Act on review findings from CODEREVIEW-2026-06-25-1

[mnsmarko]

A new code review has been opened on branch CODEREVIEW-2026-06-25-1.

• Report: docs/reviews/2026-06/CODEREVIEW-2026-06-25-1.md
• TODO: docs/reviews/2026-06/TODO-CODEREVIEW-2026-06-25-1.md

Please review the findings and either fix, defer (ONHOLD), or reject (WONTFIX) each one. Record ONHOLD/WONTFIX in the report file itself so future reviews honor them — a GitHub comment alone is not enough. Only WONTFIX/ONHOLD findings are suppressed later; anything you leave unmarked will be re-reported by the next review if it's still present in the code.

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Please leave this issue open until you're done

While this issue or its review PR stays open, the scheduler will not open another code review of this repo — so you won't get a second review stacked on top of one you're still working through. To free the repo for its next review you must resolve both:

• Close this issue, and
• Merge or close the review PR — merge it (recommended) to land the report with your WONTFIX/ONHOLD markers on the default branch, the record future runs read to avoid repeating deferred/rejected findings; or close it without merging to abandon this cycle and get a fresh review of newer code (nothing is recorded, so still-present findings come back).

Handover prompt for an AI coding agent (click to expand — paste into Claude Code / Codex in a clone of this repo, with gh authenticated)

You are picking up a completed dual-agent review. There is this open review PR (it contains only the dated report + TODO — no source changes) and a companion issue. Act on the findings, record my defer/reject decisions in the report, then merge the PR and close the issue.

• Report: docs/reviews/2026-06/CODEREVIEW-2026-06-25-1.md
• TODO: docs/reviews/2026-06/TODO-CODEREVIEW-2026-06-25-1.md
• Review branch: CODEREVIEW-2026-06-25-1 · PR base: the default branch

0. Orient. Read the report + TODO on the review branch. Each finding has an ID like 2026-06-03-1-7 and a severity. Check out the base branch and pull latest — the review was a snapshot and code may have moved since.

1. Re-anchor every finding against the CURRENT code (commits may have landed after the review). Report line numbers can be stale — locate each finding now by symbol/content, not by line number. Then: already fixed by a later commit → don't re-fix, leave it unmarked (it just won't be re-reported); no longer applicable → mark WONTFIX with a reason; still live → fix it. Never trust the report's line numbers blindly.

2. Fix the still-live findings via this repo's normal workflow (a fix branch off latest base, or direct commits per convention). Keep code fixes OUT of the review PR branch — it's report-only so it always merges cleanly. Reference the finding ID in commit messages.

3. Record defer/reject decisions IN THE REPORT FILE on the review branch (a GitHub comment is not enough — only the report is read by future runs): WONTFIX to reject, ONHOLD to defer, each with a brief reason. Anything left unmarked and still present will be re-reported next time. Commit + push these edits to the PR branch.

4. Close out with gh — the next review of this type is blocked while either the PR or issue is open, so resolve both:

• gh pr merge <pr> --squash --delete-branch (recommended — lands the report + your markers; it's report-only so it merges into the advanced base. If GitHub says the branch is behind, gh pr update-branch <pr> first.)
• gh issue close <issue> --comment "Fixed: <ids>. Deferred: <ids>. Rejected: <ids>. Already resolved by later commits: <ids>."

Abandoning instead? gh pr close <pr> (no merge) + close the issue — nothing is recorded, markers are lost, still-present findings come back. Only do this deliberately.

Report back: what you fixed, what you marked WONTFIX/ONHOLD (with reasons), what was already resolved by later commits, and the final PR/issue state.

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Findings summary

16 issues found.

Severity	Count
🟡 Medium	5
🟢 Low	11

🟡 Medium

• 2026-06-25-1-1: expand_sockname does not check malloc result before use
• 2026-06-25-1-2: pty_activity drops (or duplicates) live output to a slow/backpressured client
• 2026-06-25-1-3: Scrollback ring can be overwritten while a slow client is mid-replay
• 2026-06-25-1-7: tail -f stops showing output after a log rotation
• 2026-06-25-1-11: Signal handlers call non-async-signal-safe functions

🟢 Low

• 2026-06-25-1-4: Legacy single-dash dispatch only reads the second character; trailing letters are silently ignored
• 2026-06-25-1-5: parse_size can integer-overflow on the k/m multiplier
• 2026-06-25-1-6: Detach character with the high bit set can never match (signedness)
• 2026-06-25-1-8: tail -f never exits when its output pipe is closed
• 2026-06-25-1-9: On-disk log can grow to ~2× the configured cap before rotating
• 2026-06-25-1-10: scrollback_append copies byte-by-byte instead of using memcpy
• 2026-06-25-1-12: Duplicated "write failed" reporting block in write_buf_or_fail and write_packet_or_fail
• 2026-06-25-1-13: "Invalid number of arguments" + "Try --help" block repeated across many command handlers
• 2026-06-25-1-14: Scattered magic-number path buffers risk silent truncation and drift
• 2026-06-25-1-15: config.h defines HAVE_SYS_TIME_H and HAVE_LIBUTIL that are never referenced
• 2026-06-25-1-16: Unreachable return 0 after master_process in master_main

[mnsmarko]

Hi, this is now real person typing :)
I have to say thank you for atch, it's the best thing since invention of LLM I've seen :)

Since I was testing atch and hope to start using it, I ran this code review with our intenal tool for code and security review and thought it might help.

I can also contribute with PRs for applying those fixes if you want.