fix: accept identifier-only stream as empty payload (zig-0.16 rebase of #8)#9
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GrapeBaBa merged 1 commit intoMay 11, 2026
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`decode` and `decodeFromReader` rejected a stream that contained only the 10-byte stream-identifier chunk with `FrameError.NotFramed`, even though the Snappy framing spec treats it as a valid representation of an empty payload. Go's `snappy.NewReader` and Rust's `snap::read::FrameDecoder` both accept the same input and decode it to an empty slice; cross-client interop fixtures (e.g. leanSpec's `test_snappy_frame_empty`) emit exactly this 10-byte form for empty input. The terminal post-loop check in both decode paths now requires that both `saw_stream_identifier` and `saw_data_chunk` be unset to declare the input unframed. A stream with the identifier alone — and no data chunks — returns an empty slice. Adds two regression tests against the canonical 10-byte `"\xff\x06\x00\x00sNaPpY"` input (`decode` and `decodeFromReader`). The existing `frame roundtrip samples` test already covered round-tripping `""` through the lib's own encoder, but the encoder appends an empty data chunk in `finish()`, which masked the gap on the decode side. This is the zig-0.16-ready version of blockblaz#8 (which was cut against the 0.15.2 commit base and never reconciled with the `v0.16.0` branch).
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May 11, 2026
Reconcile the `main` and `v0.16.0` branches so the default branch ships zig 0.16 support together with the empty-stream decode fix. Both branches independently cherry-picked the same logical empty-fix on different bases (main on 0.15.2 via #8, v0.16.0 on 0.16 via #9), which produced two collisions when merging: 1. The terminal `if (!saw_data_chunk)` check in `decodeFromReader` and `decodeFramed` is the same line on both sides; keep one copy with v0.16.0's longer comment (more interop context). 2. `test "decode accepts identifier-only stream as empty payload"` and `test "decodeFromReader accepts identifier-only stream as empty payload"` appear on both branches. The main copy still uses `std.io.fixedBufferStream` / `ArrayListUnmanaged.writer`, which were removed in zig 0.16 — drop those duplicates and keep the v0.16.0 versions that use the new `std.Io.Reader.fixed(...)` / `Writer.Allocating` API. After the merge `main` carries the zig 0.16 upgrade (`df262c6`, `f939ed6`) plus a single canonical empty-fix regression suite, and `zig build test` is green under zig 0.16.0 (3/3 build steps, 13/13 tests). Downstream consumers can now point at the default branch instead of the `v0.16.0` release-style branch (which has been the only 0.16-ready snapshot until today).
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Summary
decodeanddecodeFromReaderaccept a stream that contains the identifier chunk only (no data chunks) and decode it to an empty slice — matching Go'ssnappy.NewReaderand Rust'ssnap::read::FrameDecoderand unblocking cross-client interop fixtures (e.g. leanSpec'stest_snappy_frame_empty).v0.16.0branch. fix: accept identifier-only stream as empty payload #8 was cut against the 0.15.2 commit base; its empty-fix never landed on the 0.16.0 branch, so downstream consumers on zig 0.16 currently have to choose between the fix (stuck on 0.15) and the upgrade (no fix).Why
The terminal
if (!saw_data_chunk) return FrameError.NotFramedrejects the canonical 10-byte"\xff\x06\x00\x00sNaPpY"empty-stream encoding that the Snappy framing spec allows. Peer clients accept it. zeam vendored the patched version locally to pass leanSpec interop; reconciling here removes that vendoring need.What changed
src/frames.zig: the terminal check in bothdecodeFromReaderanddecodeFramedis nowif (!saw_stream_identifier and !saw_data_chunk). Identifier-only streams fall through and return empty output; truly unframed input is still rejected.decode accepts identifier-only stream as empty payloaddecodeFromReader accepts identifier-only stream as empty payload(uses 0.16'sstd.Io.Reader.fixed(...)/Writer.Allocatingpattern, matching the existingdecodeFromReader matches decodetest in this branch.)frame roundtrip samplestest covered""through the lib's own encoder, but the encoder appends an empty data chunk infinish()— that masked the gap on the decode side, which is why the bug only surfaces under peer-emitted frames.Test plan
zig build teston zig 0.16.0 — Build Summary: 3/3 steps succeeded; 13/13 tests passed.frames.zigproduction change and re-running — both fail witherror.NotFramed).