Elamur Groupantsvfs-host-confinement
The groupant beside vfs/src/host.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | approximant |
| ast | partial | ../syntax.json |
| composition | partial | composition |
| cost | partial | Cost |
| descriptant | present | descriptant |
| invariant | partial | Invariant |
| tests | executed bounded checks | tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
lexical_first | lexical_first | partial source derived model | lexical_first |
dangling_link | dangling_link | partial source derived model | dangling_link |
ancestor_probe | ancestor_probe | partial source derived model | ancestor_probe |
check_access_race | check_access_race | partial source derived model | check_access_race |
Model text
descriptant
vfs-host-confinement
DirFs path preflight and journal wrapper.
Prospective epoch
2026-10-31: source reviewed before edits; prospective review retained under $MOVA_DATA/runs/octopus-wave31-vfs-2026-10-31/prospective.md. Predicted order/cost: Path construction O(bytes); up to depth canonicalize probes with OS-dependent work.
Observation epoch
Bounded actual calls and compiled negative controls are recorded in tests.md. Production behavior bytes unchanged; only focused test blocks added. Snapshot constant-time wording is conditional on cwd and destruction; recursive operations may partially commit.
Unsupported approximants
No executable percentage surrogate is claimed for these categorical/state/effect observations. Future 1%,2%,5%,10% require a useful metric, explicit domain and exact reference.
approximant
Forward relation
DirFs path preflight and journal wrapper.
normalize virtual path then append components under canonical root. Final symlink must canonicalize inside; otherwise probe ancestors until canonicalization succeeds. with calls operation only after successful real_path.
Domain: bounded inputs with available allocation and nonoverflowing counters unless checked explicitly. The relation is partial and source-derived.
composition
Composition
DirFs path preflight and journal wrapper. Shared state and order: normalize virtual path then append components under canonical root. Final symlink must canonicalize inside; otherwise probe ancestors until canonicalization succeeds. with calls operation only after successful real_path.
Scoped children project this same source. Their domains and effects remain conditional; source execution connects these clauses rather than independently proving their wiring. Stable root required; failed preflight recorded by with and OS closure not called.
models
Typed source models
Source-bound partial relations; no universal finite-test proof.
behavior_complement
Subject: vfs-host-confinement. Domain: DirFs path preflight and journal wrapper. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Outside final or ancestor link does not reach OS closure when Fault=None.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
reverse_reconstruction
Subject: vfs-host-confinement. Domain: DirFs path preflight and journal wrapper. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Accepted canonical path admits virtual aliases; denied result cannot uniquely identify malicious vs dangling target.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
lexical_first
Subject: vfs-host-confinement. Domain: DirFs path preflight and journal wrapper. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Above-root dotdot rejects before host canonicalization.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
dangling_link
Subject: vfs-host-confinement. Domain: DirFs path preflight and journal wrapper. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Final symlink canonicalization failure returns escape rather than following missing target.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
ancestor_probe
Subject: vfs-host-confinement. Domain: DirFs path preflight and journal wrapper. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: Nonexistent regular child uses canonical deepest existing ancestor.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
check_access_race
Subject: vfs-host-confinement. Domain: DirFs path preflight and journal wrapper. Valid allocations, bounded counters, Fault=None unless explicitly named. Observation: one call or the stated finite trace.
Operator: No atomic descriptor confinement between canonicalize and std IO.
Approximation: source-derived partial relation; complement is an inner excluded-behavior claim under these premises, converse retains compatible antecedents. Evidence: tests.md; unobserved concurrency/resource failures remain unknown.
tests
Checks and limitations
Exact named observations: dirfs_confines_to_root, gates_green_and_negative_controls_red.
Fresh receipts: $MOVA_DATA/runs/octopus-wave31-vfs-2026-10-31; run.sh retains four profile/repetition sets with raw logs and numeric statuses. native-commands.json and source-test-map.json disambiguate targets. Compiled mutations and exact restoration are separately retained in mutation-summary.json.
These finite observations are not semantic completeness. Source syntax generated twice and compared byte-for-byte. Host effects are limited to owned TMPDIR fixtures. Existing absolute_paths_never_reach_the_host and open_modes are skipped; snapbench main is skipped. Standalone helpers/reexports are only observed through named callers or representation checks; RealFs effect methods unexecuted.
invariant-and-cost
Invariant and cost
Invariant
Stable root required; failed preflight recorded by with and OS closure not called.
Cost
Path construction O(bytes); up to depth canonicalize probes with OS-dependent work.
No timing or numerical error guarantee is inferred from finite tests.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/vfs/src/host.rs.groupant/confinement.groupant/