* feat(flutter): identify Dart snapshot builds by pure APK parsing
Add a flutter-provider family with one operation, identify_flutter_build,
that reads an APK's lib/<abi>/libapp.so and libflutter.so through the
hardened ZIP reader and reports build facts as observations:
- The Dart VM snapshot hash, read 20 bytes after every snapshot magic
(f5f5dcdc). The vm and isolate sections are cross-checked: agreeing
sections collapse to one snapshot_hash, disagreeing sections keep every
candidate with snapshot_hash null and partial coverage.
- Per-ABI library digests and byte sizes, plus the engine library's GNU
build-id note and any labeled 'Dart VM version' or Android clang/LLVM
toolchain strings, verbatim; release builds without a version string
report null rather than a guess.
- The APK is digested before parsing so Evidence binds the observation to
the exact input, and a target with no libapp.so reports not-detected
with complete coverage.
The scanner is streaming with explicit pending-magic and rescan
bookkeeping, so chunk boundaries cannot double-count or drop sections, and
magic-free streams never accumulate. No engine, no external lookups: the
hash-to-SDK mapping stays with external datasets by design.
Verified against Flutter Gallery 2.9.2 (112 MB, three ABIs): every ABI
reports the same agreeing hash 65817c30a78bb44c3dc3771876b6010a from two
sections, per-ABI build-ids, and the clang toolchain line; a plain
aapt2-built APK reports not-detected with complete coverage. Scanner
goldens come from the same libraries. READMEs carry the new 'Flutter apps'
row in every supported language.
* feat(flutter): inspect Dart AOT snapshots through the ELF symbol table
Add inspect_dart_aot to the flutter family: for one ABI's libapp.so it
locates the four _kDart*Snapshot* symbols through the ELF dynamic symbol
table (ELF32 and ELF64 little-endian, bounds-checked reads; a payload
without exported symbols is refused), reports each section's offset and
size, validates data-section headers (magic, kind, length; instructions
sections honestly report nulls for the fields their layout does not
carry), and projects a bounded string pool from the isolate data section:
distinct package: source URIs (the app's dependency inventory), dart: SDK
URIs, and identifier-shaped tokens, each with counts, bounds, and partial
coverage when truncated.
The string pool is labeled as a byte-pattern projection, not deserialized
cluster semantics: typed class and function recovery remains an
SDK-specific parser, which the snapshot hash now unlocks. The ABI is
caller-selected with a deterministic default (arm64-v8a, x86_64, then
first available).
Verified against Flutter Gallery 2.9.2: all four symbols on both ELF64
(arm64-v8a) and ELF32 (armeabi-v7a) images, header validation, hash
agreement with identify_flutter_build, and a 756 package: / 201 dart:
URI pool from the isolate data section; goldens in DartElf.test.ts come
from the same libraries.
* fix(flutter): own snapshots, bound image reads, and preserve cancellation
Mirror the ownership bar the maintainers applied across the merged JEB,
ADB, and Apktool PRs:
- Copy the admitted APK into a provider-owned, read-only snapshot (EXCL
create, chmod 0400) before digesting and parsing; every later read uses
the snapshot, so a concurrently modified original cannot mix into one
observation. The result reports the snapshot's byte size and digest.
- Retain failed snapshot-root cleanup in a provider set and retry it on
close(), throwing an aggregate error when a root is still owned; root
removal is injectable so the retention is testable.
- Allocate the AOT image buffer at exactly the declared library size
before reading (bounded before allocation, not concat-after-stream),
keep the 256 MiB ceiling, and check cancellation between digest and
stream chunks through a captured abort reason.
- Accept APK paths containing spaces (covered by a fixture test) and
escape the ABI pattern's dash for v-mode regex compatibility.
Also add tests for cleanup retention with close retry and for
cancellation before any snapshot root is created.
* docs(flutter): cover the Italian README with the Flutter row
The Italian translation landed between the merged feature PRs; its table
now carries every merged row plus this one, keeping its documentation-link
set identical to README.md.
* fix(flutter): make the ABI pattern portable for v-mode validators
Use a hex-escaped hyphen in the ABI character class, matching the form
the ADB portability fix uses, so clients compiling advertised schemas in
unicodeSets mode accept the inspect_dart_aot input schema.
* refactor(flutter): reuse shared harnesses and deduplicate the vertical
The duplicate-detection gate (jscpd, 2.5% threshold) tipped to 2.51% with
the flutter files added. Reuse the existing machinery instead of repeating
it:
- FlutterBuildAnalysisService delegates to executeProviderOperation, the
shared admission/Evidence composition, instead of restating its body.
- The CLI registers both commands from one table-driven spec.
- Boundary tests use the shared serveCli and assertAdvertisedMcpContracts
harnesses rather than hand-rolled equivalents.
- The provider test consolidates the four payload-shape cases into one
table-driven case; the service test uses one admission table and
distinct phrasings.
Duplicate lines fall from 2.51% to 2.48%, back under the gate.
* fix(flutter): address review findings from real-app verification
CassieFox23 verified the PR against three real F-Droid Flutter apps and
a control app, and found five gaps. All are fixed and re-verified against
cone (info.tangential.cone), one of the tested apps:
- Build-id: the scanner now reads the descriptor length from the note
header instead of assuming 20 bytes, so 8-byte ids from older
toolchains parse; the schema accepts 8-128 hex characters. Verified
against cone's readelf-reported ids on all three ABIs.
- Compiler line: the toolchain capture bound rises from 200 to 500
characters, keeping cone's 262-character clang line verbatim.
- Zero-byte libapp.so: the extraction target is created before streaming,
so an empty entry yields a clean unsupported_target refusal for
inspect_dart_aot and elf_header_valid: false with partial coverage for
identify_flutter_build, instead of a raw ENOENT with code UNKNOWN.
- Truncated library: identify_flutter_build marks fewer than two snapshot
sections as partial coverage with a limitation naming the count, and a
missing ELF magic gets its own limitation.
- Docs: the default ABI preference now matches the code exactly
(arm64-v8a, x86_64, x86, armeabi-v7a, then the rest alphabetically).
Also: every test that read the author's /tmp/opencode goldens now builds
a self-contained synthetic ELF64 image with dynsym, four snapshot
symbols, two snapshot sections, and a string pool, so the suite runs
anywhere; the verify lane now requires a present hex build-id per ABI
instead of accepting null.
* fix(flutter): address the Codex review findings
Eight findings, all applied:
- P1: SnapshotHashScanner keeps candidates in a Set (no quadratic
Array.includes) with a 64-distinct-hash cap, so a hostile payload of
magic+hash records cannot stall the scan or bloat the response.
- P1: projectStringPool stops admitting new distinct entries once each
category reaches twice its projection bound and reports
collectionCapped; allocation and sorting now track the response, not
the payload.
- P2: ZIP reader rejections during entry iteration or entry streaming
map into the typed error algebra (cancellation vs input refusal)
instead of escaping as unhandled exceptions in both operations.
- P2: magic_valid now marks coverage only for the *Data symbols; a
complete four-symbol image with valid data magics reports complete
coverage (the instruction symbols intentionally lack the magic).
- P2: the MCP server closes the Flutter provider during shutdown, so a
retained snapshot root is retried and reported, not leaked.
- P2: LabeledStringScanner commits matches only when a printable run is
delimiter-terminated; the carry grows to 600 bytes so a 500-character
toolchain line survives any chunk boundary untruncated.
- P2: both Flutter tool effects declare writesFilesystem: true; the
owned APK snapshot and extracted libapp.so are temporary writes.
- P2: the verify lane asserts every ABI agrees on exactly one snapshot
hash instead of discarding the computed set.
* fix(flutter): address the second Codex review round
Nine findings on the first-round fixes:
- P1: identify_flutter_build enforces a cumulative extraction budget
(768 MiB) across every library entry, not just per library, so an APK
with many ABIs cannot stream an unbounded total.
- P1: a single NUL-free printable run stops materializing at 1024 bytes
and marks the pool capped, so an adversarial one-run section cannot
allocate unbounded strings.
- P1: ELF cString bounds the NUL-terminator scan to the name maximum
plus one, so malformed symbol tables cannot scan the whole image per
entry.
- P2: mapReaderFailure distinguishes ArtifactReaderFailure texts —
budget/limit rejections map to resource constraints, integrity
failures (CRC/overlap/signature) to their own input refusal — instead
of collapsing all reader failures into one message.
- P2: the labeled-string carry is cleared when a delimiter commits a
run, so consecutive toolchain lines are never concatenated.
- P2: string-pool counts are renamed *_count_at_least and documented as
lower bounds, because capped collection discards values beyond twice
the projection bound.
- P2: inspect_dart_aot marks hash disagreements, non-pair source counts,
and candidate-cap saturation as partial coverage.
- P2: only valid lowercase-hex hash records count as snapshot sources;
complete magic records with non-hex fields do not inflate agreement.
- P2: the per-entry size refusal in inspect_dart_aot moves after ABI
selection, so an oversized unselected ABI no longer refuses a small
request.
* fix(flutter): address the third Codex review round
Five findings:
- P2: the owned snapshot revalidates the source after the copy (size,
mtime, inode), so an in-place replacement or swap mid-copy refuses
the observation instead of publishing mixed bytes.
- P2: a failed ZipArtifactReader close retains the snapshot root for
close() retry instead of silently swallowing the descriptor leak,
in both operations.
- P2: snapshot headers are parsed within their symbol bounds and a
symbol smaller than the 16-byte header reports magic_valid false,
so trailing-image bytes can no longer fake a valid data section.
- P2: the verify lane counts provider.close() cleanup failures as
lane failures instead of certifying a run with retained roots.
- P2: LabeledStringScanner reports toolchain_capped when further
distinct matching lines are observed past the 4-line projection;
identify marks such results partial with a naming limitation.
* fix(flutter): address rounds three and four of the Codex review
Round three (one missed finding) plus round four (five findings):
- P2: the GNU build-id note descriptor size is decoded from all four
bytes of the little-endian field, rejecting nonzero high bytes
instead of masking them to 16 bits.
- P1: the Flutter MCP handlers route through createContractToolHandler
and the session's analysisAdmission, so close_binary and snapshot
operations drain in-flight Flutter calls instead of racing them.
- P2: the owned-snapshot copy is a streamed, abort-checked write (no
copyFile), so cancellation stops the write promptly while the
source-identity revalidation (size, mtime, inode) still guards
against mid-copy replacement.
- P2: identify marks any snapshot_hash_sources value other than exactly
two as partial, matching the inspection path's pair requirement.
- P2: the verify lane refuses to run without --apk (exit 2) instead of
printing a false-green pass, and the engine check requires every
libapp-carrying ABI to have a present libflutter with a valid hex
build-id rather than filtering missing engines away vacuously.
* fix(flutter): address the fifth Codex review round
Six findings plus the upstream duplication baseline:
- P2: the flutter-provider kind reports available in the capability
inventory, so binary_session no longer lists always-registered
Flutter tools as provider_missing.
- P2: printable runs that exceed the 1024-byte cap are discarded at
their delimiter instead of emitting their truncated prefix as a
fabricated observation.
- P2: ELF symbols must fit inside the file-backed portion of their
PT_LOAD segment (p_filesz), so addresses in gaps or BSS are refused
instead of accepting unrelated bytes.
- P2: the build-id carry spans the complete 80-byte maximum note
(16-byte header + 64-byte descriptor) so chunk-boundary splits
cannot drop the first byte.
- P2: the labeled-string carry is sized for the toolchain pattern's
true 605-byte maximum, not the previous 600.
- P2: the AOT completeness predicate requires exactly two sources and
one candidate unconditionally, so zero-source images with valid data
magics report partial instead of complete.
Also: the shared ELF fixture builder and snapshot-section helper moved
to a dedicated FlutterTestFixtures module, eliminating cross-file test
duplication; jscpd now passes at 2.50% while main sits at 2.52%.
* fix(flutter): address the sixth Codex review round
Five findings:
- P2: snapshot-hash scanning is bounded to the exported data symbols'
byte ranges, so decoy or stale magic/hash sequences elsewhere in the
image cannot inflate source counts or contribute candidates.
- P2: labeled-string runs longer than the carry bound are rejected
instead of truncated, preventing a regex prefix from being published
as a verbatim source string.
- P2: the AOT image reread checks cancellation between file reads and
before the synchronous parsing stage, so a cancelled caller cannot
receive a success from a completed 256 MiB read.
- P2: the verify lane requires exactly two snapshot sources per ABI,
matching the provider's pair requirement, instead of accepting any
count >= 2.
- P2: ELF section and program header entry sizes are validated against
the class-defined minimum widths before walking either table, so
undersized entries cannot cause field reads to cross into
neighboring bytes.
* fix(flutter): address the seventh Codex review round
Six findings:
- P2: data-symbol ranges are deduplicated by offset and size, so aliased
symbols mapping to the same bytes are scanned once and the result
marks partial coverage with a limitation naming the shared range.
- P2: openEntrySafely forwards return/throw to the underlying Readable's
iterator, so an early for-await exit closes the ZIP entry stream and
releases its producer instead of leaking a backpressured pipe.
- P2: inspect_dart_aot now reports snapshot_hash_candidates and
snapshot_hash_sources alongside snapshot_hash, so a null hash from
conflicting evidence is distinguishable from missing hash data.
- P2: overlong printable runs only set toolchain_capped when they begin
with a recognized label prefix (Dart VM version: or Android (); other
long strings such as license text are skipped without marking partial.
- P2: readElfSymbol falls back to PT_DYNAMIC/DT_SYMTAB when section
headers are absent (e_shnum 0, ET_DYN), so stripped Flutter libraries
with exported snapshot symbols are no longer refused; the dynamic
table is bounded by DT_STRSZ, DT_SYMENT, and the image end.
- P2: the verify lane exercises inspect_dart_aot for every ABI carrying
libapp.so, not just the preferred default.
* fix(flutter): address the eighth Codex review round
Five findings:
- P2: each data-symbol range gets a fresh SnapshotHashScanner so the
carry from one noncontiguous slice cannot fabricate a record spanning
into the next; results are aggregated after scanning.
- P2: dynsym name lookups are bounded to the linked string table —
st_name offsets outside the table and terminators beyond it are
rejected instead of reading unrelated payload bytes as symbol names,
in both the section-header and PT_DYNAMIC paths.
- P2: identify_flutter_build routes its reader.entries and reader.open
calls through the same collectEntriesSafely and openEntrySafely
wrappers as inspect_dart_aot, so malformed ZIPs surface as input
refusals instead of AnalysisProtocolError.
- P2: mapReaderFailure recognizes ArtifactReaderFailure texts carrying
a cancelled reason, mapping them to AnalysisCancelledError instead
of AnalysisInputError.
- P2: the cumulative extraction cap is enforced inside the chunk loop,
not after each library completes, so refusal happens before the
remaining bytes are streamed and hashed.
* fix(flutter): harden streaming, sizes, and cancellation after self-review
Four issues found in a systematic self-audit across all bug classes
from eight Codex rounds:
- createReadStream in both the digest function and the owned-snapshot
copy now receives the AbortSignal directly, so cancellation aborts
the filesystem read at the source instead of waiting for the next
chunk to arrive on a slow filesystem.
- The owned snapshot enforces a 2 GiB APK-level size cap before any
copy I/O, so a path pointing at an enormous file is refused before
disk usage grows.
- identify_flutter_build preflights the sum of declared entry sizes
against the 768 MiB cumulative budget, refusing before any ZIP
extraction when the declared total already exceeds it.
- The LabeledStringScanner triple result() call is collapsed to a
single invocation (the previous code called result() three times in
the emission, relying on end() being idempotent).
No behavior change for valid inputs; all 36 tests, check:fast, and
the cone verify lane pass unchanged.
* fix(flutter): require structurally parseable ELF headers for complete coverage
CassieFox23's third corrupt-header case: an ELF with valid magic but
zeroed section/program header offsets passes the 4-byte magic check
and the byte scanner still finds hash patterns in the data sections,
so identify_flutter_build reports complete coverage for a structurally
broken file.
The elf_header_valid check now also verifies beyond the magic:
e_type must be a known value (ET_REL/ET_EXEC/ET_DYN), at least one
of e_shoff/e_phoff must be non-zero, and at least one of
e_shnum/e_phnum must be non-zero. A file with valid magic but zeroed
structure reports partial coverage with the existing ELF-magic
limitation.
* fix(flutter): validate ELF and snapshot coverage
Share bounded ELF header parsing between identification and inspection. Accumulate headers across ZIP chunks and validate table entry widths and extents before claiming complete identification coverage.
Bind AOT hashes to the exported VM and isolate headers, validate stored snapshot lengths including the magic bytes, and preserve partial evidence for missing, malformed, aliased, or overlapping data headers.
Preserve native stream cancellations and APK resource constraints across both operations. Bound snapshot copies while streaming and retain useful input-failure diagnostics and lower-bound count wording.
Validation: 72 focused tests; check:fast; check including formatting; docs:check; test discovery; jscpd; real cone APK and non-Flutter control on Linux. Verified CLI/MCP parity for valid and corrupted ELF headers and AOT inspection across three ABIs. Native Windows and macOS were not run.
* fix(flutter): unify artifact ownership and bound ELF evidence
* fix(flutter): preserve ELF provenance and partial coverage
Read GNU build IDs only from bounded ELF note ranges and retain conflicting candidates. Preserve source versus owned storage failures and honor cancellation through parsing and final cleanup.
Separate snapshot structure from string-pool coverage. Verify every Gallery ABI with digest-bound engine labels and URI counts, and document the supported snapshot-kind layout.
---------
Co-authored-by: REA Contributor <contributor@rea.tools>
Co-authored-by: morluto <76467478+morluto@users.noreply.github.com>
Quentin Limo