/*	$OpenBSD: fifo_vnops.c,v 1.66 2018/05/02 02:24:56 visa Exp $	*/
/*	$NetBSD: fifo_vnops.c,v 1.18 1996/03/16 23:52:42 christos Exp $	*/

/*
 * Copyright (c) 1990, 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.
 *
 *	@(#)fifo_vnops.c	8.4 (Berkeley) 8/10/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/lock.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/event.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/poll.h>
#include <sys/unistd.h>

#include <miscfs/fifofs/fifo.h>

/*
 * This structure is associated with the FIFO vnode and stores
 * the state associated with the FIFO.
 */
struct fifoinfo {
	struct socket	*fi_readsock;
	struct socket	*fi_writesock;
	long		fi_readers;
	long		fi_writers;
};

struct vops fifo_vops = {
	.vop_lookup	= vop_generic_lookup,
	.vop_create	= fifo_badop,
	.vop_mknod	= fifo_badop,
	.vop_open	= fifo_open,
	.vop_close	= fifo_close,
	.vop_access	= fifo_ebadf,
	.vop_getattr	= fifo_ebadf,
	.vop_setattr	= fifo_ebadf,
	.vop_read	= fifo_read,
	.vop_write	= fifo_write,
	.vop_ioctl	= fifo_ioctl,
	.vop_poll	= fifo_poll,
	.vop_kqfilter	= fifo_kqfilter,
	.vop_revoke	= vop_generic_revoke,
	.vop_fsync	= nullop,
	.vop_remove	= fifo_badop,
	.vop_link	= fifo_badop,
	.vop_rename	= fifo_badop,
	.vop_mkdir	= fifo_badop,
	.vop_rmdir	= fifo_badop,
	.vop_symlink	= fifo_badop,
	.vop_readdir	= fifo_badop,
	.vop_readlink	= fifo_badop,
	.vop_abortop	= fifo_badop,
	.vop_inactive	= fifo_inactive,
	.vop_reclaim	= fifo_reclaim,
	.vop_lock	= vop_generic_lock,
	.vop_unlock	= vop_generic_unlock,
	.vop_bmap	= vop_generic_bmap,
	.vop_strategy	= fifo_badop,
	.vop_print	= fifo_print,
	.vop_islocked	= vop_generic_islocked,
	.vop_pathconf	= fifo_pathconf,
	.vop_advlock	= fifo_advlock,
	.vop_bwrite	= nullop
};

void	filt_fifordetach(struct knote *kn);
int	filt_fiforead(struct knote *kn, long hint);
void	filt_fifowdetach(struct knote *kn);
int	filt_fifowrite(struct knote *kn, long hint);

struct filterops fiforead_filtops =
	{ 1, NULL, filt_fifordetach, filt_fiforead };
struct filterops fifowrite_filtops =
	{ 1, NULL, filt_fifowdetach, filt_fifowrite };

/*
 * Open called to set up a new instance of a fifo or
 * to find an active instance of a fifo.
 */
/* ARGSUSED */
int
fifo_open(void *v)
{
	struct vop_open_args *ap = v;
	struct vnode *vp = ap->a_vp;
	struct fifoinfo *fip;
	struct socket *rso, *wso;
	int s, error;

	if ((fip = vp->v_fifoinfo) == NULL) {
		fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
		vp->v_fifoinfo = fip;
		if ((error = socreate(AF_UNIX, &rso, SOCK_STREAM, 0)) != 0) {
			free(fip, M_VNODE, sizeof *fip);
			vp->v_fifoinfo = NULL;
			return (error);
		}
		fip->fi_readsock = rso;
		if ((error = socreate(AF_UNIX, &wso, SOCK_STREAM, 0)) != 0) {
			(void)soclose(rso);
			free(fip, M_VNODE, sizeof *fip);
			vp->v_fifoinfo = NULL;
			return (error);
		}
		fip->fi_writesock = wso;
		if ((error = soconnect2(wso, rso)) != 0) {
			(void)soclose(wso);
			(void)soclose(rso);
			free(fip, M_VNODE, sizeof *fip);
			vp->v_fifoinfo = NULL;
			return (error);
		}
		fip->fi_readers = fip->fi_writers = 0;
		s = solock(wso);
		wso->so_state |= SS_CANTSENDMORE;
		wso->so_snd.sb_lowat = PIPE_BUF;
	} else {
		rso = fip->fi_readsock;
		wso = fip->fi_writesock;
		s = solock(wso);
	}
	if (ap->a_mode & FREAD) {
		fip->fi_readers++;
		if (fip->fi_readers == 1) {
			wso->so_state &= ~SS_CANTSENDMORE;
			if (fip->fi_writers > 0)
				wakeup(&fip->fi_writers);
		}
	}
	if (ap->a_mode & FWRITE) {
		fip->fi_writers++;
		if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
			error = ENXIO;
			sounlock(s);
			goto bad;
		}
		if (fip->fi_writers == 1) {
			rso->so_state &= ~(SS_CANTRCVMORE|SS_ISDISCONNECTED);
			if (fip->fi_readers > 0)
				wakeup(&fip->fi_readers);
		}
	}
	sounlock(s);
	if ((ap->a_mode & O_NONBLOCK) == 0) {
		if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
			VOP_UNLOCK(vp);
			error = tsleep(&fip->fi_readers,
			    PCATCH | PSOCK, "fifor", 0);
			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
			if (error)
				goto bad;
		}
		if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
			VOP_UNLOCK(vp);
			error = tsleep(&fip->fi_writers,
			    PCATCH | PSOCK, "fifow", 0);
			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
			if (error)
				goto bad;
		}
	}
	return (0);
bad:
	VOP_CLOSE(vp, ap->a_mode, ap->a_cred, ap->a_p);
	return (error);
}

/*
 * Vnode op for read
 */
/* ARGSUSED */
int
fifo_read(void *v)
{
	struct vop_read_args *ap = v;
	struct uio *uio = ap->a_uio;
	struct socket *rso = ap->a_vp->v_fifoinfo->fi_readsock;
	int error;

#ifdef DIAGNOSTIC
	if (uio->uio_rw != UIO_READ)
		panic("fifo_read mode");
#endif
	if (uio->uio_resid == 0)
		return (0);
	if (ap->a_ioflag & IO_NDELAY)
		rso->so_state |= SS_NBIO;
	VOP_UNLOCK(ap->a_vp);
	error = soreceive(rso, NULL, uio, NULL, NULL, NULL, 0);
	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
	if (ap->a_ioflag & IO_NDELAY) {
		rso->so_state &= ~SS_NBIO;
		if (error == EWOULDBLOCK &&
		    ap->a_vp->v_fifoinfo->fi_writers == 0)
			error = 0;
	}
	return (error);
}

/*
 * Vnode op for write
 */
/* ARGSUSED */
int
fifo_write(void *v)
{
	struct vop_write_args *ap = v;
	struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
	int error;

#ifdef DIAGNOSTIC
	if (ap->a_uio->uio_rw != UIO_WRITE)
		panic("fifo_write mode");
#endif
	/* XXXSMP changing state w/o lock isn't safe. */
	if (ap->a_ioflag & IO_NDELAY)
		wso->so_state |= SS_NBIO;
	VOP_UNLOCK(ap->a_vp);
	error = sosend(wso, NULL, ap->a_uio, NULL, NULL, 0);
	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
	if (ap->a_ioflag & IO_NDELAY)
		wso->so_state &= ~SS_NBIO;
	return (error);
}

/*
 * Device ioctl operation.
 */
/* ARGSUSED */
int
fifo_ioctl(void *v)
{
	struct vop_ioctl_args *ap = v;
	struct file filetmp;
	int error;

	if (ap->a_command == FIONBIO)
		return (0);
	if (ap->a_fflag & FREAD) {
		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data, ap->a_p);
		if (error)
			return (error);
	}
	if (ap->a_fflag & FWRITE) {
		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data, ap->a_p);
		if (error)
			return (error);
	}
	return (0);
}

/* ARGSUSED */
int
fifo_poll(void *v)
{
	struct vop_poll_args *ap = v;
	struct socket *rso = ap->a_vp->v_fifoinfo->fi_readsock;
	struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
	int events = 0;
	int revents = 0;
	int s;

	/*
	 * FIFOs don't support out-of-band or high priority data.
	 */
	s = solock(rso);
	if (ap->a_fflag & FREAD)
		events |= ap->a_events & (POLLIN | POLLRDNORM);
	if (ap->a_fflag & FWRITE)
		events |= ap->a_events & (POLLOUT | POLLWRNORM);

	if (events & (POLLIN | POLLRDNORM)) {
		if (soreadable(rso))
			revents |= events & (POLLIN | POLLRDNORM);
	}
	/* NOTE: POLLHUP and POLLOUT/POLLWRNORM are mutually exclusive */
	if ((rso->so_state & SS_ISDISCONNECTED) && !(ap->a_events & POLL_NOHUP)) {
		revents |= POLLHUP;
	} else if (events & (POLLOUT | POLLWRNORM)) {
		if (sowriteable(wso))
			revents |= events & (POLLOUT | POLLWRNORM);
	}
	if (revents == 0) {
		/* We want to return POLLHUP even if no valid events set. */
		if (events == 0 && !(ap->a_events & POLL_NOHUP))
			events = POLLIN;
		if (events & (POLLIN | POLLRDNORM)) {
			selrecord(ap->a_p, &rso->so_rcv.sb_sel);
			rso->so_rcv.sb_flags |= SB_SEL;
		}
		if (events & (POLLOUT | POLLWRNORM)) {
			selrecord(ap->a_p, &wso->so_snd.sb_sel);
			wso->so_snd.sb_flags |= SB_SEL;
		}
	}
	sounlock(s);
	return (revents);
}

int
fifo_inactive(void *v)
{
	struct vop_inactive_args *ap = v;

	VOP_UNLOCK(ap->a_vp);
	return (0);
}


/*
 * Device close routine
 */
/* ARGSUSED */
int
fifo_close(void *v)
{
	struct vop_close_args *ap = v;
	struct vnode *vp = ap->a_vp;
	struct fifoinfo *fip = vp->v_fifoinfo;
	int s, error1 = 0, error2 = 0;

	if (fip == NULL)
		return (0);

	if (ap->a_fflag & FREAD) {
		if (--fip->fi_readers == 0) {
			struct socket *wso = fip->fi_writesock;

			s = solock(wso);
			socantsendmore(wso);
			sounlock(s);
		}
	}
	if (ap->a_fflag & FWRITE) {
		if (--fip->fi_writers == 0) {
			struct socket *rso = fip->fi_readsock;

			s = solock(rso);
			/* SS_ISDISCONNECTED will result in POLLHUP */
			rso->so_state |= SS_ISDISCONNECTED;
			socantrcvmore(rso);
			sounlock(s);
		}
	}
	if (fip->fi_readers == 0 && fip->fi_writers == 0) {
		error1 = soclose(fip->fi_readsock);
		error2 = soclose(fip->fi_writesock);
		free(fip, M_VNODE, sizeof *fip);
		vp->v_fifoinfo = NULL;
	}
	return (error1 ? error1 : error2);
}

int
fifo_reclaim(void *v)
{
	struct vop_reclaim_args *ap = v;
	struct vnode *vp = ap->a_vp;
	struct fifoinfo *fip = vp->v_fifoinfo;

	if (fip == NULL)
		return (0);

	soclose(fip->fi_readsock);
	soclose(fip->fi_writesock);
	free(fip, M_VNODE, sizeof *fip);
	vp->v_fifoinfo = NULL;

	return (0);
}

/*
 * Print out the contents of a fifo vnode.
 */
int
fifo_print(void *v)
{
	struct vop_print_args *ap = v;

	printf("tag VT_NON");
	fifo_printinfo(ap->a_vp);
	printf("\n");
	return 0;
}

/*
 * Print out internal contents of a fifo vnode.
 */
void
fifo_printinfo(struct vnode *vp)
{
	struct fifoinfo *fip = vp->v_fifoinfo;

	printf(", fifo with %ld readers and %ld writers",
		fip->fi_readers, fip->fi_writers);
}

/*
 * Return POSIX pathconf information applicable to fifo's.
 */
int
fifo_pathconf(void *v)
{
	struct vop_pathconf_args *ap = v;
	int error = 0;

	switch (ap->a_name) {
	case _PC_LINK_MAX:
		*ap->a_retval = LINK_MAX;
		break;
	case _PC_CHOWN_RESTRICTED:
		*ap->a_retval = 1;
		break;
	case _PC_TIMESTAMP_RESOLUTION:
		*ap->a_retval = 1;
		break;
	default:
		error = EINVAL;
		break;
	}

	return (error);
}

/*
 * Fifo failed operation
 */
/*ARGSUSED*/
int
fifo_ebadf(void *v)
{

	return (EBADF);
}

/*
 * Fifo advisory byte-level locks.
 */
/* ARGSUSED */
int
fifo_advlock(void *v)
{
	return (EOPNOTSUPP);
}

/*
 * Fifo bad operation
 */
/*ARGSUSED*/
int
fifo_badop(void *v)
{

	panic("fifo_badop called");
	/* NOTREACHED */
	return(0);
}


int
fifo_kqfilter(void *v)
{
	struct vop_kqfilter_args *ap = v;
	struct socket *so = (struct socket *)ap->a_vp->v_fifoinfo->fi_readsock;
	struct sockbuf *sb;

	switch (ap->a_kn->kn_filter) {
	case EVFILT_READ:
		ap->a_kn->kn_fop = &fiforead_filtops;
		sb = &so->so_rcv;
		break;
	case EVFILT_WRITE:
		ap->a_kn->kn_fop = &fifowrite_filtops;
		sb = &so->so_snd;
		break;
	default:
		return (EINVAL);
	}

	ap->a_kn->kn_hook = so;

	SLIST_INSERT_HEAD(&sb->sb_sel.si_note, ap->a_kn, kn_selnext);
	sb->sb_flagsintr |= SB_KNOTE;

	return (0);
}

void
filt_fifordetach(struct knote *kn)
{
	struct socket *so = (struct socket *)kn->kn_hook;

	SLIST_REMOVE(&so->so_rcv.sb_sel.si_note, kn, knote, kn_selnext);
	if (SLIST_EMPTY(&so->so_rcv.sb_sel.si_note))
		so->so_rcv.sb_flagsintr &= ~SB_KNOTE;
}

int
filt_fiforead(struct knote *kn, long hint)
{
	struct socket *so = (struct socket *)kn->kn_hook;
	int rv;

	kn->kn_data = so->so_rcv.sb_cc;
	if (so->so_state & SS_CANTRCVMORE) {
		kn->kn_flags |= EV_EOF;
		rv = 1;
	} else {
		kn->kn_flags &= ~EV_EOF;
		rv = (kn->kn_data > 0);
	}

	return (rv);
}

void
filt_fifowdetach(struct knote *kn)
{
	struct socket *so = (struct socket *)kn->kn_hook;

	SLIST_REMOVE(&so->so_snd.sb_sel.si_note, kn, knote, kn_selnext);
	if (SLIST_EMPTY(&so->so_snd.sb_sel.si_note))
		so->so_snd.sb_flagsintr &= ~SB_KNOTE;
}

int
filt_fifowrite(struct knote *kn, long hint)
{
	struct socket *so = (struct socket *)kn->kn_hook;
	int rv;

	kn->kn_data = sbspace(so, &so->so_snd);
	if (so->so_state & SS_CANTSENDMORE) {
		kn->kn_flags |= EV_EOF;
		rv = 1;
	} else {
		kn->kn_flags &= ~EV_EOF;
		rv = (kn->kn_data >= so->so_snd.sb_lowat);
	}

	return (rv);
}