mirror of https://github.com/encounter/nod-rs.git
93 lines
3.0 KiB
Rust
93 lines
3.0 KiB
Rust
use std::{io, io::Read};
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/// Decodes the LZMA Properties byte (lc/lp/pb).
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/// See `lzma_lzma_lclppb_decode` in `liblzma/lzma/lzma_decoder.c`.
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#[cfg(feature = "compress-lzma")]
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pub fn lzma_lclppb_decode(options: &mut liblzma::stream::LzmaOptions, byte: u8) -> io::Result<()> {
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let mut d = byte as u32;
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if d >= (9 * 5 * 5) {
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return Err(io::Error::new(
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io::ErrorKind::InvalidData,
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format!("Invalid LZMA props byte: {}", d),
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));
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}
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options.literal_context_bits(d % 9);
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d /= 9;
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options.position_bits(d / 5);
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options.literal_position_bits(d % 5);
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Ok(())
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}
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/// Decodes LZMA properties.
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/// See `lzma_lzma_props_decode` in `liblzma/lzma/lzma_decoder.c`.
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#[cfg(feature = "compress-lzma")]
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pub fn lzma_props_decode(props: &[u8]) -> io::Result<liblzma::stream::LzmaOptions> {
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use crate::array_ref;
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if props.len() != 5 {
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return Err(io::Error::new(
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io::ErrorKind::InvalidData,
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format!("Invalid LZMA props length: {}", props.len()),
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));
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}
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let mut options = liblzma::stream::LzmaOptions::new();
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lzma_lclppb_decode(&mut options, props[0])?;
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options.dict_size(u32::from_le_bytes(*array_ref!(props, 1, 4)));
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Ok(options)
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}
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/// Decodes LZMA2 properties.
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/// See `lzma_lzma2_props_decode` in `liblzma/lzma/lzma2_decoder.c`.
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#[cfg(feature = "compress-lzma")]
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pub fn lzma2_props_decode(props: &[u8]) -> io::Result<liblzma::stream::LzmaOptions> {
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use std::cmp::Ordering;
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if props.len() != 1 {
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return Err(io::Error::new(
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io::ErrorKind::InvalidData,
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format!("Invalid LZMA2 props length: {}", props.len()),
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));
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}
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let d = props[0] as u32;
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let mut options = liblzma::stream::LzmaOptions::new();
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options.dict_size(match d.cmp(&40) {
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Ordering::Greater => {
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return Err(io::Error::new(
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io::ErrorKind::InvalidData,
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format!("Invalid LZMA2 props byte: {}", d),
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));
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}
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Ordering::Equal => u32::MAX,
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Ordering::Less => (2 | (d & 1)) << (d / 2 + 11),
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});
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Ok(options)
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}
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/// Creates a new raw LZMA decoder with the given options.
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#[cfg(feature = "compress-lzma")]
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pub fn new_lzma_decoder<R>(
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reader: R,
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options: &liblzma::stream::LzmaOptions,
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) -> io::Result<liblzma::read::XzDecoder<R>>
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where
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R: Read,
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{
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let mut filters = liblzma::stream::Filters::new();
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filters.lzma1(options);
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let stream = liblzma::stream::Stream::new_raw_decoder(&filters).map_err(io::Error::from)?;
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Ok(liblzma::read::XzDecoder::new_stream(reader, stream))
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}
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/// Creates a new raw LZMA2 decoder with the given options.
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#[cfg(feature = "compress-lzma")]
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pub fn new_lzma2_decoder<R>(
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reader: R,
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options: &liblzma::stream::LzmaOptions,
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) -> io::Result<liblzma::read::XzDecoder<R>>
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where
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R: Read,
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{
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let mut filters = liblzma::stream::Filters::new();
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filters.lzma2(options);
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let stream = liblzma::stream::Stream::new_raw_decoder(&filters).map_err(io::Error::from)?;
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Ok(liblzma::read::XzDecoder::new_stream(reader, stream))
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}
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