xref: /netbsd-src/sys/miscfs/kernfs/kernfs_vnops.c (revision 4472dbe5e3bd91ef2540bada7a7ca7384627ff9b)
1 /*	$NetBSD: kernfs_vnops.c,v 1.67 1999/08/25 14:42:35 sommerfeld 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	8.15 (Berkeley) 5/21/95
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 #include <vm/vm.h>
66 
67 #include <uvm/uvm_extern.h>
68 
69 #define KSTRING	256		/* Largest I/O available via this filesystem */
70 #define	UIO_MX 32
71 
72 #define	READ_MODE	(S_IRUSR|S_IRGRP|S_IROTH)
73 #define	WRITE_MODE	(S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH)
74 #define DIR_MODE	(S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)
75 
76 struct kern_target kern_targets[] = {
77 /* NOTE: The name must be less than UIO_MX-16 chars in length */
78 #define N(s) sizeof(s)-1, s
79      /*        name            data          tag           type  ro/rw */
80      { DT_DIR, N("."),         0,            KTT_NULL,     VDIR, DIR_MODE   },
81      { DT_DIR, N(".."),        0,            KTT_NULL,     VDIR, DIR_MODE   },
82      { DT_REG, N("boottime"),  &boottime.tv_sec, KTT_INT,  VREG, READ_MODE  },
83      { DT_REG, N("copyright"), copyright,    KTT_STRING,   VREG, READ_MODE  },
84      { DT_REG, N("hostname"),  0,            KTT_HOSTNAME, VREG, WRITE_MODE },
85      { DT_REG, N("hz"),        &hz,          KTT_INT,      VREG, READ_MODE  },
86      { DT_REG, N("loadavg"),   0,            KTT_AVENRUN,  VREG, READ_MODE  },
87      { DT_REG, N("msgbuf"),    0,	     KTT_MSGBUF,   VREG, READ_MODE  },
88      { DT_REG, N("pagesize"),  &uvmexp.pagesize, KTT_INT,  VREG, READ_MODE  },
89      { DT_REG, N("physmem"),   &physmem,     KTT_INT,      VREG, READ_MODE  },
90 #if 0
91      { DT_DIR, N("root"),      0,            KTT_NULL,     VDIR, DIR_MODE   },
92 #endif
93      { DT_BLK, N("rootdev"),   &rootdev,     KTT_DEVICE,   VBLK, READ_MODE  },
94      { DT_CHR, N("rrootdev"),  &rrootdev,    KTT_DEVICE,   VCHR, READ_MODE  },
95      { DT_REG, N("time"),      0,            KTT_TIME,     VREG, READ_MODE  },
96      { DT_REG, N("version"),   version,      KTT_STRING,   VREG, READ_MODE  },
97 #undef N
98 };
99 static int nkern_targets = sizeof(kern_targets) / sizeof(kern_targets[0]);
100 
101 int	kernfs_lookup	__P((void *));
102 #define	kernfs_create	genfs_eopnotsupp_rele
103 #define	kernfs_mknod	genfs_eopnotsupp_rele
104 #define	kernfs_open	genfs_nullop
105 #define	kernfs_close	genfs_nullop
106 int	kernfs_access	__P((void *));
107 int	kernfs_getattr	__P((void *));
108 int	kernfs_setattr	__P((void *));
109 int	kernfs_read	__P((void *));
110 int	kernfs_write	__P((void *));
111 #define	kernfs_fcntl	genfs_fcntl
112 #define	kernfs_ioctl	genfs_enoioctl
113 #define	kernfs_poll	genfs_poll
114 #define kernfs_revoke	genfs_revoke
115 #define	kernfs_mmap	genfs_eopnotsupp
116 #define	kernfs_fsync	genfs_nullop
117 #define	kernfs_seek	genfs_nullop
118 #define	kernfs_remove	genfs_eopnotsupp_rele
119 int	kernfs_link	__P((void *));
120 #define	kernfs_rename	genfs_eopnotsupp_rele
121 #define	kernfs_mkdir	genfs_eopnotsupp_rele
122 #define	kernfs_rmdir	genfs_eopnotsupp_rele
123 int	kernfs_symlink	__P((void *));
124 int	kernfs_readdir	__P((void *));
125 #define	kernfs_readlink	genfs_eopnotsupp
126 #define	kernfs_abortop	genfs_abortop
127 int	kernfs_inactive	__P((void *));
128 int	kernfs_reclaim	__P((void *));
129 #define	kernfs_lock	genfs_lock
130 #define	kernfs_unlock	genfs_unlock
131 #define	kernfs_bmap	genfs_badop
132 #define	kernfs_strategy	genfs_badop
133 int	kernfs_print	__P((void *));
134 #define	kernfs_islocked	genfs_islocked
135 int	kernfs_pathconf	__P((void *));
136 #define	kernfs_advlock	genfs_einval
137 #define	kernfs_blkatoff	genfs_eopnotsupp
138 #define	kernfs_valloc	genfs_eopnotsupp
139 #define	kernfs_vfree	genfs_nullop
140 #define	kernfs_truncate	genfs_eopnotsupp
141 #define	kernfs_update	genfs_nullop
142 #define	kernfs_bwrite	genfs_eopnotsupp
143 
144 int	kernfs_xread __P((struct kern_target *, int, char **, int));
145 int	kernfs_xwrite __P((struct kern_target *, char *, int));
146 
147 int (**kernfs_vnodeop_p) __P((void *));
148 struct vnodeopv_entry_desc kernfs_vnodeop_entries[] = {
149 	{ &vop_default_desc, vn_default_error },
150 	{ &vop_lookup_desc, kernfs_lookup },		/* lookup */
151 	{ &vop_create_desc, kernfs_create },		/* create */
152 	{ &vop_mknod_desc, kernfs_mknod },		/* mknod */
153 	{ &vop_open_desc, kernfs_open },		/* open */
154 	{ &vop_close_desc, kernfs_close },		/* close */
155 	{ &vop_access_desc, kernfs_access },		/* access */
156 	{ &vop_getattr_desc, kernfs_getattr },		/* getattr */
157 	{ &vop_setattr_desc, kernfs_setattr },		/* setattr */
158 	{ &vop_read_desc, kernfs_read },		/* read */
159 	{ &vop_write_desc, kernfs_write },		/* write */
160 	{ &vop_fcntl_desc, kernfs_fcntl },		/* fcntl */
161 	{ &vop_ioctl_desc, kernfs_ioctl },		/* ioctl */
162 	{ &vop_poll_desc, kernfs_poll },		/* poll */
163 	{ &vop_revoke_desc, kernfs_revoke },		/* revoke */
164 	{ &vop_mmap_desc, kernfs_mmap },		/* mmap */
165 	{ &vop_fsync_desc, kernfs_fsync },		/* fsync */
166 	{ &vop_seek_desc, kernfs_seek },		/* seek */
167 	{ &vop_remove_desc, kernfs_remove },		/* remove */
168 	{ &vop_link_desc, kernfs_link },		/* link */
169 	{ &vop_rename_desc, kernfs_rename },		/* rename */
170 	{ &vop_mkdir_desc, kernfs_mkdir },		/* mkdir */
171 	{ &vop_rmdir_desc, kernfs_rmdir },		/* rmdir */
172 	{ &vop_symlink_desc, kernfs_symlink },		/* symlink */
173 	{ &vop_readdir_desc, kernfs_readdir },		/* readdir */
174 	{ &vop_readlink_desc, kernfs_readlink },	/* readlink */
175 	{ &vop_abortop_desc, kernfs_abortop },		/* abortop */
176 	{ &vop_inactive_desc, kernfs_inactive },	/* inactive */
177 	{ &vop_reclaim_desc, kernfs_reclaim },		/* reclaim */
178 	{ &vop_lock_desc, kernfs_lock },		/* lock */
179 	{ &vop_unlock_desc, kernfs_unlock },		/* unlock */
180 	{ &vop_bmap_desc, kernfs_bmap },		/* bmap */
181 	{ &vop_strategy_desc, kernfs_strategy },	/* strategy */
182 	{ &vop_print_desc, kernfs_print },		/* print */
183 	{ &vop_islocked_desc, kernfs_islocked },	/* islocked */
184 	{ &vop_pathconf_desc, kernfs_pathconf },	/* pathconf */
185 	{ &vop_advlock_desc, kernfs_advlock },		/* advlock */
186 	{ &vop_blkatoff_desc, kernfs_blkatoff },	/* blkatoff */
187 	{ &vop_valloc_desc, kernfs_valloc },		/* valloc */
188 	{ &vop_vfree_desc, kernfs_vfree },		/* vfree */
189 	{ &vop_truncate_desc, kernfs_truncate },	/* truncate */
190 	{ &vop_update_desc, kernfs_update },		/* update */
191 	{ &vop_bwrite_desc, kernfs_bwrite },		/* bwrite */
192 	{ (struct vnodeop_desc*)NULL, (int(*) __P((void *)))NULL }
193 };
194 struct vnodeopv_desc kernfs_vnodeop_opv_desc =
195 	{ &kernfs_vnodeop_p, kernfs_vnodeop_entries };
196 
197 int
198 kernfs_xread(kt, off, bufp, len)
199 	struct kern_target *kt;
200 	int off;
201 	char **bufp;
202 	int len;
203 {
204 
205 	switch (kt->kt_tag) {
206 	case KTT_TIME: {
207 		struct timeval tv;
208 
209 		microtime(&tv);
210 		sprintf(*bufp, "%ld %ld\n", tv.tv_sec, tv.tv_usec);
211 		break;
212 	}
213 
214 	case KTT_INT: {
215 		int *ip = kt->kt_data;
216 
217 		sprintf(*bufp, "%d\n", *ip);
218 		break;
219 	}
220 
221 	case KTT_STRING: {
222 		char *cp = kt->kt_data;
223 
224 		*bufp = cp;
225 		break;
226 	}
227 
228 	case KTT_MSGBUF: {
229 		long n;
230 
231 		/*
232 		 * deal with cases where the message buffer has
233 		 * become corrupted.
234 		 */
235 		if (!msgbufenabled || msgbufp->msg_magic != MSG_MAGIC) {
236 			msgbufenabled = 0;
237 			return (ENXIO);
238 		}
239 
240 		/*
241 		 * Note that reads of /kern/msgbuf won't necessarily yield
242 		 * consistent results, if the message buffer is modified
243 		 * while the read is in progress.  The worst that can happen
244 		 * is that incorrect data will be read.  There's no way
245 		 * that this can crash the system unless the values in the
246 		 * message buffer header are corrupted, but that'll cause
247 		 * the system to die anyway.
248 		 */
249 		if (off >= msgbufp->msg_bufs)
250 			return (0);
251 		n = msgbufp->msg_bufx + off;
252 		if (n >= msgbufp->msg_bufs)
253 			n -= msgbufp->msg_bufs;
254 		len = min(msgbufp->msg_bufs - n, msgbufp->msg_bufs - off);
255 		*bufp = msgbufp->msg_bufc + n;
256 		return (len);
257 	}
258 
259 	case KTT_HOSTNAME: {
260 		char *cp = hostname;
261 		int xlen = hostnamelen;
262 
263 		if (xlen >= (len-2))
264 			return (EINVAL);
265 
266 		memcpy(*bufp, cp, xlen);
267 		(*bufp)[xlen] = '\n';
268 		(*bufp)[xlen+1] = '\0';
269 		break;
270 	}
271 
272 	case KTT_AVENRUN:
273 		averunnable.fscale = FSCALE;
274 		sprintf(*bufp, "%d %d %d %ld\n",
275 		    averunnable.ldavg[0], averunnable.ldavg[1],
276 		    averunnable.ldavg[2], averunnable.fscale);
277 		break;
278 
279 	default:
280 		return (0);
281 	}
282 
283 	len = strlen(*bufp);
284 	if (len <= off)
285 		return (0);
286 	*bufp += off;
287 	return (len - off);
288 }
289 
290 int
291 kernfs_xwrite(kt, buf, len)
292 	struct kern_target *kt;
293 	char *buf;
294 	int len;
295 {
296 
297 	switch (kt->kt_tag) {
298 	case KTT_HOSTNAME:
299 		if (buf[len-1] == '\n')
300 			--len;
301 		memcpy(hostname, buf, len);
302 		hostname[len] = '\0';
303 		hostnamelen = len;
304 		return (0);
305 
306 	default:
307 		return (EIO);
308 	}
309 }
310 
311 
312 /*
313  * vp is the current namei directory
314  * ndp is the name to locate in that directory...
315  */
316 int
317 kernfs_lookup(v)
318 	void *v;
319 {
320 	struct vop_lookup_args /* {
321 		struct vnode * a_dvp;
322 		struct vnode ** a_vpp;
323 		struct componentname * a_cnp;
324 	} */ *ap = v;
325 	struct componentname *cnp = ap->a_cnp;
326 	struct vnode **vpp = ap->a_vpp;
327 	struct vnode *dvp = ap->a_dvp;
328 	const char *pname = cnp->cn_nameptr;
329 	struct kern_target *kt;
330 	struct vnode *fvp;
331 	int error, i, wantpunlock;
332 
333 #ifdef KERNFS_DIAGNOSTIC
334 	printf("kernfs_lookup(%p)\n", ap);
335 	printf("kernfs_lookup(dp = %p, vpp = %p, cnp = %p)\n", dvp, vpp, ap->a_cnp);
336 	printf("kernfs_lookup(%s)\n", pname);
337 #endif
338 
339 	*vpp = NULLVP;
340 	cnp->cn_flags &= ~PDIRUNLOCK;
341 
342 	if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
343 		return (EROFS);
344 
345 	if (cnp->cn_namelen == 1 && *pname == '.') {
346 		*vpp = dvp;
347 		VREF(dvp);
348 		return (0);
349 	}
350 
351 	/*
352 	 * This code only supports a flat directory, so we don't
353 	 * need to worry about ..
354 	 */
355 
356 #if 0
357 	if (cnp->cn_namelen == 4 && memcmp(pname, "root", 4) == 0) {
358 		*vpp = rootdir;
359 		VREF(rootdir);
360 		vn_lock(rootdir, LK_SHARED | LK_RETRY);
361 		return (0);
362 	}
363 #endif
364 
365 	wantpunlock = (~cnp->cn_flags & (LOCKPARENT | ISLASTCN));
366 
367 	for (kt = kern_targets, i = 0; i < nkern_targets; kt++, i++) {
368 		if (cnp->cn_namelen == kt->kt_namlen &&
369 		    memcmp(kt->kt_name, pname, cnp->cn_namelen) == 0)
370 			goto found;
371 	}
372 
373 #ifdef KERNFS_DIAGNOSTIC
374 	printf("kernfs_lookup: i = %d, failed", i);
375 #endif
376 
377 	return (cnp->cn_nameiop == LOOKUP ? ENOENT : EROFS);
378 
379 found:
380 	if (kt->kt_tag == KTT_DEVICE) {
381 		dev_t *dp = kt->kt_data;
382 	loop:
383 		if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp)) {
384 			return (ENOENT);
385 		}
386 		*vpp = fvp;
387 		if (vget(fvp, LK_EXCLUSIVE))
388 			goto loop;
389 		if (wantpunlock) {
390 			VOP_UNLOCK(dvp, 0);
391 			cnp->cn_flags |= PDIRUNLOCK;
392 		}
393 		return (0);
394 	}
395 
396 #ifdef KERNFS_DIAGNOSTIC
397 	printf("kernfs_lookup: allocate new vnode\n");
398 #endif
399 	error = getnewvnode(VT_KERNFS, dvp->v_mount, kernfs_vnodeop_p, &fvp);
400 	if (error) {
401 		return (error);
402 	}
403 
404 	MALLOC(fvp->v_data, void *, sizeof(struct kernfs_node), M_TEMP,
405 	    M_WAITOK);
406 	VTOKERN(fvp)->kf_kt = kt;
407 	fvp->v_type = kt->kt_vtype;
408 	vn_lock(fvp, LK_EXCLUSIVE | LK_RETRY);
409 	*vpp = fvp;
410 
411 #ifdef KERNFS_DIAGNOSTIC
412 	printf("kernfs_lookup: newvp = %p\n", fvp);
413 #endif
414 	if (wantpunlock) {
415 		VOP_UNLOCK(dvp, 0);
416 		cnp->cn_flags |= PDIRUNLOCK;
417 	}
418 	return (0);
419 }
420 
421 int
422 kernfs_access(v)
423 	void *v;
424 {
425 	struct vop_access_args /* {
426 		struct vnode *a_vp;
427 		int a_mode;
428 		struct ucred *a_cred;
429 		struct proc *a_p;
430 	} */ *ap = v;
431 	struct vnode *vp = ap->a_vp;
432 	mode_t mode;
433 
434 	if (vp->v_flag & VROOT) {
435 		mode = DIR_MODE;
436 	} else {
437 		struct kern_target *kt = VTOKERN(vp)->kf_kt;
438 		mode = kt->kt_mode;
439 	}
440 
441 	return (vaccess(vp->v_type, mode, (uid_t)0, (gid_t)0, ap->a_mode,
442 	    ap->a_cred));
443 }
444 
445 int
446 kernfs_getattr(v)
447 	void *v;
448 {
449 	struct vop_getattr_args /* {
450 		struct vnode *a_vp;
451 		struct vattr *a_vap;
452 		struct ucred *a_cred;
453 		struct proc *a_p;
454 	} */ *ap = v;
455 	struct vnode *vp = ap->a_vp;
456 	struct vattr *vap = ap->a_vap;
457 	struct timeval tv;
458 	int error = 0;
459 	char strbuf[KSTRING], *buf;
460 
461 	memset((caddr_t) vap, 0, sizeof(*vap));
462 	vattr_null(vap);
463 	vap->va_uid = 0;
464 	vap->va_gid = 0;
465 	vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
466 	vap->va_size = 0;
467 	vap->va_blocksize = DEV_BSIZE;
468 	microtime(&tv);
469 	TIMEVAL_TO_TIMESPEC(&tv, &vap->va_atime);
470 	vap->va_mtime = vap->va_atime;
471 	vap->va_ctime = vap->va_ctime;
472 	vap->va_gen = 0;
473 	vap->va_flags = 0;
474 	vap->va_rdev = 0;
475 	vap->va_bytes = 0;
476 
477 	if (vp->v_flag & VROOT) {
478 #ifdef KERNFS_DIAGNOSTIC
479 		printf("kernfs_getattr: stat rootdir\n");
480 #endif
481 		vap->va_type = VDIR;
482 		vap->va_mode = DIR_MODE;
483 		vap->va_nlink = 2;
484 		vap->va_fileid = 2;
485 		vap->va_size = DEV_BSIZE;
486 	} else {
487 		struct kern_target *kt = VTOKERN(vp)->kf_kt;
488 		int nbytes, total;
489 #ifdef KERNFS_DIAGNOSTIC
490 		printf("kernfs_getattr: stat target %s\n", kt->kt_name);
491 #endif
492 		vap->va_type = kt->kt_vtype;
493 		vap->va_mode = kt->kt_mode;
494 		vap->va_nlink = 1;
495 		vap->va_fileid = 1 + (kt - kern_targets);
496 		total = 0;
497 		while (buf = strbuf,
498 		       nbytes = kernfs_xread(kt, total, &buf, sizeof(strbuf)))
499 			total += nbytes;
500 		vap->va_size = total;
501 	}
502 
503 #ifdef KERNFS_DIAGNOSTIC
504 	printf("kernfs_getattr: return error %d\n", error);
505 #endif
506 	return (error);
507 }
508 
509 /*ARGSUSED*/
510 int
511 kernfs_setattr(v)
512 	void *v;
513 {
514 	/*
515 	 * Silently ignore attribute changes.
516 	 * This allows for open with truncate to have no
517 	 * effect until some data is written.  I want to
518 	 * do it this way because all writes are atomic.
519 	 */
520 	return (0);
521 }
522 
523 int
524 kernfs_read(v)
525 	void *v;
526 {
527 	struct vop_read_args /* {
528 		struct vnode *a_vp;
529 		struct uio *a_uio;
530 		int  a_ioflag;
531 		struct ucred *a_cred;
532 	} */ *ap = v;
533 	struct vnode *vp = ap->a_vp;
534 	struct uio *uio = ap->a_uio;
535 	struct kern_target *kt;
536 	char strbuf[KSTRING], *buf;
537 	int off, len;
538 	int error;
539 
540 	if (vp->v_type == VDIR)
541 		return (EOPNOTSUPP);
542 
543 	kt = VTOKERN(vp)->kf_kt;
544 
545 #ifdef KERNFS_DIAGNOSTIC
546 	printf("kern_read %s\n", kt->kt_name);
547 #endif
548 
549 	off = uio->uio_offset;
550 #if 0
551 	while (buf = strbuf,
552 #else
553 	if (buf = strbuf,
554 #endif
555 	    len = kernfs_xread(kt, off, &buf, sizeof(strbuf))) {
556 		if ((error = uiomove(buf, len, uio)) != 0)
557 			return (error);
558 		off += len;
559 	}
560 	return (0);
561 }
562 
563 int
564 kernfs_write(v)
565 	void *v;
566 {
567 	struct vop_write_args /* {
568 		struct vnode *a_vp;
569 		struct uio *a_uio;
570 		int  a_ioflag;
571 		struct ucred *a_cred;
572 	} */ *ap = v;
573 	struct vnode *vp = ap->a_vp;
574 	struct uio *uio = ap->a_uio;
575 	struct kern_target *kt;
576 	int error, xlen;
577 	char strbuf[KSTRING];
578 
579 	if (vp->v_type == VDIR)
580 		return (EOPNOTSUPP);
581 
582 	kt = VTOKERN(vp)->kf_kt;
583 
584 	if (uio->uio_offset != 0)
585 		return (EINVAL);
586 
587 	xlen = min(uio->uio_resid, KSTRING-1);
588 	if ((error = uiomove(strbuf, xlen, uio)) != 0)
589 		return (error);
590 
591 	if (uio->uio_resid != 0)
592 		return (EIO);
593 
594 	strbuf[xlen] = '\0';
595 	xlen = strlen(strbuf);
596 	return (kernfs_xwrite(kt, strbuf, xlen));
597 }
598 
599 int
600 kernfs_readdir(v)
601 	void *v;
602 {
603 	struct vop_readdir_args /* {
604 		struct vnode *a_vp;
605 		struct uio *a_uio;
606 		struct ucred *a_cred;
607 		int *a_eofflag;
608 		off_t **a_cookies;
609 		int a_*ncookies;
610 	} */ *ap = v;
611 	struct uio *uio = ap->a_uio;
612 	struct dirent d;
613 	struct kern_target *kt;
614 	off_t i;
615 	int error;
616 	off_t *cookies = NULL;
617 	int ncookies = 0, nc = 0;
618 
619 	if (ap->a_vp->v_type != VDIR)
620 		return (ENOTDIR);
621 
622 	if (uio->uio_resid < UIO_MX)
623 		return (EINVAL);
624 	if (uio->uio_offset < 0)
625 		return (EINVAL);
626 
627 	error = 0;
628 	i = uio->uio_offset;
629 
630 	if (i >= nkern_targets)
631 		return 0;
632 
633 	memset((caddr_t)&d, 0, UIO_MX);
634 	d.d_reclen = UIO_MX;
635 
636 	if (ap->a_ncookies) {
637 		nc = uio->uio_resid / UIO_MX;
638 		nc = min(nc, (nkern_targets - i));
639 		MALLOC(cookies, off_t *, nc * sizeof(off_t), M_TEMP,
640 		    M_WAITOK);
641 		*ap->a_cookies = cookies;
642 	}
643 
644 	for (kt = &kern_targets[i];
645 	     uio->uio_resid >= UIO_MX && i < nkern_targets; kt++, i++) {
646 #ifdef KERNFS_DIAGNOSTIC
647 		printf("kernfs_readdir: i = %d\n", i);
648 #endif
649 
650 		if (kt->kt_tag == KTT_DEVICE) {
651 			dev_t *dp = kt->kt_data;
652 			struct vnode *fvp;
653 
654 			if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp))
655 				continue;
656 		}
657 
658 		d.d_fileno = i + 3;
659 		d.d_namlen = kt->kt_namlen;
660 		memcpy(d.d_name, kt->kt_name, kt->kt_namlen + 1);
661 		d.d_type = kt->kt_type;
662 
663 		if ((error = uiomove((caddr_t)&d, UIO_MX, uio)) != 0)
664 			break;
665 		if (cookies) {
666 			*cookies++ = i + 1;
667 			ncookies++;
668 		}
669 	}
670 
671 	if (ap->a_ncookies) {
672 		if (error) {
673 			FREE(*ap->a_cookies, M_TEMP);
674 			*ap->a_ncookies = 0;
675 			*ap->a_cookies = NULL;
676 		} else
677 			*ap->a_ncookies = ncookies;
678 	}
679 
680 	uio->uio_offset = i;
681 	return (error);
682 }
683 
684 int
685 kernfs_inactive(v)
686 	void *v;
687 {
688 	struct vop_inactive_args /* {
689 		struct vnode *a_vp;
690 		struct proc *a_p;
691 	} */ *ap = v;
692 	struct vnode *vp = ap->a_vp;
693 
694 #ifdef KERNFS_DIAGNOSTIC
695 	printf("kernfs_inactive(%p)\n", vp);
696 #endif
697 	/*
698 	 * Clear out the v_type field to avoid
699 	 * nasty things happening in vgone().
700 	 */
701 	VOP_UNLOCK(vp, 0);
702 	vp->v_type = VNON;
703 	return (0);
704 }
705 
706 int
707 kernfs_reclaim(v)
708 	void *v;
709 {
710 	struct vop_reclaim_args /* {
711 		struct vnode *a_vp;
712 	} */ *ap = v;
713 	struct vnode *vp = ap->a_vp;
714 
715 #ifdef KERNFS_DIAGNOSTIC
716 	printf("kernfs_reclaim(%p)\n", vp);
717 #endif
718 	if (vp->v_data) {
719 		FREE(vp->v_data, M_TEMP);
720 		vp->v_data = 0;
721 	}
722 	return (0);
723 }
724 
725 /*
726  * Return POSIX pathconf information applicable to special devices.
727  */
728 int
729 kernfs_pathconf(v)
730 	void *v;
731 {
732 	struct vop_pathconf_args /* {
733 		struct vnode *a_vp;
734 		int a_name;
735 		register_t *a_retval;
736 	} */ *ap = v;
737 
738 	switch (ap->a_name) {
739 	case _PC_LINK_MAX:
740 		*ap->a_retval = LINK_MAX;
741 		return (0);
742 	case _PC_MAX_CANON:
743 		*ap->a_retval = MAX_CANON;
744 		return (0);
745 	case _PC_MAX_INPUT:
746 		*ap->a_retval = MAX_INPUT;
747 		return (0);
748 	case _PC_PIPE_BUF:
749 		*ap->a_retval = PIPE_BUF;
750 		return (0);
751 	case _PC_CHOWN_RESTRICTED:
752 		*ap->a_retval = 1;
753 		return (0);
754 	case _PC_VDISABLE:
755 		*ap->a_retval = _POSIX_VDISABLE;
756 		return (0);
757 	case _PC_SYNC_IO:
758 		*ap->a_retval = 1;
759 		return (0);
760 	default:
761 		return (EINVAL);
762 	}
763 	/* NOTREACHED */
764 }
765 
766 /*
767  * Print out the contents of a /dev/fd vnode.
768  */
769 /* ARGSUSED */
770 int
771 kernfs_print(v)
772 	void *v;
773 {
774 
775 	printf("tag VT_KERNFS, kernfs vnode\n");
776 	return (0);
777 }
778 
779 int
780 kernfs_link(v)
781 	void *v;
782 {
783 	struct vop_link_args /* {
784 		struct vnode *a_dvp;
785 		struct vnode *a_vp;
786 		struct componentname *a_cnp;
787 	} */ *ap = v;
788 
789 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
790 	vput(ap->a_dvp);
791 	return (EROFS);
792 }
793 
794 int
795 kernfs_symlink(v)
796 	void *v;
797 {
798 	struct vop_symlink_args /* {
799 		struct vnode *a_dvp;
800 		struct vnode **a_vpp;
801 		struct componentname *a_cnp;
802 		struct vattr *a_vap;
803 		char *a_target;
804 	} */ *ap = v;
805 
806 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
807 	vput(ap->a_dvp);
808 	return (EROFS);
809 }
810