55 lines
2.4 KiB
Dart
55 lines
2.4 KiB
Dart
|
import 'dart:typed_data';
|
||
|
|
|
||
|
|
import 'package:pure_zstd/src/bit_reader.dart';
|
||
|
|
import 'package:pure_zstd/src/exception.dart';
|
||
|
|
import 'package:pure_zstd/src/fse.dart';
|
||
|
|
import 'package:test/test.dart';
|
||
|
|
|
||
|
|
/// `fseDecodeInterleaved` has no symbol count to stop on: it runs until the
|
||
|
|
/// bitstream is spent, so the only thing keeping it inside the caller's
|
||
|
|
/// buffer is its own room check. Both of its exhausted branches write a third
|
||
|
|
/// symbol in the same pass, so a check for two let `at` reach `outLimit`,
|
||
|
|
/// which is one past the end.
|
||
|
|
///
|
||
|
|
/// `HuffmanTable` calls it with a 256-byte buffer, so overrunning it indexes
|
||
|
|
/// `_weights[256]`. This is the same reproducer as the 53-byte frame in the
|
||
|
|
/// corpus, with the frame stripped away: the weight table description and the
|
||
|
|
/// bitstream the block carried, handed straight to the function.
|
||
|
|
void main() {
|
||
|
|
group('fseDecodeInterleaved', () {
|
||
|
|
// The two bytes are the whole FSE table description: accuracy log 5 and a
|
||
|
|
// distribution that gives the stream below two symbols per state pair.
|
||
|
|
final description = Uint8List.fromList([0x10, 0x3F]);
|
||
|
|
|
||
|
|
// 33 bytes of 0xAA and then the end marker, which is the stream the
|
||
|
|
// crafted block put after the description.
|
||
|
|
final stream = Uint8List.fromList([...List.filled(33, 0xAA), 0x02]);
|
||
|
|
|
||
|
|
test('refuses a stream longer than the caller has room for', () {
|
||
|
|
final table = FseTable(6);
|
||
|
|
expect(readFseTable(table, description, 0, description.length, 255), 2);
|
||
|
|
|
||
|
|
final bits = ReverseBitReader()..reset(stream, 0, stream.length);
|
||
|
|
final weights = Uint8List(256);
|
||
|
|
|
||
|
|
expect(
|
||
|
|
() => fseDecodeInterleaved(table, bits, weights, 0, weights.length),
|
||
|
|
throwsA(isA<ZstdException>()),
|
||
|
|
);
|
||
|
|
});
|
||
|
|
|
||
|
|
test('fills the buffer exactly when there is room for the last pass', () {
|
||
|
|
final table = FseTable(6);
|
||
|
|
readFseTable(table, description, 0, description.length, 255);
|
||
|
|
|
||
|
|
// Same stream, a buffer with slack. The count it returns must be the
|
||
|
|
// symbols it actually wrote, so the last pass cannot have been longer
|
||
|
|
// than the room the check left.
|
||
|
|
final bits = ReverseBitReader()..reset(stream, 0, stream.length);
|
||
|
|
final room = Uint8List(1024);
|
||
|
|
final written = fseDecodeInterleaved(table, bits, room, 0, room.length);
|
||
|
|
expect(written, greaterThan(256));
|
||
|
|
expect(written, lessThanOrEqualTo(room.length));
|
||
|
|
});
|
||
|
|
});
|
||
|
|
}
|