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Copy pathcompression.rs
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377 lines (323 loc) · 10.2 KB
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// spell-checker:ignore chunker
//! internal shared module for compression libraries
use crate::vm::function::{ArgBytesLike, ArgSize, OptionalArg};
use crate::vm::{
PyResult, VirtualMachine,
builtins::{PyBaseExceptionRef, PyBytesRef},
convert::ToPyException,
};
pub(crate) const USE_AFTER_FINISH_ERR: &str = "Error -2: inconsistent stream state";
// TODO: don't hardcode
const CHUNKSIZE: usize = u32::MAX as usize;
#[derive(FromArgs)]
pub(crate) struct DecompressArgs {
#[pyarg(positional)]
data: ArgBytesLike,
#[pyarg(any, optional)]
max_length: OptionalArg<ArgSize>,
}
impl DecompressArgs {
pub(crate) fn data(&self) -> crate::common::borrow::BorrowedValue<'_, [u8]> {
self.data.borrow_buf()
}
pub(crate) fn raw_max_length(&self) -> Option<isize> {
self.max_length.into_option().map(|ArgSize { value }| value)
}
// negative is None
pub(crate) fn max_length(&self) -> Option<usize> {
self.max_length
.into_option()
.and_then(|ArgSize { value }| usize::try_from(value).ok())
}
}
pub(crate) trait Decompressor {
type Flush: DecompressFlushKind;
type Status: DecompressStatus;
type Error;
fn total_in(&self) -> u64;
fn decompress_vec(
&mut self,
input: &[u8],
output: &mut Vec<u8>,
flush: Self::Flush,
) -> Result<Self::Status, Self::Error>;
fn maybe_set_dict(&mut self, err: Self::Error) -> Result<(), Self::Error> {
Err(err)
}
}
pub(crate) trait DecompressStatus {
fn is_stream_end(&self) -> bool;
}
pub(crate) trait DecompressFlushKind: Copy {
const SYNC: Self;
}
impl DecompressFlushKind for () {
const SYNC: Self = ();
}
pub(crate) const fn flush_sync<T: DecompressFlushKind>(_final_chunk: bool) -> T {
T::SYNC
}
#[derive(Clone)]
pub(crate) struct Chunker<'a> {
data1: &'a [u8],
data2: &'a [u8],
}
impl<'a> Chunker<'a> {
pub(crate) const fn new(data: &'a [u8]) -> Self {
Self {
data1: data,
data2: &[],
}
}
pub(crate) const fn chain(data1: &'a [u8], data2: &'a [u8]) -> Self {
if data1.is_empty() {
Self {
data1: data2,
data2: &[],
}
} else {
Self { data1, data2 }
}
}
pub(crate) const fn len(&self) -> usize {
self.data1.len() + self.data2.len()
}
pub(crate) const fn is_empty(&self) -> bool {
self.data1.is_empty()
}
pub(crate) fn to_vec(&self) -> Vec<u8> {
[self.data1, self.data2].concat()
}
pub(crate) fn chunk(&self) -> &'a [u8] {
self.data1.get(..CHUNKSIZE).unwrap_or(self.data1)
}
pub(crate) fn advance(&mut self, consumed: usize) {
self.data1 = &self.data1[consumed..];
if self.data1.is_empty() {
self.data1 = core::mem::take(&mut self.data2);
}
}
}
pub(crate) fn _decompress<D: Decompressor>(
data: &[u8],
d: &mut D,
bufsize: usize,
max_length: Option<usize>,
calc_flush: impl Fn(bool) -> D::Flush,
) -> Result<(Vec<u8>, bool), D::Error> {
let mut data = Chunker::new(data);
_decompress_chunks(&mut data, d, bufsize, max_length, calc_flush)
}
pub(crate) fn _decompress_chunks<D: Decompressor>(
data: &mut Chunker<'_>,
d: &mut D,
bufsize: usize,
max_length: Option<usize>,
calc_flush: impl Fn(bool) -> D::Flush,
) -> Result<(Vec<u8>, bool), D::Error> {
if data.is_empty() {
return Ok((Vec::new(), true));
}
let max_length = max_length.unwrap_or(usize::MAX);
let mut buf = Vec::new();
'outer: loop {
let chunk = data.chunk();
let flush = calc_flush(chunk.len() == data.len());
loop {
let additional = core::cmp::min(bufsize, max_length - buf.capacity());
if additional == 0 {
return Ok((buf, false));
}
buf.reserve_exact(additional);
let prev_in = d.total_in();
let res = d.decompress_vec(chunk, &mut buf, flush);
let consumed = d.total_in() - prev_in;
data.advance(consumed as usize);
match res {
Ok(status) => {
let stream_end = status.is_stream_end();
if stream_end || data.is_empty() {
// we've reached the end of the stream, we're done
buf.shrink_to_fit();
return Ok((buf, stream_end));
} else if !chunk.is_empty() && consumed == 0 {
// we're gonna need a bigger buffer
continue;
}
// next chunk
continue 'outer;
}
Err(e) => {
d.maybe_set_dict(e)?;
// now try the next chunk
continue 'outer;
}
};
}
}
}
pub(crate) trait Compressor {
type Status: CompressStatusKind;
type Flush: CompressFlushKind;
const CHUNKSIZE: usize;
const DEF_BUF_SIZE: usize;
fn compress_vec(
&mut self,
input: &[u8],
output: &mut Vec<u8>,
flush: Self::Flush,
vm: &VirtualMachine,
) -> PyResult<Self::Status>;
fn total_in(&mut self) -> usize;
fn new_error(message: impl Into<String>, vm: &VirtualMachine) -> PyBaseExceptionRef;
}
pub(crate) trait CompressFlushKind: Copy {
const NONE: Self;
const FINISH: Self;
fn to_usize(self) -> usize;
}
pub(crate) trait CompressStatusKind: Copy {
const EOF: Self;
fn to_usize(self) -> usize;
}
#[derive(Debug)]
pub(crate) struct CompressState<C: Compressor> {
compressor: Option<C>,
}
impl<C: Compressor> CompressState<C> {
pub(crate) const fn new(compressor: C) -> Self {
Self {
compressor: Some(compressor),
}
}
fn get_compressor(&mut self, vm: &VirtualMachine) -> PyResult<&mut C> {
self.compressor
.as_mut()
.ok_or_else(|| C::new_error(USE_AFTER_FINISH_ERR, vm))
}
pub(crate) fn compress(&mut self, data: &[u8], vm: &VirtualMachine) -> PyResult<Vec<u8>> {
let mut buf = Vec::new();
let compressor = self.get_compressor(vm)?;
for mut chunk in data.chunks(C::CHUNKSIZE) {
while !chunk.is_empty() {
buf.reserve(C::DEF_BUF_SIZE);
let prev_in = compressor.total_in();
compressor.compress_vec(chunk, &mut buf, C::Flush::NONE, vm)?;
let consumed = compressor.total_in() - prev_in;
chunk = &chunk[consumed..];
}
}
buf.shrink_to_fit();
Ok(buf)
}
pub(crate) fn flush(&mut self, mode: C::Flush, vm: &VirtualMachine) -> PyResult<Vec<u8>> {
let mut buf = Vec::new();
let compressor = self.get_compressor(vm)?;
let status = loop {
if buf.len() == buf.capacity() {
buf.reserve(C::DEF_BUF_SIZE);
}
let status = compressor.compress_vec(&[], &mut buf, mode, vm)?;
if buf.len() != buf.capacity() {
break status;
}
};
if status.to_usize() == C::Status::EOF.to_usize() {
if mode.to_usize() == C::Flush::FINISH.to_usize() {
self.compressor = None;
} else {
return Err(C::new_error("unexpected eof", vm));
}
}
buf.shrink_to_fit();
Ok(buf)
}
}
#[derive(Debug)]
pub(crate) struct DecompressState<D> {
decompress: D,
unused_data: PyBytesRef,
input_buffer: Vec<u8>,
eof: bool,
needs_input: bool,
}
impl<D: Decompressor> DecompressState<D> {
pub(crate) fn new(decompress: D, vm: &VirtualMachine) -> Self {
Self {
decompress,
unused_data: vm.ctx.empty_bytes.clone(),
input_buffer: Vec::new(),
eof: false,
needs_input: true,
}
}
pub(crate) const fn eof(&self) -> bool {
self.eof
}
#[cfg_attr(target_os = "android", allow(dead_code))]
pub(crate) const fn decompressor(&self) -> &D {
&self.decompress
}
pub(crate) fn unused_data(&self) -> PyBytesRef {
self.unused_data.clone()
}
pub(crate) const fn needs_input(&self) -> bool {
self.needs_input
}
pub(crate) fn decompress(
&mut self,
data: &[u8],
max_length: Option<usize>,
bufsize: usize,
vm: &VirtualMachine,
) -> Result<Vec<u8>, DecompressError<D::Error>> {
if self.eof {
return Err(DecompressError::Eof(EofError));
}
let input_buffer = &mut self.input_buffer;
let d = &mut self.decompress;
let mut chunks = Chunker::chain(input_buffer, data);
let prev_len = chunks.len();
let (ret, stream_end) =
match _decompress_chunks(&mut chunks, d, bufsize, max_length, flush_sync) {
Ok((buf, stream_end)) => (Ok(buf), stream_end),
Err(err) => (Err(err), false),
};
let consumed = prev_len - chunks.len();
self.eof |= stream_end;
if self.eof {
self.needs_input = false;
if !chunks.is_empty() {
self.unused_data = vm.ctx.new_bytes(chunks.to_vec());
}
} else if chunks.is_empty() {
input_buffer.clear();
self.needs_input = true;
} else {
self.needs_input = false;
if let Some(n_consumed_from_data) = consumed.checked_sub(input_buffer.len()) {
input_buffer.clear();
input_buffer.extend_from_slice(&data[n_consumed_from_data..]);
} else {
input_buffer.drain(..consumed);
input_buffer.extend_from_slice(data);
}
}
ret.map_err(DecompressError::Decompress)
}
}
pub(crate) enum DecompressError<E> {
Decompress(E),
Eof(EofError),
}
impl<E> From<E> for DecompressError<E> {
fn from(err: E) -> Self {
Self::Decompress(err)
}
}
pub(crate) struct EofError;
impl ToPyException for EofError {
fn to_pyexception(&self, vm: &VirtualMachine) -> PyBaseExceptionRef {
vm.new_eof_error("End of stream already reached")
}
}