xref: /netbsd-src/sys/miscfs/kernfs/kernfs_vnops.c (revision 2a399c6883d870daece976daec6ffa7bb7f934ce)
1 /*	$NetBSD: kernfs_vnops.c,v 1.53 1997/10/10 02:01:02 fvdl Exp $	*/
2 
3 /*
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software donated to Berkeley by
8  * Jan-Simon Pendry.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	@(#)kernfs_vnops.c	8.9 (Berkeley) 6/15/94
39  */
40 
41 /*
42  * Kernel parameter filesystem (/kern)
43  */
44 
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/vmmeter.h>
49 #include <sys/types.h>
50 #include <sys/time.h>
51 #include <sys/proc.h>
52 #include <sys/vnode.h>
53 #include <sys/malloc.h>
54 #include <sys/file.h>
55 #include <sys/stat.h>
56 #include <sys/mount.h>
57 #include <sys/namei.h>
58 #include <sys/buf.h>
59 #include <sys/dirent.h>
60 #include <sys/msgbuf.h>
61 
62 #include <miscfs/genfs/genfs.h>
63 #include <miscfs/kernfs/kernfs.h>
64 
65 #define KSTRING	256		/* Largest I/O available via this filesystem */
66 #define	UIO_MX 32
67 
68 #define	READ_MODE	(S_IRUSR|S_IRGRP|S_IROTH)
69 #define	WRITE_MODE	(S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH)
70 #define DIR_MODE	(S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
71 
72 struct kern_target kern_targets[] = {
73 /* NOTE: The name must be less than UIO_MX-16 chars in length */
74 #define N(s) sizeof(s)-1, s
75      /*        name            data          tag           type  ro/rw */
76      { DT_DIR, N("."),         0,            KTT_NULL,     VDIR, DIR_MODE   },
77      { DT_DIR, N(".."),        0,            KTT_NULL,     VDIR, DIR_MODE   },
78      { DT_REG, N("boottime"),  &boottime.tv_sec, KTT_INT,  VREG, READ_MODE  },
79      { DT_REG, N("copyright"), copyright,    KTT_STRING,   VREG, READ_MODE  },
80      { DT_REG, N("hostname"),  0,            KTT_HOSTNAME, VREG, WRITE_MODE },
81      { DT_REG, N("hz"),        &hz,          KTT_INT,      VREG, READ_MODE  },
82      { DT_REG, N("loadavg"),   0,            KTT_AVENRUN,  VREG, READ_MODE  },
83      { DT_REG, N("msgbuf"),    0,	     KTT_MSGBUF,   VREG, READ_MODE  },
84      { DT_REG, N("pagesize"),  &cnt.v_page_size, KTT_INT,  VREG, READ_MODE  },
85      { DT_REG, N("physmem"),   &physmem,     KTT_INT,      VREG, READ_MODE  },
86 #if 0
87      { DT_DIR, N("root"),      0,            KTT_NULL,     VDIR, DIR_MODE   },
88 #endif
89      { DT_BLK, N("rootdev"),   &rootdev,     KTT_DEVICE,   VBLK, READ_MODE  },
90      { DT_CHR, N("rrootdev"),  &rrootdev,    KTT_DEVICE,   VCHR, READ_MODE  },
91      { DT_REG, N("time"),      0,            KTT_TIME,     VREG, READ_MODE  },
92      { DT_REG, N("version"),   version,      KTT_STRING,   VREG, READ_MODE  },
93 #undef N
94 };
95 static int nkern_targets = sizeof(kern_targets) / sizeof(kern_targets[0]);
96 
97 int	kernfs_lookup	__P((void *));
98 #define	kernfs_create	genfs_eopnotsupp
99 #define	kernfs_mknod	genfs_eopnotsupp
100 #define	kernfs_open	genfs_nullop
101 #define	kernfs_close	genfs_nullop
102 int	kernfs_access	__P((void *));
103 int	kernfs_getattr	__P((void *));
104 int	kernfs_setattr	__P((void *));
105 int	kernfs_read	__P((void *));
106 int	kernfs_write	__P((void *));
107 #define	kernfs_ioctl	genfs_eopnotsupp
108 #define	kernfs_poll	genfs_poll
109 #define	kernfs_mmap	genfs_eopnotsupp
110 #define	kernfs_fsync	genfs_nullop
111 #define	kernfs_seek	genfs_nullop
112 #define	kernfs_remove	genfs_eopnotsupp
113 int	kernfs_link	__P((void *));
114 #define	kernfs_rename	genfs_eopnotsupp
115 #define	kernfs_mkdir	genfs_eopnotsupp
116 #define	kernfs_rmdir	genfs_eopnotsupp
117 int	kernfs_symlink	__P((void *));
118 int	kernfs_readdir	__P((void *));
119 #define	kernfs_readlink	genfs_eopnotsupp
120 #define	kernfs_abortop	genfs_abortop
121 int	kernfs_inactive	__P((void *));
122 int	kernfs_reclaim	__P((void *));
123 #define	kernfs_lock	genfs_nullop
124 #define	kernfs_unlock	genfs_nullop
125 #define	kernfs_bmap	genfs_badop
126 #define	kernfs_strategy	genfs_badop
127 int	kernfs_print	__P((void *));
128 #define	kernfs_islocked	genfs_nullop
129 int	kernfs_pathconf	__P((void *));
130 #define	kernfs_advlock	genfs_eopnotsupp
131 #define	kernfs_blkatoff	genfs_eopnotsupp
132 #define	kernfs_valloc	genfs_eopnotsupp
133 #define	kernfs_vfree	genfs_nullop
134 #define	kernfs_truncate	genfs_eopnotsupp
135 #define	kernfs_update	genfs_nullop
136 #define	kernfs_bwrite	genfs_eopnotsupp
137 
138 int	kernfs_xread __P((struct kern_target *, int, char **, int));
139 int	kernfs_xwrite __P((struct kern_target *, char *, int));
140 
141 int (**kernfs_vnodeop_p) __P((void *));
142 struct vnodeopv_entry_desc kernfs_vnodeop_entries[] = {
143 	{ &vop_default_desc, vn_default_error },
144 	{ &vop_lookup_desc, kernfs_lookup },		/* lookup */
145 	{ &vop_create_desc, kernfs_create },		/* create */
146 	{ &vop_mknod_desc, kernfs_mknod },		/* mknod */
147 	{ &vop_open_desc, kernfs_open },		/* open */
148 	{ &vop_close_desc, kernfs_close },		/* close */
149 	{ &vop_access_desc, kernfs_access },		/* access */
150 	{ &vop_getattr_desc, kernfs_getattr },		/* getattr */
151 	{ &vop_setattr_desc, kernfs_setattr },		/* setattr */
152 	{ &vop_read_desc, kernfs_read },		/* read */
153 	{ &vop_write_desc, kernfs_write },		/* write */
154 	{ &vop_ioctl_desc, kernfs_ioctl },		/* ioctl */
155 	{ &vop_poll_desc, kernfs_poll },		/* poll */
156 	{ &vop_mmap_desc, kernfs_mmap },		/* mmap */
157 	{ &vop_fsync_desc, kernfs_fsync },		/* fsync */
158 	{ &vop_seek_desc, kernfs_seek },		/* seek */
159 	{ &vop_remove_desc, kernfs_remove },		/* remove */
160 	{ &vop_link_desc, kernfs_link },		/* link */
161 	{ &vop_rename_desc, kernfs_rename },		/* rename */
162 	{ &vop_mkdir_desc, kernfs_mkdir },		/* mkdir */
163 	{ &vop_rmdir_desc, kernfs_rmdir },		/* rmdir */
164 	{ &vop_symlink_desc, kernfs_symlink },		/* symlink */
165 	{ &vop_readdir_desc, kernfs_readdir },		/* readdir */
166 	{ &vop_readlink_desc, kernfs_readlink },	/* readlink */
167 	{ &vop_abortop_desc, kernfs_abortop },		/* abortop */
168 	{ &vop_inactive_desc, kernfs_inactive },	/* inactive */
169 	{ &vop_reclaim_desc, kernfs_reclaim },		/* reclaim */
170 	{ &vop_lock_desc, kernfs_lock },		/* lock */
171 	{ &vop_unlock_desc, kernfs_unlock },		/* unlock */
172 	{ &vop_bmap_desc, kernfs_bmap },		/* bmap */
173 	{ &vop_strategy_desc, kernfs_strategy },	/* strategy */
174 	{ &vop_print_desc, kernfs_print },		/* print */
175 	{ &vop_islocked_desc, kernfs_islocked },	/* islocked */
176 	{ &vop_pathconf_desc, kernfs_pathconf },	/* pathconf */
177 	{ &vop_advlock_desc, kernfs_advlock },		/* advlock */
178 	{ &vop_blkatoff_desc, kernfs_blkatoff },	/* blkatoff */
179 	{ &vop_valloc_desc, kernfs_valloc },		/* valloc */
180 	{ &vop_vfree_desc, kernfs_vfree },		/* vfree */
181 	{ &vop_truncate_desc, kernfs_truncate },	/* truncate */
182 	{ &vop_update_desc, kernfs_update },		/* update */
183 	{ &vop_bwrite_desc, kernfs_bwrite },		/* bwrite */
184 	{ (struct vnodeop_desc*)NULL, (int(*) __P((void *)))NULL }
185 };
186 struct vnodeopv_desc kernfs_vnodeop_opv_desc =
187 	{ &kernfs_vnodeop_p, kernfs_vnodeop_entries };
188 
189 int
190 kernfs_xread(kt, off, bufp, len)
191 	struct kern_target *kt;
192 	int off;
193 	char **bufp;
194 	int len;
195 {
196 
197 	switch (kt->kt_tag) {
198 	case KTT_TIME: {
199 		struct timeval tv;
200 
201 		microtime(&tv);
202 		sprintf(*bufp, "%ld %ld\n", tv.tv_sec, tv.tv_usec);
203 		break;
204 	}
205 
206 	case KTT_INT: {
207 		int *ip = kt->kt_data;
208 
209 		sprintf(*bufp, "%d\n", *ip);
210 		break;
211 	}
212 
213 	case KTT_STRING: {
214 		char *cp = kt->kt_data;
215 
216 		*bufp = cp;
217 		break;
218 	}
219 
220 	case KTT_MSGBUF: {
221 		long n;
222 
223 		/*
224 		 * deal with cases where the message buffer has
225 		 * become corrupted.
226 		 */
227 		if (!msgbufenabled || msgbufp->msg_magic != MSG_MAGIC) {
228 			msgbufenabled = 0;
229 			return (ENXIO);
230 		}
231 
232 		/*
233 		 * Note that reads of /kern/msgbuf won't necessarily yield
234 		 * consistent results, if the message buffer is modified
235 		 * while the read is in progress.  The worst that can happen
236 		 * is that incorrect data will be read.  There's no way
237 		 * that this can crash the system unless the values in the
238 		 * message buffer header are corrupted, but that'll cause
239 		 * the system to die anyway.
240 		 */
241 		if (off >= msgbufp->msg_bufs)
242 			return (0);
243 		n = msgbufp->msg_bufx + off;
244 		if (n >= msgbufp->msg_bufs)
245 			n -= msgbufp->msg_bufs;
246 		len = min(msgbufp->msg_bufs - n, msgbufp->msg_bufs - off);
247 		*bufp = msgbufp->msg_bufc + n;
248 		return (len);
249 	}
250 
251 	case KTT_HOSTNAME: {
252 		char *cp = hostname;
253 		int xlen = hostnamelen;
254 
255 		if (xlen >= (len-2))
256 			return (EINVAL);
257 
258 		bcopy(cp, *bufp, xlen);
259 		(*bufp)[xlen] = '\n';
260 		(*bufp)[xlen+1] = '\0';
261 		break;
262 	}
263 
264 	case KTT_AVENRUN:
265 		averunnable.fscale = FSCALE;
266 		sprintf(*bufp, "%d %d %d %ld\n",
267 		    averunnable.ldavg[0], averunnable.ldavg[1],
268 		    averunnable.ldavg[2], averunnable.fscale);
269 		break;
270 
271 	default:
272 		return (0);
273 	}
274 
275 	len = strlen(*bufp);
276 	if (len <= off)
277 		return (0);
278 	*bufp += off;
279 	return (len - off);
280 }
281 
282 int
283 kernfs_xwrite(kt, buf, len)
284 	struct kern_target *kt;
285 	char *buf;
286 	int len;
287 {
288 
289 	switch (kt->kt_tag) {
290 	case KTT_HOSTNAME:
291 		if (buf[len-1] == '\n')
292 			--len;
293 		bcopy(buf, hostname, len);
294 		hostname[len] = '\0';
295 		hostnamelen = len;
296 		return (0);
297 
298 	default:
299 		return (EIO);
300 	}
301 }
302 
303 
304 /*
305  * vp is the current namei directory
306  * ndp is the name to locate in that directory...
307  */
308 int
309 kernfs_lookup(v)
310 	void *v;
311 {
312 	struct vop_lookup_args /* {
313 		struct vnode * a_dvp;
314 		struct vnode ** a_vpp;
315 		struct componentname * a_cnp;
316 	} */ *ap = v;
317 	struct componentname *cnp = ap->a_cnp;
318 	struct vnode **vpp = ap->a_vpp;
319 	struct vnode *dvp = ap->a_dvp;
320 	const char *pname = cnp->cn_nameptr;
321 	struct kern_target *kt;
322 	struct vnode *fvp;
323 	int error, i;
324 
325 #ifdef KERNFS_DIAGNOSTIC
326 	printf("kernfs_lookup(%p)\n", ap);
327 	printf("kernfs_lookup(dp = %p, vpp = %p, cnp = %p)\n", dvp, vpp, ap->a_cnp);
328 	printf("kernfs_lookup(%s)\n", pname);
329 #endif
330 
331 	*vpp = NULLVP;
332 
333 	if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
334 		return (EROFS);
335 
336 	if (cnp->cn_namelen == 1 && *pname == '.') {
337 		*vpp = dvp;
338 		VREF(dvp);
339 		/*VOP_LOCK(dvp);*/
340 		return (0);
341 	}
342 
343 #if 0
344 	if (cnp->cn_namelen == 4 && bcmp(pname, "root", 4) == 0) {
345 		*vpp = rootdir;
346 		VREF(rootdir);
347 		VOP_LOCK(rootdir);
348 		return (0);
349 	}
350 #endif
351 
352 	for (kt = kern_targets, i = 0; i < nkern_targets; kt++, i++) {
353 		if (cnp->cn_namelen == kt->kt_namlen &&
354 		    bcmp(kt->kt_name, pname, cnp->cn_namelen) == 0)
355 			goto found;
356 	}
357 
358 #ifdef KERNFS_DIAGNOSTIC
359 	printf("kernfs_lookup: i = %d, failed", i);
360 #endif
361 
362 	return (cnp->cn_nameiop == LOOKUP ? ENOENT : EROFS);
363 
364 found:
365 	if (kt->kt_tag == KTT_DEVICE) {
366 		dev_t *dp = kt->kt_data;
367 	loop:
368 		if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp))
369 			return (ENOENT);
370 		*vpp = fvp;
371 		if (vget(fvp, 1))
372 			goto loop;
373 		return (0);
374 	}
375 
376 #ifdef KERNFS_DIAGNOSTIC
377 	printf("kernfs_lookup: allocate new vnode\n");
378 #endif
379 	error = getnewvnode(VT_KERNFS, dvp->v_mount, kernfs_vnodeop_p, &fvp);
380 	if (error)
381 		return (error);
382 
383 	MALLOC(fvp->v_data, void *, sizeof(struct kernfs_node), M_TEMP,
384 	    M_WAITOK);
385 	VTOKERN(fvp)->kf_kt = kt;
386 	fvp->v_type = kt->kt_vtype;
387 	*vpp = fvp;
388 
389 #ifdef KERNFS_DIAGNOSTIC
390 	printf("kernfs_lookup: newvp = %p\n", fvp);
391 #endif
392 	return (0);
393 }
394 
395 int
396 kernfs_access(v)
397 	void *v;
398 {
399 	struct vop_access_args /* {
400 		struct vnode *a_vp;
401 		int a_mode;
402 		struct ucred *a_cred;
403 		struct proc *a_p;
404 	} */ *ap = v;
405 	struct vnode *vp = ap->a_vp;
406 	mode_t mode;
407 
408 	if (vp->v_flag & VROOT) {
409 		mode = DIR_MODE;
410 	} else {
411 		struct kern_target *kt = VTOKERN(vp)->kf_kt;
412 		mode = kt->kt_mode;
413 	}
414 
415 	return (vaccess(vp->v_type, mode, (uid_t)0, (gid_t)0, ap->a_mode,
416 	    ap->a_cred));
417 }
418 
419 int
420 kernfs_getattr(v)
421 	void *v;
422 {
423 	struct vop_getattr_args /* {
424 		struct vnode *a_vp;
425 		struct vattr *a_vap;
426 		struct ucred *a_cred;
427 		struct proc *a_p;
428 	} */ *ap = v;
429 	struct vnode *vp = ap->a_vp;
430 	struct vattr *vap = ap->a_vap;
431 	struct timeval tv;
432 	int error = 0;
433 	char strbuf[KSTRING], *buf;
434 
435 	bzero((caddr_t) vap, sizeof(*vap));
436 	vattr_null(vap);
437 	vap->va_uid = 0;
438 	vap->va_gid = 0;
439 	vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
440 	vap->va_size = 0;
441 	vap->va_blocksize = DEV_BSIZE;
442 	microtime(&tv);
443 	TIMEVAL_TO_TIMESPEC(&tv, &vap->va_atime);
444 	vap->va_mtime = vap->va_atime;
445 	vap->va_ctime = vap->va_ctime;
446 	vap->va_gen = 0;
447 	vap->va_flags = 0;
448 	vap->va_rdev = 0;
449 	vap->va_bytes = 0;
450 
451 	if (vp->v_flag & VROOT) {
452 #ifdef KERNFS_DIAGNOSTIC
453 		printf("kernfs_getattr: stat rootdir\n");
454 #endif
455 		vap->va_type = VDIR;
456 		vap->va_mode = DIR_MODE;
457 		vap->va_nlink = 2;
458 		vap->va_fileid = 2;
459 		vap->va_size = DEV_BSIZE;
460 	} else {
461 		struct kern_target *kt = VTOKERN(vp)->kf_kt;
462 		int nbytes, total;
463 #ifdef KERNFS_DIAGNOSTIC
464 		printf("kernfs_getattr: stat target %s\n", kt->kt_name);
465 #endif
466 		vap->va_type = kt->kt_vtype;
467 		vap->va_mode = kt->kt_mode;
468 		vap->va_nlink = 1;
469 		vap->va_fileid = 3 + (kt - kern_targets);
470 		total = 0;
471 		while (buf = strbuf,
472 		       nbytes = kernfs_xread(kt, total, &buf, sizeof(strbuf)))
473 			total += nbytes;
474 		vap->va_size = total;
475 	}
476 
477 #ifdef KERNFS_DIAGNOSTIC
478 	printf("kernfs_getattr: return error %d\n", error);
479 #endif
480 	return (error);
481 }
482 
483 /*ARGSUSED*/
484 int
485 kernfs_setattr(v)
486 	void *v;
487 {
488 	/*
489 	 * Silently ignore attribute changes.
490 	 * This allows for open with truncate to have no
491 	 * effect until some data is written.  I want to
492 	 * do it this way because all writes are atomic.
493 	 */
494 	return (0);
495 }
496 
497 int
498 kernfs_read(v)
499 	void *v;
500 {
501 	struct vop_read_args /* {
502 		struct vnode *a_vp;
503 		struct uio *a_uio;
504 		int  a_ioflag;
505 		struct ucred *a_cred;
506 	} */ *ap = v;
507 	struct vnode *vp = ap->a_vp;
508 	struct uio *uio = ap->a_uio;
509 	struct kern_target *kt;
510 	char strbuf[KSTRING], *buf;
511 	int off, len;
512 	int error;
513 
514 	if (vp->v_type == VDIR)
515 		return (EOPNOTSUPP);
516 
517 	kt = VTOKERN(vp)->kf_kt;
518 
519 #ifdef KERNFS_DIAGNOSTIC
520 	printf("kern_read %s\n", kt->kt_name);
521 #endif
522 
523 	off = uio->uio_offset;
524 #if 0
525 	while (buf = strbuf,
526 #else
527 	if (buf = strbuf,
528 #endif
529 	    len = kernfs_xread(kt, off, &buf, sizeof(strbuf))) {
530 		if ((error = uiomove(buf, len, uio)) != 0)
531 			return (error);
532 		off += len;
533 	}
534 	return (0);
535 }
536 
537 int
538 kernfs_write(v)
539 	void *v;
540 {
541 	struct vop_write_args /* {
542 		struct vnode *a_vp;
543 		struct uio *a_uio;
544 		int  a_ioflag;
545 		struct ucred *a_cred;
546 	} */ *ap = v;
547 	struct vnode *vp = ap->a_vp;
548 	struct uio *uio = ap->a_uio;
549 	struct kern_target *kt;
550 	int error, xlen;
551 	char strbuf[KSTRING];
552 
553 	if (vp->v_type == VDIR)
554 		return (EOPNOTSUPP);
555 
556 	kt = VTOKERN(vp)->kf_kt;
557 
558 	if (uio->uio_offset != 0)
559 		return (EINVAL);
560 
561 	xlen = min(uio->uio_resid, KSTRING-1);
562 	if ((error = uiomove(strbuf, xlen, uio)) != 0)
563 		return (error);
564 
565 	if (uio->uio_resid != 0)
566 		return (EIO);
567 
568 	strbuf[xlen] = '\0';
569 	xlen = strlen(strbuf);
570 	return (kernfs_xwrite(kt, strbuf, xlen));
571 }
572 
573 int
574 kernfs_readdir(v)
575 	void *v;
576 {
577 	struct vop_readdir_args /* {
578 		struct vnode *a_vp;
579 		struct uio *a_uio;
580 		struct ucred *a_cred;
581 		int *a_eofflag;
582 		off_t *a_cookies;
583 		int a_ncookies;
584 	} */ *ap = v;
585 	struct uio *uio = ap->a_uio;
586 	struct dirent d;
587 	struct kern_target *kt;
588 	int i;
589 	int error;
590 	off_t *cookies = ap->a_cookies;
591 	int ncookies = ap->a_ncookies;
592 
593 	if (ap->a_vp->v_type != VDIR)
594 		return (ENOTDIR);
595 
596 	if (uio->uio_resid < UIO_MX)
597 		return (EINVAL);
598 	if (uio->uio_offset < 0)
599 		return (EINVAL);
600 
601 	error = 0;
602 	i = uio->uio_offset;
603 	bzero((caddr_t)&d, UIO_MX);
604 	d.d_reclen = UIO_MX;
605 
606 	for (kt = &kern_targets[i];
607 	     uio->uio_resid >= UIO_MX && i < nkern_targets; kt++, i++) {
608 #ifdef KERNFS_DIAGNOSTIC
609 		printf("kernfs_readdir: i = %d\n", i);
610 #endif
611 
612 		if (kt->kt_tag == KTT_DEVICE) {
613 			dev_t *dp = kt->kt_data;
614 			struct vnode *fvp;
615 
616 			if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp))
617 				continue;
618 		}
619 
620 		d.d_fileno = i + 3;
621 		d.d_namlen = kt->kt_namlen;
622 		bcopy(kt->kt_name, d.d_name, kt->kt_namlen + 1);
623 		d.d_type = kt->kt_type;
624 
625 		if ((error = uiomove((caddr_t)&d, UIO_MX, uio)) != 0)
626 			break;
627 		if (ncookies-- > 0)
628 			*cookies++ = i + 1;
629 	}
630 
631 	uio->uio_offset = i;
632 	return (error);
633 }
634 
635 int
636 kernfs_inactive(v)
637 	void *v;
638 {
639 	struct vop_inactive_args /* {
640 		struct vnode *a_vp;
641 	} */ *ap = v;
642 	struct vnode *vp = ap->a_vp;
643 
644 #ifdef KERNFS_DIAGNOSTIC
645 	printf("kernfs_inactive(%p)\n", vp);
646 #endif
647 	/*
648 	 * Clear out the v_type field to avoid
649 	 * nasty things happening in vgone().
650 	 */
651 	vp->v_type = VNON;
652 	return (0);
653 }
654 
655 int
656 kernfs_reclaim(v)
657 	void *v;
658 {
659 	struct vop_reclaim_args /* {
660 		struct vnode *a_vp;
661 	} */ *ap = v;
662 	struct vnode *vp = ap->a_vp;
663 
664 #ifdef KERNFS_DIAGNOSTIC
665 	printf("kernfs_reclaim(%p)\n", vp);
666 #endif
667 	if (vp->v_data) {
668 		FREE(vp->v_data, M_TEMP);
669 		vp->v_data = 0;
670 	}
671 	return (0);
672 }
673 
674 /*
675  * Return POSIX pathconf information applicable to special devices.
676  */
677 int
678 kernfs_pathconf(v)
679 	void *v;
680 {
681 	struct vop_pathconf_args /* {
682 		struct vnode *a_vp;
683 		int a_name;
684 		register_t *a_retval;
685 	} */ *ap = v;
686 
687 	switch (ap->a_name) {
688 	case _PC_LINK_MAX:
689 		*ap->a_retval = LINK_MAX;
690 		return (0);
691 	case _PC_MAX_CANON:
692 		*ap->a_retval = MAX_CANON;
693 		return (0);
694 	case _PC_MAX_INPUT:
695 		*ap->a_retval = MAX_INPUT;
696 		return (0);
697 	case _PC_PIPE_BUF:
698 		*ap->a_retval = PIPE_BUF;
699 		return (0);
700 	case _PC_CHOWN_RESTRICTED:
701 		*ap->a_retval = 1;
702 		return (0);
703 	case _PC_VDISABLE:
704 		*ap->a_retval = _POSIX_VDISABLE;
705 		return (0);
706 	default:
707 		return (EINVAL);
708 	}
709 	/* NOTREACHED */
710 }
711 
712 /*
713  * Print out the contents of a /dev/fd vnode.
714  */
715 /* ARGSUSED */
716 int
717 kernfs_print(v)
718 	void *v;
719 {
720 
721 	printf("tag VT_KERNFS, kernfs vnode\n");
722 	return (0);
723 }
724 
725 int
726 kernfs_link(v)
727 	void *v;
728 {
729 	struct vop_link_args /* {
730 		struct vnode *a_dvp;
731 		struct vnode *a_vp;
732 		struct componentname *a_cnp;
733 	} */ *ap = v;
734 
735 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
736 	vput(ap->a_dvp);
737 	return (EROFS);
738 }
739 
740 int
741 kernfs_symlink(v)
742 	void *v;
743 {
744 	struct vop_symlink_args /* {
745 		struct vnode *a_dvp;
746 		struct vnode **a_vpp;
747 		struct componentname *a_cnp;
748 		struct vattr *a_vap;
749 		char *a_target;
750 	} */ *ap = v;
751 
752 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
753 	vput(ap->a_dvp);
754 	return (EROFS);
755 }
756