Function hurray_file_writer_finish 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn hurray_file_writer_finish(
    handle: *mut HurrayFileWriter,
    kv: *const HurrayKvEntry,
    kv_count: usize,
) -> HurrayStatus

Writes the KV section, the footer index and the 40-byte trailer, completing the file.

Until this returns HURRAY_OK the bytes on the sink are not a container: the index a reader opens from is written here. Calling it twice after it returned HURRAY_OK fails.

A footer that failed before any of its bytes reached the sink may be written again: nothing was emitted, so the file is still completable (ADR-041 § 6b). This is the one retry worth having here — the data is already on the sink, and only the index is missing. A footer that failed after its first byte poisons the writer like any other torn item.

kv MAY be null with a kv_count of 0 for a file with no metadata section. Keys MUST be non-empty, at most 65 535 bytes, and unique. Entries read out of another file with hurray_file_reader_kv_entry can be passed straight in.

The writer handle stays alive and MUST still be destroyed with hurray_file_writer_destroy; any flush or close belongs to the transport’s release callback, because only the caller knows what its sink is.

Safety

• handle MUST point to a live HurrayFileWriter.
• If kv_count is non-zero, kv MUST point to kv_count readable HurrayKvEntry values whose own pointers are readable for their declared lengths, all unmodified until this call returns.