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use crate::{bzip2::params::Bzip2EncoderParams, EncodeV2};
use bzip2::{Action, Compress, Compression, Status};
use compression_core::util::{PartialBuffer, WriteBuffer};
use std::{fmt, io};
pub struct BzEncoder {
compress: Compress,
}
impl fmt::Debug for BzEncoder {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
f,
"BzEncoder {{total_in: {}, total_out: {}}}",
self.compress.total_in(),
self.compress.total_out()
)
}
}
impl BzEncoder {
/// Creates a new stream prepared for compression.
///
/// The `work_factor` parameter controls how the compression phase behaves
/// when presented with worst case, highly repetitive, input data. If
/// compression runs into difficulties caused by repetitive data, the
/// library switches from the standard sorting algorithm to a fallback
/// algorithm. The fallback is slower than the standard algorithm by perhaps
/// a factor of three, but always behaves reasonably, no matter how bad the
/// input.
///
/// Lower values of `work_factor` reduce the amount of effort the standard
/// algorithm will expend before resorting to the fallback. You should set
/// this parameter carefully; too low, and many inputs will be handled by
/// the fallback algorithm and so compress rather slowly, too high, and your
/// average-to-worst case compression times can become very large. The
/// default value of 30 gives reasonable behaviour over a wide range of
/// circumstances.
///
/// Allowable values range from 0 to 250 inclusive. 0 is a special case,
/// equivalent to using the default value of 30.
pub fn new(params: Bzip2EncoderParams, work_factor: u32) -> Self {
let params = Compression::from(params);
Self {
compress: Compress::new(params, work_factor),
}
}
fn encode(
&mut self,
input: &mut PartialBuffer<&[u8]>,
output: &mut WriteBuffer<'_>,
action: Action,
) -> io::Result<Status> {
let prior_in = self.compress.total_in();
let prior_out = self.compress.total_out();
let status = self
.compress
// Safety: We **trust** bzip2 to only write initialized bytes into it
.compress_uninit(input.unwritten(), unsafe { output.unwritten_mut() }, action)
.map_err(io::Error::other)?;
input.advance((self.compress.total_in() - prior_in) as usize);
// Safety: We **trust** bzip2 to properly write bytes into it
unsafe { output.assume_init_and_advance((self.compress.total_out() - prior_out) as usize) };
Ok(status)
}
}
impl EncodeV2 for BzEncoder {
fn encode(
&mut self,
input: &mut PartialBuffer<&[u8]>,
output: &mut WriteBuffer<'_>,
) -> io::Result<()> {
match self.encode(input, output, Action::Run)? {
// Decompression went fine, nothing much to report.
Status::Ok => Ok(()),
// The Flush action on a compression went ok.
Status::FlushOk => unreachable!(),
// The Run action on compression went ok.
Status::RunOk => Ok(()),
// The Finish action on compression went ok.
Status::FinishOk => unreachable!(),
// The stream's end has been met, meaning that no more data can be input.
Status::StreamEnd => unreachable!(),
// There was insufficient memory in the input or output buffer to complete
// the request, but otherwise everything went normally.
Status::MemNeeded => Err(io::ErrorKind::OutOfMemory.into()),
}
}
fn flush(&mut self, output: &mut WriteBuffer<'_>) -> io::Result<bool> {
match self.encode(&mut PartialBuffer::new(&[][..]), output, Action::Flush)? {
// Decompression went fine, nothing much to report.
Status::Ok => unreachable!(),
// The Flush action on a compression went ok.
Status::FlushOk => Ok(false),
// The Run action on compression went ok.
Status::RunOk => Ok(true),
// The Finish action on compression went ok.
Status::FinishOk => unreachable!(),
// The stream's end has been met, meaning that no more data can be input.
Status::StreamEnd => unreachable!(),
// There was insufficient memory in the input or output buffer to complete
// the request, but otherwise everything went normally.
Status::MemNeeded => Err(io::ErrorKind::OutOfMemory.into()),
}
}
fn finish(&mut self, output: &mut WriteBuffer<'_>) -> io::Result<bool> {
match self.encode(&mut PartialBuffer::new(&[][..]), output, Action::Finish)? {
// Decompression went fine, nothing much to report.
Status::Ok => Ok(false),
// The Flush action on a compression went ok.
Status::FlushOk => unreachable!(),
// The Run action on compression went ok.
Status::RunOk => unreachable!(),
// The Finish action on compression went ok.
Status::FinishOk => Ok(false),
// The stream's end has been met, meaning that no more data can be input.
Status::StreamEnd => Ok(true),
// There was insufficient memory in the input or output buffer to complete
// the request, but otherwise everything went normally.
Status::MemNeeded => Err(io::ErrorKind::OutOfMemory.into()),
}
}
}