Two P3 hardening items from the review: a descendant that changes its
own process group escapes the deadline's group kill, and could then leak
or block the parent.
- The deadline path now also sends a pid-targeted SIGKILL to the direct
child, so child.wait() is bounded even if the child left the group and
the group kill missed it.
- The normal-exit path drains stdout and stderr non-blocking instead of
read_to_string: the child has exited so its output is already
buffered, but an escaped grandchild holding a write end would keep the
pipe from EOF and hang a blocking read. The drain is capped so a
descendant that keeps writing cannot spin it. first_buffered_line now
shares that drain.
Verified: a probe child whose grandchild setpgid-escapes and holds the
pipe returns in 25 ms instead of hanging, and a direct child that
escapes and blocks is bounded to the deadline instead of its full
sleep.
Mariano Abad
8ec37ed531