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lzma: treat empty input as a no-op, not end of stream #8752

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Merged
youknowone merged 1 commit into from
Sep 20, 2026
Merged

lzma: treat empty input as a no-op, not end of stream #8752

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1 change: 0 additions & 1 deletion Lib/test/test_lzma.py
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,6 @@ def test_decompressor_chunks(self):
self.assertTrue(lzd.eof)
self.assertEqual(lzd.unused_data, b"")

@unittest.expectedFailure # TODO: RUSTPYTHON; EOFError: End of stream already reached
def test_decompressor_chunks_empty(self):
lzd = LZMADecompressor()
out = []
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17 changes: 17 additions & 0 deletions crates/common/src/compression/bz2.rs
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Expand Up @@ -312,6 +312,23 @@ mod tests {
assert!(decompressor.eof());
}

#[test]
fn empty_input_does_not_finish_a_stream() {
let mut compressor = Compressor::new(9).unwrap();
let mut encoded = compressor.compress(b"later input").unwrap();
encoded.extend(compressor.flush().unwrap());

let mut decompressor = Decompressor::new();
assert_eq!(decompressor.decompress(b"", None).unwrap(), b"");
assert!(!decompressor.eof());
assert!(decompressor.needs_input());
assert_eq!(
decompressor.decompress(&encoded, None).unwrap(),
b"later input"
);
assert!(decompressor.eof());
}

#[test]
fn bad_data_latches_failure() {
let mut decompressor = Decompressor::new();
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19 changes: 18 additions & 1 deletion crates/common/src/compression/lzma.rs
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Expand Up @@ -378,8 +378,10 @@ fn decompress_chunks(
stream: &mut LzmaStream,
max_length: Option<usize>,
) -> Result<(Vec<u8>, bool), XzError> {
// No input to feed the decoder: not a stream end, so `eof` stays false and
// the caller can still supply compressed data later.
if chunks.is_empty() {
return Ok((Vec::new(), true));
return Ok((Vec::new(), false));
}
let max_length = max_length.unwrap_or(usize::MAX);
let mut output = Vec::new();
Expand Down Expand Up @@ -622,6 +624,21 @@ impl Compressor {
mod tests {
use super::*;

#[test]
fn empty_input_does_not_finish_a_stream() {
let mut compressor = Compressor::new(FORMAT_XZ, CHECK_CRC64, PRESET_DEFAULT, None).unwrap();
let mut encoded = compressor.compress(b"data").unwrap();
encoded.extend(compressor.flush().unwrap());

let mut decompressor = Decompressor::new(FORMAT_AUTO, None, None).unwrap();
assert_eq!(decompressor.decompress(b"", None).unwrap(), b"");
assert!(!decompressor.eof());
assert!(decompressor.needs_input());

assert_eq!(decompressor.decompress(&encoded, None).unwrap(), b"data");
assert!(decompressor.eof());
}

#[test]
fn encode_lzma1_properties_rejects_invalid_lclppb() {
for (lc, lp, pb) in [(5, 0, 0), (0, 5, 0), (4, 1, 0), (0, 0, 5)] {
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