fix(daemon): keep the socket path under the AF_UNIX limit - #267
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The socket address is <runtime dir>/daemon.sock, but sun_path caps a unix socket at 104 bytes on macOS (108 on Linux) where ordinary files get PATH_MAX. A deep $HOME -- a sandbox, a container, a CI runner -- pushes past it, and bind() fails with "AF_UNIX path too long" surfacing as "Daemon process exited before it became ready", which reads like a broken install rather than a path-length problem. Fall back to a short temp-dir address keyed by a hash of the runtime dir when the natural path is too long, so distinct runtime dirs keep distinct sockets; the uid is in the name because /tmp is shared on Linux. Client and daemon both resolve through daemon_socket_path(), so they agree either way. Found by an eval agent working in a sandbox with a long $HOME; it lost several turns diagnosing the daemon before deducing the COCOINDEX_CODE_RUNTIME_DIR workaround. Note pytest's own tmp_path is ~118 bytes on macOS, so the overflow is not an exotic case. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LksW8LnigLAiFnrgLauW8M
junzh0u
marked this pull request as ready for review
August 5, 2026 04:21
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great fix, thanks @junzh0u ! |
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Summary
The daemon socket lives at
<runtime dir>/daemon.sock, but a unix socket address is capped at 104 bytes on macOS/BSD (108 on Linux) where ordinary files get ~1024. A deep runtime dir — long$HOME, sandbox, container, CI workspace — makesbind()fail withOSError: AF_UNIX path too long, which reaches the user as "Daemon process exited before it became ready" and reads like a broken install. A home directory ~72 bytes deep is enough, since/.cocoindex_code/daemon.sockadds 28.When the natural path is over the limit, fall back to a short temp-dir address named
ccc-<uid>-<hash of runtime dir>.sock— hashed so daemons differing only byCOCOINDEX_CODE_RUNTIME_DIRkeep distinct sockets, uid because/tmpis shared on Linux. Below the limit, nothing changes.Validation
Real output, using the runtime dir from a sandbox that hit this:
Reproduce the original failure on macOS — fails before, starts after:
Worth knowing on review: the limit applies to the string passed to
bind(), not the path after symlink resolution (verified directly — a 102-byte/var/...address binds even though it resolves to 110 under/private). So the check measures the unresolved string.uv run pytest— 298 passed, 3 new (short path unchanged, fallback under the limit, two over-long runtime dirs don't collide)uv run prek run --all-files— passedOperational impact
None — no migration, no config change, no new setting. A daemon already running keeps its socket, since it was under the limit or it would not have started. Windows named pipes are unaffected; that branch only shares the new hash helper.
Independent of #243 (daemon startup races) — different files, different failure mode.
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