Framing acceptances 2, 3, 4, 5, 7 and 8. Evidence collection only: no
tolerance rule, no change to which process is signalled, no disposition
change.
Three distinct failures previously rendered as one string.
**The PTY fallback is now named.** When a PTY's foreground-group lookup
yields no group, the target falls back to the leader — and until now that
rendered "leader-pid", identical to a pipe child that never had a
terminal. `portable-pty::MasterPty::process_group_leader` collapses every
failure into `None` before pmacs can see it, so the errno was gone too.
pmacs now performs the query itself and reports four distinct outcomes:
no master fd, a failed duplicate with its errno, a failed `tcgetpgrp`
with its errno, and a non-positive answer.
Doing that without `unsafe` is the interesting part. `nix::unistd::
tcgetpgrp` needs `AsFd`; `MasterPty` exposes only `Option<RawFd>`; and
every std route between them is `unsafe`, which this crate forbids.
`filedescriptor::OwnedHandle::dup` takes any `AsRawFd` through a safe
blanket impl and returns an owned handle that IS `AsFd`, so a
lifetime-tied view implementing one safe trait is the whole bridge. The
borrow is what makes it sound: the view cannot outlive the master, so the
descriptor cannot close underneath it.
**The report names the signal.** A failed SIGUSR1 and a failed SIGTERM
were the same text. Note this is a reporting gap only — every failed
`kill` returns before the fatal-signal branch, so failed signals are
disposition-identical whatever they are. A separate control pins that the
fatal/non-fatal difference is real for calls that SUCCEED, which is what
gives the first test its meaning.
**`measured_group` is a real observation.** `expected_group` is
`-leader_pid`, and on the spawn-group path the target is `-leader_pid`
too, so the report printed the same number three times and their
agreement was arithmetic rather than evidence. `getpgid` supplies the one
field that can disagree. It establishes no identity — it is read inside
the same read-then-act window, and no portable mechanism closes that for
a group.
Bites, each by an actual revert, all observed to fail:
- collapsing the PTY fallback back into a bare "leader-pid";
- dropping `signal=` from the report;
- making the measured group restate the pid it was handed;
- replacing the job-control fixture with a plain `sleep`, as a positive
control on the divergence fixture itself.
All four exact-string sites were updated individually, never by a blanket
rewrite: a wholesale rewrite of expected strings is how a format
regression hides. `:2501`'s first-call disposition pin is retained and
updated for the new format rather than replaced.
`nix`'s `process` feature is now declared explicitly. It already arrived
transitively — nix's own `signal` feature depends on it — which is stable
but invisible, and a real requirement resting on another feature's
internals is one refactor away from vanishing. `filedescriptor` is
declared directly for the same reason: pmacs now calls its API.
The reap ledger's comment claiming "EPERM cannot happen for our own
children" is corrected. Its bounded-growth policy is unchanged, but the
justification was wrong: the probe targets a group, and owning the
spawned child says nothing about a group unless the child is still a
member — which nothing measures. The handoff records this together with
the limit of the evidence: the occurrence does NOT establish that the
child itself received EPERM.
Levi Neuwirth
b27df705bb