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//! Extra streaming compression functionality.
//!
//! As of now this is mainly intended for use to build a higher-level wrapper.
//!
//! There is no DeflateState as the needed state is contained in the compressor struct itself.
use crate::deflate::core::{compress, CompressorOxide, TDEFLFlush, TDEFLStatus};
use crate::{MZError, MZFlush, MZStatus, StreamResult};
/// Try to compress from input to output with the given [`CompressorOxide`].
///
/// # Errors
///
/// Returns [`MZError::Buf`] If the size of the `output` slice is empty or no progress was made due
/// to lack of expected input data, or if called without [`MZFlush::Finish`] after the compression
/// was already finished.
///
/// Returns [`MZError::Param`] if the compressor parameters are set wrong.
///
/// Returns [`MZError::Stream`] when lower-level decompressor returns a
/// [`TDEFLStatus::PutBufFailed`]; may not actually be possible.
pub fn deflate(
compressor: &mut CompressorOxide,
input: &[u8],
output: &mut [u8],
flush: MZFlush,
) -> StreamResult {
if output.is_empty() {
return StreamResult::error(MZError::Buf);
}
if compressor.prev_return_status() == TDEFLStatus::Done {
return if flush == MZFlush::Finish {
StreamResult {
bytes_written: 0,
bytes_consumed: 0,
status: Ok(MZStatus::StreamEnd),
}
} else {
StreamResult::error(MZError::Buf)
};
}
let mut bytes_written = 0;
let mut bytes_consumed = 0;
let mut next_in = input;
let mut next_out = output;
let status = loop {
let in_bytes;
let out_bytes;
let defl_status = {
let res = compress(compressor, next_in, next_out, TDEFLFlush::from(flush));
in_bytes = res.1;
out_bytes = res.2;
res.0
};
next_in = &next_in[in_bytes..];
next_out = &mut next_out[out_bytes..];
bytes_consumed += in_bytes;
bytes_written += out_bytes;
// Check if we are done, or compression failed.
match defl_status {
TDEFLStatus::BadParam => break Err(MZError::Param),
// Don't think this can happen as we're not using a custom callback.
TDEFLStatus::PutBufFailed => break Err(MZError::Stream),
TDEFLStatus::Done => break Ok(MZStatus::StreamEnd),
_ => (),
};
// All the output space was used, so wait for more.
if next_out.is_empty() {
break Ok(MZStatus::Ok);
}
if next_in.is_empty() && (flush != MZFlush::Finish) {
let total_changed = bytes_written > 0 || bytes_consumed > 0;
break if (flush != MZFlush::None) || total_changed {
// We wrote or consumed something, and/or did a flush (sync/partial etc.).
Ok(MZStatus::Ok)
} else {
// No more input data, not flushing, and nothing was consumed or written,
// so couldn't make any progress.
Err(MZError::Buf)
};
}
};
StreamResult {
bytes_consumed,
bytes_written,
status,
}
}
#[cfg(test)]
mod test {
use super::deflate;
use crate::deflate::CompressorOxide;
use crate::inflate::decompress_to_vec_zlib;
use crate::{MZFlush, MZStatus};
use alloc::boxed::Box;
use alloc::vec;
#[test]
fn test_state() {
let data = b"Hello zlib!";
let mut compressed = vec![0; 50];
let mut compressor = Box::<CompressorOxide>::default();
let res = deflate(&mut compressor, data, &mut compressed, MZFlush::Finish);
let status = res.status.expect("Failed to compress!");
let decomp =
decompress_to_vec_zlib(&compressed).expect("Failed to decompress compressed data");
assert_eq!(status, MZStatus::StreamEnd);
assert_eq!(decomp[..], data[..]);
assert_eq!(res.bytes_consumed, data.len());
}
}