test(fuzz): add dedicated fuzz targets for rar2/rar3/rar5 - #120
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…ta fixtures Review findings on the in-band filter implementation, all three fixed by moving to incremental filter application (flush_completed_filters): - A slot-0 filter-table reset now applies the completed-window prefix and cancels everything still pending, mirroring unrar's InitFilters — a canceled filter must never rewrite output. Previously pending filters survived the reset and ran at finish. - The pending queue is capped at 8192 concurrent filters (unrar's MAX_UNPACK_FILTERS); when the cap is hit after draining completed windows the stream is rejected as corrupt. - A filter window the stream never finishes producing is now Corrupt instead of silently returning pre-filter bytes as success. (unrar writes the raw bytes and relies on the container CRC to flag the file; surfacing the error directly matches this crate's malformed-input policy.) Flushing is prefix-only — a completed window queued behind an incomplete one waits — so overlapping windows (filter chains) always apply in declaration order. Output is append-only and LZ back-references read the unfiltered window, so early application is equivalent to end-of-stream application. New coverage: - Declaration-level unit tests (reset/cancel semantics, the cap, slot-reuse remembered lengths, prefix ordering, truncated-window integration test) driving the parser with the real 29-byte Delta program. - rar5 end-to-end real-archive fixtures: a Delta-filtered member run and a whole six-member solid group exercising add_file_boundary against the archives' own data-CRCs, plus a regression guard showing exactly the x86 member corrupts when boundaries are not registered. - Both fuzz targets from the rar-fuzz-targets branch (KarpelesLab#120) merge-tested against this branch and run under ASan seeded with corpus payloads: decoder_rar3 328k runs / decoder_rar5 341k runs, no findings. Docs: README capability matrix updated for both formats; rar5 module docs now describe Delta support and the solid-group calling convention. Known gap, documented: the 57-byte E8E9 program has no real-archive fixture because no current archiver emits it (rar 6.24 uses the E8-only program); its fingerprint cites libarchive and the transform is unit-tested.
MagicalTux
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Aug 16, 2026
…ta fixtures Review findings on the in-band filter implementation, all three fixed by moving to incremental filter application (flush_completed_filters): - A slot-0 filter-table reset now applies the completed-window prefix and cancels everything still pending, mirroring unrar's InitFilters — a canceled filter must never rewrite output. Previously pending filters survived the reset and ran at finish. - The pending queue is capped at 8192 concurrent filters (unrar's MAX_UNPACK_FILTERS); when the cap is hit after draining completed windows the stream is rejected as corrupt. - A filter window the stream never finishes producing is now Corrupt instead of silently returning pre-filter bytes as success. (unrar writes the raw bytes and relies on the container CRC to flag the file; surfacing the error directly matches this crate's malformed-input policy.) Flushing is prefix-only — a completed window queued behind an incomplete one waits — so overlapping windows (filter chains) always apply in declaration order. Output is append-only and LZ back-references read the unfiltered window, so early application is equivalent to end-of-stream application. New coverage: - Declaration-level unit tests (reset/cancel semantics, the cap, slot-reuse remembered lengths, prefix ordering, truncated-window integration test) driving the parser with the real 29-byte Delta program. - rar5 end-to-end real-archive fixtures: a Delta-filtered member run and a whole six-member solid group exercising add_file_boundary against the archives' own data-CRCs, plus a regression guard showing exactly the x86 member corrupts when boundaries are not registered. - Both fuzz targets from the rar-fuzz-targets branch (KarpelesLab#120) merge-tested against this branch and run under ASan seeded with corpus payloads: decoder_rar3 328k runs / decoder_rar5 341k runs, no findings. Docs: README capability matrix updated for both formats; rar5 module docs now describe Delta support and the solid-group calling convention. Known gap, documented: the 57-byte E8E9 program has no real-archive fixture because no current archiver emits it (rar 6.24 uses the E8-only program); its fingerprint cites libarchive and the transform is unit-tested.
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CONTRIBUTING promises every decoder a fuzz target, but the RAR decoders were only reachable through decoder_dispatch. Add one each, house pattern. Since RAR streams do not self-delimit, each derives out-of-band params from an input prefix (unpack size, rar3 E8 flag, rar5 window selector), capped at 1 MiB / 4 MiB so the fuzzer explores without gigabyte allocations. Registered in fuzz/Cargo.toml and the fuzz.yml matrix.
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CONTRIBUTING says every decoder gets a fuzz target, but the RAR decoders only had coverage via
decoder_dispatch. This adds dedicateddecoder_rar2/rar3/rar5targets following the existing pattern (loop-guard, out-of-band params derived from an input prefix — unpack size capped at 1 MiB, rar5 window capped at 4 MiB). Registered infuzz/Cargo.tomland thefuzz.ymlmatrix.Smoke-ran each ~10 min locally (nightly + cargo-fuzz): no crashes/OOMs/timeouts.