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Matt Van HornandMatt Van Horn 645735fc0f feat(windows): inspect Shell Link (.lnk) shortcut files (#7859 )

* feat(windows): inspect Shell Link (.lnk) shortcut files

Add inspect_windows_shortcut / inspect-windows-shortcut to read one
local Shell Link without resolving or executing the target. The report
keeps header flags and FILETIMEs, IDList items, LinkInfo volume and
network names, StringData, ExtraData including Tracker droid facts
labelled derived, and derived observations such as argument length
and a minimized ShowCommand.

* fix(windows): tighten Shell Link string reads and coverage

- Decode counted StringData over its full CountCharacters payload.
- Locate LinkInfo string terminators before charging max_string_bytes
and before decoding; an unterminated string is a coverage issue.
- Mark an IDList without a TerminalID and an out-of-range
LinkInfoHeaderSize as partial coverage.
- Report arguments_present and argument_length as null when
HasArguments is set but the field could not be read.
- Derive target_extension from the joined base path and suffix.
- Keep ISO dates for FILETIME and UUIDv1 timestamps before 1970.
- Retain the completed file snapshot on parse failures.
- Reject an empty CLI path before normalization.
- Select the shortcut contract from its family in focused tests.
- Fixture StringData no longer writes a NUL into the counted payload.

* style: format docs index and Shell Link boundary type

Apply oxfmt to the two files format:check reports so Static checks passes.

* fix(windows): reject network share paths for Shell Link reads

inspect_windows_shortcut is advertised as offline, but the Windows path
schema admits UNC paths, and lstat on one can contact an SMB server and
offer the caller's credentials.

Reject UNC, extended UNC, and other host-prefixed device paths in the
provider before any filesystem call. Extended drive paths such as
\\?\C:\x stay allowed. A mapped network drive cannot be told from a
local drive by its path, and the docs say so.

* fix(windows): decode Unicode Shell Link file-entry names

File-entry items with bit 0x04 of the type byte, such as 0x36, store a
UTF-16LE name, but the parser always read it as Latin-1. The read stopped
at the first zero byte, so report.exe became r and an IDList-only
shortcut reported the wrong target_extension. Read those names as
UTF-16LE.

* fix(windows): read volume labels by exact Shell Link discriminator

VolumeLabelOffset 0x14 selects VolumeLabelOffsetUnicode and is not itself a
label offset, and that Unicode field exists for no other value. The parser
treated any offset of 0x14 or more as having both, so a Unicode-only label such
as "OS" also produced a false ANSI label "O", and an ANSI label stored past 0x14
had its own bytes read as a Unicode offset.

Branch on the exact value in parseVolume, the one place that interprets it, and
report a VolumeID too short to hold the selected field. The fixture wrote both
encodings for a Unicode volume, which hid the false label, so it now writes one.

* fix(windows): limit network share rejection to Windows hosts

POSIX hosts read repeated leading slashes as one local root, so an
accepted selection such as ///tmp/shortcut.lnk is a local file there.
Apply the host-prefixed path check only on Windows, and take the
platform through the provider constructor so the Windows path forms
stay covered on every test host.

* fix(windows): compare shortcut icons only against full paths

A stored IDList filename or relative path cannot show that an icon at a
full path is elsewhere, so the comparison reported a false difference.
Report null unless the icon and a recorded target are both full paths,
and assert the missing TerminalID issue by code and offset instead of
its message.

* fix(windows): keep unread ExtraData blocks unknown

A walk that stopped before or inside ExtraData still reported the blocks
that HasExpString and HasExpIcon expect as absent, though they were never
checked for. Report a block as absent only after the TerminalBlock shows the
section was read in full. Without one the block stays unknown and coverage
stays partial.

* fix(native): ignore LNK network provider type unless ValidNetType is set

CommonNetworkRelativeLink NetworkProviderType is only meaningful when the
ValidNetType flag (0x2) is set. Return null otherwise.

* fix(native): accept any ExtraData TerminalSize below 4 as the terminal

MS-SHLLINK requires TerminalSize to be less than 4, not exactly 0. Treat
1, 2 and 3 as the terminal block instead of a malformed block.

* fix(native): derive shortcut target facts from the stored environment target

Include the EnvironmentVariableDataBlock literal target among the target
candidates for target_extension and the icon comparison. Variables are not
expanded and the target is not opened.

* fix(windows-shortcut): keep unexpanded variable paths unresolved in icon comparison

A stored environment target such as C:\Users\%USERNAME%\app.exe could be
compared as different from C:\Users\Alice\app.exe. Variable-bearing paths
are never expanded, so the icon comparison now returns null unless a fixed
target matches the icon exactly.

* test: drop redundant ok assertion before typed error guard

The testing guide asks for the typed error to be thrown before asserting a
successful Result value, and says a preceding .ok assertion adds no coverage.

* fix(windows): point out-of-range LinkInfo offsets at their field

A LinkInfo, VolumeID or CommonNetworkRelativeLink offset that points
past its structure was reported at base + offset. With an offset such
as 0xffffffff that position exceeds uint32, so the report failed its
schema and the service discarded the whole partial result.

Report such issues at the offending offset field instead, which keeps
every issue offset and coverage.failing_offset inside the file. Cover
each LinkInfo offset field in the parser tests and the
LocalBasePathOffset case through the stable filesystem service.

* fix(windows): require RFC 4122 variant before deriving Tracker UUID facts

A version nibble of 1 alone does not identify a version-1 UUID. Also require the clock_seq_hi_and_reserved top bits to be 10, so other GUID layouts keep their raw value and derive no MAC or timestamp.

* fix(windows): ignore DeviceNameOffset fields unless ValidDevice is set

MS-SHLLINK 2.3.2 says DeviceNameOffset and DeviceNameOffsetUnicode are
ignored when the ValidDevice flag is clear. parseNetwork read both
regardless, so garbage in those fields became device-name facts or
malformed_structure issues. Read the flags once and only read the device
name fields when ValidDevice is set.

* fix(windows): keep unsupported Tracker headers as raw data

Check TrackerDataBlock Length (0x58) and Version (0) before decoding.
A block with any other header is retained as raw bytes with a
malformed_structure issue, so it no longer yields MAC and timestamp
facts under complete coverage.

* fix(windows): compare shortcut icon paths by normalized location

Collapse "." and ".." segments and repeated separators in the icon
comparison as text only, never opening a path. ".." stops at the drive
or UNC share root, and \\?\ and \\.\ paths stay verbatim.

Join LocalBasePath with CommonPathSuffix as the target and use the bare
base only when the suffix is empty, as the network share branch does.

Read the selected shortcut with lstat and open only, so a rejected
symlink's destination is never resolved.

* fix(windows): keep the UNC share in the root after repeated separators

normalizePath took the host and the next split part as the UNC root, so
\\server\\share\..\app.exe kept an empty share and let .. remove the
real share. Drop empty parts before picking the root so paths on
different shares stay different.

* fix(cli): parse windows shortcut limits as decimals

The four inspect-windows-shortcut limit options now go through
cliDecimalField like the other inspection commands, so values such as
0x10 are rejected and cliDecimalArguments.test.ts passes.

* fix(native): reject linked parents of windows shortcuts

A parent directory symlink or junction pointing at a UNC share was
followed by the first lstat, since the network check reads only the
path text and the symlink rejection covers only the final component.
On Windows, lstat each ancestor from the drive root down and reject
the path at the first link, before anything follows it.

* docs(native): move Windows shortcut guide and add its feature spec

Move the Shell Link guide to docs/guides/native/windows-shortcut.md and
list it under Native binaries in the site navigation, keeping the
/windows-shortcut public route. Update README, translated README, CLI
page and authored skill links to the new physical path.

Add docs/specs/native/windows-shortcut/ with spec.md, plan.md and
tasks.md, as required by docs/development/documentation.md.

* fix(native): admit the windows shortcut parent walk

On Windows the ancestor link walk ran before the provider's resource
admission, so close() could finish while the walk kept calling lstat.
Run the walk inside the same admission as the read, and check the
caller's signal before each ancestor lstat.

* fix(native): walk the effective parents of windows shortcuts

The ancestor link walk checked every prefix of the path as written, so
C:\alias\..\real\a.lnk was refused when C:\alias is a directory link,
although Windows removes alias\.. before opening the file. Walk the
ancestors left after removing . and .. components, keeping the
caller's spelling, never climbing above an absolute root, and leaving
\\?\ paths as written since Windows does not normalize them.

* test(native): assert the linked parent as a structured fact

The parent link regression matched the phrase "junction, which" in the
refusal message, so a wording edit would fail it. Report the linked
ancestor as observed.linked_ancestor on the input issue and assert that
fact instead of the explanatory text.

* test(native): bound the shortcut close gate and release it in finally

Race the parent walk lstat acknowledgement against inspection settling
with awaitAcknowledgement, then release the gate and join the inspect
and close work in finally so a failure reports its cause instead of
waiting for the Vitest timeout.

* fix(native): walk Windows shortcut parents lazily

windowsAncestors built and kept every parent prefix before the first
lstat, so a path with thousands of components allocated memory
quadratic in its length. It now keeps only the normalized components
and yields each parent from a running prefix as the walk reaches it.

---------

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>

2026-11-09 20:19:44 +08:00

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Windows Shell Link shortcut inspection

Problem and outcome

REA has no Shell Link reader. An analyst holding a local .lnk file cannot ask which target, arguments, working directory, icon location, volume or network names, and ExtraData blocks it records without resolving the target, calling COM or using a Windows host. Add one static inspector that reads a selected local file and returns those facts as inline Evidence.

Requirements

Add inspect_windows_shortcut (MCP) and inspect-windows-shortcut (CLI). MCP requires an absolute path; the CLI resolves a relative path against the caller's working directory.
Accept only a regular file. Reject symbolic links, UNC and other host-prefixed device paths before any filesystem call, and on Windows a path whose parent is a symbolic link or junction.
Validate the 76-byte ShellLinkHeader (HeaderSize 0x4C and the Shell Link CLSID) and decode LinkFlags, FileAttributes, FILETIMEs, file size, icon index, ShowCommand and hotkey.
Decode LinkTargetIDList items whose layouts match documented shell-item headers; keep every other item raw with a SHA-256 of its payload.
Decode LinkInfo volume and network names, StringData per LinkFlags, and enumerate every ExtraData block. Unknown signatures stay raw with SHA-256. Tracker version-1 MAC and timestamp values are labelled derived.
Emit only documented-field observations: argument presence and length, target extension, minimized ShowCommand, and whether the icon location differs from a recorded full target path (null when not comparable).
Bound file size, IDList items, ExtraData blocks and retained string bytes, with caller-adjustable limits and documented maximums. Honor cancellation.
Never open, resolve or execute the link target, call COM or contact a network for a local-volume path.

Acceptance

Synthesized fixtures cover a hidden-window PowerShell shortcut with an icon mismatch, network-share LinkInfo, Tracker version 1, ANSI strings, truncated StringData, an unknown ExtraData signature and a wrong CLSID. Malformed headers and exhausted budgets fail without partial success; truncation after a valid header returns partial coverage with coverage.failing_offset, and coverage is never complete when issues are present. CLI and stdio MCP acceptance, MCP advertisement, filesystem symlink, budget and cancellation boundaries, stable-artifact consumers and native acquisition finalization are covered.

Out of scope

Resolving or launching the target, COM IShellLink calls, Windows SDK use, recovering the original system ANSI code page, verdicts about intent, and routing .lnk files through inspect_artifact.

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