forked from unom/punktfunk
enricobuehler
3fac1a6da1
Every capability probe drops libav's log level to AV_LOG_FATAL around an encoder open it expects to fail, then restores what was there before. That level is one process-global int and the probes genuinely overlap — they are reached both from `/serverinfo` and from session bring-up. Two overlapping save/restore pairs interleave as get(INFO) → get(FATAL) → set(INFO) → set(FATAL), and the process is then pinned at AV_LOG_FATAL permanently: every later libav diagnostic silently dropped, including the ones you want when a stream fails to open later on. Replaces the four hand-rolled save/restore pairs with one RAII guard over a single shared mutex. The audit filed two sites; there are four — the NVENC 4:4:4 and 10-bit probes in `linux/mod.rs` and both VAAPI probes, which is why the lock has to be shared across the two modules rather than kept local to either. Being RAII also closes a smaller hole the old shape had: the restore was a statement after the open, so any early return added to those functions later would have leaked the quiet level. Now it cannot. The guard is poison-tolerant — a probe that panicked mid-window has already restored the level through `Drop`, so refusing the lock forever afterwards would be strictly worse than proceeding. It is not re-entrant, which is safe here because no probe body reaches another probe (they only call encoder-open helpers); that invariant is written down at the type. Serialising the probes costs nothing measurable: they are process-once behind their caches and each already pays for a real encoder open. Verified with the canonical Linux gate (docker linux/amd64): fmt, clippy --all-targets at default and at nvenc,vulkan-encode,pyrowave, and the pf-encode test leg (37 passed).