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GFILI @057173B - complete instruction-level carve (L07, segment 006-S3FS)

What GFILI is: the SINTRAN III file-system routine that resolves a file specification (already tokenised) to an on-disk object entry - directory index + object descriptor + version. It is the lookup core behind MON 50 OPEN (via OPFIL -> FCON -> FFILE -> GCFIL -> GFILI) and the whole FILSYS name family. It does NOT create files and does NOT check access rights - those are separate routines (CROBJ, GFIAC) in the callers.

Source of truth: 006-S3FS.asm (this folder), whole-segment nd100-dis. Addresses octal; every citation is ADDR (line N). Version L-VSX-500 (L07). Symbols: 006-S3FS.symbols.txt. Binary: ../../../segments/006-S3FS.bin, load base 26000B; byte offset of A = (A-26000B)*2. Body span: 057173B (entry) .. 057504B (next symbol DIRUN@057505B). The constant/pointer pool sits mid-routine at 057353B-057373B (normal NPL literal-pool placement).

Evidence tags: [V] = read from the bytes at the cited addr/line. [I] = inferred from control-flow + symbol names, not fully value-decoded. [OPEN] = not determined.

Runtime convention: reentrant stack. JPL I <p> calls via a pointer cell = SPUSH@003752; result returned by callee doing MIN ,B4 k times, so SPOP@003776 returns to caller+k (skip-count multi-return). ,Bn = frame-relative local. SAT c loads an ASCII code (octal): 50=(, 51=), 47=', 56=., 72=:.

1. Routines GFILI calls (all resolved from the pointer pool) [V]

Constant/pointer pool 057353B-057373B [V, lines 13345-13361]:

Cell Value Symbol Role
057353 003752 SPUSH push reentrant frame
057354 000006 (const 6) frame size arg
057355 056645 SEPOB split spec into subparts; fill empty dir from GDEFD
057356 057374 (landing) SEPOB-fail landing
057357 030062 GETCH fetch one spec char
057360-062 023/035/033 (consts) entry field offsets
057363 042622 SEPFS split file/type/version fields
057364 057376 (landing) SEPFS-fail landing / re-scan loop entry
057365 056326 GOBJI object/file-name scan in one directory
057366 057405 (landing) GOBJI-fail landing = fallback engine
057367 000044 (const)
057370 057627 GVERS parse requested version field -> number
057371 057567 GNEXV walk the version chain (get next version entry)
057372 000046 (const)
057373 003776 SPOP pop frame / return

Fallback-block pool 057457B-057467B [V, lines 13413-13421]:

Cell Value Symbol Role
057460 050124 GDIRT directory-table accessor (advance to next dir)
057461 010506 (commoncode) list-end / exit-dispatch helper (below load base)
057462 055540 GSYSI get user (SYSTEM) index (by name via GMUSI)
057463 010500 (commoncode) exit-dispatch helper
057466 056326 GOBJI SECOND object scan (under SYSTEM)
057467 057267 (landing) SYSTEM-hit -> re-enter version chain

Not in either pool: GFIAC@057771 is never referenced anywhere in 057173B-057504B. [V - I read every pointer cell]. GFILI does pure name->entry resolution; the friend/public/ring access check is run by the CALLER after GFILI returns. (This confirms the earlier [I] as [V].)

2. Stage-by-stage walk [V bytes; per-line]

A. Entry + frame (057173-057200)

057173 STD I 157                 ; save link (SPUSH linkage)                     (13233)
057176 SAB 51                    ; B := 51  (frame base)                         (13236)
057177 JPL I 154 -> SPUSH        ; push reentrant frame                          (13237)
057200 STT ,B40                  ; ,B40 := caller's T  (fallback-allow token)    (13238)
,B40 is seeded from the caller's T. Callers that permit the SYSTEM fallback pass T = -1 (see the gate in stage F). [V store; [I] that the caller's convention value is -1, but the gate at 057415 compares against -1.]

B. Split spec + detect explicit (USER) (057201-057217)

057203 JPL I 152 -> SEPOB        ; split spec; SEPOB fills empty dir via GDEFD   (13241)
057204 JMP I 152 -> 057374       ; SEPOB fail -> store status, return            (13242)
057205 STT ,B43 ; 057206 STA ,B41; ,B43 = directory index, ,B41 = name descriptor(13243-44)
057210 STA ,B42                  ; ,B42 = object descriptor copy                 (13246)
057211 LDX ,B0 ; 057212 (T:=0)
057213 JPL I 144 -> GETCH        ; read spec char[0]                             (13249)
057214 SAT 50 ('(')              ; is first char '(' = a (USER) prefix ?         (13250)
057215 SKP IF DA EQL ST
057216 JMP 2 -> 057220           ;  char != '(' : leave ,B40 (= -1, fallback ON) (13252)
057217 STZ ,B40                  ;  char == '(' : ,B40 := 0  (fallback OFF)       (13253)
Decisive gate mechanism [V]: if the spec begins with '(' (an explicit (USER) prefix), ,B40 is zeroed; otherwise it stays at the caller's -1. Stage F only runs the SYSTEM fallback when ,B40 == -1. This is the byte-level implementation of the Users Guide rule "if a user name is specified, only that user's directory is searched."

C. Field split + FIRST object scan (057220-057265)

057220-057230 init entry fields (const 20 -> +23, 4 -> +33, 5 -> +35)            (13254-62)
057242 JPL I 121 -> SEPFS        ; split file:type;version                       (13272)
057243 JMP I 121 -> 057376       ; SEPFS fail -> tail                            (13273)
057257-057262 load ,B43(dir) + ,B41(name) as scan args
057263 JPL I 102 -> GOBJI        ; FIRST file-name scan in directory ,B43        (13289)
057264 JMP I 102 -> 057405       ; GOBJI +0 (fail) -> FALLBACK ENGINE (stage F)  (13290)
057265 STD ,B44 ; 057266 STD ,B46; GOBJI success: found entry -> version best    (13291-92)
GOBJI returns via skip-count; the +0 (no unique file) return lands on 057264, which jumps to the fallback engine at 057405. A unique hit falls through to the version chain.

D. Version chain (057266-057337)

057274 JPL I 74 -> GVERS         ; parse requested version field to a number     (13298)
057276 JAF -> 057314             ; no version requested -> skip explicit-match    (13300)
057277-057313 loop: GNEXV (057301) walk chain, keep entry whose version == req   (13303)
057314-057336 loop: GNEXV (057326), MIN ,B50 counts, pick highest/!default       (13326)
057337 STD ,B44 ; STD ,B46       ; final selected version entry                  (13332-33)
GNEXV (057567) reads entry version keys from cells +41B/+44B and shifts them (057600 LDA ,X 41 ; 057602 LDA ,X 44 ; SAD/SHA ZIN SHR 13497-13503) [V]. GVERS (057627) parses the version subpart chars via GETCH, terminator '(47) (13528) [V]. Full numeric semantics = [I].

E. Success return (057337-057351)

057343 LDA ,B42 -> ,B0           ; return object descriptor                      (13337-38)
057345 LDA ,B43 -> ,B1           ; return directory index                        (13339-40)
057347 MIN ,B4                   ; skip-count = 1  (success)                      (13341)
057351 JMP I 22 -> SPOP          ; pop frame, return to caller+1                  (13343)

F. Fallback engine (057376-057504) [V - the current-user -> SYSTEM path]

Entered two ways: from GOBJI-fail (057405), or looped back from a re-scan (057376). 

057376 STA ,B2                   ; (loop-back) save status                        (13364)
057401 JPL I 57 -> GDIRT         ; (loop-back) advance directory                  (13367)
    -- direct GOBJI-fail entry: --
057405 STA ,B2                   ; save GOBJI status                              (13371)
057406 SAT 56 ; 057407 SKP IF DA UEQ ST   ; status == 56 "No such file name"?     (13372-73)
057410 JMP 4 -> 057414           ;  yes -> try fallback                           (13374)
057411 SAT 57 ; 057412 SKP IF DA EQL ST   ; status == 57 "Ambiguous"?             (13375-76)
057413 JMP 43 -> 057456          ;  neither 56 nor 57 -> return the error         (13377)
057414 LDA ,B40 ; 057415 SAT -1 ; 057416 SKP IF DA EQL ST   ; ,B40 == -1 ?        (13378-80)
057417 JMP 37 -> 057456          ;  ,B40 != -1 (user named) -> NO fallback         (13381)
    -- ,B40 == -1 (unqualified): walk dirs then SYSTEM --
057422 JPL I 36 -> GDIRT         ; advance to next directory                       (13384)
057423 JMP -25 -> 057376         ;  GDIRT+0: more dirs -> loop back, re-scan        (13385)
057424 JPL I 35 -> 010506        ;  GDIRT+1: list-end helper                        (13386)
057425 JPL I 35 -> GSYSI         ;  GDIRT+2: get (SYSTEM) user index                (13387)
057433 JPL I 25 -> GDIRT         ; get SYSTEM's directory                           (13393)
057443 JPL I 23 -> GOBJI         ; SECOND scan, under SYSTEM                         (13401)
057444 JMP 34 -> 057500          ;  SYSTEM GOBJI fail -> final 56 -> return          (13402)
057445 STD ,B44 ; STD ,B46       ; SYSTEM hit: save entry                            (13403-04)
057455 JMP I 12 -> 057267        ; -> re-enter version chain (stage D) with SYSTEM hit(13411)
    -- error exits --
057456 JMP -57 -> 057377         ; (error path)                                      (13412)
057470-057504 map GSYSI/GMUSI user errors: 46 no-such-user, 45 ambiguous-user       (13422-33)
057500 SAT 56 ... -> 057504      ; SYSTEM also missing -> final "No such file" (56)   (13430)

So the observable resolution order for an unqualified spec [V]: 1. caller's default directory (GDEFD inside SEPOB) -> GOBJI (057263). 2. on 56/57, walk further directories via GDIRT, re-scanning GOBJI (057422 -> loop 057376). 3. when the walk is exhausted, GSYSI -> SYSTEM directory -> GOBJI again (057443). 4. SYSTEM miss -> final 56 "No such file name" (057500-057504). An explicit (USER) prefix zeroes ,B40 (stage B) and short-circuits all of 2-4.

3. Frame local map (as used in the body) [V stores unless marked]

Local Meaning Evidence
,B0 / ,B1 in: spec ptr; out: object descriptor / dir index 057211, 057343-057346
,B2 working status word (from SEPOB/GOBJI) 057405 STA ,B2
,B3 out: version/result word 057342 STA ,B3
,B40 fallback-allow flag: -1 = allow SYSTEM fallback, 0 = user named -> no fallback 057200 seed, 057217 zero, 057414-057417 gate
,B41 object-name descriptor (GOBJI arg) 057206, 057262
,B42 object descriptor copy (returned in ,B0) 057210, 057343
,B43 current directory index (GOBJI/GDIRT arg) 057205, 057261, 057420
,B44 / ,B46 version-chain "best entry so far" (double word) 057265, 057337, 057445
,B47 version key under compare 057303-057307
,B50 version-loop counter 057316, 057330-057334

4. Answers this carve nails down

  • GFILI is lookup-only. No create path in its pool (create is CROBJ@063726B, reached from GCFIL@064670B on a quoted name). [V - full pool listed in section 1.]
  • GFIAC (access check) is NOT part of GFILI. Name resolution and permission are separate stages; a file is found by name first, access-checked by the caller second. [V - GFIAC absent from body.]
  • The current-user -> (SYSTEM) fallback lives here, inside GFILI, and is gated on the spec having no (USER) prefix (,B40). It is SINTRAN-internal, not the linker's. [V] - see companion CARVE-ANSWER-UNQUALIFIED-OPEN-USER-SYSTEM-FALLBACK.md.

5. Still OPEN (honest)

  • Exact numeric semantics of the version chain (GVERS parse + GNEXV compare) - structure verified, the "which version wins" arithmetic (default vs highest) not fully decoded.
  • The 010506/010500 commoncode exit-dispatch helpers (below this segment's load base).
  • The literal string GSYSI feeds GMUSI to name user SYSTEM (word 055560=010017, not decoded) - so "SYSTEM" rests on the symbol name + the Users Guide, not a decoded ASCII constant.
  • Which T value each GFILI caller passes at entry (seeding ,B40); the gate compares -1, and the (USER)-prefix zeroing is byte-proven, but the caller-side seed is not traced here.

Companions in this folder: CARVE-ANSWER-UNQUALIFIED-OPEN-USER-SYSTEM-FALLBACK.md (the fallback question), FLPAR-MDEAB-FILENAME-RESOLVER-CARVE.md (name MATCHING inside a directory). Status-of-record: SINTRAN/CARVING-HANDOFF.md section 1.8.