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Replace select backends with poll backends.  selscan() and pollscan()
now call the poll backend.  With this change we implement greater
poll(2) functionality instead of emulating it via the select backend.
Adapted from NetBSD and including some changes from FreeBSD.
Tested by many, deraadt@ OK

/*	$OpenBSD: file.h,v 1.23 2003/09/23 16:51:13 millert Exp $	*/
/*	$NetBSD: file.h,v 1.11 1995/03/26 20:24:13 jtc Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	@(#)file.h	8.2 (Berkeley) 8/20/94
 */

#include <sys/fcntl.h>
#include <sys/unistd.h>

#ifdef _KERNEL
#include <sys/queue.h>

struct proc;
struct uio;
struct knote;
struct stat;
struct file;

struct	fileops {
	int	(*fo_read)(struct file *, off_t *, struct uio *,
		    struct ucred *);
	int	(*fo_write)(struct file *, off_t *, struct uio *,
		    struct ucred *);
	int	(*fo_ioctl)(struct file *, u_long, caddr_t,
		    struct proc *);
	int	(*fo_poll)(struct file *, int, struct proc *);
	int	(*fo_kqfilter)(struct file *, struct knote *);
	int	(*fo_stat)(struct file *, struct stat *, struct proc *);
	int	(*fo_close)(struct file *, struct proc *);
};

/*
 * Kernel descriptor table.
 * One entry for each open kernel vnode and socket.
 */
struct file {
	LIST_ENTRY(file) f_list;/* list of active files */
	short	f_flag;		/* see fcntl.h */
#define	DTYPE_VNODE	1	/* file */
#define	DTYPE_SOCKET	2	/* communications endpoint */
#define	DTYPE_PIPE	3	/* pipe */
#define	DTYPE_KQUEUE	4	/* event queue */
#define	DTYPE_CRYPTO	5	/* crypto */
#define	DTYPE_SYSTRACE	6	/* system call tracing */
	short	f_type;		/* descriptor type */
	long	f_count;	/* reference count */
	long	f_msgcount;	/* references from message queue */
	struct	ucred *f_cred;	/* credentials associated with descriptor */
	struct	fileops *f_ops;
	off_t	f_offset;
	void 	*f_data;	/* private data */
	int	f_iflags;	/* internal flags */
	int	f_usecount;	/* number of users (temporary references). */
};

#define FIF_WANTCLOSE		0x01	/* a close is waiting for usecount */
#define FIF_LARVAL		0x02	/* not fully constructed, don't use */

#define FILE_IS_USABLE(fp) \
	(((fp)->f_iflags & (FIF_WANTCLOSE|FIF_LARVAL)) == 0)

#define FREF(fp) do { (fp)->f_usecount++; } while (0)
#define FRELE(fp) do {					\
	--(fp)->f_usecount;					\
	if (((fp)->f_iflags & FIF_WANTCLOSE) != 0)		\
		wakeup(&(fp)->f_usecount);			\
} while (0)

#define FILE_SET_MATURE(fp) do {				\
	(fp)->f_iflags &= ~FIF_LARVAL;				\
	FRELE(fp);						\
} while (0)

LIST_HEAD(filelist, file);
extern struct filelist filehead;	/* head of list of open files */
extern int maxfiles;			/* kernel limit on number of open files */
extern int nfiles;			/* actual number of open files */
extern struct fileops vnops;		/* vnode operations for files */

int     dofileread(struct proc *, int, struct file *, void *, size_t,
            off_t *, register_t *);
int     dofilewrite(struct proc *, int, struct file *, const void *,
            size_t, off_t *, register_t *);

#endif /* _KERNEL */