/*	$NetBSD: event.h,v 1.55 2023/07/28 18:19:01 christos Exp $	*/

/*-
 * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	$FreeBSD: src/sys/sys/event.h,v 1.12 2001/02/24 01:44:03 jlemon Exp $
 */

#ifndef _SYS_EVENT_H_
#define	_SYS_EVENT_H_

#include <sys/featuretest.h>
#include <sys/types.h>			/* for size_t */
#include <sys/inttypes.h>		/* for uintptr_t */
#include <sys/null.h>			/* for NULL */

#define	EVFILT_READ		0U
#define	EVFILT_WRITE		1U
#define	EVFILT_AIO		2U	/* attached to aio requests */
#define	EVFILT_VNODE		3U	/* attached to vnodes */
#define	EVFILT_PROC		4U	/* attached to struct proc */
#define	EVFILT_SIGNAL		5U	/* attached to struct proc */
#define	EVFILT_TIMER		6U	/* arbitrary timer (in ms) */
#define	EVFILT_FS		7U	/* filesystem events */
#define	EVFILT_USER		8U	/* user events */
#define	EVFILT_EMPTY		9U
#define	EVFILT_SYSCOUNT		10U	/* number of filters */

#ifdef EVFILT_NAMES
static const char *evfiltnames[] = {
	"EVFILT_READ",
	"EVFILT_WRITE",
	"EVFILT_AIO",
	"EVFILT_VNODE",
	"EVFILT_PROC",
	"EVFILT_SIGNAL",
	"EVFILT_TIMER",
	"EVFILT_FS",
	"EVFILT_USER",
	"EVFILT_EMPTY",
};
#endif

struct kevent {
	uintptr_t	ident;		/* identifier for this event */
	uint32_t	filter;		/* filter for event */
	uint32_t	flags;		/* action flags for kqueue */
	uint32_t	fflags;		/* filter flag value */
	int64_t		data;		/* filter data value */
	void		*udata;		/* opaque user data identifier */
	uint64_t	ext[4];		/* extensions */
};

static __inline void
_EV_SET(struct kevent *_kevp, uintptr_t _ident, uint32_t _filter,
    uint32_t _flags, uint32_t _fflags, int64_t _data, void *_udata)
{
	_kevp->ident = _ident;
	_kevp->filter = _filter;
	_kevp->flags = _flags;
	_kevp->fflags = _fflags;
	_kevp->data = _data;
	_kevp->udata = _udata;
}

#define EV_SET(kevp, ident, filter, flags, fflags, data, udata)	\
    _EV_SET((kevp), __CAST(uintptr_t, (ident)), (filter), (flags), \
    (fflags), (data), __CAST(void *, (udata)))

/* actions */
#define	EV_ADD		0x0001U		/* add event to kq (implies ENABLE) */
#define	EV_DELETE	0x0002U		/* delete event from kq */
#define	EV_ENABLE	0x0004U		/* enable event */
#define	EV_DISABLE	0x0008U		/* disable event (not reported) */

/* flags */
#define	EV_ONESHOT	0x0010U		/* only report one occurrence */
#define	EV_CLEAR	0x0020U		/* clear event state after reporting */
#define EV_RECEIPT	0x0040U		/* force EV_ERROR on success, data=0 */
#define EV_DISPATCH	0x0080U		/* disable event after reporting */

#define	EV_SYSFLAGS	0xF000U		/* reserved by system */
#define	EV_FLAG1	0x2000U		/* filter-specific flag */

/* returned values */
#define	EV_EOF		0x8000U		/* EOF detected */
#define	EV_ERROR	0x4000U		/* error, data contains errno */

/*
 * data/hint flags/masks for EVFILT_USER, shared with userspace
 *
 * On input, the top two bits of fflags specifies how the lower twenty four
 * bits should be applied to the stored value of fflags.
 *
 * On output, the top two bits will always be set to NOTE_FFNOP and the
 * remaining twenty four bits will contain the stored fflags value.
 */
#define	NOTE_FFNOP	0x00000000U		/* ignore input fflags */
#define	NOTE_FFAND	0x40000000U		/* AND fflags */
#define	NOTE_FFOR	0x80000000U		/* OR fflags */
#define	NOTE_FFCOPY	0xc0000000U		/* copy fflags */

#define	NOTE_FFCTRLMASK	0xc0000000U		/* masks for operations */
#define	NOTE_FFLAGSMASK	0x00ffffffU

#define	NOTE_TRIGGER	0x01000000U		/* Cause the event to be
						   triggered for output. */
/*
 * hint flag for in-kernel use - must not equal any existing note
 */
#ifdef _KERNEL
#define NOTE_SUBMIT	0x01000000U		/* initial knote submission */
#endif
/*
 * data/hint flags for EVFILT_{READ|WRITE}, shared with userspace
 */
#define	NOTE_LOWAT	0x0001U			/* low water mark */

/*
 * data/hint flags for EVFILT_VNODE, shared with userspace
 */
#define	NOTE_DELETE	0x0001U			/* vnode was removed */
#define	NOTE_WRITE	0x0002U			/* data contents changed */
#define	NOTE_EXTEND	0x0004U			/* size increased */
#define	NOTE_ATTRIB	0x0008U			/* attributes changed */
#define	NOTE_LINK	0x0010U			/* link count changed */
#define	NOTE_RENAME	0x0020U			/* vnode was renamed */
#define	NOTE_REVOKE	0x0040U			/* vnode access was revoked */
#define	NOTE_OPEN	0x0080U			/* vnode was opened */
#define	NOTE_CLOSE	0x0100U			/* file closed (no FWRITE) */
#define	NOTE_CLOSE_WRITE 0x0200U		/* file closed (FWRITE) */
#define	NOTE_READ	0x0400U			/* file was read */

/*
 * data/hint flags for EVFILT_PROC, shared with userspace
 */
#define	NOTE_EXIT	0x80000000U		/* process exited */
#define	NOTE_FORK	0x40000000U		/* process forked */
#define	NOTE_EXEC	0x20000000U		/* process exec'd */
#define	NOTE_PCTRLMASK	0xf0000000U		/* mask for hint bits */
#define	NOTE_PDATAMASK	0x000fffffU		/* mask for pid */

/* additional flags for EVFILT_PROC */
#define	NOTE_TRACK	0x00000001U		/* follow across forks */
#define	NOTE_TRACKERR	0x00000002U		/* could not track child */
#define	NOTE_CHILD	0x00000004U		/* am a child process */

/* additional flags for EVFILT_TIMER */
#define	NOTE_MSECONDS	0x00000000U		/* data is milliseconds */
#define	NOTE_SECONDS	0x00000001U		/* data is seconds */
#define	NOTE_USECONDS	0x00000002U		/* data is microseconds */
#define	NOTE_NSECONDS	0x00000003U		/* data is nanoseconds */
#define	NOTE_ABSTIME	0x00000010U		/* timeout is absolute */
#ifdef _KERNEL
#define	NOTE_TIMER_UNITMASK 0x0003U
#endif /* _KERNEL */

/*
 * This is currently visible to userland to work around broken
 * programs which pull in <sys/proc.h> or <sys/select.h>.
 */
#include <sys/queue.h>
struct knote;
SLIST_HEAD(klist, knote);


/*
 * ioctl(2)s supported on kqueue descriptors.
 */
#include <sys/ioctl.h>

struct kfilter_mapping {
	char		*name;		/* name to lookup or return */
	size_t		len;		/* length of name */
	uint32_t	filter;		/* filter to lookup or return */
};

/* map filter to name (max size len) */
#define KFILTER_BYFILTER	_IOWR('k', 0, struct kfilter_mapping)
/* map name to filter (len ignored) */
#define KFILTER_BYNAME		_IOWR('k', 1, struct kfilter_mapping)

#ifdef _KERNEL

#define	KNOTE(list, hint)	if (!SLIST_EMPTY(list)) knote(list, hint)

/*
 * Flag indicating hint is a signal.  Used by EVFILT_SIGNAL, and also
 * shared by EVFILT_PROC  (all knotes attached to p->p_klist)
 */
#define	NOTE_SIGNAL	0x08000000U

/*
 * Hint values for the optional f_touch event filter.  If f_touch is not set
 * to NULL and f_isfd is zero the f_touch filter will be called with the type
 * argument set to EVENT_REGISTER during a kevent() system call.  It is also
 * called under the same conditions with the type argument set to EVENT_PROCESS
 * when the event has been triggered.
 */
#define	EVENT_REGISTER	1
#define	EVENT_PROCESS	2

/*
 * Callback methods for each filter type.
 */
struct filterops {
	int	f_flags;		/* flags; see below */
	int	(*f_attach)	(struct knote *);
					/* called when knote is ADDed */
	void	(*f_detach)	(struct knote *);
					/* called when knote is DELETEd */
	int	(*f_event)	(struct knote *, long);
					/* called when event is triggered */
	int	(*f_touch)	(struct knote *, struct kevent *, long);
};

/* filterops flags */
#define	FILTEROP_ISFD	__BIT(0)	/* ident == file descriptor */
#define	FILTEROP_MPSAFE	__BIT(1)	/* does not require KERNEL_LOCK */

/*
 * Field locking:
 *
 * f	kn_kq->kq_fdp->fd_lock
 * q	kn_kq->kq_lock
 * o	object mutex (e.g. device driver or vnode interlock)
 */
struct kfilter;

struct knote {
	SLIST_ENTRY(knote)	kn_link;	/* f: for fd */
	SLIST_ENTRY(knote)	kn_selnext;	/* o: for struct selinfo */
	TAILQ_ENTRY(knote)	kn_tqe;		/* q: for struct kqueue */
	struct kqueue		*kn_kq;		/* q: which queue we are on */
	struct kevent		kn_kevent;	/* (see below for locking) */
	uint32_t		kn_status;	/* q: flags below */
	uint32_t		kn_sfflags;	/*    saved filter flags */
	uintptr_t		kn_sdata;	/*    saved data field */
	void			*kn_obj;	/*    monitored obj */
	const struct filterops	*kn_fop;
	struct kfilter		*kn_kfilter;
	void 			*kn_hook;
	int			kn_hookid;

#define	KN_ACTIVE	0x01U			/* event has been triggered */
#define	KN_QUEUED	0x02U			/* event is on queue */
#define	KN_DISABLED	0x04U			/* event is disabled */
#define	KN_DETACHED	0x08U			/* knote is detached */
#define	KN_MARKER	0x10U			/* is a marker */
#define	KN_BUSY		0x20U			/* is being scanned */
#define	KN_WILLDETACH	0x40U			/* being detached imminently */
/* Toggling KN_BUSY also requires kn_kq->kq_fdp->fd_lock. */
#define __KN_FLAG_BITS \
    "\20" \
    "\1ACTIVE" \
    "\2QUEUED" \
    "\3DISABLED" \
    "\4DETACHED" \
    "\5MARKER" \
    "\6BUSY" \
    "\7WILLDETACH"


/*
 * The only time knote::kn_flags can be modified without synchronization
 * is during filter attach, because the knote has not yet been published.
 * This is usually to set EV_CLEAR or EV_ONESHOT as mandatory flags for
 * that filter.
 */
#define	kn_id		kn_kevent.ident
#define	kn_filter	kn_kevent.filter
#define	kn_flags	kn_kevent.flags		/* q */
#define	kn_fflags	kn_kevent.fflags	/* o */
#define	kn_data		kn_kevent.data		/* o */
};

#include <sys/systm.h>	/* for copyin_t */

struct lwp;
struct timespec;

void	kqueue_init(void);
void	knote(struct klist *, long);
void	knote_fdclose(int);
void	knote_set_eof(struct knote *, uint32_t);
void	knote_clear_eof(struct knote *);

typedef	int (*kevent_fetch_changes_t)(void *, const struct kevent *,
    struct kevent *, size_t, int);
typedef	int (*kevent_put_events_t)(void *, struct kevent *, struct kevent *,
    size_t, int);

struct kevent_ops {
	void *keo_private;
	copyin_t keo_fetch_timeout;
	kevent_fetch_changes_t keo_fetch_changes;
	kevent_put_events_t keo_put_events;
};


int	kevent_fetch_changes(void *, const struct kevent *, struct kevent *,
    size_t, int);
int 	kevent_put_events(void *, struct kevent *, struct kevent *, size_t,
    int);
int	kevent1(register_t *, int, const struct kevent *,
    size_t, struct kevent *, size_t, const struct timespec *,
    const struct kevent_ops *);

int	kfilter_register(const char *, const struct filterops *, int *);
int	kfilter_unregister(const char *);

int	filt_seltrue(struct knote *, long);
extern const struct filterops seltrue_filtops;

void	klist_init(struct klist *);
void	klist_fini(struct klist *);
void	klist_insert(struct klist *, struct knote *);
bool	klist_remove(struct klist *, struct knote *);

#else 	/* !_KERNEL */

#include <sys/cdefs.h>
struct timespec;

__BEGIN_DECLS
#if defined(_NETBSD_SOURCE)
int	kqueue(void);
int	kqueue1(int);
#ifndef __LIBC12_SOURCE__
int	kevent(int, const struct kevent *, size_t, struct kevent *, size_t,
		    const struct timespec *) __RENAME(__kevent100);
#endif
#endif /* !_POSIX_C_SOURCE */
__END_DECLS

#endif /* !_KERNEL */

#endif /* !_SYS_EVENT_H_ */