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ENDIR-COMPLETE - exhaustive ENTER-DIRECTORY worker carve

Complete control-flow carve of ENDIR = 140176B (the @ENTER-DIRECTORY worker) in SINTRAN III L07, segment 006-S3FS, load base 26000B. Where the sibling folder ../ENTER-DIRECTORY/ carves the downstream call chain (GDIRA / CHDSI / RXDIR / WXDIR) on the happy path, this folder carves every branch and every error exit inside ENDIR itself - the five SAA error rungs, the name-mismatch tail, and the four error-exit handlers.

Evidence rule: every claim is graded VERIFIED (re-read from 006-S3FS.bin, disassembly shown) or INFERRED (reasoned from bytes + architecture) or OPEN (crosses into an uncarved routine). Byte offset = (addr - 26000B) * 2 (decimal); values are OCTAL; on-disk multi-byte values are big-endian words.

1. Correction to the human trace

SINTRAN/Filesystem/code-logic/enter-directory.md section 7 lists error 40B as raised at 140140B SAA 40. That is a mis-citation. Byte-verified:

  • 140140B (170440 = SAA 40) sits before ENDIR's entry point (140176B), in the preceding routine's shared error tail. No ENDIR path reaches it.
  • The SAA 40 that ENDIR actually reaches is 140777B (dd off=76798 word=170440), in the name-mismatch tail entered from the name compare at 140352/140353.

Both words exist and both equal 170440; the trace pointed at the wrong one. This README uses 140777B. (Byte evidence, per the no-contradiction-without- bytes rule.)

2. The five error rungs (code -> condition -> meaning)

All five SAA immediates are VERIFIED from the bytes. The branch condition that reaches each is VERIFIED where a single decisive test proves it, INFERRED where a helper's success/failure semantics are assumed.

Code SAA @ Exit Condition that reaches it Meaning (ref-manual D.2.1) Verdict
147B 140254 (170547) EXIT_D 141024 MON 124 ForceReserve returns A < 0 at 140252-140253 (JAP 3 not taken) Device unit reserved for special use SAA VERIFIED; condition VERIFIED (MON 124 + JAP)
145B 140261 (170545) EXIT_COMMON 141000 BSKP ONE 150 DA on datafield word 0 finds the device-type bit SET at 140257 (JMP 3 not taken) Illegal on tape device SAA VERIFIED; that bit == tape = INFERRED
42B 140315 (170442) EXIT_E 141004 BSKP ONE 120 DA on ,B 24 flag scratch finds bit CLEAR at 140307 (JMP 10 not taken) - a main directory entered out of release order Main directory not last one released SAA VERIFIED; branch INFERRED
40B 140777 (170440) EXIT_COMMON 141000 name compare SKP IF DA EQL ST at 140352 fails (JMP I 53 -> 140773), OR helper at 140360 fails (JMP I 45 -> 140773) Directory not on specified unit (name did not match the on-unit label) SAA VERIFIED; branch VERIFIED (compare -> tail traced)
32B 140370 (170432) EXIT_COMMON 141000 already-entered probe at 140363 returns nonzero and neither skip (JMP 6/JAZ 5) is taken at 140364-140365 Directory entered (a directory of this name is already entered) SAA VERIFIED; branch INFERRED
35B (CHDSI/WXDIR 037747) via CHDSI err -> 141000 surfaced through CHDSI when WXDIR write-back fails; not an ENDIR-local SAA Master block transfer error VERIFIED in ../ENTER-DIRECTORY

35B is included because the CHDSI error return (140403 -> 141000) can carry it; it is raised inside WXDIR (037747 SAA 35), not by ENDIR. The CHDSI cross-system owner reject code is INFERRED (see ../ENTER-DIRECTORY sec 5.4).

3. The four error-exit handlers (what each exit DOES)

Every exit begins STA ,B 2 = store the A-register error code into local ,B 2, the value ENDIR returns to the command interpreter. They differ in (a) whether they run the reserve-release unwind (RLDIR + MON 125 ForceRelease, undoing the MON 124 done at 140252) and (b) which error-report pointer they load.

Handler Addr Reached by Runs reserve-release? Notes
EXIT_COMMON 141000 145B, 32B, 40B, CHDSI-err (140403), 140264/140271/140274/140325 YES - falls through 141003 into the 141005 unwind (RLDIR + conditional MON 125) dd off=76800 word=004402
EXIT_E 141004 42B (140317), post-mount guards 140747/140760 YES - RLDIR at 141007, then MON 125 at 141014 if df[4]!=0 dd off=76808 word=004402; MON 125 dd off=76824 word=153125
EXIT_B 141016 early parse errors 140212/140214, parse-tail-A 140772 NO - nothing reserved yet dd off... word=004402; returns via 140726
EXIT_C 141020 parse errors 140223/140225, ISETP/ICLEP fail 140300/140305 NO returns via 140726
EXIT_D 141024 147B reserve-fail (140255) NO effective release - the MON 124 itself FAILED, so df[4] release path finds nothing extra dd off=76302(ptr) word=141024

Key consequence: any error AFTER a successful MON 124 reserve (145B, 32B, 40B, 42B, CHDSI failure) unwinds through a path that calls MON 125 ForceRelease so the unit is not left reserved. The 147B path does not, because its reserve never succeeded.

4. Full ENDIR control flow

ENDIR 140176 STD I 30 / SAB 27               prologue, 23-word frame
  |  140202-140225  arg fetch + parse (GDIRE 131732 @140222)
  |      err 140204 -> 140770 -> EXIT_B 141016
  |      err 140212/140214       -> EXIT_B 141016
  |      err 140223/140225       -> EXIT_C 141020
  v
STAGE 2  140244 GDIRA 030225 -> df (,B 25)
  |  140250 df[4]!=0 ?  --yes--> 140252 MON 124 ForceReserve
  |                                 A<0 -> SAA 147 @140254 -> EXIT_D 141024
  |  140256 df[0] tape-bit set ? --yes--> SAA 145 @140261 -> EXIT_COMMON 141000
  |  140263/140270/140272 helpers   err -> EXIT_COMMON 141000
  |  140277 ISETP / 140304 ICLEP    err -> EXIT_C 141020
  v
STAGE 3  140306 flag & 0o120 clear ? --yes--> SAA 42 @140315 -> EXIT_E 141004
  |  140320/140324 helpers          err -> EXIT_COMMON 141000
  v
STAGE 4  140326-140352 byte-wise name compare
  |  140352 name != label ?        --yes--> 140773 -> SAA 40 @140777 -> EXIT_COMMON
  |  140360 helper fail            --yes--> 140773 -> SAA 40 @140777 -> EXIT_COMMON
  |  140363 already-entered probe  --yes--> SAA 32 @140370 -> EXIT_COMMON 141000
  v
STAGE 5  140402 JPL I 33 = CHDSI 037763   *** THE MOUNT ***
  |  140403 CHDSI err -> EXIT_COMMON 141000
  v  140404 CHDSI ok -> 140436 post-mount bookkeeping
POST-MOUNT 140436+  in-core directory-table update
       guards 140747/140760 -> EXIT_E 141004   (release on failure)
       success -> return rc=0  (directory MOUNTED)

5. VERIFIED / INFERRED / OPEN

Item Verdict
ENDIR entry 140176 = 021030, SAB 27 frame VERIFIED (dd off=76028)
MON 124 ForceReserve @140252 = 153124 VERIFIED (dd off=76116)
All five SAA immediates 147/145/42/40/32 (bytes) VERIFIED (dd off=76120/76130/76186/76798/76272)
147B trigger = reserve fail (JAP not taken) VERIFIED
40B trigger = name compare fail -> 140773 -> 140777 VERIFIED
145B trigger = device-type bit; which bit = tape SAA VERIFIED / bit = INFERRED
42B trigger = main-dir ordering guard SAA VERIFIED / branch INFERRED
32B trigger = already-entered probe SAA VERIFIED / branch INFERRED
Error-exit ptrs 141024/141000/141004 (@140407/140410/140422) VERIFIED (dd off=76302/76304/76324)
MON 125 ForceRelease in EXIT_E @141014 = 153125 VERIFIED (dd off=76824)
CHDSI ptr @140435 = 037763, GDIRA ptr @140405/140244 = 030225 VERIFIED (dd off=76346/76298)
Release-on-error semantics (EXIT_COMMON/EXIT_E run MON 125) VERIFIED (control flow)
Intermediate helper roles (010500, 050323, 053047, 037377, 034557, 036511, 035231, 035531, 041552, 047402, 035476) OPEN - other 006-S3FS routines, not carved here; roles labelled INFERRED from context
GDIRE = 131732B (helper @140222) VERIFIED (ptr) / role INFERRED
CHDSI cross-system owner reject exact code INFERRED (see ../ENTER-DIRECTORY sec 5.4)
Post-mount in-core table field semantics (140436+) OPEN - partially carved

Provenance: carved 006-S3FS SINTRAN L07 bytes, load base 26000B; ENDIR body 140176-140404, error handlers 140770-141041; every dd offset listed above reproduced from versions/L-VSX-500/segments/006-S3FS.bin. Error meanings from Reference-Manuals/ND-60.050.06 SINTRAN III Users Guide.md table D.2.1.