xref: /freebsd/sys/fs/fifofs/fifo_vnops.c (revision 6af83ee0d2941d18880b6aaa2b4facd1d30c6106)
1 /*-
2  * Copyright (c) 1990, 1993, 1995
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)fifo_vnops.c	8.10 (Berkeley) 5/27/95
30  * $FreeBSD$
31  */
32 
33 #include <sys/param.h>
34 #include <sys/event.h>
35 #include <sys/file.h>
36 #include <sys/filedesc.h>
37 #include <sys/filio.h>
38 #include <sys/fcntl.h>
39 #include <sys/kernel.h>
40 #include <sys/lock.h>
41 #include <sys/mutex.h>
42 #include <sys/malloc.h>
43 #include <sys/poll.h>
44 #include <sys/proc.h> /* XXXKSE */
45 #include <sys/signalvar.h>
46 #include <sys/socket.h>
47 #include <sys/socketvar.h>
48 #include <sys/sx.h>
49 #include <sys/systm.h>
50 #include <sys/un.h>
51 #include <sys/unistd.h>
52 #include <sys/vnode.h>
53 #include <fs/fifofs/fifo.h>
54 
55 static fo_rdwr_t        fifo_read_f;
56 static fo_rdwr_t        fifo_write_f;
57 static fo_ioctl_t       fifo_ioctl_f;
58 static fo_poll_t        fifo_poll_f;
59 static fo_kqfilter_t    fifo_kqfilter_f;
60 static fo_stat_t        fifo_stat_f;
61 static fo_close_t       fifo_close_f;
62 
63 struct fileops fifo_ops_f = {
64 	.fo_read =      fifo_read_f,
65 	.fo_write =     fifo_write_f,
66 	.fo_ioctl =     fifo_ioctl_f,
67 	.fo_poll =      fifo_poll_f,
68 	.fo_kqfilter =  fifo_kqfilter_f,
69 	.fo_stat =      fifo_stat_f,
70 	.fo_close =     fifo_close_f,
71 	.fo_flags =     DFLAG_PASSABLE | DFLAG_SEEKABLE
72 };
73 
74 /*
75  * This structure is associated with the FIFO vnode and stores
76  * the state associated with the FIFO.
77  */
78 struct fifoinfo {
79 	struct socket	*fi_readsock;
80 	struct socket	*fi_writesock;
81 	long		fi_readers;
82 	long		fi_writers;
83 };
84 
85 static vop_print_t	fifo_print;
86 static vop_open_t	fifo_open;
87 static vop_close_t	fifo_close;
88 static vop_ioctl_t	fifo_ioctl;
89 static vop_kqfilter_t	fifo_kqfilter;
90 static vop_pathconf_t	fifo_pathconf;
91 static vop_advlock_t	fifo_advlock;
92 
93 static void	filt_fifordetach(struct knote *kn);
94 static int	filt_fiforead(struct knote *kn, long hint);
95 static void	filt_fifowdetach(struct knote *kn);
96 static int	filt_fifowrite(struct knote *kn, long hint);
97 
98 static struct filterops fiforead_filtops =
99 	{ 1, NULL, filt_fifordetach, filt_fiforead };
100 static struct filterops fifowrite_filtops =
101 	{ 1, NULL, filt_fifowdetach, filt_fifowrite };
102 
103 struct vop_vector fifo_specops = {
104 	.vop_default =		&default_vnodeops,
105 
106 	.vop_access =		VOP_EBADF,
107 	.vop_advlock =		fifo_advlock,
108 	.vop_close =		fifo_close,
109 	.vop_create =		VOP_PANIC,
110 	.vop_getattr =		VOP_EBADF,
111 	.vop_ioctl =		fifo_ioctl,
112 	.vop_kqfilter =		fifo_kqfilter,
113 	.vop_lease =		VOP_NULL,
114 	.vop_link =		VOP_PANIC,
115 	.vop_mkdir =		VOP_PANIC,
116 	.vop_mknod =		VOP_PANIC,
117 	.vop_open =		fifo_open,
118 	.vop_pathconf =		fifo_pathconf,
119 	.vop_print =		fifo_print,
120 	.vop_read =		VOP_PANIC,
121 	.vop_readdir =		VOP_PANIC,
122 	.vop_readlink =		VOP_PANIC,
123 	.vop_reallocblks =	VOP_PANIC,
124 	.vop_reclaim =		VOP_NULL,
125 	.vop_remove =		VOP_PANIC,
126 	.vop_rename =		VOP_PANIC,
127 	.vop_rmdir =		VOP_PANIC,
128 	.vop_setattr =		VOP_EBADF,
129 	.vop_symlink =		VOP_PANIC,
130 	.vop_write =		VOP_PANIC,
131 };
132 
133 struct mtx fifo_mtx;
134 MTX_SYSINIT(fifo, &fifo_mtx, "fifo mutex", MTX_DEF);
135 
136 /*
137  * Dispose of fifo resources.
138  */
139 static void
140 fifo_cleanup(struct vnode *vp)
141 {
142 	struct fifoinfo *fip = vp->v_fifoinfo;
143 
144 	ASSERT_VOP_LOCKED(vp, "fifo_cleanup");
145 	if (fip->fi_readers == 0 && fip->fi_writers == 0) {
146 		vp->v_fifoinfo = NULL;
147 		(void)soclose(fip->fi_readsock);
148 		(void)soclose(fip->fi_writesock);
149 		FREE(fip, M_VNODE);
150 	}
151 }
152 
153 /*
154  * Open called to set up a new instance of a fifo or
155  * to find an active instance of a fifo.
156  */
157 /* ARGSUSED */
158 static int
159 fifo_open(ap)
160 	struct vop_open_args /* {
161 		struct vnode *a_vp;
162 		int  a_mode;
163 		struct ucred *a_cred;
164 		struct thread *a_td;
165 	} */ *ap;
166 {
167 	struct vnode *vp = ap->a_vp;
168 	struct fifoinfo *fip;
169 	struct thread *td = ap->a_td;
170 	struct ucred *cred = ap->a_cred;
171 	struct socket *rso, *wso;
172 	struct file *fp;
173 	int error;
174 
175 	if ((fip = vp->v_fifoinfo) == NULL) {
176 		MALLOC(fip, struct fifoinfo *, sizeof(*fip), M_VNODE, M_WAITOK);
177 		error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, cred, td);
178 		if (error)
179 			goto fail1;
180 		fip->fi_readsock = rso;
181 		error = socreate(AF_LOCAL, &wso, SOCK_STREAM, 0, cred, td);
182 		if (error)
183 			goto fail2;
184 		fip->fi_writesock = wso;
185 		error = uipc_connect2(wso, rso);
186 		if (error) {
187 			(void)soclose(wso);
188 fail2:
189 			(void)soclose(rso);
190 fail1:
191 			free(fip, M_VNODE);
192 			return (error);
193 		}
194 		fip->fi_readers = fip->fi_writers = 0;
195 		wso->so_snd.sb_lowat = PIPE_BUF;
196 		SOCKBUF_LOCK(&rso->so_rcv);
197 		rso->so_rcv.sb_state |= SBS_CANTRCVMORE;
198 		SOCKBUF_UNLOCK(&rso->so_rcv);
199 		vp->v_fifoinfo = fip;
200 	}
201 
202 	/*
203 	 * General access to fi_readers and fi_writers is protected using
204 	 * the vnode lock.
205 	 *
206 	 * Protect the increment of fi_readers and fi_writers and the
207 	 * associated calls to wakeup() with the fifo mutex in addition
208 	 * to the vnode lock.  This allows the vnode lock to be dropped
209 	 * for the msleep() calls below, and using the fifo mutex with
210 	 * msleep() prevents the wakeup from being missed.
211 	 */
212 	mtx_lock(&fifo_mtx);
213 	if (ap->a_mode & FREAD) {
214 		fip->fi_readers++;
215 		if (fip->fi_readers == 1) {
216 			SOCKBUF_LOCK(&fip->fi_writesock->so_snd);
217 			fip->fi_writesock->so_snd.sb_state &= ~SBS_CANTSENDMORE;
218 			SOCKBUF_UNLOCK(&fip->fi_writesock->so_snd);
219 			if (fip->fi_writers > 0) {
220 				wakeup(&fip->fi_writers);
221 				sowwakeup(fip->fi_writesock);
222 			}
223 		}
224 	}
225 	if (ap->a_mode & FWRITE) {
226 		if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
227 			mtx_unlock(&fifo_mtx);
228 			return (ENXIO);
229 		}
230 		fip->fi_writers++;
231 		if (fip->fi_writers == 1) {
232 			SOCKBUF_LOCK(&fip->fi_writesock->so_rcv);
233 			fip->fi_readsock->so_rcv.sb_state &= ~SBS_CANTRCVMORE;
234 			SOCKBUF_UNLOCK(&fip->fi_writesock->so_rcv);
235 			if (fip->fi_readers > 0) {
236 				wakeup(&fip->fi_readers);
237 				sorwakeup(fip->fi_writesock);
238 			}
239 		}
240 	}
241 	if ((ap->a_mode & O_NONBLOCK) == 0) {
242 		if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
243 			VOP_UNLOCK(vp, 0, td);
244 			error = msleep(&fip->fi_readers, &fifo_mtx,
245 			    PDROP | PCATCH | PSOCK, "fifoor", 0);
246 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
247 			if (error) {
248 				fip->fi_readers--;
249 				if (fip->fi_readers == 0) {
250 					socantsendmore(fip->fi_writesock);
251 					fifo_cleanup(vp);
252 				}
253 				return (error);
254 			}
255 			mtx_lock(&fifo_mtx);
256 			/*
257 			 * We must have got woken up because we had a writer.
258 			 * That (and not still having one) is the condition
259 			 * that we must wait for.
260 			 */
261 		}
262 		if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
263 			VOP_UNLOCK(vp, 0, td);
264 			error = msleep(&fip->fi_writers, &fifo_mtx,
265 			    PDROP | PCATCH | PSOCK, "fifoow", 0);
266 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
267 			if (error) {
268 				fip->fi_writers--;
269 				if (fip->fi_writers == 0) {
270 					socantrcvmore(fip->fi_readsock);
271 					fifo_cleanup(vp);
272 				}
273 				return (error);
274 			}
275 			/*
276 			 * We must have got woken up because we had
277 			 * a reader.  That (and not still having one)
278 			 * is the condition that we must wait for.
279 			 */
280 			mtx_lock(&fifo_mtx);
281 		}
282 	}
283 	mtx_unlock(&fifo_mtx);
284 	KASSERT(ap->a_fdidx >= 0, ("can't fifo/vnode bypass %d", ap->a_fdidx));
285 	fp = ap->a_td->td_proc->p_fd->fd_ofiles[ap->a_fdidx];
286 	KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
287 	fp->f_ops = &fifo_ops_f;
288 	fp->f_data = fip;
289 	return (0);
290 }
291 
292 /*
293  * Device ioctl operation.
294  */
295 /* ARGSUSED */
296 static int
297 fifo_ioctl(ap)
298 	struct vop_ioctl_args /* {
299 		struct vnode *a_vp;
300 		u_long  a_command;
301 		caddr_t  a_data;
302 		int  a_fflag;
303 		struct ucred *a_cred;
304 		struct thread *a_td;
305 	} */ *ap;
306 {
307 	struct file filetmp;	/* Local, so need not be locked. */
308 	int error;
309 
310 	if (ap->a_command == FIONBIO)
311 		return (0);
312 	if (ap->a_fflag & FREAD) {
313 		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
314 		filetmp.f_cred = ap->a_cred;
315 		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
316 		    ap->a_td->td_ucred, ap->a_td);
317 		if (error)
318 			return (error);
319 	}
320 	if (ap->a_fflag & FWRITE) {
321 		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
322 		filetmp.f_cred = ap->a_cred;
323 		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data,
324 		    ap->a_td->td_ucred, ap->a_td);
325 		if (error)
326 			return (error);
327 	}
328 	return (0);
329 }
330 
331 /* ARGSUSED */
332 static int
333 fifo_kqfilter(ap)
334 	struct vop_kqfilter_args /* {
335 		struct vnode *a_vp;
336 		struct knote *a_kn;
337 	} */ *ap;
338 {
339 	struct fifoinfo *fi = ap->a_vp->v_fifoinfo;
340 	struct socket *so;
341 	struct sockbuf *sb;
342 
343 	switch (ap->a_kn->kn_filter) {
344 	case EVFILT_READ:
345 		ap->a_kn->kn_fop = &fiforead_filtops;
346 		so = fi->fi_readsock;
347 		sb = &so->so_rcv;
348 		break;
349 	case EVFILT_WRITE:
350 		ap->a_kn->kn_fop = &fifowrite_filtops;
351 		so = fi->fi_writesock;
352 		sb = &so->so_snd;
353 		break;
354 	default:
355 		return (1);
356 	}
357 
358 	ap->a_kn->kn_hook = (caddr_t)so;
359 
360 	SOCKBUF_LOCK(sb);
361 	knlist_add(&sb->sb_sel.si_note, ap->a_kn, 1);
362 	sb->sb_flags |= SB_KNOTE;
363 	SOCKBUF_UNLOCK(sb);
364 
365 	return (0);
366 }
367 
368 static void
369 filt_fifordetach(struct knote *kn)
370 {
371 	struct socket *so = (struct socket *)kn->kn_hook;
372 
373 	SOCKBUF_LOCK(&so->so_rcv);
374 	knlist_remove(&so->so_rcv.sb_sel.si_note, kn, 1);
375 	if (knlist_empty(&so->so_rcv.sb_sel.si_note))
376 		so->so_rcv.sb_flags &= ~SB_KNOTE;
377 	SOCKBUF_UNLOCK(&so->so_rcv);
378 }
379 
380 static int
381 filt_fiforead(struct knote *kn, long hint)
382 {
383 	struct socket *so = (struct socket *)kn->kn_hook;
384 	int need_lock, result;
385 
386 	need_lock = !SOCKBUF_OWNED(&so->so_rcv);
387 	if (need_lock)
388 		SOCKBUF_LOCK(&so->so_rcv);
389 	kn->kn_data = so->so_rcv.sb_cc;
390 	if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
391 		kn->kn_flags |= EV_EOF;
392 		result = 1;
393 	} else {
394 		kn->kn_flags &= ~EV_EOF;
395 		result = (kn->kn_data > 0);
396 	}
397 	if (need_lock)
398 		SOCKBUF_UNLOCK(&so->so_rcv);
399 	return (result);
400 }
401 
402 static void
403 filt_fifowdetach(struct knote *kn)
404 {
405 	struct socket *so = (struct socket *)kn->kn_hook;
406 
407 	SOCKBUF_LOCK(&so->so_snd);
408 	knlist_remove(&so->so_snd.sb_sel.si_note, kn, 1);
409 	if (knlist_empty(&so->so_snd.sb_sel.si_note))
410 		so->so_snd.sb_flags &= ~SB_KNOTE;
411 	SOCKBUF_UNLOCK(&so->so_snd);
412 }
413 
414 static int
415 filt_fifowrite(struct knote *kn, long hint)
416 {
417 	struct socket *so = (struct socket *)kn->kn_hook;
418 	int need_lock, result;
419 
420 	need_lock = !SOCKBUF_OWNED(&so->so_snd);
421 	if (need_lock)
422 		SOCKBUF_LOCK(&so->so_snd);
423 	kn->kn_data = sbspace(&so->so_snd);
424 	if (so->so_snd.sb_state & SBS_CANTSENDMORE) {
425 		kn->kn_flags |= EV_EOF;
426 		result = 1;
427 	} else {
428 		kn->kn_flags &= ~EV_EOF;
429 	        result = (kn->kn_data >= so->so_snd.sb_lowat);
430 	}
431 	if (need_lock)
432 		SOCKBUF_UNLOCK(&so->so_snd);
433 	return (result);
434 }
435 
436 /*
437  * Device close routine
438  */
439 /* ARGSUSED */
440 static int
441 fifo_close(ap)
442 	struct vop_close_args /* {
443 		struct vnode *a_vp;
444 		int  a_fflag;
445 		struct ucred *a_cred;
446 		struct thread *a_td;
447 	} */ *ap;
448 {
449 	struct vnode *vp = ap->a_vp;
450 	struct thread *td = ap->a_td;
451 	struct fifoinfo *fip = vp->v_fifoinfo;
452 
453 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
454 
455 	if (ap->a_fflag & FREAD) {
456 		fip->fi_readers--;
457 		if (fip->fi_readers == 0)
458 			socantsendmore(fip->fi_writesock);
459 	}
460 	if (ap->a_fflag & FWRITE) {
461 		fip->fi_writers--;
462 		if (fip->fi_writers == 0)
463 			socantrcvmore(fip->fi_readsock);
464 	}
465 	fifo_cleanup(vp);
466 	VOP_UNLOCK(vp, 0, td);
467 	return (0);
468 }
469 
470 /*
471  * Print out internal contents of a fifo vnode.
472  */
473 int
474 fifo_printinfo(vp)
475 	struct vnode *vp;
476 {
477 	register struct fifoinfo *fip = vp->v_fifoinfo;
478 
479 	printf(", fifo with %ld readers and %ld writers",
480 		fip->fi_readers, fip->fi_writers);
481 	return (0);
482 }
483 
484 /*
485  * Print out the contents of a fifo vnode.
486  */
487 static int
488 fifo_print(ap)
489 	struct vop_print_args /* {
490 		struct vnode *a_vp;
491 	} */ *ap;
492 {
493 	fifo_printinfo(ap->a_vp);
494 	printf("\n");
495 	return (0);
496 }
497 
498 /*
499  * Return POSIX pathconf information applicable to fifo's.
500  */
501 static int
502 fifo_pathconf(ap)
503 	struct vop_pathconf_args /* {
504 		struct vnode *a_vp;
505 		int a_name;
506 		int *a_retval;
507 	} */ *ap;
508 {
509 
510 	switch (ap->a_name) {
511 	case _PC_LINK_MAX:
512 		*ap->a_retval = LINK_MAX;
513 		return (0);
514 	case _PC_PIPE_BUF:
515 		*ap->a_retval = PIPE_BUF;
516 		return (0);
517 	case _PC_CHOWN_RESTRICTED:
518 		*ap->a_retval = 1;
519 		return (0);
520 	default:
521 		return (EINVAL);
522 	}
523 	/* NOTREACHED */
524 }
525 
526 /*
527  * Fifo advisory byte-level locks.
528  */
529 /* ARGSUSED */
530 static int
531 fifo_advlock(ap)
532 	struct vop_advlock_args /* {
533 		struct vnode *a_vp;
534 		caddr_t  a_id;
535 		int  a_op;
536 		struct flock *a_fl;
537 		int  a_flags;
538 	} */ *ap;
539 {
540 
541 	return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
542 }
543 
544 static int
545 fifo_close_f(struct file *fp, struct thread *td)
546 {
547 
548 	return (vnops.fo_close(fp, td));
549 }
550 
551 static int
552 fifo_ioctl_f(struct file *fp, u_long com, void *data, struct ucred *cred, struct thread *td)
553 {
554 	struct fifoinfo *fi;
555 	struct file filetmp;	/* Local, so need not be locked. */
556 	int error;
557 
558 	error = ENOTTY;
559 	fi = fp->f_data;
560 	if (com == FIONBIO)
561 		return (0);
562 	if (fp->f_flag & FREAD) {
563 		filetmp.f_data = fi->fi_readsock;
564 		filetmp.f_cred = cred;
565 		error = soo_ioctl(&filetmp, com, data, cred, td);
566 		if (error)
567 			return (error);
568 	}
569 	if (fp->f_flag & FWRITE) {
570 		filetmp.f_data = fi->fi_writesock;
571 		filetmp.f_cred = cred;
572 		error = soo_ioctl(&filetmp, com, data, cred, td);
573 	}
574 	return (error);
575 }
576 
577 static int
578 fifo_kqfilter_f(struct file *fp, struct knote *kn)
579 {
580 	struct fifoinfo *fi;
581 	struct socket *so;
582 	struct sockbuf *sb;
583 
584 	fi = fp->f_data;
585 	switch (kn->kn_filter) {
586 	case EVFILT_READ:
587 		kn->kn_fop = &fiforead_filtops;
588 		so = fi->fi_readsock;
589 		sb = &so->so_rcv;
590 		break;
591 	case EVFILT_WRITE:
592 		kn->kn_fop = &fifowrite_filtops;
593 		so = fi->fi_writesock;
594 		sb = &so->so_snd;
595 		break;
596 	default:
597 		return (1);
598 	}
599 
600 	kn->kn_hook = (caddr_t)so;
601 
602 	SOCKBUF_LOCK(sb);
603 	knlist_add(&sb->sb_sel.si_note, kn, 1);
604 	sb->sb_flags |= SB_KNOTE;
605 	SOCKBUF_UNLOCK(sb);
606 
607 	return (0);
608 }
609 
610 static int
611 fifo_poll_f(struct file *fp, int events, struct ucred *cred, struct thread *td)
612 {
613 	struct fifoinfo *fip;
614 	struct file filetmp;
615 	int levents, revents = 0;
616 
617 	fip = fp->f_data;
618 	levents = events &
619 	    (POLLIN | POLLINIGNEOF | POLLPRI | POLLRDNORM | POLLRDBAND);
620 	if (levents) {
621 		/*
622 		 * If POLLIN or POLLRDNORM is requested and POLLINIGNEOF is
623 		 * not, then convert the first two to the last one.  This
624 		 * tells the socket poll function to ignore EOF so that we
625 		 * block if there is no writer (and no data).  Callers can
626 		 * set POLLINIGNEOF to get non-blocking behavior.
627 		 */
628 		if (levents & (POLLIN | POLLRDNORM) &&
629 		    !(levents & POLLINIGNEOF)) {
630 			levents &= ~(POLLIN | POLLRDNORM);
631 			levents |= POLLINIGNEOF;
632 		}
633 
634 		filetmp.f_data = fip->fi_readsock;
635 		filetmp.f_cred = cred;
636 		if (filetmp.f_data)
637 			revents |= soo_poll(&filetmp, levents, cred, td);
638 
639 		/* Reverse the above conversion. */
640 		if ((revents & POLLINIGNEOF) && !(events & POLLINIGNEOF)) {
641 			revents |= (events & (POLLIN | POLLRDNORM));
642 			revents &= ~POLLINIGNEOF;
643 		}
644 	}
645 	levents = events & (POLLOUT | POLLWRNORM | POLLWRBAND);
646 	if (events) {
647 		filetmp.f_data = fip->fi_writesock;
648 		filetmp.f_cred = cred;
649 		if (filetmp.f_data) {
650 			revents |= soo_poll(&filetmp, events, cred, td);
651 		}
652 	}
653 	return (revents);
654 }
655 
656 static int
657 fifo_read_f(struct file *fp, struct uio *uio, struct ucred *cred, int flags, struct thread *td)
658 {
659 	struct fifoinfo *fip;
660 	int error, sflags;
661 
662 	fip = fp->f_data;
663 	KASSERT(uio->uio_rw == UIO_READ,("fifo_read mode"));
664 	if (uio->uio_resid == 0)
665 		return (0);
666 	sflags = (fp->f_flag & FNONBLOCK) ? MSG_NBIO : 0;
667 	error = soreceive(fip->fi_readsock, NULL, uio, NULL, NULL, &sflags);
668 	return (error);
669 }
670 
671 static int
672 fifo_stat_f(struct file *fp, struct stat *sb, struct ucred *cred, struct thread *td)
673 {
674 
675 	return (vnops.fo_stat(fp, sb, cred, td));
676 }
677 
678 static int
679 fifo_write_f(struct file *fp, struct uio *uio, struct ucred *cred, int flags, struct thread *td)
680 {
681 	struct fifoinfo *fip;
682 	int error, sflags;
683 
684 	fip = fp->f_data;
685 	KASSERT(uio->uio_rw == UIO_WRITE,("fifo_write mode"));
686 	sflags = (fp->f_flag & FNONBLOCK) ? MSG_NBIO : 0;
687 	error = sosend(fip->fi_writesock, NULL, uio, 0, NULL, sflags, td);
688 	return (error);
689 }
690 
691