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Refuse sandbox /write and /read of a workspace FIFO without hanging - #329
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open() on a named pipe blocked forever; write_to_workspace holds the per-tenant mutex across that open, so mkfifo stalled every same-tenant /exec and /write until restart. Open O_NONBLOCK and reject non-regular files. Co-authored-by: Tyler Reckart <tylerreckart@users.noreply.github.com>
tylerreckart
marked this pull request as ready for review
September 21, 2026 13:23
…lock # Conflicts: # CHANGELOG.md
tylerreckart
enabled auto-merge (squash)
September 21, 2026 13:23
Keep both Unreleased changelog entries. Co-authored-by: Cursor <cursoragent@cursor.com>
Keep both Unreleased changelog entries. Co-authored-by: Cursor <cursoragent@cursor.com>
Keep both Unreleased changelog entries. Co-authored-by: Cursor <cursoragent@cursor.com>
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Problem
write_to_workspaceandread_from_workspacecalledopen()withoutO_NONBLOCK. A workspace named pipe (mkfifo hang.txt) blocks thatopen()until a peer attaches./writeholds the per-tenant sandbox mutex across the open, so one FIFO stalled every same-tenant/execand/writeuntil process restart./readhung only the requesting turn.Fix
Open with
O_NONBLOCK. Writer-only FIFOs returnENXIO; a successful open of a non-regular file is still rejected by the existingfstat+S_ISREGcheck.Tests
unit_sandbox_quota—/writeand/readof amkfifotarget return an error within 1s (watchdog fails the test ifopen()hangs).Independently mergeable against
main. Touchessandbox.cppwrite/readopen()flags (same file as #325/#326'sread_check_hooknear the read path, different hunks) plus CHANGELOG[Unreleased]. Rebase after whichever sibling merges first.