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      1 /*	$NetBSD: fifo_vnops.c,v 1.91 2021/10/11 01:07:36 thorpej Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2008 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 /*
     30  * Copyright (c) 1990, 1993, 1995
     31  *	The Regents of the University of California.  All rights reserved.
     32  *
     33  * Redistribution and use in source and binary forms, with or without
     34  * modification, are permitted provided that the following conditions
     35  * are met:
     36  * 1. Redistributions of source code must retain the above copyright
     37  *    notice, this list of conditions and the following disclaimer.
     38  * 2. Redistributions in binary form must reproduce the above copyright
     39  *    notice, this list of conditions and the following disclaimer in the
     40  *    documentation and/or other materials provided with the distribution.
     41  * 3. Neither the name of the University nor the names of its contributors
     42  *    may be used to endorse or promote products derived from this software
     43  *    without specific prior written permission.
     44  *
     45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     55  * SUCH DAMAGE.
     56  *
     57  *	@(#)fifo_vnops.c	8.10 (Berkeley) 5/27/95
     58  */
     59 
     60 #include <sys/cdefs.h>
     61 __KERNEL_RCSID(0, "$NetBSD: fifo_vnops.c,v 1.91 2021/10/11 01:07:36 thorpej Exp $");
     62 
     63 #include <sys/param.h>
     64 #include <sys/systm.h>
     65 #include <sys/proc.h>
     66 #include <sys/time.h>
     67 #include <sys/namei.h>
     68 #include <sys/vnode.h>
     69 #include <sys/socket.h>
     70 #include <sys/protosw.h>
     71 #include <sys/socketvar.h>
     72 #include <sys/stat.h>
     73 #include <sys/ioctl.h>
     74 #include <sys/file.h>
     75 #include <sys/errno.h>
     76 #include <sys/kmem.h>
     77 #include <sys/un.h>
     78 #include <sys/poll.h>
     79 #include <sys/event.h>
     80 #include <sys/condvar.h>
     81 
     82 #include <miscfs/fifofs/fifo.h>
     83 #include <miscfs/genfs/genfs.h>
     84 
     85 /*
     86  * This structure is associated with the FIFO vnode and stores
     87  * the state associated with the FIFO.
     88  */
     89 struct fifoinfo {
     90 	struct socket	*fi_readsock;
     91 	struct socket	*fi_writesock;
     92 	kcondvar_t	fi_rcv;
     93 	int		fi_readers;
     94 	kcondvar_t	fi_wcv;
     95 	int		fi_writers;
     96 };
     97 
     98 /*
     99  * Trivial lookup routine that always fails.
    100  */
    101 /* ARGSUSED */
    102 static int
    103 fifo_lookup(void *v)
    104 {
    105 	struct vop_lookup_v2_args /* {
    106 		struct vnode		*a_dvp;
    107 		struct vnode		**a_vpp;
    108 		struct componentname	*a_cnp;
    109 	} */ *ap = v;
    110 
    111 	*ap->a_vpp = NULL;
    112 	return (ENOTDIR);
    113 }
    114 
    115 /*
    116  * Open called to set up a new instance of a fifo or
    117  * to find an active instance of a fifo.
    118  */
    119 static int
    120 fifo_open(void *v)
    121 {
    122 	struct vop_open_args /* {
    123 		struct vnode	*a_vp;
    124 		int		a_mode;
    125 		kauth_cred_t	a_cred;
    126 	} */ *ap = v;
    127 	struct lwp	*l = curlwp;
    128 	struct vnode	*vp;
    129 	struct fifoinfo	*fip;
    130 	struct socket	*rso, *wso;
    131 	int		error;
    132 
    133 	vp = ap->a_vp;
    134 	KASSERT(VOP_ISLOCKED(vp));
    135 
    136 	if ((fip = vp->v_fifoinfo) == NULL) {
    137 		fip = kmem_alloc(sizeof(*fip), KM_SLEEP);
    138 		error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, l, NULL);
    139 		if (error != 0) {
    140 			kmem_free(fip, sizeof(*fip));
    141 			return (error);
    142 		}
    143 		fip->fi_readsock = rso;
    144 		error = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0, l, rso);
    145 		if (error != 0) {
    146 			(void)soclose(rso);
    147 			kmem_free(fip, sizeof(*fip));
    148 			return (error);
    149 		}
    150 		fip->fi_writesock = wso;
    151 		solock(wso);
    152 		if ((error = unp_connect2(wso, rso)) != 0) {
    153 			sounlock(wso);
    154 			(void)soclose(wso);
    155 			(void)soclose(rso);
    156 			kmem_free(fip, sizeof(*fip));
    157 			return (error);
    158 		}
    159 
    160 		/*
    161 		 * FIFOs must be readable when there is at least 1
    162 		 * byte of data available in the receive buffer.
    163 		 *
    164 		 * FIFOs must be writable when there is space for
    165 		 * at least PIPE_BUF bytes in the send buffer.
    166 		 * If we're increasing the low water mark for the
    167 		 * send buffer, then mimic how soreserve() would
    168 		 * have set the high water mark.
    169 		 */
    170 		rso->so_rcv.sb_lowat = 1;
    171 		if (wso->so_snd.sb_lowat < PIPE_BUF) {
    172 			wso->so_snd.sb_hiwat = PIPE_BUF * 2;
    173 		}
    174 		wso->so_snd.sb_lowat = PIPE_BUF;
    175 
    176 		fip->fi_readers = 0;
    177 		fip->fi_writers = 0;
    178 		wso->so_state |= SS_CANTRCVMORE;
    179 		rso->so_state |= SS_CANTSENDMORE;
    180 		cv_init(&fip->fi_rcv, "fiford");
    181 		cv_init(&fip->fi_wcv, "fifowr");
    182 		vp->v_fifoinfo = fip;
    183 	} else {
    184 		wso = fip->fi_writesock;
    185 		rso = fip->fi_readsock;
    186 		solock(wso);
    187 	}
    188 
    189 	if (ap->a_mode & FREAD) {
    190 		if (fip->fi_readers++ == 0) {
    191 			wso->so_state &= ~SS_CANTSENDMORE;
    192 			cv_broadcast(&fip->fi_wcv);
    193 		}
    194 	}
    195 	if (ap->a_mode & FWRITE) {
    196 		if (fip->fi_writers++ == 0) {
    197 			rso->so_state &= ~SS_CANTRCVMORE;
    198 			cv_broadcast(&fip->fi_rcv);
    199 		}
    200 	}
    201 	if (ap->a_mode & FREAD) {
    202 		if (ap->a_mode & O_NONBLOCK) {
    203 		} else {
    204 			while (!soreadable(rso) && fip->fi_writers == 0) {
    205 				VOP_UNLOCK(vp);
    206 				error = cv_wait_sig(&fip->fi_rcv,
    207 				    wso->so_lock);
    208 				sounlock(wso);
    209 				vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    210 				if (error)
    211 					goto bad;
    212 				solock(wso);
    213 			}
    214 		}
    215 	}
    216 	if (ap->a_mode & FWRITE) {
    217 		if (ap->a_mode & O_NONBLOCK) {
    218 			if (fip->fi_readers == 0) {
    219 				error = ENXIO;
    220 				sounlock(wso);
    221 				goto bad;
    222 			}
    223 		} else {
    224 			while (fip->fi_readers == 0) {
    225 				VOP_UNLOCK(vp);
    226 				error = cv_wait_sig(&fip->fi_wcv,
    227 				    wso->so_lock);
    228 				sounlock(wso);
    229 				vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    230 				if (error)
    231 					goto bad;
    232 				solock(wso);
    233 			}
    234 		}
    235 	}
    236 	sounlock(wso);
    237 	return (0);
    238  bad:
    239 	VOP_CLOSE(vp, ap->a_mode, ap->a_cred);
    240 	return (error);
    241 }
    242 
    243 /*
    244  * Vnode op for read
    245  */
    246 /* ARGSUSED */
    247 static int
    248 fifo_read(void *v)
    249 {
    250 	struct vop_read_args /* {
    251 		struct vnode	*a_vp;
    252 		struct uio	*a_uio;
    253 		int		a_ioflag;
    254 		kauth_cred_t	a_cred;
    255 	} */ *ap = v;
    256 	struct uio	*uio;
    257 	struct socket	*rso;
    258 	int		error, sflags;
    259 	size_t		startresid;
    260 
    261 	uio = ap->a_uio;
    262 	rso = ap->a_vp->v_fifoinfo->fi_readsock;
    263 #ifdef DIAGNOSTIC
    264 	if (uio->uio_rw != UIO_READ)
    265 		panic("fifo_read mode");
    266 #endif
    267 	if (uio->uio_resid == 0)
    268 		return (0);
    269 	startresid = uio->uio_resid;
    270 	VOP_UNLOCK(ap->a_vp);
    271 	sflags = (ap->a_ioflag & IO_NDELAY) ? MSG_NBIO : 0;
    272 	error = (*rso->so_receive)(rso, NULL, uio, NULL, NULL, &sflags);
    273 	/*
    274 	 * Clear EOF indication after first such return.
    275 	 */
    276 	if (error == 0 && uio->uio_resid == startresid)
    277 		rso->so_state &= ~SS_CANTRCVMORE;
    278 	if (ap->a_ioflag & IO_NDELAY) {
    279 		if (error == EWOULDBLOCK &&
    280 		    ap->a_vp->v_fifoinfo->fi_writers == 0)
    281 			error = 0;
    282 	}
    283 	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
    284 	return (error);
    285 }
    286 
    287 /*
    288  * Vnode op for write
    289  */
    290 /* ARGSUSED */
    291 static int
    292 fifo_write(void *v)
    293 {
    294 	struct vop_write_args /* {
    295 		struct vnode	*a_vp;
    296 		struct uio	*a_uio;
    297 		int		a_ioflag;
    298 		kauth_cred_t	a_cred;
    299 	} */ *ap = v;
    300 	struct socket	*wso;
    301 	int		error, sflags;
    302 
    303 	wso = ap->a_vp->v_fifoinfo->fi_writesock;
    304 #ifdef DIAGNOSTIC
    305 	if (ap->a_uio->uio_rw != UIO_WRITE)
    306 		panic("fifo_write mode");
    307 #endif
    308 	VOP_UNLOCK(ap->a_vp);
    309 	sflags = (ap->a_ioflag & IO_NDELAY) ? MSG_NBIO : 0;
    310 	error = (*wso->so_send)(wso, NULL, ap->a_uio, 0, NULL, sflags, curlwp);
    311 	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
    312 	return (error);
    313 }
    314 
    315 /*
    316  * Device ioctl operation.
    317  */
    318 /* ARGSUSED */
    319 static int
    320 fifo_ioctl(void *v)
    321 {
    322 	struct vop_ioctl_args /* {
    323 		struct vnode	*a_vp;
    324 		u_long		a_command;
    325 		void		*a_data;
    326 		int		a_fflag;
    327 		kauth_cred_t	a_cred;
    328 		struct lwp	*a_l;
    329 	} */ *ap = v;
    330 	struct file	filetmp;
    331 	int		error;
    332 
    333 	if (ap->a_command == FIONBIO)
    334 		return (0);
    335 	if (ap->a_fflag & FREAD) {
    336 		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
    337 		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data);
    338 		if (error)
    339 			return (error);
    340 	}
    341 	if (ap->a_fflag & FWRITE) {
    342 		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
    343 		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data);
    344 		if (error)
    345 			return (error);
    346 	}
    347 	return (0);
    348 }
    349 
    350 /* ARGSUSED */
    351 static int
    352 fifo_poll(void *v)
    353 {
    354 	struct vop_poll_args /* {
    355 		struct vnode	*a_vp;
    356 		int		a_events;
    357 	} */ *ap = v;
    358 	struct socket	*rso = ap->a_vp->v_fifoinfo->fi_readsock;
    359 	struct socket	*wso = ap->a_vp->v_fifoinfo->fi_writesock;
    360 	struct socket	*lso = NULL;
    361 	int		events;
    362 
    363 	/*
    364 	 * N.B. We're using a slightly different naming convention
    365 	 * for these variables that most poll handlers.
    366 	 */
    367 	int		revents = 0;
    368 	int		wevents = 0;
    369 
    370 	if (rso != NULL) {
    371 		lso = rso;
    372 	} else if (wso != NULL) {
    373 		lso = wso;
    374 	}
    375 
    376 	if (lso == NULL) {
    377 		/* No associated sockets -> no events to report. */
    378 		return 0;
    379 	}
    380 
    381 	KASSERT(rso == NULL || lso->so_lock == rso->so_lock);
    382 	KASSERT(wso == NULL || lso->so_lock == wso->so_lock);
    383 
    384 	solock(lso);
    385 
    386 	if (rso != NULL) {
    387 		events = ap->a_events & (POLLIN | POLLRDNORM);
    388 		if (events != 0 && soreadable(rso)) {
    389 			revents |= events;
    390 		}
    391 		if (rso->so_state & SS_CANTRCVMORE) {
    392 			revents |= POLLHUP;
    393 		}
    394 		/*
    395 		 * We always selrecord the read side here regardless
    396 		 * of the caller's read interest because we need to
    397 		 * action POLLHUP.
    398 		 */
    399 		if (revents == 0) {
    400 			selrecord(curlwp, &rso->so_rcv.sb_sel);
    401 			rso->so_rcv.sb_flags |= SB_NOTIFY;
    402 		}
    403 	}
    404 
    405 	/* POSIX sez: POLLHUP and POLLOUT are mutually-exclusive. */
    406 	if (wso != NULL && (revents & POLLHUP) == 0) {
    407 		events = ap->a_events & (POLLOUT | POLLWRNORM);
    408 		if (events != 0 && sowritable(wso)) {
    409 			wevents |= events;
    410 		}
    411 		if (wevents == 0 && events != 0) {
    412 			selrecord(curlwp, &wso->so_snd.sb_sel);
    413 			wso->so_snd.sb_flags |= SB_NOTIFY;
    414 		}
    415 	}
    416 
    417 	sounlock(lso);
    418 
    419 	return (revents | wevents);
    420 }
    421 
    422 static int
    423 fifo_inactive(void *v)
    424 {
    425 	struct vop_inactive_v2_args /* {
    426 		struct vnode	*a_vp;
    427 		struct lwp	*a_l;
    428 	} */ *ap __unused = v;
    429 
    430 	return (0);
    431 }
    432 
    433 /*
    434  * This is a noop, simply returning what one has been given.
    435  */
    436 static int
    437 fifo_bmap(void *v)
    438 {
    439 	struct vop_bmap_args /* {
    440 		struct vnode	*a_vp;
    441 		daddr_t		a_bn;
    442 		struct vnode	**a_vpp;
    443 		daddr_t		*a_bnp;
    444 		int		*a_runp;
    445 	} */ *ap = v;
    446 
    447 	if (ap->a_vpp != NULL)
    448 		*ap->a_vpp = ap->a_vp;
    449 	if (ap->a_bnp != NULL)
    450 		*ap->a_bnp = ap->a_bn;
    451 	if (ap->a_runp != NULL)
    452 		*ap->a_runp = 0;
    453 	return (0);
    454 }
    455 
    456 /*
    457  * This is like socantrcvmore(), but we send the POLL_HUP code.
    458  */
    459 static void
    460 fifo_socantrcvmore(struct socket *so)
    461 {
    462 	KASSERT(solocked(so));
    463 
    464 	so->so_state |= SS_CANTRCVMORE;
    465 	if (sb_notify(&so->so_rcv)) {
    466 		sowakeup(so, &so->so_rcv, POLL_HUP);
    467 	}
    468 }
    469 
    470 /*
    471  * Device close routine
    472  */
    473 /* ARGSUSED */
    474 static int
    475 fifo_close(void *v)
    476 {
    477 	struct vop_close_args /* {
    478 		struct vnode	*a_vp;
    479 		int		a_fflag;
    480 		kauth_cred_t	a_cred;
    481 		struct lwp	*a_l;
    482 	} */ *ap = v;
    483 	struct vnode	*vp;
    484 	struct fifoinfo	*fip;
    485 	struct socket *wso, *rso;
    486 	int isrevoke;
    487 
    488 	vp = ap->a_vp;
    489 	fip = vp->v_fifoinfo;
    490 	isrevoke = (ap->a_fflag & (FREAD | FWRITE | FNONBLOCK)) == FNONBLOCK;
    491 	wso = fip->fi_writesock;
    492 	rso = fip->fi_readsock;
    493 	solock(wso);
    494 	if (isrevoke) {
    495 		if (fip->fi_readers != 0) {
    496 			fip->fi_readers = 0;
    497 			socantsendmore(wso);
    498 		}
    499 		if (fip->fi_writers != 0) {
    500 			fip->fi_writers = 0;
    501 			fifo_socantrcvmore(rso);
    502 		}
    503 	} else {
    504 		if ((ap->a_fflag & FREAD) && --fip->fi_readers == 0)
    505 			socantsendmore(wso);
    506 		if ((ap->a_fflag & FWRITE) && --fip->fi_writers == 0)
    507 			fifo_socantrcvmore(rso);
    508 	}
    509 	if ((fip->fi_readers + fip->fi_writers) == 0) {
    510 		sounlock(wso);
    511 		(void) soclose(rso);
    512 		(void) soclose(wso);
    513 		cv_destroy(&fip->fi_rcv);
    514 		cv_destroy(&fip->fi_wcv);
    515 		kmem_free(fip, sizeof(*fip));
    516 		vp->v_fifoinfo = NULL;
    517 	} else
    518 		sounlock(wso);
    519 	return (0);
    520 }
    521 
    522 /*
    523  * Print out internal contents of a fifo vnode.
    524  */
    525 static void
    526 fifo_printinfo(struct vnode *vp)
    527 {
    528 	struct fifoinfo	*fip;
    529 
    530 	fip = vp->v_fifoinfo;
    531 	printf(", fifo with %d readers and %d writers",
    532 	    fip->fi_readers, fip->fi_writers);
    533 }
    534 
    535 /*
    536  * Print out the contents of a fifo vnode.
    537  */
    538 static int
    539 fifo_print(void *v)
    540 {
    541 	struct vop_print_args /* {
    542 		struct vnode	*a_vp;
    543 	} */ *ap = v;
    544 
    545 	/*
    546 	 * We are most likely being called with the vnode belonging
    547 	 * to some file system and this is not printed.
    548 	 */
    549 	if (ap->a_vp->v_tag == VT_NON)
    550 		printf("tag VT_NON");
    551 
    552 	fifo_printinfo(ap->a_vp);
    553 	printf("\n");
    554 	return 0;
    555 }
    556 
    557 /*
    558  * Return POSIX pathconf information applicable to fifo's.
    559  */
    560 static int
    561 fifo_pathconf(void *v)
    562 {
    563 	struct vop_pathconf_args /* {
    564 		struct vnode	*a_vp;
    565 		int		a_name;
    566 		register_t	*a_retval;
    567 	} */ *ap = v;
    568 
    569 	switch (ap->a_name) {
    570 	case _PC_LINK_MAX:
    571 		*ap->a_retval = LINK_MAX;
    572 		return (0);
    573 	case _PC_PIPE_BUF:
    574 		*ap->a_retval = PIPE_BUF;
    575 		return (0);
    576 	case _PC_CHOWN_RESTRICTED:
    577 		*ap->a_retval = 1;
    578 		return (0);
    579 	case _PC_SYNC_IO:
    580 		*ap->a_retval = 1;
    581 		return (0);
    582 	default:
    583 		return genfs_pathconf(ap);
    584 	}
    585 	/* NOTREACHED */
    586 }
    587 
    588 static void
    589 filt_fifordetach(struct knote *kn)
    590 {
    591 	struct socket *so;
    592 
    593 	so = (struct socket *)kn->kn_hook;
    594 	solock(so);
    595 	if (selremove_knote(&so->so_rcv.sb_sel, kn))
    596 		so->so_rcv.sb_flags &= ~SB_KNOTE;
    597 	sounlock(so);
    598 }
    599 
    600 static int
    601 filt_fiforead(struct knote *kn, long hint)
    602 {
    603 	struct socket *so;
    604 	int rv;
    605 
    606 	so = (struct socket *)kn->kn_hook;
    607 	if (hint != NOTE_SUBMIT)
    608 		solock(so);
    609 	kn->kn_data = so->so_rcv.sb_cc;
    610 	if (so->so_state & SS_CANTRCVMORE) {
    611 		knote_set_eof(kn, 0);
    612 		rv = 1;
    613 	} else {
    614 		knote_clear_eof(kn);
    615 		rv = (kn->kn_data >= so->so_rcv.sb_lowat);
    616 	}
    617 	if (hint != NOTE_SUBMIT)
    618 		sounlock(so);
    619 	return rv;
    620 }
    621 
    622 static void
    623 filt_fifowdetach(struct knote *kn)
    624 {
    625 	struct socket *so;
    626 
    627 	so = (struct socket *)kn->kn_hook;
    628 	solock(so);
    629 	if (selremove_knote(&so->so_snd.sb_sel, kn))
    630 		so->so_snd.sb_flags &= ~SB_KNOTE;
    631 	sounlock(so);
    632 }
    633 
    634 static int
    635 filt_fifowrite(struct knote *kn, long hint)
    636 {
    637 	struct socket *so;
    638 	int rv;
    639 
    640 	so = (struct socket *)kn->kn_hook;
    641 	if (hint != NOTE_SUBMIT)
    642 		solock(so);
    643 	kn->kn_data = sbspace(&so->so_snd);
    644 	if (so->so_state & SS_CANTSENDMORE) {
    645 		knote_set_eof(kn, 0);
    646 		rv = 1;
    647 	} else {
    648 		knote_clear_eof(kn);
    649 		rv = (kn->kn_data >= so->so_snd.sb_lowat);
    650 	}
    651 	if (hint != NOTE_SUBMIT)
    652 		sounlock(so);
    653 	return rv;
    654 }
    655 
    656 static const struct filterops fiforead_filtops = {
    657 	.f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
    658 	.f_attach = NULL,
    659 	.f_detach = filt_fifordetach,
    660 	.f_event = filt_fiforead,
    661 };
    662 
    663 static const struct filterops fifowrite_filtops = {
    664 	.f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
    665 	.f_attach = NULL,
    666 	.f_detach = filt_fifowdetach,
    667 	.f_event = filt_fifowrite,
    668 };
    669 
    670 /* ARGSUSED */
    671 static int
    672 fifo_kqfilter(void *v)
    673 {
    674 	struct vop_kqfilter_args /* {
    675 		struct vnode *a_vp;
    676 		struct knote *a_kn;
    677 	} */ *ap = v;
    678 	struct socket	*so;
    679 	struct sockbuf	*sb;
    680 
    681 	switch (ap->a_kn->kn_filter) {
    682 	case EVFILT_READ:
    683 		so = (struct socket *)ap->a_vp->v_fifoinfo->fi_readsock;
    684 		ap->a_kn->kn_fop = &fiforead_filtops;
    685 		sb = &so->so_rcv;
    686 		break;
    687 	case EVFILT_WRITE:
    688 		so = (struct socket *)ap->a_vp->v_fifoinfo->fi_writesock;
    689 		ap->a_kn->kn_fop = &fifowrite_filtops;
    690 		sb = &so->so_snd;
    691 		break;
    692 	default:
    693 		return (EINVAL);
    694 	}
    695 
    696 	ap->a_kn->kn_hook = so;
    697 
    698 	solock(so);
    699 	selrecord_knote(&sb->sb_sel, ap->a_kn);
    700 	sb->sb_flags |= SB_KNOTE;
    701 	sounlock(so);
    702 
    703 	return (0);
    704 }
    705 
    706 int (**fifo_vnodeop_p)(void *);
    707 const struct vnodeopv_entry_desc fifo_vnodeop_entries[] = {
    708 	{ &vop_default_desc, vn_default_error },
    709 	{ &vop_parsepath_desc, genfs_parsepath },	/* parsepath */
    710 	{ &vop_lookup_desc, fifo_lookup },		/* lookup */
    711 	{ &vop_create_desc, genfs_badop },		/* create */
    712 	{ &vop_mknod_desc, genfs_badop },		/* mknod */
    713 	{ &vop_open_desc, fifo_open },			/* open */
    714 	{ &vop_close_desc, fifo_close },		/* close */
    715 	{ &vop_access_desc, genfs_ebadf },		/* access */
    716 	{ &vop_accessx_desc, genfs_accessx },		/* accessx */
    717 	{ &vop_getattr_desc, genfs_ebadf },		/* getattr */
    718 	{ &vop_setattr_desc, genfs_ebadf },		/* setattr */
    719 	{ &vop_read_desc, fifo_read },			/* read */
    720 	{ &vop_write_desc, fifo_write },		/* write */
    721 	{ &vop_fallocate_desc, genfs_eopnotsupp },	/* fallocate */
    722 	{ &vop_fdiscard_desc, genfs_eopnotsupp },	/* fdiscard */
    723 	{ &vop_ioctl_desc, fifo_ioctl },		/* ioctl */
    724 	{ &vop_poll_desc, fifo_poll },			/* poll */
    725 	{ &vop_kqfilter_desc, fifo_kqfilter },		/* kqfilter */
    726 	{ &vop_revoke_desc, genfs_revoke },		/* revoke */
    727 	{ &vop_mmap_desc, genfs_badop },		/* mmap */
    728 	{ &vop_fsync_desc, genfs_nullop },		/* fsync */
    729 	{ &vop_seek_desc, genfs_badop },		/* seek */
    730 	{ &vop_remove_desc, genfs_badop },		/* remove */
    731 	{ &vop_link_desc, genfs_badop },		/* link */
    732 	{ &vop_rename_desc, genfs_badop },		/* rename */
    733 	{ &vop_mkdir_desc, genfs_badop },		/* mkdir */
    734 	{ &vop_rmdir_desc, genfs_badop },		/* rmdir */
    735 	{ &vop_symlink_desc, genfs_badop },		/* symlink */
    736 	{ &vop_readdir_desc, genfs_badop },		/* readdir */
    737 	{ &vop_readlink_desc, genfs_badop },		/* readlink */
    738 	{ &vop_abortop_desc, genfs_badop },		/* abortop */
    739 	{ &vop_inactive_desc, fifo_inactive },		/* inactive */
    740 	{ &vop_reclaim_desc, genfs_nullop },		/* reclaim */
    741 	{ &vop_lock_desc, genfs_lock },			/* lock */
    742 	{ &vop_unlock_desc, genfs_unlock },		/* unlock */
    743 	{ &vop_bmap_desc, fifo_bmap },			/* bmap */
    744 	{ &vop_strategy_desc, genfs_badop },		/* strategy */
    745 	{ &vop_print_desc, fifo_print },		/* print */
    746 	{ &vop_islocked_desc, genfs_islocked },		/* islocked */
    747 	{ &vop_pathconf_desc, fifo_pathconf },		/* pathconf */
    748 	{ &vop_advlock_desc, genfs_einval },		/* advlock */
    749 	{ &vop_bwrite_desc, genfs_nullop },		/* bwrite */
    750 	{ &vop_putpages_desc, genfs_null_putpages },	/* putpages */
    751 	{ NULL, NULL }
    752 };
    753 const struct vnodeopv_desc fifo_vnodeop_opv_desc =
    754 	{ &fifo_vnodeop_p, fifo_vnodeop_entries };
    755