Fix 1 (correctness): resolve_fmts_key_map's per-index phase probe read a
single representative segment via read_unit (whose read_sectors(...).ok()?
swallows read errors into None) with no fault fallback. A transient live-drive
read fault (e.g. NOT READY 2/04/3E on the BU40N) made every probe read return
None, giving even==0 && odd==0 — indistinguishable from a genuine wrong key —
so resolve_tie_phase returned FmtsKeyMissing and aborted the entire multi-title
rip even though the forensic index keys were valid and in hand.
Extract the probe into probe_index_phase, which returns Phase / WrongKey /
ReadFault. It mirrors the anchor loop's tolerance: it tries multiple same-index
segments and only concludes WrongKey once a read actually succeeded and decrypted
to no clean parity. If every read of every same-index segment faults it returns
ReadFault; the caller then leaves the phase unresolved so the range-builder
defaults to Phase::All (decrypt both parities, demux drops the garbled alternate
half) instead of aborting. A wrong key can never be masked as a read fault:
ReadFault requires that not a single read succeeded, so zero decrypt evidence.
Fix 2 (test coverage): resolve_mux_key_map's multi-CPS branch was only exercised
with an all-zero source, so pick(), the KeyFetch cold path, and the fail-loud
DecryptFailed guard never ran. Add tests over real AACS ciphertext (via
aacs_encrypt_unit_for_test) covering pick() selecting the correct pool index,
the DecryptFailed guard firing when a clean sample matches no held/fetched key,
and the fetch cold path recovering a missing unit key. Mutation-verified.
Fix 3 (doc): move the reader_event_fn EventKind->MuxEvents mapping doc off
session_mux_keys onto reader_event_fn.
Matthew Jackson
7ba43d9c02