The public and deprecated block APIs previously entered a C-owned
ZSTD_compressContinue_internal routine, which mixed frame-header sequencing,
window maintenance, block dispatch, and frame-size accounting with the private
CCtx match state. That made the high-level compression boundary both harder
to test and easy to diverge from the already-ported frame-chunk body.
Add an explicit C/Rust projection containing only scalar state and callback
slots. Rust now owns stage validation and transitions, header sequencing,
frame-versus-block dispatch, and consumed/produced progression, while C
callbacks retain access to the private match state and context-sensitive block
operations. The same path now covers compressContinue, deprecated block
compression, and compressEnd without exposing the unstable CCtx layout.
Test Plan:
- `cargo test --manifest-path rust/Cargo.toml --all-targets -- --test-threads=1` -- 473 passed.
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression,decompression,dict-builder,legacy-v01,legacy-v02,legacy-v03,legacy-v04,legacy-v05,legacy-v06,legacy-v07 --all-targets -- --test-threads=1` -- 528 passed.
- Native `test-fuzzer`, `test-zstream`, `test-decodecorpus`, `test-cli-tests`, and `test-zstd` -- passed.
- `cargo clippy` default, benches, and tests for library and CLI -- passed.
ddidderr
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