Elamur Groupantsvirtual-filesystem-state
The groupant beside models/virtual-filesystem-state.groupant 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 | forward |
| ast | not materialized | |
| composition | partial | composition |
| cost | symbolic source derived | cost |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | see source local evidence | checks |
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 |
backend-dispatch | tagged_union | partial source derived model | backend-dispatch |
state-trace-split | snapshot_projection | partial source derived model | state-trace-split |
failure-effects | effect_boundary | partial source derived model | failure-effects |
caller-join | representation_transport | partial source derived model | caller-join |
Model text
descriptant
virtual-filesystem-state: wave31
Actual callers: mlab/src/interp.rs owns Box<dyn vfs::FileSystem>, mlab/src/builtins/files.rs and table.rs call it; open selects backend. Memory path->error->journal joins tested. wasi-host is sibling consumer of Vfs/Errno projections, not owned here. snapbench and test fixtures are independent observation paths, not production callers.
This source-bound partial group organizes existing Mova code. Native evidence and excluded effects are recorded in source sidecars and the root wave31 report. Registration is not a universal proof or whole-system runtime claim.
model
virtual-filesystem-state
forward
FileSystem routes tagged mem/dir/real implementations. Vfs edits resolve paths, validate permissions/quotas, COW mutate then journal. Errno projects failures to Linux/WASI. Snapshot restores tree/counters but not journal/policy. Host import/export are explicit partial-effect paths.
invariant
Bounded Fault=None single-file quota rejection preserves dump; shared snapshots preserve prior tree bytes. Journal total counts retained+dropped before overflow. Host confinement requires stable filesystem and simple temp prefixes.
cost
Memory resolve O(expanded bytes+sum log fanout), COW O(sum shared-directory fanouts+copied payload); snapshot O(cwd bytes), restore additionally last-reference destruction. Host I/O and sorting separate. No benchmark throughput claim.
composition
Actual callers: mlab/src/interp.rs owns Box<dyn vfs::FileSystem>, mlab/src/builtins/files.rs and table.rs call it; open selects backend. Memory path->error->journal joins tested. wasi-host is sibling consumer of Vfs/Errno projections, not owned here. snapbench and test fixtures are independent observation paths, not production callers.
domain
CPU synthetic finite trees, valid UTF8 paths, bounded counters/allocation, dedicated TMPDIR host fixtures. No concurrent host mutations; trusted export roots and safe temporary prefixes.
limitations
No universal POSIX equivalence, atomic host confinement or transactional mkdir_all/import/export. RealFs operations and snapbench main unexecuted. No useful effect-preserving percentage surrogate.
checks
- 20 exact named tests twice debug and twice release
- Seven compiled actual-source negative controls with byte restoration
- Two identical syntax projections per source
catalog
behavior-complement
Under Fault=None and bounded arithmetic, single-file quota failures do not install edits; virtual absolute paths cannot implicitly read host. Host race and transfer partial effects excluded from this inner source-derived claim.
reverse-reconstruction
Restored state admits arbitrary intervening histories; journal drops and TSV sanitization erase information. Linux errno1 admits Perm and NotCapable; backend tag required to interpret metadata.
backend-dispatch
open(mem,limits) installs Vfs, real ignores limits, dir canonicalizes root; shared trait does not imply identical journals or metadata.
state-trace-split
Snapshot includes root,cwd,clock,next_ino,usage,tmp and excludes limits,journal,fault. Restoration equality applies to dump projection.
failure-effects
Single-file quota preflight precedes tick; mkdir_all/import/export can preserve a successful prefix. No parent-wide rollback follows.
caller-join
mlab file/table builtins use Interp.fs trait; sibling WASI translates errno via wasi number while host Display uses Linux number. Do not identify these numeric coordinate systems.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/models/virtual-filesystem-state.groupant/