Move the platform-specific dictionary mapping and release operations behind the
Rust CLI archive while keeping size policy, diagnostics, and FIO_Dict_t
ownership decisions in C. POSIX descriptors and Windows handles are cleaned up
on every failure path, and zero-length dictionaries use an owned sentinel so
the existing non-null dictionary invariant remains valid.
Test Plan:
- cargo test --manifest-path rust/cli/Cargo.toml --lib fileio_backend (24 passed)
- cargo clippy --manifest-path rust/cli/Cargo.toml --lib -- -D warnings
- make -C programs -j2 zstd
- --mmap-dict compression/decompression round trip with programs/README.md
- programs/zstd --mmap-dict --test on the generated frame
- rustfmt +nightly --edition 2021 rust/src/fileio_backend.rs --check
- git diff --check
ddidderr
f7a2576761