xref: /openbsd-src/sys/miscfs/fifofs/fifo_vnops.c (revision 25c4e8bd056e974b28f4a0ffd39d76c190a56013) 
1 /*	$OpenBSD: fifo_vnops.c,v 1.96 2022/07/01 09:56:17 mvs Exp $	*/
2 /*	$NetBSD: fifo_vnops.c,v 1.18 1996/03/16 23:52:42 christos Exp $	*/
3 
4 /*
5  * Copyright (c) 1990, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	@(#)fifo_vnops.c	8.4 (Berkeley) 8/10/94
33  */
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/time.h>
38 #include <sys/namei.h>
39 #include <sys/vnode.h>
40 #include <sys/lock.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
43 #include <sys/socketvar.h>
44 #include <sys/stat.h>
45 #include <sys/ioctl.h>
46 #include <sys/fcntl.h>
47 #include <sys/file.h>
48 #include <sys/event.h>
49 #include <sys/errno.h>
50 #include <sys/malloc.h>
51 #include <sys/unistd.h>
52 
53 #include <miscfs/fifofs/fifo.h>
54 
55 /*
56  * This structure is associated with the FIFO vnode and stores
57  * the state associated with the FIFO.
58  */
59 struct fifoinfo {
60 	struct socket	*fi_readsock;
61 	struct socket	*fi_writesock;
62 	long		fi_readers;
63 	long		fi_writers;
64 };
65 
66 const struct vops fifo_vops = {
67 	.vop_lookup	= vop_generic_lookup,
68 	.vop_create	= vop_generic_badop,
69 	.vop_mknod	= vop_generic_badop,
70 	.vop_open	= fifo_open,
71 	.vop_close	= fifo_close,
72 	.vop_access	= fifo_ebadf,
73 	.vop_getattr	= fifo_ebadf,
74 	.vop_setattr	= fifo_ebadf,
75 	.vop_read	= fifo_read,
76 	.vop_write	= fifo_write,
77 	.vop_ioctl	= fifo_ioctl,
78 	.vop_kqfilter	= fifo_kqfilter,
79 	.vop_revoke	= vop_generic_revoke,
80 	.vop_fsync	= nullop,
81 	.vop_remove	= vop_generic_badop,
82 	.vop_link	= vop_generic_badop,
83 	.vop_rename	= vop_generic_badop,
84 	.vop_mkdir	= vop_generic_badop,
85 	.vop_rmdir	= vop_generic_badop,
86 	.vop_symlink	= vop_generic_badop,
87 	.vop_readdir	= vop_generic_badop,
88 	.vop_readlink	= vop_generic_badop,
89 	.vop_abortop	= vop_generic_badop,
90 	.vop_inactive	= fifo_inactive,
91 	.vop_reclaim	= fifo_reclaim,
92 	.vop_lock	= nullop,
93 	.vop_unlock	= nullop,
94 	.vop_islocked	= nullop,
95 	.vop_bmap	= vop_generic_bmap,
96 	.vop_strategy	= vop_generic_badop,
97 	.vop_print	= fifo_print,
98 	.vop_pathconf	= fifo_pathconf,
99 	.vop_advlock	= fifo_advlock,
100 	.vop_bwrite	= nullop
101 };
102 
103 void	filt_fifordetach(struct knote *kn);
104 int	filt_fiforead(struct knote *kn, long hint);
105 void	filt_fifowdetach(struct knote *kn);
106 int	filt_fifowrite(struct knote *kn, long hint);
107 int	filt_fifoexcept(struct knote *kn, long hint);
108 int	filt_fifomodify(struct kevent *kev, struct knote *kn);
109 int	filt_fifoprocess(struct knote *kn, struct kevent *kev);
110 
111 const struct filterops fiforead_filtops = {
112 	.f_flags	= FILTEROP_ISFD | FILTEROP_MPSAFE,
113 	.f_attach	= NULL,
114 	.f_detach	= filt_fifordetach,
115 	.f_event	= filt_fiforead,
116 	.f_modify	= filt_fifomodify,
117 	.f_process	= filt_fifoprocess,
118 };
119 
120 const struct filterops fifowrite_filtops = {
121 	.f_flags	= FILTEROP_ISFD | FILTEROP_MPSAFE,
122 	.f_attach	= NULL,
123 	.f_detach	= filt_fifowdetach,
124 	.f_event	= filt_fifowrite,
125 	.f_modify	= filt_fifomodify,
126 	.f_process	= filt_fifoprocess,
127 };
128 
129 const struct filterops fifoexcept_filtops = {
130 	.f_flags	= FILTEROP_ISFD | FILTEROP_MPSAFE,
131 	.f_attach	= NULL,
132 	.f_detach	= filt_fifordetach,
133 	.f_event	= filt_fifoexcept,
134 	.f_modify	= filt_fifomodify,
135 	.f_process	= filt_fifoprocess,
136 };
137 
138 /*
139  * Open called to set up a new instance of a fifo or
140  * to find an active instance of a fifo.
141  */
142 /* ARGSUSED */
143 int
144 fifo_open(void *v)
145 {
146 	struct vop_open_args *ap = v;
147 	struct vnode *vp = ap->a_vp;
148 	struct fifoinfo *fip;
149 	struct socket *rso, *wso;
150 	int error;
151 
152 	if ((fip = vp->v_fifoinfo) == NULL) {
153 		fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
154 		vp->v_fifoinfo = fip;
155 		if ((error = socreate(AF_UNIX, &rso, SOCK_STREAM, 0)) != 0) {
156 			free(fip, M_VNODE, sizeof *fip);
157 			vp->v_fifoinfo = NULL;
158 			return (error);
159 		}
160 		fip->fi_readsock = rso;
161 		if ((error = socreate(AF_UNIX, &wso, SOCK_STREAM, 0)) != 0) {
162 			(void)soclose(rso, 0);
163 			free(fip, M_VNODE, sizeof *fip);
164 			vp->v_fifoinfo = NULL;
165 			return (error);
166 		}
167 		fip->fi_writesock = wso;
168 		if ((error = soconnect2(wso, rso)) != 0) {
169 			(void)soclose(wso, 0);
170 			(void)soclose(rso, 0);
171 			free(fip, M_VNODE, sizeof *fip);
172 			vp->v_fifoinfo = NULL;
173 			return (error);
174 		}
175 		fip->fi_readers = fip->fi_writers = 0;
176 		solock(wso);
177 		wso->so_state |= SS_CANTSENDMORE;
178 		wso->so_snd.sb_lowat = PIPE_BUF;
179 		sounlock(wso);
180 	} else {
181 		rso = fip->fi_readsock;
182 		wso = fip->fi_writesock;
183 	}
184 	if (ap->a_mode & FREAD) {
185 		fip->fi_readers++;
186 		if (fip->fi_readers == 1) {
187 			solock(wso);
188 			wso->so_state &= ~SS_CANTSENDMORE;
189 			sounlock(wso);
190 			if (fip->fi_writers > 0)
191 				wakeup(&fip->fi_writers);
192 		}
193 	}
194 	if (ap->a_mode & FWRITE) {
195 		fip->fi_writers++;
196 		if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
197 			error = ENXIO;
198 			goto bad;
199 		}
200 		if (fip->fi_writers == 1) {
201 			solock(rso);
202 			rso->so_state &= ~(SS_CANTRCVMORE|SS_ISDISCONNECTED);
203 			sounlock(rso);
204 			if (fip->fi_readers > 0)
205 				wakeup(&fip->fi_readers);
206 		}
207 	}
208 	if ((ap->a_mode & O_NONBLOCK) == 0) {
209 		if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
210 			VOP_UNLOCK(vp);
211 			error = tsleep_nsec(&fip->fi_readers,
212 			    PCATCH | PSOCK, "fifor", INFSLP);
213 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
214 			if (error)
215 				goto bad;
216 		}
217 		if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
218 			VOP_UNLOCK(vp);
219 			error = tsleep_nsec(&fip->fi_writers,
220 			    PCATCH | PSOCK, "fifow", INFSLP);
221 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
222 			if (error)
223 				goto bad;
224 		}
225 	}
226 	return (0);
227 bad:
228 	VOP_CLOSE(vp, ap->a_mode, ap->a_cred, ap->a_p);
229 	return (error);
230 }
231 
232 /*
233  * Vnode op for read
234  */
235 /* ARGSUSED */
236 int
237 fifo_read(void *v)
238 {
239 	struct vop_read_args *ap = v;
240 	struct uio *uio = ap->a_uio;
241 	struct socket *rso = ap->a_vp->v_fifoinfo->fi_readsock;
242 	int error, flags = 0;
243 
244 #ifdef DIAGNOSTIC
245 	if (uio->uio_rw != UIO_READ)
246 		panic("fifo_read mode");
247 #endif
248 	if (uio->uio_resid == 0)
249 		return (0);
250 	if (ap->a_ioflag & IO_NDELAY)
251 		flags |= MSG_DONTWAIT;
252 	VOP_UNLOCK(ap->a_vp);
253 	error = soreceive(rso, NULL, uio, NULL, NULL, &flags, 0);
254 	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
255 	if (ap->a_ioflag & IO_NDELAY) {
256 		if (error == EWOULDBLOCK &&
257 		    ap->a_vp->v_fifoinfo->fi_writers == 0)
258 			error = 0;
259 	}
260 	return (error);
261 }
262 
263 /*
264  * Vnode op for write
265  */
266 /* ARGSUSED */
267 int
268 fifo_write(void *v)
269 {
270 	struct vop_write_args *ap = v;
271 	struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
272 	int error, flags = 0;
273 
274 #ifdef DIAGNOSTIC
275 	if (ap->a_uio->uio_rw != UIO_WRITE)
276 		panic("fifo_write mode");
277 #endif
278 	if (ap->a_ioflag & IO_NDELAY)
279 		flags |= MSG_DONTWAIT;
280 	VOP_UNLOCK(ap->a_vp);
281 	error = sosend(wso, NULL, ap->a_uio, NULL, NULL, flags);
282 	vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY);
283 	return (error);
284 }
285 
286 /*
287  * Device ioctl operation.
288  */
289 /* ARGSUSED */
290 int
291 fifo_ioctl(void *v)
292 {
293 	struct vop_ioctl_args *ap = v;
294 	struct file filetmp;
295 	int error;
296 
297 	if (ap->a_command == FIONBIO)
298 		return (0);
299 	if (ap->a_fflag & FREAD) {
300 		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
301 		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data, ap->a_p);
302 		if (error)
303 			return (error);
304 	}
305 	if (ap->a_fflag & FWRITE) {
306 		filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
307 		error = soo_ioctl(&filetmp, ap->a_command, ap->a_data, ap->a_p);
308 		if (error)
309 			return (error);
310 	}
311 	return (0);
312 }
313 
314 int
315 fifo_inactive(void *v)
316 {
317 	struct vop_inactive_args *ap = v;
318 
319 	VOP_UNLOCK(ap->a_vp);
320 	return (0);
321 }
322 
323 
324 /*
325  * Device close routine
326  */
327 /* ARGSUSED */
328 int
329 fifo_close(void *v)
330 {
331 	struct vop_close_args *ap = v;
332 	struct vnode *vp = ap->a_vp;
333 	struct fifoinfo *fip = vp->v_fifoinfo;
334 	int error1 = 0, error2 = 0;
335 
336 	if (fip == NULL)
337 		return (0);
338 
339 	if (ap->a_fflag & FREAD) {
340 		if (--fip->fi_readers == 0) {
341 			struct socket *wso = fip->fi_writesock;
342 
343 			solock(wso);
344 			socantsendmore(wso);
345 			sounlock(wso);
346 		}
347 	}
348 	if (ap->a_fflag & FWRITE) {
349 		if (--fip->fi_writers == 0) {
350 			struct socket *rso = fip->fi_readsock;
351 
352 			solock(rso);
353 			/* SS_ISDISCONNECTED will result in POLLHUP */
354 			rso->so_state |= SS_ISDISCONNECTED;
355 			socantrcvmore(rso);
356 			sounlock(rso);
357 		}
358 	}
359 	if (fip->fi_readers == 0 && fip->fi_writers == 0) {
360 		error1 = soclose(fip->fi_readsock, 0);
361 		error2 = soclose(fip->fi_writesock, 0);
362 		free(fip, M_VNODE, sizeof *fip);
363 		vp->v_fifoinfo = NULL;
364 	}
365 	return (error1 ? error1 : error2);
366 }
367 
368 int
369 fifo_reclaim(void *v)
370 {
371 	struct vop_reclaim_args *ap = v;
372 	struct vnode *vp = ap->a_vp;
373 	struct fifoinfo *fip = vp->v_fifoinfo;
374 
375 	if (fip == NULL)
376 		return (0);
377 
378 	soclose(fip->fi_readsock, 0);
379 	soclose(fip->fi_writesock, 0);
380 	free(fip, M_VNODE, sizeof *fip);
381 	vp->v_fifoinfo = NULL;
382 
383 	return (0);
384 }
385 
386 /*
387  * Print out the contents of a fifo vnode.
388  */
389 int
390 fifo_print(void *v)
391 {
392 	struct vop_print_args *ap = v;
393 
394 	printf("tag VT_NON");
395 	fifo_printinfo(ap->a_vp);
396 	printf("\n");
397 	return 0;
398 }
399 
400 /*
401  * Print out internal contents of a fifo vnode.
402  */
403 void
404 fifo_printinfo(struct vnode *vp)
405 {
406 	struct fifoinfo *fip = vp->v_fifoinfo;
407 
408 	printf(", fifo with %ld readers and %ld writers",
409 		fip->fi_readers, fip->fi_writers);
410 }
411 
412 /*
413  * Return POSIX pathconf information applicable to fifo's.
414  */
415 int
416 fifo_pathconf(void *v)
417 {
418 	struct vop_pathconf_args *ap = v;
419 	int error = 0;
420 
421 	switch (ap->a_name) {
422 	case _PC_LINK_MAX:
423 		*ap->a_retval = LINK_MAX;
424 		break;
425 	case _PC_CHOWN_RESTRICTED:
426 		*ap->a_retval = 1;
427 		break;
428 	case _PC_TIMESTAMP_RESOLUTION:
429 		*ap->a_retval = 1;
430 		break;
431 	default:
432 		error = EINVAL;
433 		break;
434 	}
435 
436 	return (error);
437 }
438 
439 /*
440  * Fifo failed operation
441  */
442 /*ARGSUSED*/
443 int
444 fifo_ebadf(void *v)
445 {
446 
447 	return (EBADF);
448 }
449 
450 /*
451  * Fifo advisory byte-level locks.
452  */
453 /* ARGSUSED */
454 int
455 fifo_advlock(void *v)
456 {
457 	return (EOPNOTSUPP);
458 }
459 
460 int
461 fifo_kqfilter(void *v)
462 {
463 	struct vop_kqfilter_args *ap = v;
464 	struct fifoinfo *fip = ap->a_vp->v_fifoinfo;
465 	struct sockbuf *sb;
466 	struct socket *so;
467 
468 	switch (ap->a_kn->kn_filter) {
469 	case EVFILT_READ:
470 		if (!(ap->a_fflag & FREAD))
471 			return (EINVAL);
472 		ap->a_kn->kn_fop = &fiforead_filtops;
473 		so = fip->fi_readsock;
474 		sb = &so->so_rcv;
475 		break;
476 	case EVFILT_WRITE:
477 		if (!(ap->a_fflag & FWRITE)) {
478 			/* Tell upper layer to ask for POLLUP only */
479 			if (ap->a_kn->kn_flags & (__EV_POLL | __EV_SELECT))
480 				return (EPERM);
481 			return (EINVAL);
482 		}
483 		ap->a_kn->kn_fop = &fifowrite_filtops;
484 		so = fip->fi_writesock;
485 		sb = &so->so_snd;
486 		break;
487 	case EVFILT_EXCEPT:
488 		if (ap->a_kn->kn_flags & __EV_SELECT) {
489 			/* Prevent triggering exceptfds. */
490 			return (EPERM);
491 		}
492 		if ((ap->a_kn->kn_flags & __EV_POLL) == 0) {
493 			/* Disallow usage through kevent(2). */
494 			return (EINVAL);
495 		}
496 		ap->a_kn->kn_fop = &fifoexcept_filtops;
497 		so = fip->fi_readsock;
498 		sb = &so->so_rcv;
499 		break;
500 	default:
501 		return (EINVAL);
502 	}
503 
504 	ap->a_kn->kn_hook = so;
505 
506 	klist_insert(&sb->sb_sel.si_note, ap->a_kn);
507 
508 	return (0);
509 }
510 
511 void
512 filt_fifordetach(struct knote *kn)
513 {
514 	struct socket *so = (struct socket *)kn->kn_hook;
515 
516 	klist_remove(&so->so_rcv.sb_sel.si_note, kn);
517 }
518 
519 int
520 filt_fiforead(struct knote *kn, long hint)
521 {
522 	struct socket *so = kn->kn_hook;
523 	int rv;
524 
525 	soassertlocked(so);
526 
527 	kn->kn_data = so->so_rcv.sb_cc;
528 	if (so->so_state & SS_CANTRCVMORE) {
529 		kn->kn_flags |= EV_EOF;
530 		if (kn->kn_flags & __EV_POLL) {
531 			if (so->so_state & SS_ISDISCONNECTED)
532 				kn->kn_flags |= __EV_HUP;
533 			else
534 				kn->kn_flags &= ~__EV_HUP;
535 		}
536 		rv = 1;
537 	} else {
538 		kn->kn_flags &= ~(EV_EOF | __EV_HUP);
539 		rv = (kn->kn_data > 0);
540 	}
541 
542 	return (rv);
543 }
544 
545 void
546 filt_fifowdetach(struct knote *kn)
547 {
548 	struct socket *so = (struct socket *)kn->kn_hook;
549 
550 	klist_remove(&so->so_snd.sb_sel.si_note, kn);
551 }
552 
553 int
554 filt_fifowrite(struct knote *kn, long hint)
555 {
556 	struct socket *so = kn->kn_hook;
557 	int rv;
558 
559 	soassertlocked(so);
560 
561 	kn->kn_data = sbspace(so, &so->so_snd);
562 	if (so->so_state & SS_CANTSENDMORE) {
563 		kn->kn_flags |= EV_EOF;
564 		rv = 1;
565 	} else {
566 		kn->kn_flags &= ~EV_EOF;
567 		rv = (kn->kn_data >= so->so_snd.sb_lowat);
568 	}
569 
570 	return (rv);
571 }
572 
573 int
574 filt_fifoexcept(struct knote *kn, long hint)
575 {
576 	struct socket *so = kn->kn_hook;
577 	int rv = 0;
578 
579 	soassertlocked(so);
580 
581 	if (kn->kn_flags & __EV_POLL) {
582 		if (so->so_state & SS_ISDISCONNECTED) {
583 			kn->kn_flags |= __EV_HUP;
584 			rv = 1;
585 		} else {
586 			kn->kn_flags &= ~__EV_HUP;
587 		}
588 	}
589 
590 	return (rv);
591 }
592 
593 int
594 filt_fifomodify(struct kevent *kev, struct knote *kn)
595 {
596 	struct socket *so = kn->kn_hook;
597 	int rv;
598 
599 	solock(so);
600 	rv = knote_modify(kev, kn);
601 	sounlock(so);
602 
603 	return (rv);
604 }
605 
606 int
607 filt_fifoprocess(struct knote *kn, struct kevent *kev)
608 {
609 	struct socket *so = kn->kn_hook;
610 	int rv;
611 
612 	solock(so);
613 	rv = knote_process(kn, kev);
614 	sounlock(so);
615 
616 	return (rv);
617 }
618