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James Tucker
5a05ac11d5
Bound the server shutdown wait and the output drain after a session process exits. Descendants can keep stdio open after the session process exits, so neither wait can depend on EOF alone. Abort the SSH channel on drain timeout without sending EOF concurrently with an outstanding output write. Close all PTY master descriptors on cancellation and let the terminal driver send SIGHUP. Duplicate the masters with CLOEXEC and O_NONBLOCK before wrapping them with os.NewFile so the runtime poller can interrupt pending I/O on Close. Keep the PTY child's blocking mode intact. Use RawConn.Control for duplication and window changes to synchronize with Close and avoid restoring blocking mode on the original master through File.Fd. Non-PTY sessions receive SIGHUP explicitly. Keep SIGKILL escalation for monitor sessions and add it for directly launched sessions. Use os.Process.Signal on the direct path to synchronize signaling with reaping. Make the escalation delay configurable alongside the shutdown and I/O drain timeouts. Use a process-completion channel to stop the cancellation worker on normal exit, and join the worker before sending exit status so any cancellation message is written before channel teardown. Cover normal completion and cancellation through live monitored SSH sessions. Fixes tailscale/corp#50380 Fixes #22059 Updates #20628 Updates #21827 Signed-off-by: James Tucker <james@tailscale.com> Change-Id: I2a66741ba156a607dc3df70a79e140f19737b7a5