Cloudberry Kingdom (PPSA23827, #3177) calls kqueue right after start-up
and stopped on the throwing declarations merged with #3337; Palworld's
Discord module (PPSA23126, #2648) imports kevent.
kqueue reserves a host null-device descriptor in the file descriptor
space and registers it as an event queue that reports each ready event
once per call and moves level-triggered ones behind the others, as
kqueue_scan does. close and sceKernelClose close the queue and drop the
descriptor's events from every queue, dup2 drops them for the target,
and dup/dup2 of a kqueue throw, so a reused descriptor number is never
read as a stale kqueue.
kevent follows FreeBSD 11 kern_event.c (release/11.0.1 34bd3475):
kqueue_kevent for the changelist (filter 0 skipped, EV_SYSFLAGS
cleared, EV_ERROR receipts with the errno in data, EV_RECEIPT, the
early return when nevents is exhausted), kqueue_register for EV_ADD,
EV_DELETE, EV_ENABLE, EBADF, ENOENT and EINVAL, kqueue_scan for the
timeout (EINVAL for a bad timespec, zero polls, above INT32_MAX waits
forever) and filt_timerattach, filt_usertouch for the timer and user
filters. Read and write events reuse the guest socket poll of
sceKernelAddReadEvent/WriteEvent.
Throws: other filters, EV_DISABLE, EV_DISPATCH, EV_FORCEONESHOT,
NOTE_LOWAT, EV_CLEAR on a socket, read/write events on non-socket
descriptors or another kqueue, changes to an existing timer (11.0 and
11.4 differ), a NOTE_NSECONDS fraction above one second and a negative
nevents. Recorded in TechnicalDebt.
Test guest_kqueue covers creation and close, timers, a user event
triggered from another thread, read and write events on a socket pair,
EV_ERROR receipts, the timeout and the error cases.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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