inotify queues IN_MOVED_FROM and IN_MOVED_TO of a rename one after the
other. The watcher thread could read the first before the second was
queued and report a rename inside the directory as a move to another
directory (NOTE_WRITE | NOTE_EXTEND instead of NOTE_WRITE), which made
guest_kqueue abort on loaded runners.
The watcher now reads the queue until it is empty and, when a move half
has no partner, calls getdents64 on the directory before reading again:
that takes the directory lock rename holds until both halves are queued.
Cloudberry Kingdom (PPSA23827, #3177) registers its first kevent change
as a file watch: ident 3, EVFILT_VNODE, flags 0x25
(EV_ADD|EV_ENABLE|EV_CLEAR), fflags 0x37
(NOTE_DELETE|WRITE|EXTEND|LINK|RENAME). Palworld's Discord module
(PPSA23126, #2648) imports sceKernelAddFileEvent and
sceKernelDeleteFileEvent, which no library exported.
EVFILT_VNODE watches the host file or directory behind the descriptor
and turns host changes into FreeBSD 11 vnode hints, added whole when
they share a bit with the requested fflags as filt_vfsvnode does
(sys/kern/vfs_subr.c, release/11.0.1 34bd3475): a growing write is
NOTE_WRITE|NOTE_EXTEND, a shrinking truncate or an attribute change
NOTE_ATTRIB, a link count change NOTE_LINK or NOTE_DELETE, a pending
delete NOTE_DELETE, a new path NOTE_RENAME, and in a directory a new,
removed or renamed entry NOTE_WRITE (with NOTE_LINK for a subdirectory,
as vop_mkdir_post/vop_rmdir_post). Windows uses FindFirstChangeNotification
on the parent directory (and the watched directory) and compares handle
snapshots every 50 ms, since a write through an open handle is not
reported until it is flushed or closed (measured); Linux uses inotify.
Closing the descriptor, deleting the event or the queue stops the
watcher.
sceKernelAddFileEvent(eq, fd, watch, udata) and
sceKernelDeleteFileEvent(eq, fd) take the OpenOrbis 0a1aaf9d
(libkernel.h:35,109) and SharpProspero 5dfdb4b0 (KernelEqueue.cs:164,168)
signatures; NIDs cG3t15OK4Ow and UmXngHKB6is confirmed with
tools/nid_names.py. The watch bits are the fflags and the event is added
with EV_CLEAR, which is not confirmed on a title.
Throws: NOTE_REVOKE, NOTE_OPEN, NOTE_CLOSE, NOTE_CLOSE_WRITE, NOTE_READ
and unknown bits, NOTE_EXTEND on a directory on Windows (a move from
another directory cannot be told from a creation) and descriptors that
are not files, directories, pipes or sockets (pipes, sockets and kqueues
fail with EINVAL as in FreeBSD). Recorded in TechnicalDebt.
guest_kqueue adds a vnode watch that sees a write to a temporary file
with Cloudberry's flags, fflags filtering, a re-registration, the sce
pair on an equeue, EINVAL for sockets, pipes and the kqueue itself, the
close of a watched descriptor and a directory watch.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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>
Dean Galvin
Yossi Yadgar
David