Control::handle_shutdown() closes m_directory_events (the inotify directory
watch) only in the normal-shutdown branch (!m_shutdownQuick). On a quick
shutdown (SIGTERM -> receive_quick_shutdown) the m_shutdownQuick branch skips
it, so the watch stays registered in the poll. ~Control() then destroys the
still-open directory_events and Event::~Event()'s assert(m_poll_event == nullptr)
(added with the 0.16.13 poll/event rework) aborts:
main -> Control::~Control() -> ~directory_events -> ~Event() -> abort
Close it in Control::cleanup() instead, which runs on every shutdown path after
the session is saved; close() is idempotent, so the normal path that already
closed it in handle_shutdown() is unaffected.
Reproducible: configure a directory.watch.added watch, then SIGTERM the client
-> SIGABRT (core in Event::~Event); SIGINT (normal shutdown) is clean. With this
change SIGTERM exits cleanly too.
Since the 0.16.13 callback/poll rework, an EPOLLERR on stdin (controlling
terminal or pty hangup) reaches Poll::process(), which aborts the whole
client with an internal_error because InputEvent never registered for error
events:
Poll::process() received error event for event not in error: input-fd:0
Register stdin for error events (insert_error) and handle event_error() by
dropping stdin from the poll set with this_thread::poll()->remove_and_close().
rtorrent then keeps running without keyboard input instead of dying.
remove() guards on the fd state (is_open()), mirroring SCgiTask: event_error()
clears the fd after remove_and_close(), and the shutdown path (Control::cleanup)
still calls remove(); without the guard the second remove_and_close() throws
'event not found' via event_mask(). insert()/remove() take the thread poll
implicitly (this_thread::poll()) instead of a Poll* argument.
Inline nlohmann/json for the JSON parsing itself, and handle requests
with the same SCGI interface as XML-RPC.
Based off the work in https://github.com/jesec/rtorrent
Jari Sundell