() / total_out()` is the compression ratio.
///
/// [`flush`]: Self::flush
/// [`total_in`]: Self::total_in
pub fn total_out(&self) -> u64 {
self.data.total_out()
}
/// Returns the number of bytes consumed by the decompressor
/// (e.g. the number of bytes written to this stream.)
pub fn total_in(&self) -> u64 {
self.data.total_in()
}
}
impl<W: Write> Write for BzDecoder<W> {
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
if self.done {
return Ok(0);
}
loop {
self.dump()?;
let before = self.total_in();
let res = self.data.decompress_vec(data, &mut self.buf);
let written = (self.total_in() - before) as usize;
// make sure that a subsequent call exits early when there is nothing useful left to do
self.done |= matches!(res, Err(_) | Ok(Status::StreamEnd));
if let Err(e) = res {
return Err(io::Error::new(io::ErrorKind::InvalidInput, e));
}
if written > 0 || data.is_empty() || self.done {
return Ok(written);
}
}
}
fn flush(&mut self) -> io::Result<()> {
self.dump()?;
self.obj.as_mut().unwrap().flush()
}
}
impl<W: Write> Drop for BzDecoder<W> {
fn drop(&mut self) {
if self.obj.is_some() {
let _ = self.try_finish();
}
}
}
impl<W: Write> Drop for BzEncoder<W> {
fn drop(&mut self) {
if self.obj.is_some() && !self.panicked {
let _ = self.try_finish();
}
}
}
#[cfg(test)]
mod tests {
use super::{BzDecoder, BzEncoder};
use crate::Compression;
use partial_io::quickcheck_types::{GenInterrupted, PartialWithErrors};
use partial_io::PartialWrite;
use std::io::prelude::*;
#[test]
fn smoke() {
let d = BzDecoder::new(Vec::new());
let mut c = BzEncoder::new(d, Compression::default());
c.write_all(b"12834").unwrap();
let s = "12345".repeat(100000);
c.write_all(s.as_bytes()).unwrap();
let data = c.finish().unwrap().finish().unwrap();
assert_eq!(&data[0..5], b"12834");
assert_eq!(data.len(), 500005);
assert!(format!("12834{}", s).as_bytes() == &*data);
}
#[test]
fn roundtrip_empty() {
// this encodes and then decodes an empty input file
let d = BzDecoder::new(Vec::new());
let mut c = BzEncoder::new(d, Compression::default());
let _ = c.write(b"").unwrap();
let data = c.finish().unwrap().finish().unwrap();
assert_eq!(&data[..], b"");
}
#[test]
fn finish_empty_explicit() {
// The empty sequence is not a valid .bzip2 file!
// A valid file at least includes the magic bytes, the checksum, etc.
//
// This used to loop infinitely, see
//
// - https://github.com/trifectatechfoundation/bzip2-rs/issues/96
// - https://github.com/trifectatechfoundation/bzip2-rs/pull/97
let mut d = BzDecoder::new(Vec::new());
d.write(b"").unwrap();
let e = d.finish().unwrap_err();
assert_eq!(e.kind(), std::io::ErrorKind::UnexpectedEof);
}
#[test]
fn finish_empty_drop() {
// the drop implementation used to loop infinitely for empty input
//
// see https://github.com/trifectatechfoundation/bzip2-rs/pull/118
let d = BzDecoder::new(Vec::new());
drop(d);
}
#[test]
fn write_invalid() {
// see https://github.com/trifectatechfoundation/bzip2-rs/issues/98
let mut d = BzDecoder::new(Vec::new());
let e = d.write(b"BZh\xfb").unwrap_err();
assert_eq!(e.kind(), std::io::ErrorKind::InvalidInput);
}
#[test]
fn qc() {
::quickcheck::quickcheck(test as fn(_) -> _);
fn test(v: Vec<u8>) -> bool {
let w = BzDecoder::new(Vec::new());
let mut w = BzEncoder::new(w, Compression::default());
w.write_all(&v).unwrap();
v == w.finish().unwrap().finish().unwrap()
}
}
#[test]
fn qc_partial() {
quickcheck::quickcheck(test as fn(_, _, _) -> _);
fn test(
v: Vec<u8>,
encode_ops: PartialWithErrors<GenInterrupted>,
decode_ops: PartialWithErrors<GenInterrupted>,
) -> bool {
let w = BzDecoder::new(PartialWrite::new(Vec::new(), decode_ops));
let mut w = BzEncoder::new(PartialWrite::new(w, encode_ops), Compression::default());
w.write_all(&v).unwrap();
v == w
.finish()
.unwrap()
.into_inner()
.finish()
.unwrap()
.into_inner()
}
}
#[test]
fn terminate_on_drop() {
// Test that dropping the BzEncoder flushes bytes to the output, so that
// we get a valid, decompressable datastream
//
// see https://github.com/trifectatechfoundation/bzip2-rs/pull/121
let s = "12345".repeat(100);
let mut compressed = Vec::new();
{
let mut c: Box<dyn std::io::Write> =
Box::new(BzEncoder::new(&mut compressed, Compression::default()));
c.write_all(b"12834").unwrap();
c.write_all(s.as_bytes()).unwrap();
c.flush().unwrap();
}
assert!(!compressed.is_empty());
let uncompressed = {
let mut d = BzDecoder::new(Vec::new());
d.write_all(&compressed).unwrap();
d.finish().unwrap()
};
assert_eq!(&uncompressed[0..5], b"12834");
assert_eq!(uncompressed.len(), s.len() + "12834".len());
assert!(format!("12834{}", s).as_bytes() == &*uncompressed);
}
}