xref: /freebsd-11-stable/sys/kern/kern_descrip.c

/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 *
 *	@(#)kern_descrip.c	8.6 (Berkeley) 4/19/94
 * $FreeBSD: head/sys/kern/kern_descrip.c 52955 1999-11-07 05:58:38Z green $
 */

#include "opt_compat.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/conf.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/socketvar.h>
#include <sys/stat.h>
#include <sys/filio.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/unistd.h>
#include <sys/resourcevar.h>
#include <sys/pipe.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>

static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
MALLOC_DEFINE(M_FILE, "file", "Open file structure");
static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");


static	 d_open_t  fdopen;
#define NUMFDESC 64

#define CDEV_MAJOR 22
static struct cdevsw fildesc_cdevsw = {
	/* open */	fdopen,
	/* close */	noclose,
	/* read */	noread,
	/* write */	nowrite,
	/* ioctl */	noioctl,
	/* poll */	nopoll,
	/* mmap */	nommap,
	/* strategy */	nostrategy,
	/* name */	"FD",
	/* maj */	CDEV_MAJOR,
	/* dump */	nodump,
	/* psize */	nopsize,
	/* flags */	0,
	/* bmaj */	-1
};

static int finishdup __P((struct filedesc *fdp, int old, int new, register_t *retval));
static int badfo_readwrite __P((struct file *fp, struct uio *uio,
    struct ucred *cred, int flags, struct proc *p));
static int badfo_ioctl __P((struct file *fp, u_long com, caddr_t data,
    struct proc *p));
static int badfo_poll __P((struct file *fp, int events,
    struct ucred *cred, struct proc *p));
static int badfo_close __P((struct file *fp, struct proc *p));
/*
 * Descriptor management.
 */
struct filelist filehead;	/* head of list of open files */
int nfiles;			/* actual number of open files */
extern int cmask;

/*
 * System calls on descriptors.
 */
#ifndef _SYS_SYSPROTO_H_
struct getdtablesize_args {
	int	dummy;
};
#endif
/* ARGSUSED */
int
getdtablesize(p, uap)
	struct proc *p;
	struct getdtablesize_args *uap;
{

	p->p_retval[0] =
	    min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
	return (0);
}

/*
 * Duplicate a file descriptor to a particular value.
 */
#ifndef _SYS_SYSPROTO_H_
struct dup2_args {
	u_int	from;
	u_int	to;
};
#endif
/* ARGSUSED */
int
dup2(p, uap)
	struct proc *p;
	struct dup2_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register u_int old = uap->from, new = uap->to;
	int i, error;

	if (old >= fdp->fd_nfiles ||
	    fdp->fd_ofiles[old] == NULL ||
	    new >= p->p_rlimit[RLIMIT_NOFILE].rlim_cur ||
	    new >= maxfilesperproc)
		return (EBADF);
	if (old == new) {
		p->p_retval[0] = new;
		return (0);
	}
	if (new >= fdp->fd_nfiles) {
		if ((error = fdalloc(p, new, &i)))
			return (error);
		if (new != i)
			panic("dup2: fdalloc");
	} else if (fdp->fd_ofiles[new]) {
		if (fdp->fd_ofileflags[new] & UF_MAPPED)
			(void) munmapfd(p, new);
		/*
		 * dup2() must succeed even if the close has an error.
		 */
		(void) closef(fdp->fd_ofiles[new], p);
	}
	return (finishdup(fdp, (int)old, (int)new, p->p_retval));
}

/*
 * Duplicate a file descriptor.
 */
#ifndef _SYS_SYSPROTO_H_
struct dup_args {
	u_int	fd;
};
#endif
/* ARGSUSED */
int
dup(p, uap)
	struct proc *p;
	struct dup_args *uap;
{
	register struct filedesc *fdp;
	u_int old;
	int new, error;

	old = uap->fd;

#if 0
	/*
	 * XXX Compatibility
	 */
	if (old &~ 077) { uap->fd &= 077; return (dup2(p, uap, p->p_retval)); }
#endif

	fdp = p->p_fd;
	if (old >= fdp->fd_nfiles || fdp->fd_ofiles[old] == NULL)
		return (EBADF);
	if ((error = fdalloc(p, 0, &new)))
		return (error);
	return (finishdup(fdp, (int)old, new, p->p_retval));
}

/*
 * The file control system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct fcntl_args {
	int	fd;
	int	cmd;
	long	arg;
};
#endif
/* ARGSUSED */
int
fcntl(p, uap)
	struct proc *p;
	register struct fcntl_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	register char *pop;
	struct vnode *vp;
	int i, tmp, error, flg = F_POSIX;
	struct flock fl;
	u_int newmin;

	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
		return (EBADF);
	pop = &fdp->fd_ofileflags[uap->fd];
	switch (uap->cmd) {

	case F_DUPFD:
		newmin = uap->arg;
		if (newmin >= p->p_rlimit[RLIMIT_NOFILE].rlim_cur ||
		    newmin >= maxfilesperproc)
			return (EINVAL);
		if ((error = fdalloc(p, newmin, &i)))
			return (error);
		return (finishdup(fdp, uap->fd, i, p->p_retval));

	case F_GETFD:
		p->p_retval[0] = *pop & 1;
		return (0);

	case F_SETFD:
		*pop = (*pop &~ 1) | (uap->arg & 1);
		return (0);

	case F_GETFL:
		p->p_retval[0] = OFLAGS(fp->f_flag);
		return (0);

	case F_SETFL:
		fp->f_flag &= ~FCNTLFLAGS;
		fp->f_flag |= FFLAGS(uap->arg & ~O_ACCMODE) & FCNTLFLAGS;
		tmp = fp->f_flag & FNONBLOCK;
		error = fo_ioctl(fp, FIONBIO, (caddr_t)&tmp, p);
		if (error)
			return (error);
		tmp = fp->f_flag & FASYNC;
		error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp, p);
		if (!error)
			return (0);
		fp->f_flag &= ~FNONBLOCK;
		tmp = 0;
		(void)fo_ioctl(fp, FIONBIO, (caddr_t)&tmp, p);
		return (error);

	case F_GETOWN:
		return (fo_ioctl(fp, FIOGETOWN, (caddr_t)p->p_retval, p));

	case F_SETOWN:
		return (fo_ioctl(fp, FIOSETOWN, (caddr_t)&uap->arg, p));

	case F_SETLKW:
		flg |= F_WAIT;
		/* Fall into F_SETLK */

	case F_SETLK:
		if (fp->f_type != DTYPE_VNODE)
			return (EBADF);
		vp = (struct vnode *)fp->f_data;
		/* Copy in the lock structure */
		error = copyin((caddr_t)(intptr_t)uap->arg, (caddr_t)&fl,
		    sizeof(fl));
		if (error)
			return (error);
		if (fl.l_whence == SEEK_CUR)
			fl.l_start += fp->f_offset;
		switch (fl.l_type) {

		case F_RDLCK:
			if ((fp->f_flag & FREAD) == 0)
				return (EBADF);
			p->p_flag |= P_ADVLOCK;
			return (VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, &fl, flg));

		case F_WRLCK:
			if ((fp->f_flag & FWRITE) == 0)
				return (EBADF);
			p->p_flag |= P_ADVLOCK;
			return (VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, &fl, flg));

		case F_UNLCK:
			return (VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, &fl,
				F_POSIX));

		default:
			return (EINVAL);
		}

	case F_GETLK:
		if (fp->f_type != DTYPE_VNODE)
			return (EBADF);
		vp = (struct vnode *)fp->f_data;
		/* Copy in the lock structure */
		error = copyin((caddr_t)(intptr_t)uap->arg, (caddr_t)&fl,
		    sizeof(fl));
		if (error)
			return (error);
		if (fl.l_type != F_RDLCK && fl.l_type != F_WRLCK &&
		    fl.l_type != F_UNLCK)
			return (EINVAL);
		if (fl.l_whence == SEEK_CUR)
			fl.l_start += fp->f_offset;
		if ((error = VOP_ADVLOCK(vp,(caddr_t)p->p_leader,F_GETLK,&fl,F_POSIX)))
			return (error);
		return (copyout((caddr_t)&fl, (caddr_t)(intptr_t)uap->arg,
		    sizeof(fl)));

	default:
		return (EINVAL);
	}
	/* NOTREACHED */
}

/*
 * Common code for dup, dup2, and fcntl(F_DUPFD).
 */
static int
finishdup(fdp, old, new, retval)
	register struct filedesc *fdp;
	register int old, new;
	register_t *retval;
{
	register struct file *fp;

	fp = fdp->fd_ofiles[old];
	fdp->fd_ofiles[new] = fp;
	fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE;
	fhold(fp);
	if (new > fdp->fd_lastfile)
		fdp->fd_lastfile = new;
	*retval = new;
	return (0);
}

/*
 * If sigio is on the list associated with a process or process group,
 * disable signalling from the device, remove sigio from the list and
 * free sigio.
 */
void
funsetown(sigio)
	struct sigio *sigio;
{
	int s;

	if (sigio == NULL)
		return;
	s = splhigh();
	*(sigio->sio_myref) = NULL;
	splx(s);
	if (sigio->sio_pgid < 0) {
		SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
			     sigio, sio_pgsigio);
	} else /* if ((*sigiop)->sio_pgid > 0) */ {
		SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
			     sigio, sio_pgsigio);
	}
	crfree(sigio->sio_ucred);
	FREE(sigio, M_SIGIO);
}

/* Free a list of sigio structures. */
void
funsetownlst(sigiolst)
	struct sigiolst *sigiolst;
{
	struct sigio *sigio;

	while ((sigio = sigiolst->slh_first) != NULL)
		funsetown(sigio);
}

/*
 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
 *
 * After permission checking, add a sigio structure to the sigio list for
 * the process or process group.
 */
int
fsetown(pgid, sigiop)
	pid_t pgid;
	struct sigio **sigiop;
{
	struct proc *proc;
	struct pgrp *pgrp;
	struct sigio *sigio;
	int s;

	if (pgid == 0) {
		funsetown(*sigiop);
		return (0);
	}
	if (pgid > 0) {
		proc = pfind(pgid);
		if (proc == NULL)
			return (ESRCH);
		/*
		 * Policy - Don't allow a process to FSETOWN a process
		 * in another session.
		 *
		 * Remove this test to allow maximum flexibility or
		 * restrict FSETOWN to the current process or process
		 * group for maximum safety.
		 */
		else if (proc->p_session != curproc->p_session)
			return (EPERM);
		pgrp = NULL;
	} else /* if (pgid < 0) */ {
		pgrp = pgfind(-pgid);
		if (pgrp == NULL)
			return (ESRCH);
		/*
		 * Policy - Don't allow a process to FSETOWN a process
		 * in another session.
		 *
		 * Remove this test to allow maximum flexibility or
		 * restrict FSETOWN to the current process or process
		 * group for maximum safety.
		 */
		else if (pgrp->pg_session != curproc->p_session)
			return (EPERM);
		proc = NULL;
	}
	funsetown(*sigiop);
	MALLOC(sigio, struct sigio *, sizeof(struct sigio), M_SIGIO,
	       M_WAITOK);
	if (pgid > 0) {
		SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
		sigio->sio_proc = proc;
	} else {
		SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
		sigio->sio_pgrp = pgrp;
	}
	sigio->sio_pgid = pgid;
	crhold(curproc->p_ucred);
	sigio->sio_ucred = curproc->p_ucred;
	/* It would be convenient if p_ruid was in ucred. */
	sigio->sio_ruid = curproc->p_cred->p_ruid;
	sigio->sio_myref = sigiop;
	s = splhigh();
	*sigiop = sigio;
	splx(s);
	return (0);
}

/*
 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
 */
pid_t
fgetown(sigio)
	struct sigio *sigio;
{
	return (sigio != NULL ? sigio->sio_pgid : 0);
}

/*
 * Close a file descriptor.
 */
#ifndef _SYS_SYSPROTO_H_
struct close_args {
        int     fd;
};
#endif
/* ARGSUSED */
int
close(p, uap)
	struct proc *p;
	struct close_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	register int fd = uap->fd;
	register u_char *pf;

	if ((unsigned)fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[fd]) == NULL)
		return (EBADF);
	pf = (u_char *)&fdp->fd_ofileflags[fd];
	if (*pf & UF_MAPPED)
		(void) munmapfd(p, fd);
	fdp->fd_ofiles[fd] = NULL;
	while (fdp->fd_lastfile > 0 && fdp->fd_ofiles[fdp->fd_lastfile] == NULL)
		fdp->fd_lastfile--;
	if (fd < fdp->fd_freefile)
		fdp->fd_freefile = fd;
	*pf = 0;
	return (closef(fp, p));
}

#if defined(COMPAT_43) || defined(COMPAT_SUNOS)
/*
 * Return status information about a file descriptor.
 */
#ifndef _SYS_SYSPROTO_H_
struct ofstat_args {
	int	fd;
	struct	ostat *sb;
};
#endif
/* ARGSUSED */
int
ofstat(p, uap)
	struct proc *p;
	register struct ofstat_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	struct stat ub;
	struct ostat oub;
	int error;

	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
		return (EBADF);
	switch (fp->f_type) {

	case DTYPE_FIFO:
	case DTYPE_VNODE:
		error = vn_stat((struct vnode *)fp->f_data, &ub, p);
		break;

	case DTYPE_SOCKET:
		error = soo_stat((struct socket *)fp->f_data, &ub);
		break;

	case DTYPE_PIPE:
		error = pipe_stat((struct pipe *)fp->f_data, &ub);
		break;

	default:
		panic("ofstat");
		/*NOTREACHED*/
	}
	cvtstat(&ub, &oub);
	if (error == 0)
		error = copyout((caddr_t)&oub, (caddr_t)uap->sb, sizeof (oub));
	return (error);
}
#endif /* COMPAT_43 || COMPAT_SUNOS */

/*
 * Return status information about a file descriptor.
 */
#ifndef _SYS_SYSPROTO_H_
struct fstat_args {
	int	fd;
	struct	stat *sb;
};
#endif
/* ARGSUSED */
int
fstat(p, uap)
	struct proc *p;
	register struct fstat_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	struct stat ub;
	int error;

	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
		return (EBADF);
	switch (fp->f_type) {

	case DTYPE_FIFO:
	case DTYPE_VNODE:
		error = vn_stat((struct vnode *)fp->f_data, &ub, p);
		break;

	case DTYPE_SOCKET:
		error = soo_stat((struct socket *)fp->f_data, &ub);
		break;

	case DTYPE_PIPE:
		error = pipe_stat((struct pipe *)fp->f_data, &ub);
		break;

	default:
		panic("fstat");
		/*NOTREACHED*/
	}
	if (error == 0)
		error = copyout((caddr_t)&ub, (caddr_t)uap->sb, sizeof (ub));
	return (error);
}

/*
 * Return status information about a file descriptor.
 */
#ifndef _SYS_SYSPROTO_H_
struct nfstat_args {
	int	fd;
	struct	nstat *sb;
};
#endif
/* ARGSUSED */
int
nfstat(p, uap)
	struct proc *p;
	register struct nfstat_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	struct stat ub;
	struct nstat nub;
	int error;

	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
		return (EBADF);
	switch (fp->f_type) {

	case DTYPE_FIFO:
	case DTYPE_VNODE:
		error = vn_stat((struct vnode *)fp->f_data, &ub, p);
		break;

	case DTYPE_SOCKET:
		error = soo_stat((struct socket *)fp->f_data, &ub);
		break;

	case DTYPE_PIPE:
		error = pipe_stat((struct pipe *)fp->f_data, &ub);
		break;

	default:
		panic("fstat");
		/*NOTREACHED*/
	}
	if (error == 0) {
		cvtnstat(&ub, &nub);
		error = copyout((caddr_t)&nub, (caddr_t)uap->sb, sizeof (nub));
	}
	return (error);
}

/*
 * Return pathconf information about a file descriptor.
 */
#ifndef _SYS_SYSPROTO_H_
struct fpathconf_args {
	int	fd;
	int	name;
};
#endif
/* ARGSUSED */
int
fpathconf(p, uap)
	struct proc *p;
	register struct fpathconf_args *uap;
{
	struct filedesc *fdp = p->p_fd;
	struct file *fp;
	struct vnode *vp;

	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
		return (EBADF);
	switch (fp->f_type) {

	case DTYPE_PIPE:
	case DTYPE_SOCKET:
		if (uap->name != _PC_PIPE_BUF)
			return (EINVAL);
		p->p_retval[0] = PIPE_BUF;
		return (0);

	case DTYPE_FIFO:
	case DTYPE_VNODE:
		vp = (struct vnode *)fp->f_data;
		return (VOP_PATHCONF(vp, uap->name, p->p_retval));

	default:
		panic("fpathconf");
	}
	/*NOTREACHED*/
}

/*
 * Allocate a file descriptor for the process.
 */
static int fdexpand;
SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand, 0, "");

int
fdalloc(p, want, result)
	struct proc *p;
	int want;
	int *result;
{
	register struct filedesc *fdp = p->p_fd;
	register int i;
	int lim, last, nfiles;
	struct file **newofile;
	char *newofileflags;

	/*
	 * Search for a free descriptor starting at the higher
	 * of want or fd_freefile.  If that fails, consider
	 * expanding the ofile array.
	 */
	lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
	for (;;) {
		last = min(fdp->fd_nfiles, lim);
		if ((i = want) < fdp->fd_freefile)
			i = fdp->fd_freefile;
		for (; i < last; i++) {
			if (fdp->fd_ofiles[i] == NULL) {
				fdp->fd_ofileflags[i] = 0;
				if (i > fdp->fd_lastfile)
					fdp->fd_lastfile = i;
				if (want <= fdp->fd_freefile)
					fdp->fd_freefile = i;
				*result = i;
				return (0);
			}
		}

		/*
		 * No space in current array.  Expand?
		 */
		if (fdp->fd_nfiles >= lim)
			return (EMFILE);
		if (fdp->fd_nfiles < NDEXTENT)
			nfiles = NDEXTENT;
		else
			nfiles = 2 * fdp->fd_nfiles;
		MALLOC(newofile, struct file **, nfiles * OFILESIZE,
		    M_FILEDESC, M_WAITOK);
		newofileflags = (char *) &newofile[nfiles];
		/*
		 * Copy the existing ofile and ofileflags arrays
		 * and zero the new portion of each array.
		 */
		bcopy(fdp->fd_ofiles, newofile,
			(i = sizeof(struct file *) * fdp->fd_nfiles));
		bzero((char *)newofile + i, nfiles * sizeof(struct file *) - i);
		bcopy(fdp->fd_ofileflags, newofileflags,
			(i = sizeof(char) * fdp->fd_nfiles));
		bzero(newofileflags + i, nfiles * sizeof(char) - i);
		if (fdp->fd_nfiles > NDFILE)
			FREE(fdp->fd_ofiles, M_FILEDESC);
		fdp->fd_ofiles = newofile;
		fdp->fd_ofileflags = newofileflags;
		fdp->fd_nfiles = nfiles;
		fdexpand++;
	}
	return (0);
}

/*
 * Check to see whether n user file descriptors
 * are available to the process p.
 */
int
fdavail(p, n)
	struct proc *p;
	register int n;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file **fpp;
	register int i, lim, last;

	lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc);
	if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0)
		return (1);

	last = min(fdp->fd_nfiles, lim);
	fpp = &fdp->fd_ofiles[fdp->fd_freefile];
	for (i = last - fdp->fd_freefile; --i >= 0; fpp++)
		if (*fpp == NULL && --n <= 0)
			return (1);
	return (0);
}

/*
 * Create a new open file structure and allocate
 * a file decriptor for the process that refers to it.
 */
int
falloc(p, resultfp, resultfd)
	register struct proc *p;
	struct file **resultfp;
	int *resultfd;
{
	register struct file *fp, *fq;
	int error, i;

	if ((error = fdalloc(p, 0, &i)))
		return (error);
	if (nfiles >= maxfiles) {
		tablefull("file");
		return (ENFILE);
	}
	/*
	 * Allocate a new file descriptor.
	 * If the process has file descriptor zero open, add to the list
	 * of open files at that point, otherwise put it at the front of
	 * the list of open files.
	 */
	nfiles++;
	MALLOC(fp, struct file *, sizeof(struct file), M_FILE, M_WAITOK);
	bzero(fp, sizeof(struct file));
	fp->f_count = 1;
	fp->f_cred = p->p_ucred;
	fp->f_ops = &badfileops;
	fp->f_seqcount = 1;
	crhold(fp->f_cred);
	if ((fq = p->p_fd->fd_ofiles[0])) {
		LIST_INSERT_AFTER(fq, fp, f_list);
	} else {
		LIST_INSERT_HEAD(&filehead, fp, f_list);
	}
	p->p_fd->fd_ofiles[i] = fp;
	if (resultfp)
		*resultfp = fp;
	if (resultfd)
		*resultfd = i;
	return (0);
}

/*
 * Free a file descriptor.
 */
void
ffree(fp)
	register struct file *fp;
{
	LIST_REMOVE(fp, f_list);
	crfree(fp->f_cred);
#if defined(DIAGNOSTIC) || defined(INVARIANTS)
	fp->f_count = 0;
#endif
	nfiles--;
	FREE(fp, M_FILE);
}

/*
 * Build a new filedesc structure.
 */
struct filedesc *
fdinit(p)
	struct proc *p;
{
	register struct filedesc0 *newfdp;
	register struct filedesc *fdp = p->p_fd;

	MALLOC(newfdp, struct filedesc0 *, sizeof(struct filedesc0),
	    M_FILEDESC, M_WAITOK);
	bzero(newfdp, sizeof(struct filedesc0));
	newfdp->fd_fd.fd_cdir = fdp->fd_cdir;
	VREF(newfdp->fd_fd.fd_cdir);
	newfdp->fd_fd.fd_rdir = fdp->fd_rdir;
	VREF(newfdp->fd_fd.fd_rdir);
	newfdp->fd_fd.fd_jdir = fdp->fd_jdir;
	if (newfdp->fd_fd.fd_jdir)
		VREF(newfdp->fd_fd.fd_jdir);

	/* Create the file descriptor table. */
	newfdp->fd_fd.fd_refcnt = 1;
	newfdp->fd_fd.fd_cmask = cmask;
	newfdp->fd_fd.fd_ofiles = newfdp->fd_dfiles;
	newfdp->fd_fd.fd_ofileflags = newfdp->fd_dfileflags;
	newfdp->fd_fd.fd_nfiles = NDFILE;

	newfdp->fd_fd.fd_freefile = 0;
	newfdp->fd_fd.fd_lastfile = 0;

	return (&newfdp->fd_fd);
}

/*
 * Share a filedesc structure.
 */
struct filedesc *
fdshare(p)
	struct proc *p;
{
	p->p_fd->fd_refcnt++;
	return (p->p_fd);
}

/*
 * Copy a filedesc structure.
 */
struct filedesc *
fdcopy(p)
	struct proc *p;
{
	register struct filedesc *newfdp, *fdp = p->p_fd;
	register struct file **fpp;
	register int i;

/*
 * Certain daemons might not have file descriptors
 */
	if (fdp == NULL)
		return NULL;

	MALLOC(newfdp, struct filedesc *, sizeof(struct filedesc0),
	    M_FILEDESC, M_WAITOK);
	bcopy(fdp, newfdp, sizeof(struct filedesc));
	VREF(newfdp->fd_cdir);
	VREF(newfdp->fd_rdir);
	if (newfdp->fd_jdir)
		VREF(newfdp->fd_jdir);
	newfdp->fd_refcnt = 1;

	/*
	 * If the number of open files fits in the internal arrays
	 * of the open file structure, use them, otherwise allocate
	 * additional memory for the number of descriptors currently
	 * in use.
	 */
	if (newfdp->fd_lastfile < NDFILE) {
		newfdp->fd_ofiles = ((struct filedesc0 *) newfdp)->fd_dfiles;
		newfdp->fd_ofileflags =
		    ((struct filedesc0 *) newfdp)->fd_dfileflags;
		i = NDFILE;
	} else {
		/*
		 * Compute the smallest multiple of NDEXTENT needed
		 * for the file descriptors currently in use,
		 * allowing the table to shrink.
		 */
		i = newfdp->fd_nfiles;
		while (i > 2 * NDEXTENT && i > newfdp->fd_lastfile * 2)
			i /= 2;
		MALLOC(newfdp->fd_ofiles, struct file **, i * OFILESIZE,
		    M_FILEDESC, M_WAITOK);
		newfdp->fd_ofileflags = (char *) &newfdp->fd_ofiles[i];
	}
	newfdp->fd_nfiles = i;
	bcopy(fdp->fd_ofiles, newfdp->fd_ofiles, i * sizeof(struct file **));
	bcopy(fdp->fd_ofileflags, newfdp->fd_ofileflags, i * sizeof(char));
	fpp = newfdp->fd_ofiles;
	for (i = newfdp->fd_lastfile; i-- >= 0; fpp++)
		if (*fpp != NULL)
			fhold(*fpp);
	return (newfdp);
}

/*
 * Release a filedesc structure.
 */
void
fdfree(p)
	struct proc *p;
{
	register struct filedesc *fdp = p->p_fd;
	struct file **fpp;
	register int i;

/*
 * Certain daemons might not have file descriptors
 */
	if (fdp == NULL)
		return;

	if (--fdp->fd_refcnt > 0)
		return;
	fpp = fdp->fd_ofiles;
	for (i = fdp->fd_lastfile; i-- >= 0; fpp++)
		if (*fpp)
			(void) closef(*fpp, p);
	if (fdp->fd_nfiles > NDFILE)
		FREE(fdp->fd_ofiles, M_FILEDESC);
	vrele(fdp->fd_cdir);
	vrele(fdp->fd_rdir);
	if(fdp->fd_jdir)
		vrele(fdp->fd_jdir);
	FREE(fdp, M_FILEDESC);
}

/*
 * Close any files on exec?
 */
void
fdcloseexec(p)
	struct proc *p;
{
	struct filedesc *fdp = p->p_fd;
	struct file **fpp;
	char *fdfp;
	register int i;

/*
 * Certain daemons might not have file descriptors
 */
	if (fdp == NULL)
		return;

	fpp = fdp->fd_ofiles;
	fdfp = fdp->fd_ofileflags;
	for (i = 0; i <= fdp->fd_lastfile; i++, fpp++, fdfp++)
		if (*fpp != NULL && (*fdfp & UF_EXCLOSE)) {
			if (*fdfp & UF_MAPPED)
				(void) munmapfd(p, i);
			(void) closef(*fpp, p);
			*fpp = NULL;
			*fdfp = 0;
			if (i < fdp->fd_freefile)
				fdp->fd_freefile = i;
		}
	while (fdp->fd_lastfile > 0 && fdp->fd_ofiles[fdp->fd_lastfile] == NULL)
		fdp->fd_lastfile--;
}

/*
 * Internal form of close.
 * Decrement reference count on file structure.
 * Note: p may be NULL when closing a file
 * that was being passed in a message.
 */
int
closef(fp, p)
	register struct file *fp;
	register struct proc *p;
{
	struct vnode *vp;
	struct flock lf;

	if (fp == NULL)
		return (0);
	/*
	 * POSIX record locking dictates that any close releases ALL
	 * locks owned by this process.  This is handled by setting
	 * a flag in the unlock to free ONLY locks obeying POSIX
	 * semantics, and not to free BSD-style file locks.
	 * If the descriptor was in a message, POSIX-style locks
	 * aren't passed with the descriptor.
	 */
	if (p && (p->p_flag & P_ADVLOCK) && fp->f_type == DTYPE_VNODE) {
		lf.l_whence = SEEK_SET;
		lf.l_start = 0;
		lf.l_len = 0;
		lf.l_type = F_UNLCK;
		vp = (struct vnode *)fp->f_data;
		(void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, &lf, F_POSIX);
	}
	return (fdrop(fp, p));
}

int
fdrop(fp, p)
	struct file *fp;
	struct proc *p;
{
	struct flock lf;
	struct vnode *vp;
	int error;

	if (--fp->f_count > 0)
		return (0);
	if (fp->f_count < 0)
		panic("fdrop: count < 0");
	if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE) {
		lf.l_whence = SEEK_SET;
		lf.l_start = 0;
		lf.l_len = 0;
		lf.l_type = F_UNLCK;
		vp = (struct vnode *)fp->f_data;
		(void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
	}
	if (fp->f_ops != &badfileops)
		error = fo_close(fp, p);
	else
		error = 0;
	ffree(fp);
	return (error);
}

/*
 * Apply an advisory lock on a file descriptor.
 *
 * Just attempt to get a record lock of the requested type on
 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
 */
#ifndef _SYS_SYSPROTO_H_
struct flock_args {
	int	fd;
	int	how;
};
#endif
/* ARGSUSED */
int
flock(p, uap)
	struct proc *p;
	register struct flock_args *uap;
{
	register struct filedesc *fdp = p->p_fd;
	register struct file *fp;
	struct vnode *vp;
	struct flock lf;

	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
		return (EBADF);
	if (fp->f_type != DTYPE_VNODE)
		return (EOPNOTSUPP);
	vp = (struct vnode *)fp->f_data;
	lf.l_whence = SEEK_SET;
	lf.l_start = 0;
	lf.l_len = 0;
	if (uap->how & LOCK_UN) {
		lf.l_type = F_UNLCK;
		fp->f_flag &= ~FHASLOCK;
		return (VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK));
	}
	if (uap->how & LOCK_EX)
		lf.l_type = F_WRLCK;
	else if (uap->how & LOCK_SH)
		lf.l_type = F_RDLCK;
	else
		return (EBADF);
	fp->f_flag |= FHASLOCK;
	if (uap->how & LOCK_NB)
		return (VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_FLOCK));
	return (VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_FLOCK|F_WAIT));
}

/*
 * File Descriptor pseudo-device driver (/dev/fd/).
 *
 * Opening minor device N dup()s the file (if any) connected to file
 * descriptor N belonging to the calling process.  Note that this driver
 * consists of only the ``open()'' routine, because all subsequent
 * references to this file will be direct to the other driver.
 */
/* ARGSUSED */
static int
fdopen(dev, mode, type, p)
	dev_t dev;
	int mode, type;
	struct proc *p;
{

	/*
	 * XXX Kludge: set curproc->p_dupfd to contain the value of the
	 * the file descriptor being sought for duplication. The error
	 * return ensures that the vnode for this device will be released
	 * by vn_open. Open will detect this special error and take the
	 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
	 * will simply report the error.
	 */
	p->p_dupfd = minor(dev);
	return (ENODEV);
}

/*
 * Duplicate the specified descriptor to a free descriptor.
 */
int
dupfdopen(fdp, indx, dfd, mode, error)
	register struct filedesc *fdp;
	register int indx, dfd;
	int mode;
	int error;
{
	register struct file *wfp;
	struct file *fp;

	/*
	 * If the to-be-dup'd fd number is greater than the allowed number
	 * of file descriptors, or the fd to be dup'd has already been
	 * closed, reject.  Note, check for new == old is necessary as
	 * falloc could allocate an already closed to-be-dup'd descriptor
	 * as the new descriptor.
	 */
	fp = fdp->fd_ofiles[indx];
	if ((u_int)dfd >= fdp->fd_nfiles ||
	    (wfp = fdp->fd_ofiles[dfd]) == NULL || fp == wfp)
		return (EBADF);

	/*
	 * There are two cases of interest here.
	 *
	 * For ENODEV simply dup (dfd) to file descriptor
	 * (indx) and return.
	 *
	 * For ENXIO steal away the file structure from (dfd) and
	 * store it in (indx).  (dfd) is effectively closed by
	 * this operation.
	 *
	 * Any other error code is just returned.
	 */
	switch (error) {
	case ENODEV:
		/*
		 * Check that the mode the file is being opened for is a
		 * subset of the mode of the existing descriptor.
		 */
		if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag)
			return (EACCES);
		fdp->fd_ofiles[indx] = wfp;
		fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
		fhold(wfp);
		if (indx > fdp->fd_lastfile)
			fdp->fd_lastfile = indx;
		return (0);

	case ENXIO:
		/*
		 * Steal away the file pointer from dfd, and stuff it into indx.
		 */
		fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd];
		fdp->fd_ofiles[dfd] = NULL;
		fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
		fdp->fd_ofileflags[dfd] = 0;
		/*
		 * Complete the clean up of the filedesc structure by
		 * recomputing the various hints.
		 */
		if (indx > fdp->fd_lastfile)
			fdp->fd_lastfile = indx;
		else
			while (fdp->fd_lastfile > 0 &&
			       fdp->fd_ofiles[fdp->fd_lastfile] == NULL)
				fdp->fd_lastfile--;
			if (dfd < fdp->fd_freefile)
				fdp->fd_freefile = dfd;
		return (0);

	default:
		return (error);
	}
	/* NOTREACHED */
}

/*
 * Get file structures.
 */
static int
sysctl_kern_file SYSCTL_HANDLER_ARGS
{
	int error;
	struct file *fp;

	if (!req->oldptr) {
		/*
		 * overestimate by 10 files
		 */
		return (SYSCTL_OUT(req, 0, sizeof(filehead) +
				(nfiles + 10) * sizeof(struct file)));
	}

	error = SYSCTL_OUT(req, (caddr_t)&filehead, sizeof(filehead));
	if (error)
		return (error);

	/*
	 * followed by an array of file structures
	 */
	for (fp = filehead.lh_first; fp != NULL; fp = fp->f_list.le_next) {
		error = SYSCTL_OUT(req, (caddr_t)fp, sizeof (struct file));
		if (error)
			return (error);
	}
	return (0);
}

SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
    0, 0, sysctl_kern_file, "S,file", "Entire file table");

SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
    &maxfilesperproc, 0, "Maximum files allowed open per process");

SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
    &maxfiles, 0, "Maximum number of files");

static void
fildesc_drvinit(void *unused)
{
	int fd;

	cdevsw_add(&fildesc_cdevsw);
	for (fd = 0; fd < NUMFDESC; fd++)
		make_dev(&fildesc_cdevsw, fd,
		    UID_BIN, GID_BIN, 0666, "fd/%d", fd);
	make_dev(&fildesc_cdevsw, 0, UID_ROOT, GID_WHEEL, 0666, "stdin");
	make_dev(&fildesc_cdevsw, 1, UID_ROOT, GID_WHEEL, 0666, "stdout");
	make_dev(&fildesc_cdevsw, 2, UID_ROOT, GID_WHEEL, 0666, "stderr");
}

struct fileops badfileops = {
	badfo_readwrite,
	badfo_readwrite,
	badfo_ioctl,
	badfo_poll,
	badfo_close
};

static int
badfo_readwrite(fp, uio, cred, flags, p)
	struct file *fp;
	struct uio *uio;
	struct ucred *cred;
	struct proc *p;
	int flags;
{

	return (EBADF);
}

static int
badfo_ioctl(fp, com, data, p)
	struct file *fp;
	u_long com;
	caddr_t data;
	struct proc *p;
{

	return (EBADF);
}

static int
badfo_poll(fp, events, cred, p)
	struct file *fp;
	int events;
	struct ucred *cred;
	struct proc *p;
{

	return (0);
}

static int
badfo_close(fp, p)
	struct file *fp;
	struct proc *p;
{

	return (EBADF);
}

SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
					fildesc_drvinit,NULL)