infrastructure-write-blocker

Software write-blocking via blockdev --setro, with mandatory post-set verification -- never claims a device is write-blocked without confirming it

Tier	infrastructure
Role	unclassified (baselined)
Path	`crates/infrastructure/write-blocker`
Edition	2021
Targets	infrastructure_write_blocker
Public items	6 across 0 modules
Tests	8

What it is for

Software write-blocking via blockdev --setro/--getro, with mandatory post-set verification. A write blocker that can silently fail to block is worse than no write blocker at all — this crate never emits a "write-blocked" citation without confirming the kernel actually reports the device read-only afterward.

Real behavior verified on this machine before writing this parser (not assumed): blockdev --getro <dev> always exits 0 regardless of state — the read-only/ read-write flag is only in stdout ("0\n" writable, "1\n" read-only). Exit code alone cannot be trusted to reflect device state, only whether the ioctl call itself succeeded.

No kernel patch required — this is the standard BLKROSET ioctl via blockdev, distinct from and much smaller in scope than a full custom write-blocking kernel patch (e.g. msuhanov/Linux-write-blocker).

Capabilities

`WriteBlockerError`

Software write-blocking via blockdev --setro/--getro, with mandatory

Item
`pub enum WriteBlockerError`
`fn parse_getro_output(stdout : & str) -> Result <bool, WriteBlockerError>`
`async fn get_read_only(blockdev_bin : impl Into <PathBuf>, device : & str, limits : ExecLimits,) -> Result <bool, WriteBlockerError>`
`async fn set_read_only(blockdev_bin : impl Into <PathBuf>, device : & str, limits : ExecLimits,) -> Result <(), WriteBlockerError>`
`async fn enable_and_verify(blockdev_bin : impl Into <PathBuf>, device : & str, limits : ExecLimits,) -> Result <Observation, WriteBlockerError>`
`fn verify_outcome(device : & str, reported_read_only : bool,) -> Result <Observation, WriteBlockerError>`

How to use it

No examples/ target and no doctest in this crate's rustdoc. The tests listed under Verification are the closest executable usage.

Module structure

No public modules: the crate root is its whole surface.

Public surface

`crate root`

Item	What it is
`pub enum WriteBlockerError`	Every way a write-block operation can fail.
`fn parse_getro_output(stdout : & str) -> Result <bool, WriteBlockerError>`	Parse `blockdev --getro`'s stdout (`"0\n"` writable, `"1\n"` read-only) into a bool
`async fn get_read_only(blockdev_bin : impl Into <PathBuf>, device : & str, limits : ExecLimits,) -> Result <bool, WriteBlockerError>`	Query current read-only state via `blockdev --getro <device>`.
`async fn set_read_only(blockdev_bin : impl Into <PathBuf>, device : & str, limits : ExecLimits,) -> Result <(), WriteBlockerError>`	Set a device read-only via `blockdev --setro <device>`
`async fn enable_and_verify(blockdev_bin : impl Into <PathBuf>, device : & str, limits : ExecLimits,) -> Result <Observation, WriteBlockerError>`	The forensic entrypoint: set read-only, then verify it actually took effect before citing anything
`fn verify_outcome(device : & str, reported_read_only : bool,) -> Result <Observation, WriteBlockerError>`	The verification decision itself: what a post-set `--getro` reading means

No pub use re-exports: every item above is declared in this crate.

Boundary

Reaches into foundation.

Shares tier infrastructure with 82 other crates: infrastructure-acquire, infrastructure-adapters-google-calendar, infrastructure-adapters-google-gmail, infrastructure-adapters-google-places, infrastructure-adapters-google-trends, infrastructure-adapters-shodan, infrastructure-adapters-yelp, infrastructure-agent, … (82 total).

_What this crate deliberately does NOT own is a judgment. No committed registry records one for it, so none is stated here._

Where it sits

Tier (ontology)	`infrastructure`
Architectural role (taxonomy)	`unclassified (baselined)`
Location	`crates/infrastructure/write-blocker`
Vocabulary in force (lexicon)	`current`

Tier flow. Which tiers this crate's own edges cross.

flowchart LR
  n_infrastructure["infrastructure"] --> n_foundation["foundation"]

Dependencies

Runtime, in this workspace.

Crate	Tier	Optional	Only on
`foundation-bounded-io`	foundation	no	always
`infrastructure-host-forensics`	infrastructure	no	always

Runtime, from outside the workspace.

Crate	Requirement	Features	Optional	Only on
`thiserror`	`^2`	—	no	always

Development, from outside the workspace.

Crate	Requirement	Features	Optional	Only on
`tokio`	`^1`	`full`	no	always

Build. None.

Depended on by. 1 workspace crate.

Signal flow — what reaches this crate, and what it reaches.

flowchart LR
  n_operations_block_imaging["operations-block-imaging"] -->|uses| SELF
  SELF["infrastructure-write-blocker"]
  SELF -->|runtime| n_foundation_bounded_io["foundation-bounded-io"]
  SELF -->|runtime| n_infrastructure_host_forensics["infrastructure-host-forensics"]
  classDef self fill:#1f883d,stroke:#1f883d,color:#fff;
  class SELF self;

Feature flags

No Cargo features are defined: every capability is unconditional, so no consumer can receive a half-wired crate.

Targets

Kind	Name	Source
lib	`infrastructure_write_blocker`	`src/lib.rs`

Error model

Error type	Named by
`WriteBlockerError`	`enable_and_verify`, `get_read_only`, `parse_getro_output`, `set_read_only`, `verify_outcome`

Operational characteristics

Property	Evidence
async public surface	yes
async runtime	none detected
database access	none detected
network I/O	none detected
unsafe code	none detected
environment variables	yes

No unsafe block, unsafe fn, unsafe impl or unsafe trait was found by the parser anywhere in this crate's source.

Configuration

Variable	Read in
`CARGO_MANIFEST_DIR`	`src/lib.rs`

1 workspace crate depends on this one: operations-block-imaging.

Verification

Kind	Count
Unit tests	8
Integration tests	0
Examples	0
Doctests	0

Evidence by module. How often each public module is named by something executable.

Module	Tests	Examples	Consumers
`crate root`	6	0	1

What the tests establish, by name:

a_confirmed_read_only_device_yields_a_citable_observation — src/lib.rs
a_device_the_kernel_still_reports_writable_fails_verification — src/lib.rs
enable_and_verify_fails_loud_when_getro_disagrees — src/lib.rs
enable_and_verify_succeeds_when_getro_confirms_readonly — src/lib.rs
get_read_only_wires_stdout_through_the_parser — src/lib.rs
parse_getro_output_reads_readonly — src/lib.rs
parse_getro_output_reads_writable — src/lib.rs
parse_getro_output_rejects_unexpected_values — src/lib.rs

Documentation coverage

Measure	Documented	Total
Public items with rustdoc	6	6
Public modules with a `//!` block	0	0

pie showData
    title Public items with rustdoc
    "Documented" : 6
    "No rustdoc detected" : 0

Metrics

Metric	Value
Rust source files	1
Source lines	249
Code lines	163
Public API items	6
Public modules	0
Tests	8
Examples	0
Cargo features	0
Direct runtime dependencies	3
Workspace reverse dependencies	1

pie showData
    title Public API by kind
    "enum" : 1
    "function" : 5

pie showData
    title Rust source composition
    "Code" : 163
    "Blank or comment" : 86

Generation

Rendered by tools-corpus corpus readme from repository evidence alone, renderer schema 2, lexicon current. No model, network service or database was consulted. Regenerate with tools-corpus corpus readme --write; verify with --check.