fix(lab): rewrite raw POSIX path regex without ambiguous alternation

[luvs01]

Summary

RAW_POSIX_PATH_RE in src/lab/events/limits.ts matched path segments with (?:\/|[^/\0\r\n]+)+ — an alternation of two branches that can both consume the same characters inside an unbounded group. On pathological path strings the regex engine repartitions the input combinatorially (ReDoS shape).

The rewrite expresses the same language without the ambiguous alternation: [^/\0\r\n]+(?:\/+[^/\0\r\n]+)*\/* — one or more non-slash characters, then slash-separated groups, then optional trailing slashes. Each character position has exactly one way to be consumed, so matching stays linear.

Verification

• bun test tests/lab/lab-post-merge-hardening.test.ts — 9 pass, including the linear-time pathological-path case.

Checklist

• Base is dev
• Tests updated for the new behavior

Summary by CodeRabbit

• Bug Fixes
  • Path validation now recognizes nonempty path segments separated by one or more slashes and accepts multiple trailing slashes. Malformed filesystem paths, including paths with interior double slashes or tabs, are rejected.
  • Long HTTPS URLs and paths beginning with double slashes remain accepted.
• Tests
  • Added checks for pathological path values and URL handling, including a check that validation completes within one second.

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📝 Walkthrough

Walkthrough

The raw POSIX path pattern now matches nonempty segments separated by slash runs and allows multiple trailing slashes. Tests check rejection of pathological paths and acceptance of a long HTTPS URL and cwd=//.

Changes

Raw Path Validation

Layer / File(s)	Summary
Path pattern and admission tests src/lab/events/limits.ts, tests/lab/lab-post-merge-hardening.test.ts	RAW_POSIX_PATH_RE now matches nonempty segments separated by slash runs and permits multiple trailing slashes. Tests check rejection with raw_path, acceptance of a long HTTPS URL and cwd=//, and completion in under 1,000 ms.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix

Merge Risk: 🔵 Low · up to 6ca8f

The matcher change has no demonstrated runtime defect, but the added cases do not protect its performance improvement from regression. This is a bounded follow-up test gap rather than a merge blocker.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: rewriting the ambiguous RAW_POSIX_PATH_RE for safer POSIX path matching.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
In `@tests/lab/lab-post-merge-hardening.test.ts`:
- Around line 227-249: Update the pathological-path regression test around
enforceEventStructureLimits to use inputs known to trigger catastrophic
backtracking in the pre-change RAW_POSIX_PATH_RE, so the test distinguishes the
old matcher from the fixed one. Add an explicit test timeout that bounds
execution while preserving assertions for raw-path rejection and URL acceptance.

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• src/lab/events/limits.ts
• tests/lab/lab-post-merge-hardening.test.ts

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[lidge-jun]

리뷰 · 우선순위 46 / 80

이 풀리퀘스트는 바탕이 dev예요. 실험 기록 안에 컴퓨터 파일 경로가 들어왔는지 찾는 식을 다시 썼어요.

그 식은 src/lab/events/limits.ts 35행의 RAW_POSIX_PATH_RE예요. 예전 식은 슬래시(/)와 슬래시가 아닌 글자 덩어리를 한 묶음 안에서 번갈아 골랐어요. 코드 검사가 이 모양을 아주 느려질 수 있다고 표시했어요. 새 식은 글자 덩어리를 먼저 한 번 읽고, 그 뒤에 슬래시들 + 글자 덩어리만 반복해요. 끝나는 슬래시는 마지막에 읽어요. 한 칸의 글자를 읽는 방법이 하나예요.

어떤 글을 거절하는지는 그대로예요. 원래 테스트의 /tmp, /tmp/, /tmp//secret, file:로 위장한 경로, https:// 주소는 옛 식과 새 식의 결과가 같아요. 이번 테스트의 긴 줄도 같아요. cwd=/ 뒤에 a/를 2000번 붙이면 4005바이트이고 경로로 거절해요. a//를 1300번 붙이면 3905바이트이고 역시 거절해요. https://example.com/ 뒤에 a/를 2000번 붙이면 4020바이트이고 통과해요. 한 칸 한도는 4096바이트라서, 길이 때문에 먼저 잘리지 않고 경로 검사까지 도착해요. types.ts와 config.ts는 이번 글에 없어요. 이 식만 고치는 다른 열린 글은 없어요.

라인 - tests/lab/lab-post-merge-hardening.test.ts 228–230행 — 주석은 긴 경로에서 예전 식이 느려지고, 그 식이 돌아오면 테스트 시간 초과로 잡힌다고 해요. 여기 있는 두 줄은 예전 식에서도 바로 맞아요. a/ 2000번은 약 0.1밀리초, a// 1300번은 약 0.02밀리초예요. 테스트는 거절인지만 보고 시간은 재지 않아요. 식을 예전으로 되돌려도 이 테스트는 통과해요.

메인테이너의 판단이 필요한 지점

코드 검사가 표시한 모양을 지우는 수정으로 남길지 정해 주세요. 테스트에 넣은 줄만 재면 예전 식도 이미 빨라요. 맞는 읽기를 첫 번에 끝내서, 글자를 다시 나누는 데까지 가지 않아요.

너의 추천

방향은 맞아요. 바탕은 dev예요. 닫을 중복 글은 없어요. 거절과 통과는 예전과 같아요. 이대로 넣어도 돼요.

228행 주석을 사실대로 고치거나, 정말로 오래 걸리는 글을 넣고 1초보다 짧은지 재 주세요. 지금 줄로는 느려지는지 알 수 없어요.

이 댓글은 grok-bot이 작성했습니다

[luvs01]

유지관리자 권고를 반영했습니다 (head: 6ca8f9b).

• 228행 주석 정직성 수정: "예전 식이 이 입력에서 느려져 테스트 시간 초과로 잡힌다"는 미검증 주장을 제거하고, 실제 고정 대상을 명시했습니다 — 각 입력이 4 KiB 필드 상한 아래라 정규식까지 도달하며, 거절/통과 판정 변경은 속도와 무관하게 오류라는 점.
• 실측 타이밍 단언 추가: performance.now()로 rejected+allowed 루프를 감싸 1초 미만을 단언합니다(실측 0.55ms로 여유 있음). 기존 10초 테스트 타임아웃은 유지.

검증: lab-post-merge-hardening 9/9 통과, tsc --noEmit 클린.

[Ingwannu]

Reviewed exact head 6ca8f9b3e7232e918e44c104b797f43035291b9c. The rewritten matcher gives each segment/slash run one structural parse while preserving the old first-character, interior-slash, trailing-slash, URL, and field-size behavior. Focused bounded suite passed 9/9; the adversarial-path group completed in ~0.7 ms under CPUQuota=200%, MemoryMax=4G, swap disabled.