Adds scanGitAttributes(repoDir) — pure function that parses
.gitattributes after a sandboxed clone and returns the
{filter,diff,merge} driver entries that would run on checkout. The
clone CLI prints each entry as a "MEDIUM" stderr advisory followed by
a recommendation to verify the smudge/clean command before moving the
clone outside the sandbox.
Why: filter drivers execute arbitrary shell during checkout (smudge
runs on read, clean on write). Even with the existing sandboxed clone,
downstream consumers that re-checkout files outside the sandbox can be
exploited. Surfacing the directive list lets the caller decide whether
to proceed.
Out-of-scope: in-line content of the smudge command is not analysed —
the advisory is for human review, not automatic blocking.
Tests:
- tests/lib/git-clone-gitattributes.test.mjs (8 cases): LFS-style,
custom driver, missing/empty/comment-only files, line-number
tracking, inline-comment stripping, unreadable path graceful return.
