## Summary
- add a unit test to ensure the macOS seatbelt policy allows POSIX
semaphores
- add a macOS-only test that runs a Python multiprocessing Lock under
Seatbelt
## Testing
- `cargo test -p codex_core seatbelt_base_policy_allows_ipc_posix_sem
--no-fail-fast` (failed: failed to download from
`https://static.crates.io/crates/tokio-stream/0.1.17/download`)
- `cargo test -p codex_core seatbelt_base_policy_allows_ipc_posix_sem
--no-fail-fast --offline` (failed: attempting to make an HTTP request,
but --offline was specified)
- `cargo test --all-features --no-fail-fast --offline` (failed:
attempting to make an HTTP request, but --offline was specified)
- `just fmt` (failed: command not found: just)
- `just fix` (failed: command not found: just)
Ran tests locally to confirm it passes on master and failed before my
previous change
------
https://chatgpt.com/codex/tasks/task_i_6890f221e0a4833381cfb53e11499bcc
The following test script fails in the codex sandbox:
```
import multiprocessing
from multiprocessing import Lock, Process
def f(lock):
with lock:
print("Lock acquired in child process")
if __name__ == '__main__':
lock = Lock()
p = Process(target=f, args=(lock,))
p.start()
p.join()
```
with
```
Traceback (most recent call last):
File "/Users/david.hao/code/codex/codex-rs/cli/test.py", line 9, in <module>
lock = Lock()
^^^^^^
File "/Users/david.hao/.local/share/uv/python/cpython-3.12.9-macos-aarch64-none/lib/python3.12/multiprocessing/context.py", line 68, in Lock
return Lock(ctx=self.get_context())
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/david.hao/.local/share/uv/python/cpython-3.12.9-macos-aarch64-none/lib/python3.12/multiprocessing/synchronize.py", line 169, in __init__
SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx)
File "/Users/david.hao/.local/share/uv/python/cpython-3.12.9-macos-aarch64-none/lib/python3.12/multiprocessing/synchronize.py", line 57, in __init__
sl = self._semlock = _multiprocessing.SemLock(
^^^^^^^^^^^^^^^^^^^^^^^^^
PermissionError: [Errno 1] Operation not permitted
```
After reading, adding this line to the sandbox configs fixes things -
MacOS multiprocessing appears to use sem_lock(), which opens an IPC
which is considered a disk write even though no file is created. I
interrogated ChatGPT about whether it's okay to loosen, and my
impression after reading is that it is, although would appreciate a
close look
Breadcrumb: You can run `cargo run -- debug seatbelt --full-auto <cmd>`
to test the sandbox
David Z HaoandGitHub