Cesarus85--mjolnir-vr/docs/object_matching_logs/libcmt_strerror_obj.md

libs/libcmt/strerror.obj exact-match ledger

This atomic lane starts from campaign commit 8446572d. The object was MISSING at config index 764, absent from config/parked.json, every Git ref, worktree, and existing object log. January owns one function and one 40-byte BSS section.

Plain-English behavior

strerror obtains the current thread's CRT state and lazily allocates a 134-byte message buffer. If allocation fails, it uses a shared 40-byte backup buffer. It clamps invalid negative or out-of-range error numbers to the CRT's fallback entry, copies that message into the selected buffer, and returns it.

Provenance and ownership

The XDK 3911 libcmt.lib archive has SHA-256 60aa4c87c97eeb6662b31d9d37cf3caba1afabaec72c47b090e7a0ce8b632f55. Its obj\i386\strerror.obj member has SHA-256 de82ead29d2e9e81e594492a79f54222ae6212db642447ad5d593d6ac48070d6, compiler identifier 0x001c2426, ordinary C CodeView records, and source path d:\xbox-finalfre\private\sdktools\crt\crtw32\misc\strerror.c. The public historical Microsoft Xbox CRT source at the same path supplies the original compound allocator condition and _sys_err_msg expression topology. January bytes and strict ownership remain authoritative.

Strict target inventory:

• _strerror: 81 bytes, five relocations, normalized SHA-256 13ea92a78de571574228df99f0bcbabf5329174c0d63c86d587515698f25f25b;
• relocations at +2 to __getptd, +20 to _malloc, +31 to _bss_004e3eb0, +48 to __sys_nerr, and +63 to __sys_errlist, all with exact types and zero addends;
• _bss_004e3eb0: external symbol at section offset zero, 40 zero bytes, zero relocations, SHA-256 2c34ce1df23b838c5abf2a7f6437cca3d3067ed509ff25f11df6b11b582b51eb;
• no other runtime data or function aliases.

The original compiler called the backup buffer a function-local static. January's csplit ownership instead exposes the same bytes as external _bss_004e3eb0. The production declaration follows the authoritative split object, and the hardened comparator verifies that both the function relocation and the data symbol storage/value agree—this is not an alias waiver.

Experiment matrix

ID	One source factor	Size T/B	Relocs T/B	Result	Decision
E01	Nested allocator tests plus explicit range assignment	81/79	5/5	correct operations, but cached message pointer and two-byte-short bounds CFG	rejected
E02	Authentic Microsoft compound field == NULL && (field = malloc(...)) == NULL	81/81	5/5	allocator half exact; bounds compare direction still differs	retained as proven control
E03	Authentic _sys_err_msg conditional expression instead of mutating error_number	81/81	5/5	all code bytes/hash exact; only local-static name disagrees with csplit owner	retained
E04	Name the proven external 40-byte csplit BSS owner and reference it directly	81/81	5/5	function, BSS bytes, relocations, linkage, and ownership all strict exact	accepted

Strict verification

XDK 3911 CL 13.00.9254.1 compiled with unchanged libcmt /O1 /Gy /I"xbox/include" flags. The hardened comparator reports section_infos_equal for _strerror; a separate section comparison reports the 40-byte BSS equal. Both objects expose _bss_004e3eb0 as external storage class 2 at offset zero. No relocation identity, addend, or section ownership is being masked.

The full halobetacache_build and libcmt_build pass. Regenerated progress reports 330/833 objects overall, 267/468 Halo objects, and 63/212 libcmt objects. Libcmt has 85/476 exact functions, 4,298/55,015 exact code bytes, and 364/8,637 exact data bytes. This object contributes one object, one function, 81 code bytes, and 40 BSS bytes. The semantic audit reports zero unit errors.

The clean-commit fail-closed per-unit snapshot/check was followed by deletion of the generated object and a forced rebuild. _strerror remains still_exact; the gate also freezes the BSS bytes and symbol ownership. There are no failures, warnings, changed non-exact siblings, newly exact surprises, or ownership changes. The complete tooling suite passes 179/179 tests.

House/Berth and original-bug audit

The source uses named types, constants, parameters, a typed thread-data prefix, and readable control flow recovered from primary provenance. It uses no assembly, volatile, forced inlining, undefined behavior, type-punning, opaque cast, packing/alignment trick, flag change, byte patch, or comparator waiver. The compound condition is retained because it is the authentic concise source and measurably controls the exact store/test schedule.

The original design has an unavoidable thread-safety fallback: if allocation fails, all threads share the 40-byte backup. That behavior is preserved for exact matching. A defensive implementation would return a constant immutable fallback or synchronize access, but would intentionally change ownership and runtime behavior.