xref: /netbsd/sys/miscfs/kernfs/kernfs_vnops.c (revision bf9ec67e)
1 /*	$NetBSD: kernfs_vnops.c,v 1.79 2001/12/06 04:27:42 chs 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/cdefs.h>
46 __KERNEL_RCSID(0, "$NetBSD: kernfs_vnops.c,v 1.79 2001/12/06 04:27:42 chs Exp $");
47 
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/kernel.h>
51 #include <sys/vmmeter.h>
52 #include <sys/time.h>
53 #include <sys/proc.h>
54 #include <sys/vnode.h>
55 #include <sys/malloc.h>
56 #include <sys/file.h>
57 #include <sys/stat.h>
58 #include <sys/mount.h>
59 #include <sys/namei.h>
60 #include <sys/buf.h>
61 #include <sys/dirent.h>
62 #include <sys/msgbuf.h>
63 
64 #include <miscfs/genfs/genfs.h>
65 #include <miscfs/kernfs/kernfs.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 const 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 			/* XXX cast away const */
84      { DT_REG, N("copyright"), (void *)copyright,
85      					     KTT_STRING,   VREG, READ_MODE  },
86      { DT_REG, N("hostname"),  0,            KTT_HOSTNAME, VREG, WRITE_MODE },
87      { DT_REG, N("hz"),        &hz,          KTT_INT,      VREG, READ_MODE  },
88      { DT_REG, N("loadavg"),   0,            KTT_AVENRUN,  VREG, READ_MODE  },
89      { DT_REG, N("msgbuf"),    0,	     KTT_MSGBUF,   VREG, READ_MODE  },
90      { DT_REG, N("pagesize"),  &uvmexp.pagesize, KTT_INT,  VREG, READ_MODE  },
91      { DT_REG, N("physmem"),   &physmem,     KTT_INT,      VREG, READ_MODE  },
92 #if 0
93      { DT_DIR, N("root"),      0,            KTT_NULL,     VDIR, DIR_MODE   },
94 #endif
95      { DT_BLK, N("rootdev"),   &rootdev,     KTT_DEVICE,   VBLK, READ_MODE  },
96      { DT_CHR, N("rrootdev"),  &rrootdev,    KTT_DEVICE,   VCHR, READ_MODE  },
97      { DT_REG, N("time"),      0,            KTT_TIME,     VREG, READ_MODE  },
98 			/* XXX cast away const */
99      { DT_REG, N("version"),   (void *)version,
100      					     KTT_STRING,   VREG, READ_MODE  },
101 #undef N
102 };
103 static int nkern_targets = sizeof(kern_targets) / sizeof(kern_targets[0]);
104 
105 int	kernfs_lookup	__P((void *));
106 #define	kernfs_create	genfs_eopnotsupp_rele
107 #define	kernfs_mknod	genfs_eopnotsupp_rele
108 #define	kernfs_open	genfs_nullop
109 #define	kernfs_close	genfs_nullop
110 int	kernfs_access	__P((void *));
111 int	kernfs_getattr	__P((void *));
112 int	kernfs_setattr	__P((void *));
113 int	kernfs_read	__P((void *));
114 int	kernfs_write	__P((void *));
115 #define	kernfs_fcntl	genfs_fcntl
116 #define	kernfs_ioctl	genfs_enoioctl
117 #define	kernfs_poll	genfs_poll
118 #define kernfs_revoke	genfs_revoke
119 #define	kernfs_fsync	genfs_nullop
120 #define	kernfs_seek	genfs_nullop
121 #define	kernfs_remove	genfs_eopnotsupp_rele
122 int	kernfs_link	__P((void *));
123 #define	kernfs_rename	genfs_eopnotsupp_rele
124 #define	kernfs_mkdir	genfs_eopnotsupp_rele
125 #define	kernfs_rmdir	genfs_eopnotsupp_rele
126 int	kernfs_symlink	__P((void *));
127 int	kernfs_readdir	__P((void *));
128 #define	kernfs_readlink	genfs_eopnotsupp
129 #define	kernfs_abortop	genfs_abortop
130 int	kernfs_inactive	__P((void *));
131 int	kernfs_reclaim	__P((void *));
132 #define	kernfs_lock	genfs_lock
133 #define	kernfs_unlock	genfs_unlock
134 #define	kernfs_bmap	genfs_badop
135 #define	kernfs_strategy	genfs_badop
136 int	kernfs_print	__P((void *));
137 #define	kernfs_islocked	genfs_islocked
138 int	kernfs_pathconf	__P((void *));
139 #define	kernfs_advlock	genfs_einval
140 #define	kernfs_blkatoff	genfs_eopnotsupp
141 #define	kernfs_valloc	genfs_eopnotsupp
142 #define	kernfs_vfree	genfs_nullop
143 #define	kernfs_truncate	genfs_eopnotsupp
144 #define	kernfs_update	genfs_nullop
145 #define	kernfs_bwrite	genfs_eopnotsupp
146 #define	kernfs_putpages	genfs_putpages
147 
148 int	kernfs_xread __P((const struct kern_target *, int, char **, int));
149 int	kernfs_xwrite __P((const struct kern_target *, char *, int));
150 
151 int (**kernfs_vnodeop_p) __P((void *));
152 const struct vnodeopv_entry_desc kernfs_vnodeop_entries[] = {
153 	{ &vop_default_desc, vn_default_error },
154 	{ &vop_lookup_desc, kernfs_lookup },		/* lookup */
155 	{ &vop_create_desc, kernfs_create },		/* create */
156 	{ &vop_mknod_desc, kernfs_mknod },		/* mknod */
157 	{ &vop_open_desc, kernfs_open },		/* open */
158 	{ &vop_close_desc, kernfs_close },		/* close */
159 	{ &vop_access_desc, kernfs_access },		/* access */
160 	{ &vop_getattr_desc, kernfs_getattr },		/* getattr */
161 	{ &vop_setattr_desc, kernfs_setattr },		/* setattr */
162 	{ &vop_read_desc, kernfs_read },		/* read */
163 	{ &vop_write_desc, kernfs_write },		/* write */
164 	{ &vop_fcntl_desc, kernfs_fcntl },		/* fcntl */
165 	{ &vop_ioctl_desc, kernfs_ioctl },		/* ioctl */
166 	{ &vop_poll_desc, kernfs_poll },		/* poll */
167 	{ &vop_revoke_desc, kernfs_revoke },		/* revoke */
168 	{ &vop_fsync_desc, kernfs_fsync },		/* fsync */
169 	{ &vop_seek_desc, kernfs_seek },		/* seek */
170 	{ &vop_remove_desc, kernfs_remove },		/* remove */
171 	{ &vop_link_desc, kernfs_link },		/* link */
172 	{ &vop_rename_desc, kernfs_rename },		/* rename */
173 	{ &vop_mkdir_desc, kernfs_mkdir },		/* mkdir */
174 	{ &vop_rmdir_desc, kernfs_rmdir },		/* rmdir */
175 	{ &vop_symlink_desc, kernfs_symlink },		/* symlink */
176 	{ &vop_readdir_desc, kernfs_readdir },		/* readdir */
177 	{ &vop_readlink_desc, kernfs_readlink },	/* readlink */
178 	{ &vop_abortop_desc, kernfs_abortop },		/* abortop */
179 	{ &vop_inactive_desc, kernfs_inactive },	/* inactive */
180 	{ &vop_reclaim_desc, kernfs_reclaim },		/* reclaim */
181 	{ &vop_lock_desc, kernfs_lock },		/* lock */
182 	{ &vop_unlock_desc, kernfs_unlock },		/* unlock */
183 	{ &vop_bmap_desc, kernfs_bmap },		/* bmap */
184 	{ &vop_strategy_desc, kernfs_strategy },	/* strategy */
185 	{ &vop_print_desc, kernfs_print },		/* print */
186 	{ &vop_islocked_desc, kernfs_islocked },	/* islocked */
187 	{ &vop_pathconf_desc, kernfs_pathconf },	/* pathconf */
188 	{ &vop_advlock_desc, kernfs_advlock },		/* advlock */
189 	{ &vop_blkatoff_desc, kernfs_blkatoff },	/* blkatoff */
190 	{ &vop_valloc_desc, kernfs_valloc },		/* valloc */
191 	{ &vop_vfree_desc, kernfs_vfree },		/* vfree */
192 	{ &vop_truncate_desc, kernfs_truncate },	/* truncate */
193 	{ &vop_update_desc, kernfs_update },		/* update */
194 	{ &vop_bwrite_desc, kernfs_bwrite },		/* bwrite */
195 	{ &vop_putpages_desc, kernfs_putpages },	/* putpages */
196 	{ NULL, NULL }
197 };
198 const struct vnodeopv_desc kernfs_vnodeop_opv_desc =
199 	{ &kernfs_vnodeop_p, kernfs_vnodeop_entries };
200 
201 int
202 kernfs_xread(kt, off, bufp, len)
203 	const struct kern_target *kt;
204 	int off;
205 	char **bufp;
206 	int len;
207 {
208 
209 	switch (kt->kt_tag) {
210 	case KTT_TIME: {
211 		struct timeval tv;
212 
213 		microtime(&tv);
214 		sprintf(*bufp, "%ld %ld\n", tv.tv_sec, tv.tv_usec);
215 		break;
216 	}
217 
218 	case KTT_INT: {
219 		int *ip = kt->kt_data;
220 
221 		sprintf(*bufp, "%d\n", *ip);
222 		break;
223 	}
224 
225 	case KTT_STRING: {
226 		char *cp = kt->kt_data;
227 
228 		*bufp = cp;
229 		break;
230 	}
231 
232 	case KTT_MSGBUF: {
233 		long n;
234 
235 		/*
236 		 * deal with cases where the message buffer has
237 		 * become corrupted.
238 		 */
239 		if (!msgbufenabled || msgbufp->msg_magic != MSG_MAGIC) {
240 			msgbufenabled = 0;
241 			return (ENXIO);
242 		}
243 
244 		/*
245 		 * Note that reads of /kern/msgbuf won't necessarily yield
246 		 * consistent results, if the message buffer is modified
247 		 * while the read is in progress.  The worst that can happen
248 		 * is that incorrect data will be read.  There's no way
249 		 * that this can crash the system unless the values in the
250 		 * message buffer header are corrupted, but that'll cause
251 		 * the system to die anyway.
252 		 */
253 		if (off >= msgbufp->msg_bufs)
254 			return (0);
255 		n = msgbufp->msg_bufx + off;
256 		if (n >= msgbufp->msg_bufs)
257 			n -= msgbufp->msg_bufs;
258 		len = min(msgbufp->msg_bufs - n, msgbufp->msg_bufs - off);
259 		*bufp = msgbufp->msg_bufc + n;
260 		return (len);
261 	}
262 
263 	case KTT_HOSTNAME: {
264 		char *cp = hostname;
265 		int xlen = hostnamelen;
266 
267 		if (xlen >= (len-2))
268 			return (EINVAL);
269 
270 		memcpy(*bufp, cp, xlen);
271 		(*bufp)[xlen] = '\n';
272 		(*bufp)[xlen+1] = '\0';
273 		break;
274 	}
275 
276 	case KTT_AVENRUN:
277 		averunnable.fscale = FSCALE;
278 		sprintf(*bufp, "%d %d %d %ld\n",
279 		    averunnable.ldavg[0], averunnable.ldavg[1],
280 		    averunnable.ldavg[2], averunnable.fscale);
281 		break;
282 
283 	default:
284 		return (0);
285 	}
286 
287 	len = strlen(*bufp);
288 	if (len <= off)
289 		return (0);
290 	*bufp += off;
291 	return (len - off);
292 }
293 
294 int
295 kernfs_xwrite(kt, buf, len)
296 	const struct kern_target *kt;
297 	char *buf;
298 	int len;
299 {
300 
301 	switch (kt->kt_tag) {
302 	case KTT_HOSTNAME:
303 		if (buf[len-1] == '\n')
304 			--len;
305 		memcpy(hostname, buf, len);
306 		hostname[len] = '\0';
307 		hostnamelen = len;
308 		return (0);
309 
310 	default:
311 		return (EIO);
312 	}
313 }
314 
315 
316 /*
317  * vp is the current namei directory
318  * ndp is the name to locate in that directory...
319  */
320 int
321 kernfs_lookup(v)
322 	void *v;
323 {
324 	struct vop_lookup_args /* {
325 		struct vnode * a_dvp;
326 		struct vnode ** a_vpp;
327 		struct componentname * a_cnp;
328 	} */ *ap = v;
329 	struct componentname *cnp = ap->a_cnp;
330 	struct vnode **vpp = ap->a_vpp;
331 	struct vnode *dvp = ap->a_dvp;
332 	const char *pname = cnp->cn_nameptr;
333 	const struct kern_target *kt;
334 	struct vnode *fvp;
335 	int error, i, wantpunlock;
336 
337 #ifdef KERNFS_DIAGNOSTIC
338 	printf("kernfs_lookup(%p)\n", ap);
339 	printf("kernfs_lookup(dp = %p, vpp = %p, cnp = %p)\n", dvp, vpp, ap->a_cnp);
340 	printf("kernfs_lookup(%s)\n", pname);
341 #endif
342 
343 	*vpp = NULLVP;
344 	cnp->cn_flags &= ~PDIRUNLOCK;
345 
346 	if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
347 		return (EROFS);
348 
349 	if (cnp->cn_namelen == 1 && *pname == '.') {
350 		*vpp = dvp;
351 		VREF(dvp);
352 		return (0);
353 	}
354 
355 	/*
356 	 * This code only supports a flat directory, so we don't
357 	 * need to worry about ..
358 	 */
359 
360 #if 0
361 	if (cnp->cn_namelen == 4 && memcmp(pname, "root", 4) == 0) {
362 		*vpp = rootdir;
363 		VREF(rootdir);
364 		vn_lock(rootdir, LK_SHARED | LK_RETRY);
365 		return (0);
366 	}
367 #endif
368 
369 	wantpunlock = (~cnp->cn_flags & (LOCKPARENT | ISLASTCN));
370 
371 	for (kt = kern_targets, i = 0; i < nkern_targets; kt++, i++) {
372 		if (cnp->cn_namelen == kt->kt_namlen &&
373 		    memcmp(kt->kt_name, pname, cnp->cn_namelen) == 0)
374 			goto found;
375 	}
376 
377 #ifdef KERNFS_DIAGNOSTIC
378 	printf("kernfs_lookup: i = %d, failed", i);
379 #endif
380 
381 	return (cnp->cn_nameiop == LOOKUP ? ENOENT : EROFS);
382 
383 found:
384 	if (kt->kt_tag == KTT_DEVICE) {
385 		dev_t *dp = kt->kt_data;
386 	loop:
387 		if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp)) {
388 			return (ENOENT);
389 		}
390 		*vpp = fvp;
391 		if (vget(fvp, LK_EXCLUSIVE))
392 			goto loop;
393 		if (wantpunlock) {
394 			VOP_UNLOCK(dvp, 0);
395 			cnp->cn_flags |= PDIRUNLOCK;
396 		}
397 		return (0);
398 	}
399 
400 #ifdef KERNFS_DIAGNOSTIC
401 	printf("kernfs_lookup: allocate new vnode\n");
402 #endif
403 	error = getnewvnode(VT_KERNFS, dvp->v_mount, kernfs_vnodeop_p, &fvp);
404 	if (error) {
405 		return (error);
406 	}
407 
408 	MALLOC(fvp->v_data, void *, sizeof(struct kernfs_node), M_TEMP,
409 	    M_WAITOK);
410 	VTOKERN(fvp)->kf_kt = kt;
411 	fvp->v_type = kt->kt_vtype;
412 	vn_lock(fvp, LK_EXCLUSIVE | LK_RETRY);
413 	*vpp = fvp;
414 
415 #ifdef KERNFS_DIAGNOSTIC
416 	printf("kernfs_lookup: newvp = %p\n", fvp);
417 #endif
418 	if (wantpunlock) {
419 		VOP_UNLOCK(dvp, 0);
420 		cnp->cn_flags |= PDIRUNLOCK;
421 	}
422 	return (0);
423 }
424 
425 int
426 kernfs_access(v)
427 	void *v;
428 {
429 	struct vop_access_args /* {
430 		struct vnode *a_vp;
431 		int a_mode;
432 		struct ucred *a_cred;
433 		struct proc *a_p;
434 	} */ *ap = v;
435 	struct vnode *vp = ap->a_vp;
436 	mode_t mode;
437 
438 	if (vp->v_flag & VROOT) {
439 		mode = DIR_MODE;
440 	} else {
441 		const struct kern_target *kt = VTOKERN(vp)->kf_kt;
442 		mode = kt->kt_mode;
443 	}
444 
445 	return (vaccess(vp->v_type, mode, (uid_t)0, (gid_t)0, ap->a_mode,
446 	    ap->a_cred));
447 }
448 
449 int
450 kernfs_getattr(v)
451 	void *v;
452 {
453 	struct vop_getattr_args /* {
454 		struct vnode *a_vp;
455 		struct vattr *a_vap;
456 		struct ucred *a_cred;
457 		struct proc *a_p;
458 	} */ *ap = v;
459 	struct vnode *vp = ap->a_vp;
460 	struct vattr *vap = ap->a_vap;
461 	struct timeval tv;
462 	int error = 0;
463 	char strbuf[KSTRING], *buf;
464 
465 	memset((caddr_t) vap, 0, sizeof(*vap));
466 	vattr_null(vap);
467 	vap->va_uid = 0;
468 	vap->va_gid = 0;
469 	vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
470 	vap->va_size = 0;
471 	vap->va_blocksize = DEV_BSIZE;
472 	microtime(&tv);
473 	TIMEVAL_TO_TIMESPEC(&tv, &vap->va_atime);
474 	vap->va_mtime = vap->va_atime;
475 	vap->va_ctime = vap->va_ctime;
476 	vap->va_gen = 0;
477 	vap->va_flags = 0;
478 	vap->va_rdev = 0;
479 	vap->va_bytes = 0;
480 
481 	if (vp->v_flag & VROOT) {
482 #ifdef KERNFS_DIAGNOSTIC
483 		printf("kernfs_getattr: stat rootdir\n");
484 #endif
485 		vap->va_type = VDIR;
486 		vap->va_mode = DIR_MODE;
487 		vap->va_nlink = 2;
488 		vap->va_fileid = 2;
489 		vap->va_size = DEV_BSIZE;
490 	} else {
491 		const struct kern_target *kt = VTOKERN(vp)->kf_kt;
492 		int nbytes, total;
493 #ifdef KERNFS_DIAGNOSTIC
494 		printf("kernfs_getattr: stat target %s\n", kt->kt_name);
495 #endif
496 		vap->va_type = kt->kt_vtype;
497 		vap->va_mode = kt->kt_mode;
498 		vap->va_nlink = 1;
499 		vap->va_fileid = 1 + (kt - kern_targets);
500 		total = 0;
501 		while (buf = strbuf,
502 		       nbytes = kernfs_xread(kt, total, &buf, sizeof(strbuf)))
503 			total += nbytes;
504 		vap->va_size = total;
505 	}
506 
507 #ifdef KERNFS_DIAGNOSTIC
508 	printf("kernfs_getattr: return error %d\n", error);
509 #endif
510 	return (error);
511 }
512 
513 /*ARGSUSED*/
514 int
515 kernfs_setattr(v)
516 	void *v;
517 {
518 	/*
519 	 * Silently ignore attribute changes.
520 	 * This allows for open with truncate to have no
521 	 * effect until some data is written.  I want to
522 	 * do it this way because all writes are atomic.
523 	 */
524 	return (0);
525 }
526 
527 int
528 kernfs_read(v)
529 	void *v;
530 {
531 	struct vop_read_args /* {
532 		struct vnode *a_vp;
533 		struct uio *a_uio;
534 		int  a_ioflag;
535 		struct ucred *a_cred;
536 	} */ *ap = v;
537 	struct vnode *vp = ap->a_vp;
538 	struct uio *uio = ap->a_uio;
539 	const struct kern_target *kt;
540 	char strbuf[KSTRING], *buf;
541 	int off, len;
542 	int error;
543 
544 	if (vp->v_type == VDIR)
545 		return (EOPNOTSUPP);
546 
547 	kt = VTOKERN(vp)->kf_kt;
548 
549 #ifdef KERNFS_DIAGNOSTIC
550 	printf("kern_read %s\n", kt->kt_name);
551 #endif
552 
553 	off = uio->uio_offset;
554 #if 0
555 	while (buf = strbuf,
556 #else
557 	if (buf = strbuf,
558 #endif
559 	    len = kernfs_xread(kt, off, &buf, sizeof(strbuf))) {
560 		if ((error = uiomove(buf, len, uio)) != 0)
561 			return (error);
562 		off += len;
563 	}
564 	return (0);
565 }
566 
567 int
568 kernfs_write(v)
569 	void *v;
570 {
571 	struct vop_write_args /* {
572 		struct vnode *a_vp;
573 		struct uio *a_uio;
574 		int  a_ioflag;
575 		struct ucred *a_cred;
576 	} */ *ap = v;
577 	struct vnode *vp = ap->a_vp;
578 	struct uio *uio = ap->a_uio;
579 	const struct kern_target *kt;
580 	int error, xlen;
581 	char strbuf[KSTRING];
582 
583 	if (vp->v_type == VDIR)
584 		return (EOPNOTSUPP);
585 
586 	kt = VTOKERN(vp)->kf_kt;
587 
588 	if (uio->uio_offset != 0)
589 		return (EINVAL);
590 
591 	xlen = min(uio->uio_resid, KSTRING-1);
592 	if ((error = uiomove(strbuf, xlen, uio)) != 0)
593 		return (error);
594 
595 	if (uio->uio_resid != 0)
596 		return (EIO);
597 
598 	strbuf[xlen] = '\0';
599 	xlen = strlen(strbuf);
600 	return (kernfs_xwrite(kt, strbuf, xlen));
601 }
602 
603 int
604 kernfs_readdir(v)
605 	void *v;
606 {
607 	struct vop_readdir_args /* {
608 		struct vnode *a_vp;
609 		struct uio *a_uio;
610 		struct ucred *a_cred;
611 		int *a_eofflag;
612 		off_t **a_cookies;
613 		int a_*ncookies;
614 	} */ *ap = v;
615 	struct uio *uio = ap->a_uio;
616 	struct dirent d;
617 	const struct kern_target *kt;
618 	off_t i;
619 	int error;
620 	off_t *cookies = NULL;
621 	int ncookies = 0, nc = 0;
622 
623 	if (ap->a_vp->v_type != VDIR)
624 		return (ENOTDIR);
625 
626 	if (uio->uio_resid < UIO_MX)
627 		return (EINVAL);
628 	if (uio->uio_offset < 0)
629 		return (EINVAL);
630 
631 	error = 0;
632 	i = uio->uio_offset;
633 
634 	if (i >= nkern_targets)
635 		return 0;
636 
637 	memset((caddr_t)&d, 0, UIO_MX);
638 	d.d_reclen = UIO_MX;
639 
640 	if (ap->a_ncookies) {
641 		nc = uio->uio_resid / UIO_MX;
642 		nc = min(nc, (nkern_targets - i));
643 		cookies = malloc(nc * sizeof(off_t), M_TEMP, M_WAITOK);
644 		*ap->a_cookies = cookies;
645 	}
646 
647 	for (kt = &kern_targets[i];
648 	     uio->uio_resid >= UIO_MX && i < nkern_targets; kt++, i++) {
649 #ifdef KERNFS_DIAGNOSTIC
650 		printf("kernfs_readdir: i = %d\n", (int)i);
651 #endif
652 
653 		if (kt->kt_tag == KTT_DEVICE) {
654 			dev_t *dp = kt->kt_data;
655 			struct vnode *fvp;
656 
657 			if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp))
658 				continue;
659 		}
660 
661 		d.d_fileno = i + 3;
662 		d.d_namlen = kt->kt_namlen;
663 		memcpy(d.d_name, kt->kt_name, kt->kt_namlen + 1);
664 		d.d_type = kt->kt_type;
665 
666 		if ((error = uiomove((caddr_t)&d, UIO_MX, uio)) != 0)
667 			break;
668 		if (cookies) {
669 			*cookies++ = i + 1;
670 			ncookies++;
671 		}
672 	}
673 
674 	if (ap->a_ncookies) {
675 		if (error) {
676 			free(*ap->a_cookies, M_TEMP);
677 			*ap->a_ncookies = 0;
678 			*ap->a_cookies = NULL;
679 		} else
680 			*ap->a_ncookies = ncookies;
681 	}
682 
683 	uio->uio_offset = i;
684 	return (error);
685 }
686 
687 int
688 kernfs_inactive(v)
689 	void *v;
690 {
691 	struct vop_inactive_args /* {
692 		struct vnode *a_vp;
693 		struct proc *a_p;
694 	} */ *ap = v;
695 	struct vnode *vp = ap->a_vp;
696 
697 #ifdef KERNFS_DIAGNOSTIC
698 	printf("kernfs_inactive(%p)\n", vp);
699 #endif
700 	/*
701 	 * Clear out the v_type field to avoid
702 	 * nasty things happening in vgone().
703 	 */
704 	VOP_UNLOCK(vp, 0);
705 	vp->v_type = VNON;
706 	return (0);
707 }
708 
709 int
710 kernfs_reclaim(v)
711 	void *v;
712 {
713 	struct vop_reclaim_args /* {
714 		struct vnode *a_vp;
715 	} */ *ap = v;
716 	struct vnode *vp = ap->a_vp;
717 
718 #ifdef KERNFS_DIAGNOSTIC
719 	printf("kernfs_reclaim(%p)\n", vp);
720 #endif
721 	if (vp->v_data) {
722 		FREE(vp->v_data, M_TEMP);
723 		vp->v_data = 0;
724 	}
725 	return (0);
726 }
727 
728 /*
729  * Return POSIX pathconf information applicable to special devices.
730  */
731 int
732 kernfs_pathconf(v)
733 	void *v;
734 {
735 	struct vop_pathconf_args /* {
736 		struct vnode *a_vp;
737 		int a_name;
738 		register_t *a_retval;
739 	} */ *ap = v;
740 
741 	switch (ap->a_name) {
742 	case _PC_LINK_MAX:
743 		*ap->a_retval = LINK_MAX;
744 		return (0);
745 	case _PC_MAX_CANON:
746 		*ap->a_retval = MAX_CANON;
747 		return (0);
748 	case _PC_MAX_INPUT:
749 		*ap->a_retval = MAX_INPUT;
750 		return (0);
751 	case _PC_PIPE_BUF:
752 		*ap->a_retval = PIPE_BUF;
753 		return (0);
754 	case _PC_CHOWN_RESTRICTED:
755 		*ap->a_retval = 1;
756 		return (0);
757 	case _PC_VDISABLE:
758 		*ap->a_retval = _POSIX_VDISABLE;
759 		return (0);
760 	case _PC_SYNC_IO:
761 		*ap->a_retval = 1;
762 		return (0);
763 	default:
764 		return (EINVAL);
765 	}
766 	/* NOTREACHED */
767 }
768 
769 /*
770  * Print out the contents of a /dev/fd vnode.
771  */
772 /* ARGSUSED */
773 int
774 kernfs_print(v)
775 	void *v;
776 {
777 
778 	printf("tag VT_KERNFS, kernfs vnode\n");
779 	return (0);
780 }
781 
782 int
783 kernfs_link(v)
784 	void *v;
785 {
786 	struct vop_link_args /* {
787 		struct vnode *a_dvp;
788 		struct vnode *a_vp;
789 		struct componentname *a_cnp;
790 	} */ *ap = v;
791 
792 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
793 	vput(ap->a_dvp);
794 	return (EROFS);
795 }
796 
797 int
798 kernfs_symlink(v)
799 	void *v;
800 {
801 	struct vop_symlink_args /* {
802 		struct vnode *a_dvp;
803 		struct vnode **a_vpp;
804 		struct componentname *a_cnp;
805 		struct vattr *a_vap;
806 		char *a_target;
807 	} */ *ap = v;
808 
809 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
810 	vput(ap->a_dvp);
811 	return (EROFS);
812 }
813