xref: /netbsd-src/sys/miscfs/specfs/spec_vnops.c (revision 1f2744e6e4915c9da2a3f980279398c4cf7d5e6d)
1 /*	$NetBSD: spec_vnops.c,v 1.22 1994/12/14 18:49:38 mycroft Exp $	*/
2 
3 /*
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  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  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  *
35  *	@(#)spec_vnops.c	8.8 (Berkeley) 11/21/94
36  */
37 
38 #include <sys/param.h>
39 #include <sys/proc.h>
40 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/conf.h>
43 #include <sys/buf.h>
44 #include <sys/mount.h>
45 #include <sys/namei.h>
46 #include <sys/vnode.h>
47 #include <sys/stat.h>
48 #include <sys/errno.h>
49 #include <sys/ioctl.h>
50 #include <sys/file.h>
51 #include <sys/disklabel.h>
52 #include <miscfs/specfs/specdev.h>
53 
54 /* symbolic sleep message strings for devices */
55 char	devopn[] = "devopn";
56 char	devio[] = "devio";
57 char	devwait[] = "devwait";
58 char	devin[] = "devin";
59 char	devout[] = "devout";
60 char	devioc[] = "devioc";
61 char	devcls[] = "devcls";
62 
63 int (**spec_vnodeop_p)();
64 struct vnodeopv_entry_desc spec_vnodeop_entries[] = {
65 	{ &vop_default_desc, vn_default_error },
66 	{ &vop_lookup_desc, spec_lookup },		/* lookup */
67 	{ &vop_create_desc, spec_create },		/* create */
68 	{ &vop_mknod_desc, spec_mknod },		/* mknod */
69 	{ &vop_open_desc, spec_open },			/* open */
70 	{ &vop_close_desc, spec_close },		/* close */
71 	{ &vop_access_desc, spec_access },		/* access */
72 	{ &vop_getattr_desc, spec_getattr },		/* getattr */
73 	{ &vop_setattr_desc, spec_setattr },		/* setattr */
74 	{ &vop_read_desc, spec_read },			/* read */
75 	{ &vop_write_desc, spec_write },		/* write */
76 	{ &vop_lease_desc, spec_lease_check },		/* lease */
77 	{ &vop_ioctl_desc, spec_ioctl },		/* ioctl */
78 	{ &vop_select_desc, spec_select },		/* select */
79 	{ &vop_mmap_desc, spec_mmap },			/* mmap */
80 	{ &vop_fsync_desc, spec_fsync },		/* fsync */
81 	{ &vop_seek_desc, spec_seek },			/* seek */
82 	{ &vop_remove_desc, spec_remove },		/* remove */
83 	{ &vop_link_desc, spec_link },			/* link */
84 	{ &vop_rename_desc, spec_rename },		/* rename */
85 	{ &vop_mkdir_desc, spec_mkdir },		/* mkdir */
86 	{ &vop_rmdir_desc, spec_rmdir },		/* rmdir */
87 	{ &vop_symlink_desc, spec_symlink },		/* symlink */
88 	{ &vop_readdir_desc, spec_readdir },		/* readdir */
89 	{ &vop_readlink_desc, spec_readlink },		/* readlink */
90 	{ &vop_abortop_desc, spec_abortop },		/* abortop */
91 	{ &vop_inactive_desc, spec_inactive },		/* inactive */
92 	{ &vop_reclaim_desc, spec_reclaim },		/* reclaim */
93 	{ &vop_lock_desc, spec_lock },			/* lock */
94 	{ &vop_unlock_desc, spec_unlock },		/* unlock */
95 	{ &vop_bmap_desc, spec_bmap },			/* bmap */
96 	{ &vop_strategy_desc, spec_strategy },		/* strategy */
97 	{ &vop_print_desc, spec_print },		/* print */
98 	{ &vop_islocked_desc, spec_islocked },		/* islocked */
99 	{ &vop_pathconf_desc, spec_pathconf },		/* pathconf */
100 	{ &vop_advlock_desc, spec_advlock },		/* advlock */
101 	{ &vop_blkatoff_desc, spec_blkatoff },		/* blkatoff */
102 	{ &vop_valloc_desc, spec_valloc },		/* valloc */
103 	{ &vop_vfree_desc, spec_vfree },		/* vfree */
104 	{ &vop_truncate_desc, spec_truncate },		/* truncate */
105 	{ &vop_update_desc, spec_update },		/* update */
106 	{ &vop_bwrite_desc, spec_bwrite },		/* bwrite */
107 	{ (struct vnodeop_desc*)NULL, (int(*)())NULL }
108 };
109 struct vnodeopv_desc spec_vnodeop_opv_desc =
110 	{ &spec_vnodeop_p, spec_vnodeop_entries };
111 
112 /*
113  * Trivial lookup routine that always fails.
114  */
115 int
116 spec_lookup(ap)
117 	struct vop_lookup_args /* {
118 		struct vnode *a_dvp;
119 		struct vnode **a_vpp;
120 		struct componentname *a_cnp;
121 	} */ *ap;
122 {
123 
124 	*ap->a_vpp = NULL;
125 	return (ENOTDIR);
126 }
127 
128 /*
129  * Open a special file.
130  */
131 /* ARGSUSED */
132 spec_open(ap)
133 	struct vop_open_args /* {
134 		struct vnode *a_vp;
135 		int  a_mode;
136 		struct ucred *a_cred;
137 		struct proc *a_p;
138 	} */ *ap;
139 {
140 	struct vnode *bvp, *vp = ap->a_vp;
141 	dev_t bdev, dev = (dev_t)vp->v_rdev;
142 	register int maj = major(dev);
143 	int error;
144 
145 	/*
146 	 * Don't allow open if fs is mounted -nodev.
147 	 */
148 	if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_NODEV))
149 		return (ENXIO);
150 
151 	switch (vp->v_type) {
152 
153 	case VCHR:
154 		if ((u_int)maj >= nchrdev)
155 			return (ENXIO);
156 		if (ap->a_cred != FSCRED && (ap->a_mode & FWRITE)) {
157 			/*
158 			 * When running in very secure mode, do not allow
159 			 * opens for writing of any disk character devices.
160 			 */
161 			if (securelevel >= 2 && isdisk(dev, VCHR))
162 				return (EPERM);
163 			/*
164 			 * When running in secure mode, do not allow opens
165 			 * for writing of /dev/mem, /dev/kmem, or character
166 			 * devices whose corresponding block devices are
167 			 * currently mounted.
168 			 */
169 			if (securelevel >= 1) {
170 				if ((bdev = chrtoblk(dev)) != NODEV &&
171 				    vfinddev(bdev, VBLK, &bvp) &&
172 				    bvp->v_usecount > 0 &&
173 				    (error = vfs_mountedon(bvp)))
174 					return (error);
175 				if (iskmemdev(dev))
176 					return (EPERM);
177 			}
178 		}
179 		VOP_UNLOCK(vp);
180 		error = (*cdevsw[maj].d_open)(dev, ap->a_mode, S_IFCHR, ap->a_p);
181 		VOP_LOCK(vp);
182 		return (error);
183 
184 	case VBLK:
185 		if ((u_int)maj >= nblkdev)
186 			return (ENXIO);
187 		/*
188 		 * When running in very secure mode, do not allow
189 		 * opens for writing of any disk block devices.
190 		 */
191 		if (securelevel >= 2 && ap->a_cred != FSCRED &&
192 		    (ap->a_mode & FWRITE) && isdisk(dev, VBLK))
193 			return (EPERM);
194 		/*
195 		 * Do not allow opens of block devices that are
196 		 * currently mounted.
197 		 */
198 		if (error = vfs_mountedon(vp))
199 			return (error);
200 		return ((*bdevsw[maj].d_open)(dev, ap->a_mode, S_IFBLK, ap->a_p));
201 	}
202 	return (0);
203 }
204 
205 /*
206  * Vnode op for read
207  */
208 /* ARGSUSED */
209 spec_read(ap)
210 	struct vop_read_args /* {
211 		struct vnode *a_vp;
212 		struct uio *a_uio;
213 		int  a_ioflag;
214 		struct ucred *a_cred;
215 	} */ *ap;
216 {
217 	register struct vnode *vp = ap->a_vp;
218 	register struct uio *uio = ap->a_uio;
219  	struct proc *p = uio->uio_procp;
220 	struct buf *bp;
221 	daddr_t bn, nextbn;
222 	long bsize, bscale, ssize;
223 	struct partinfo dpart;
224 	int n, on, majordev, (*ioctl)();
225 	int error = 0;
226 	dev_t dev;
227 
228 #ifdef DIAGNOSTIC
229 	if (uio->uio_rw != UIO_READ)
230 		panic("spec_read mode");
231 	if (uio->uio_segflg == UIO_USERSPACE && uio->uio_procp != curproc)
232 		panic("spec_read proc");
233 #endif
234 	if (uio->uio_resid == 0)
235 		return (0);
236 
237 	switch (vp->v_type) {
238 
239 	case VCHR:
240 		VOP_UNLOCK(vp);
241 		error = (*cdevsw[major(vp->v_rdev)].d_read)
242 			(vp->v_rdev, uio, ap->a_ioflag);
243 		VOP_LOCK(vp);
244 		return (error);
245 
246 	case VBLK:
247 		if (uio->uio_offset < 0)
248 			return (EINVAL);
249 		bsize = BLKDEV_IOSIZE;
250 		ssize = DEV_BSIZE;
251 		dev = vp->v_rdev;
252 		if ((majordev = major(dev)) < nblkdev &&
253 		    (ioctl = bdevsw[majordev].d_ioctl) != NULL &&
254 		    (*ioctl)(dev, DIOCGPART, (caddr_t)&dpart, FREAD, p) == 0) {
255 			if (dpart.part->p_fstype == FS_BSDFFS &&
256 			    dpart.part->p_frag != 0 && dpart.part->p_fsize != 0)
257 				bsize = dpart.part->p_frag *
258 				    dpart.part->p_fsize;
259 			if (dpart.disklab->d_secsize != 0)
260 				ssize = dpart.disklab->d_secsize;
261 		}
262 		bscale = bsize / ssize;
263 		do {
264 			bn = (uio->uio_offset / ssize) &~ (bscale - 1);
265 			on = uio->uio_offset % bsize;
266 			n = min((unsigned)(bsize - on), uio->uio_resid);
267 			if (vp->v_lastr + bscale == bn) {
268 				nextbn = bn + bscale;
269 				error = breadn(vp, bn, (int)bsize, &nextbn,
270 					(int *)&bsize, 1, NOCRED, &bp);
271 			} else
272 				error = bread(vp, bn, (int)bsize, NOCRED, &bp);
273 			vp->v_lastr = bn;
274 			n = min(n, bsize - bp->b_resid);
275 			if (error) {
276 				brelse(bp);
277 				return (error);
278 			}
279 			error = uiomove((char *)bp->b_data + on, n, uio);
280 			if (n + on == bsize)
281 				bp->b_flags |= B_AGE;
282 			brelse(bp);
283 		} while (error == 0 && uio->uio_resid > 0 && n != 0);
284 		return (error);
285 
286 	default:
287 		panic("spec_read type");
288 	}
289 	/* NOTREACHED */
290 }
291 
292 /*
293  * Vnode op for write
294  */
295 /* ARGSUSED */
296 spec_write(ap)
297 	struct vop_write_args /* {
298 		struct vnode *a_vp;
299 		struct uio *a_uio;
300 		int  a_ioflag;
301 		struct ucred *a_cred;
302 	} */ *ap;
303 {
304 	register struct vnode *vp = ap->a_vp;
305 	register struct uio *uio = ap->a_uio;
306 	struct proc *p = uio->uio_procp;
307 	struct buf *bp;
308 	daddr_t bn;
309 	int bsize, blkmask, ssize;
310 	struct partinfo dpart;
311 	register int n, on;
312 	int error = 0;
313 
314 #ifdef DIAGNOSTIC
315 	if (uio->uio_rw != UIO_WRITE)
316 		panic("spec_write mode");
317 	if (uio->uio_segflg == UIO_USERSPACE && uio->uio_procp != curproc)
318 		panic("spec_write proc");
319 #endif
320 
321 	switch (vp->v_type) {
322 
323 	case VCHR:
324 		VOP_UNLOCK(vp);
325 		error = (*cdevsw[major(vp->v_rdev)].d_write)
326 			(vp->v_rdev, uio, ap->a_ioflag);
327 		VOP_LOCK(vp);
328 		return (error);
329 
330 	case VBLK:
331 		if (uio->uio_resid == 0)
332 			return (0);
333 		if (uio->uio_offset < 0)
334 			return (EINVAL);
335 		bsize = BLKDEV_IOSIZE;
336 		ssize = DEV_BSIZE;
337 		if ((*bdevsw[major(vp->v_rdev)].d_ioctl)(vp->v_rdev, DIOCGPART,
338 		    (caddr_t)&dpart, FREAD, p) == 0) {
339 			if (dpart.part->p_fstype == FS_BSDFFS &&
340 			    dpart.part->p_frag != 0 && dpart.part->p_fsize != 0)
341 				bsize = dpart.part->p_frag *
342 				    dpart.part->p_fsize;
343 			if (dpart.disklab->d_secsize != 0)
344 				ssize = dpart.disklab->d_secsize;
345 		}
346 		blkmask = (bsize / ssize) - 1;
347 		do {
348 			bn = (uio->uio_offset / ssize) &~ blkmask;
349 			on = uio->uio_offset % bsize;
350 			n = min((unsigned)(bsize - on), uio->uio_resid);
351 			if (n == bsize)
352 				bp = getblk(vp, bn, bsize, 0, 0);
353 			else
354 				error = bread(vp, bn, bsize, NOCRED, &bp);
355 			n = min(n, bsize - bp->b_resid);
356 			if (error) {
357 				brelse(bp);
358 				return (error);
359 			}
360 			error = uiomove((char *)bp->b_data + on, n, uio);
361 			if (n + on == bsize) {
362 				bp->b_flags |= B_AGE;
363 				bawrite(bp);
364 			} else
365 				bdwrite(bp);
366 		} while (error == 0 && uio->uio_resid > 0 && n != 0);
367 		return (error);
368 
369 	default:
370 		panic("spec_write type");
371 	}
372 	/* NOTREACHED */
373 }
374 
375 /*
376  * Device ioctl operation.
377  */
378 /* ARGSUSED */
379 spec_ioctl(ap)
380 	struct vop_ioctl_args /* {
381 		struct vnode *a_vp;
382 		u_long a_command;
383 		caddr_t  a_data;
384 		int  a_fflag;
385 		struct ucred *a_cred;
386 		struct proc *a_p;
387 	} */ *ap;
388 {
389 	dev_t dev = ap->a_vp->v_rdev;
390 
391 	switch (ap->a_vp->v_type) {
392 
393 	case VCHR:
394 		return ((*cdevsw[major(dev)].d_ioctl)(dev, ap->a_command, ap->a_data,
395 		    ap->a_fflag, ap->a_p));
396 
397 	case VBLK:
398 		if (ap->a_command == 0 && (long)ap->a_data == B_TAPE)
399 			if (bdevsw[major(dev)].d_flags & B_TAPE)
400 				return (0);
401 			else
402 				return (1);
403 		return ((*bdevsw[major(dev)].d_ioctl)(dev, ap->a_command, ap->a_data,
404 		   ap->a_fflag, ap->a_p));
405 
406 	default:
407 		panic("spec_ioctl");
408 		/* NOTREACHED */
409 	}
410 }
411 
412 /* ARGSUSED */
413 spec_select(ap)
414 	struct vop_select_args /* {
415 		struct vnode *a_vp;
416 		int  a_which;
417 		int  a_fflags;
418 		struct ucred *a_cred;
419 		struct proc *a_p;
420 	} */ *ap;
421 {
422 	register dev_t dev;
423 
424 	switch (ap->a_vp->v_type) {
425 
426 	default:
427 		return (1);		/* XXX */
428 
429 	case VCHR:
430 		dev = ap->a_vp->v_rdev;
431 		return (*cdevsw[major(dev)].d_select)(dev, ap->a_which, ap->a_p);
432 	}
433 }
434 /*
435  * Synch buffers associated with a block device
436  */
437 /* ARGSUSED */
438 int
439 spec_fsync(ap)
440 	struct vop_fsync_args /* {
441 		struct vnode *a_vp;
442 		struct ucred *a_cred;
443 		int  a_waitfor;
444 		struct proc *a_p;
445 	} */ *ap;
446 {
447 	register struct vnode *vp = ap->a_vp;
448 	register struct buf *bp;
449 	struct buf *nbp;
450 	int s;
451 
452 	if (vp->v_type == VCHR)
453 		return (0);
454 	/*
455 	 * Flush all dirty buffers associated with a block device.
456 	 */
457 loop:
458 	s = splbio();
459 	for (bp = vp->v_dirtyblkhd.lh_first; bp; bp = nbp) {
460 		nbp = bp->b_vnbufs.le_next;
461 		if ((bp->b_flags & B_BUSY))
462 			continue;
463 		if ((bp->b_flags & B_DELWRI) == 0)
464 			panic("spec_fsync: not dirty");
465 		bremfree(bp);
466 		bp->b_flags |= B_BUSY;
467 		splx(s);
468 		bawrite(bp);
469 		goto loop;
470 	}
471 	if (ap->a_waitfor == MNT_WAIT) {
472 		while (vp->v_numoutput) {
473 			vp->v_flag |= VBWAIT;
474 			sleep((caddr_t)&vp->v_numoutput, PRIBIO + 1);
475 		}
476 #ifdef DIAGNOSTIC
477 		if (vp->v_dirtyblkhd.lh_first) {
478 			vprint("spec_fsync: dirty", vp);
479 			goto loop;
480 		}
481 #endif
482 	}
483 	splx(s);
484 	return (0);
485 }
486 
487 /*
488  * Just call the device strategy routine
489  */
490 spec_strategy(ap)
491 	struct vop_strategy_args /* {
492 		struct buf *a_bp;
493 	} */ *ap;
494 {
495 
496 	(*bdevsw[major(ap->a_bp->b_dev)].d_strategy)(ap->a_bp);
497 	return (0);
498 }
499 
500 /*
501  * This is a noop, simply returning what one has been given.
502  */
503 spec_bmap(ap)
504 	struct vop_bmap_args /* {
505 		struct vnode *a_vp;
506 		daddr_t  a_bn;
507 		struct vnode **a_vpp;
508 		daddr_t *a_bnp;
509 	} */ *ap;
510 {
511 
512 	if (ap->a_vpp != NULL)
513 		*ap->a_vpp = ap->a_vp;
514 	if (ap->a_bnp != NULL)
515 		*ap->a_bnp = ap->a_bn;
516 	return (0);
517 }
518 
519 /*
520  * At the moment we do not do any locking.
521  */
522 /* ARGSUSED */
523 spec_lock(ap)
524 	struct vop_lock_args /* {
525 		struct vnode *a_vp;
526 	} */ *ap;
527 {
528 
529 	return (0);
530 }
531 
532 /* ARGSUSED */
533 spec_unlock(ap)
534 	struct vop_unlock_args /* {
535 		struct vnode *a_vp;
536 	} */ *ap;
537 {
538 
539 	return (0);
540 }
541 
542 /*
543  * Device close routine
544  */
545 /* ARGSUSED */
546 spec_close(ap)
547 	struct vop_close_args /* {
548 		struct vnode *a_vp;
549 		int  a_fflag;
550 		struct ucred *a_cred;
551 		struct proc *a_p;
552 	} */ *ap;
553 {
554 	register struct vnode *vp = ap->a_vp;
555 	dev_t dev = vp->v_rdev;
556 	int (*devclose) __P((dev_t, int, int, struct proc *));
557 	int mode, error;
558 
559 	switch (vp->v_type) {
560 
561 	case VCHR:
562 		/*
563 		 * Hack: a tty device that is a controlling terminal
564 		 * has a reference from the session structure.
565 		 * We cannot easily tell that a character device is
566 		 * a controlling terminal, unless it is the closing
567 		 * process' controlling terminal.  In that case,
568 		 * if the reference count is 2 (this last descriptor
569 		 * plus the session), release the reference from the session.
570 		 */
571 		if (vcount(vp) == 2 && ap->a_p &&
572 		    vp == ap->a_p->p_session->s_ttyvp) {
573 			vrele(vp);
574 			ap->a_p->p_session->s_ttyvp = NULL;
575 		}
576 		/*
577 		 * If the vnode is locked, then we are in the midst
578 		 * of forcably closing the device, otherwise we only
579 		 * close on last reference.
580 		 */
581 		if (vcount(vp) > 1 && (vp->v_flag & VXLOCK) == 0)
582 			return (0);
583 		devclose = cdevsw[major(dev)].d_close;
584 		mode = S_IFCHR;
585 		break;
586 
587 	case VBLK:
588 		/*
589 		 * On last close of a block device (that isn't mounted)
590 		 * we must invalidate any in core blocks, so that
591 		 * we can, for instance, change floppy disks.
592 		 */
593 		if (error = vinvalbuf(vp, V_SAVE, ap->a_cred, ap->a_p, 0, 0))
594 			return (error);
595 		/*
596 		 * We do not want to really close the device if it
597 		 * is still in use unless we are trying to close it
598 		 * forcibly. Since every use (buffer, vnode, swap, cmap)
599 		 * holds a reference to the vnode, and because we mark
600 		 * any other vnodes that alias this device, when the
601 		 * sum of the reference counts on all the aliased
602 		 * vnodes descends to one, we are on last close.
603 		 */
604 		if (vcount(vp) > 1 && (vp->v_flag & VXLOCK) == 0)
605 			return (0);
606 		devclose = bdevsw[major(dev)].d_close;
607 		mode = S_IFBLK;
608 		break;
609 
610 	default:
611 		panic("spec_close: not special");
612 	}
613 
614 	return ((*devclose)(dev, ap->a_fflag, mode, ap->a_p));
615 }
616 
617 /*
618  * Print out the contents of a special device vnode.
619  */
620 spec_print(ap)
621 	struct vop_print_args /* {
622 		struct vnode *a_vp;
623 	} */ *ap;
624 {
625 
626 	printf("tag VT_NON, dev %d, %d\n", major(ap->a_vp->v_rdev),
627 		minor(ap->a_vp->v_rdev));
628 }
629 
630 /*
631  * Return POSIX pathconf information applicable to special devices.
632  */
633 spec_pathconf(ap)
634 	struct vop_pathconf_args /* {
635 		struct vnode *a_vp;
636 		int a_name;
637 		register_t *a_retval;
638 	} */ *ap;
639 {
640 
641 	switch (ap->a_name) {
642 	case _PC_LINK_MAX:
643 		*ap->a_retval = LINK_MAX;
644 		return (0);
645 	case _PC_MAX_CANON:
646 		*ap->a_retval = MAX_CANON;
647 		return (0);
648 	case _PC_MAX_INPUT:
649 		*ap->a_retval = MAX_INPUT;
650 		return (0);
651 	case _PC_PIPE_BUF:
652 		*ap->a_retval = PIPE_BUF;
653 		return (0);
654 	case _PC_CHOWN_RESTRICTED:
655 		*ap->a_retval = 1;
656 		return (0);
657 	case _PC_VDISABLE:
658 		*ap->a_retval = _POSIX_VDISABLE;
659 		return (0);
660 	default:
661 		return (EINVAL);
662 	}
663 	/* NOTREACHED */
664 }
665 
666 /*
667  * Special device advisory byte-level locks.
668  */
669 /* ARGSUSED */
670 spec_advlock(ap)
671 	struct vop_advlock_args /* {
672 		struct vnode *a_vp;
673 		caddr_t  a_id;
674 		int  a_op;
675 		struct flock *a_fl;
676 		int  a_flags;
677 	} */ *ap;
678 {
679 
680 	return (EOPNOTSUPP);
681 }
682 
683 /*
684  * Special device failed operation
685  */
686 spec_ebadf()
687 {
688 
689 	return (EBADF);
690 }
691 
692 /*
693  * Special device bad operation
694  */
695 spec_badop()
696 {
697 
698 	panic("spec_badop called");
699 	/* NOTREACHED */
700 }
701