PTR-005: sniff/ sha-hex decode, memcmp, raw record arrays

The 2026-06-15 audit found sniff/ builds a 20-byte writable slice via sha.data+20 to feed a hex decode (11 sites), uses memcmp where typed equality exists, and carries record arrays as T*+count. Behavior-preserving, one worktree; hermetic .be tests stay green.

Input

Context

sha-hex decode pattern (u8s bin={sha.data, sha.data+20}; HEXu8sDrainSome(bin, hex)), 11×: sniff/AT.c:848, sniff/CLASS.c:313, sniff/GET.c:500,1296,1774,1791,1857, sniff/PATCH.c:991,1195,1230,1266.
memcmp(...,20) sha-equality: sniff/PATCH.c:131 (sha_eq reimplements sha1Eq), sniff/GET.c:143 (vs EMPTY_BLOB_SHA), sniff/GET.c:504.
sniff/SNIFF.c:358-393 (+ decls sniff/SNIFF.h:168,173) — sniff_step_fn(ulogreccp recs, u32 n, void *ctx) fed from a raw ulogrec group[LSM_MAX_INPUTS]: classic ptr+len.
sniff/PATCH.c:88 — parse_tree(entry *out, u32 *nout, u32 cap, …); sniff/PATCH.c:118,69,108 — insertion sort over raw entry*+n and memcmp name compares.
sniff/DEL.c:616-638 — raw p/end/q NUL-separated tokenizer (q++, q-p, best_b+best_len, q+1). sniff/PUT.c:753-859 — mvsrc[0]+=2, *(probe[1]-1), probe[1]--, direct urow.path[0]=…. sniff/LS.c:67-109 — path[0]+plen, {path[0], slash+1}, memchr(lo, …, hi-lo).
field-literal matching: memcmp(field[0],"parent",6) at sniff/PATCH.c:1193,1228,1261, sniff/GET.c:1149,1293,1461; {tv[0], tv[0]+40} hex slices alongside.

Goals

Replace every sha-hex site with call(sha1FromHex, &sha, frag) (bounds-checked, BADRANGE if <40). Highest-volume cleanup.
Delete sha_eq, use sha1Eq; wrap EMPTY_BLOB_SHA once via sha1FromBin and compare with sha1Eq.
sniff_step_fn → a typed ulogrecsc slice built once; the callee can't desync recs/n.
parse_tree → an entryb/gauge + entrybFeed1 (the Bx.h instantiation exists); sort the entry slice via abc/Sx.h+entryZ; comparator via u8csZ/u8csEq.
DEL/PUT/LS: u8csFind/$eat for the NUL scan, u8csUsed(s,2)/u8csLast/u8csShed/u8csMv for the slice juggling, a_rest(u8c, rel, path, plen) for prefix-skip; build the synthetic URI via a_path/PATHu8bFeed.
Field literals → u8csEq(field, a_cstr(p,"parent")).

Constraints

Behavior-preserving; hermetic .be store tests + sniff fuzzers green; the sniff binary needs its own rebuild (separate target from be).
void *ctx callback contexts (AT/CLASS/POST/DEL/GET/SUBS) are the sanctioned idiom — out of scope.

WIP

Design decisions

Land the 11-site sha-hex swap first as one mechanical pass (single canonical helper), then the memcmp and array conversions.

TODOs

Repro-first: lock outputs on the sniff test tables.
sha-hex decode 11× → sha1FromHex.
sha_eq/memcmp sha-eq → sha1Eq; EMPTY_BLOB_SHA via sha1FromBin.
sniff_step_fn → ulogrecsc.
parse_tree/sort_entries → entryb+entryZ sort.
DEL/PUT/LS pointer juggling → slice helpers; field literals → u8csEq.
Rebuild sniff + ctest; report done vs skipped.

Blockers and bummers

None known; sniff is a separate binary — rebuild it, not just be.

Outcome

pending.