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kernfs_vnops.c revision 1.48
      1 /*	$NetBSD: kernfs_vnops.c,v 1.48 1996/10/25 21:58:00 cgd 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 {
     73 	u_char kt_type;
     74 	u_char kt_namlen;
     75 	char *kt_name;
     76 	void *kt_data;
     77 #define	KTT_NULL	 1
     78 #define	KTT_TIME	 5
     79 #define KTT_INT		17
     80 #define	KTT_STRING	31
     81 #define KTT_HOSTNAME	47
     82 #define KTT_AVENRUN	53
     83 #define KTT_DEVICE	71
     84 #define	KTT_MSGBUF	89
     85 	u_char kt_tag;
     86 	u_char kt_vtype;
     87 	mode_t kt_mode;
     88 } kern_targets[] = {
     89 /* NOTE: The name must be less than UIO_MX-16 chars in length */
     90 #define N(s) sizeof(s)-1, s
     91      /*        name            data          tag           type  ro/rw */
     92      { DT_DIR, N("."),         0,            KTT_NULL,     VDIR, DIR_MODE   },
     93      { DT_DIR, N(".."),        0,            KTT_NULL,     VDIR, DIR_MODE   },
     94      { DT_REG, N("boottime"),  &boottime.tv_sec, KTT_INT,  VREG, READ_MODE  },
     95      { DT_REG, N("copyright"), copyright,    KTT_STRING,   VREG, READ_MODE  },
     96      { DT_REG, N("hostname"),  0,            KTT_HOSTNAME, VREG, WRITE_MODE },
     97      { DT_REG, N("hz"),        &hz,          KTT_INT,      VREG, READ_MODE  },
     98      { DT_REG, N("loadavg"),   0,            KTT_AVENRUN,  VREG, READ_MODE  },
     99      { DT_REG, N("msgbuf"),    0,	     KTT_MSGBUF,   VREG, READ_MODE  },
    100      { DT_REG, N("pagesize"),  &cnt.v_page_size, KTT_INT,  VREG, READ_MODE  },
    101      { DT_REG, N("physmem"),   &physmem,     KTT_INT,      VREG, READ_MODE  },
    102 #if 0
    103      { DT_DIR, N("root"),      0,            KTT_NULL,     VDIR, DIR_MODE   },
    104 #endif
    105      { DT_BLK, N("rootdev"),   &rootdev,     KTT_DEVICE,   VBLK, READ_MODE  },
    106      { DT_CHR, N("rrootdev"),  &rrootdev,    KTT_DEVICE,   VCHR, READ_MODE  },
    107      { DT_REG, N("time"),      0,            KTT_TIME,     VREG, READ_MODE  },
    108      { DT_REG, N("version"),   version,      KTT_STRING,   VREG, READ_MODE  },
    109 #undef N
    110 };
    111 static int nkern_targets = sizeof(kern_targets) / sizeof(kern_targets[0]);
    112 
    113 int	kernfs_lookup	__P((void *));
    114 #define	kernfs_create	genfs_eopnotsupp
    115 #define	kernfs_mknod	genfs_eopnotsupp
    116 #define	kernfs_open	genfs_nullop
    117 #define	kernfs_close	genfs_nullop
    118 int	kernfs_access	__P((void *));
    119 int	kernfs_getattr	__P((void *));
    120 int	kernfs_setattr	__P((void *));
    121 int	kernfs_read	__P((void *));
    122 int	kernfs_write	__P((void *));
    123 #define	kernfs_ioctl	genfs_eopnotsupp
    124 #define	kernfs_poll	genfs_poll
    125 #define	kernfs_mmap	genfs_eopnotsupp
    126 #define	kernfs_fsync	genfs_nullop
    127 #define	kernfs_seek	genfs_nullop
    128 #define	kernfs_remove	genfs_eopnotsupp
    129 int	kernfs_link	__P((void *));
    130 #define	kernfs_rename	genfs_eopnotsupp
    131 #define	kernfs_mkdir	genfs_eopnotsupp
    132 #define	kernfs_rmdir	genfs_eopnotsupp
    133 int	kernfs_symlink	__P((void *));
    134 int	kernfs_readdir	__P((void *));
    135 #define	kernfs_readlink	genfs_eopnotsupp
    136 #define	kernfs_abortop	genfs_abortop
    137 int	kernfs_inactive	__P((void *));
    138 int	kernfs_reclaim	__P((void *));
    139 #define	kernfs_lock	genfs_nullop
    140 #define	kernfs_unlock	genfs_nullop
    141 #define	kernfs_bmap	genfs_badop
    142 #define	kernfs_strategy	genfs_badop
    143 int	kernfs_print	__P((void *));
    144 #define	kernfs_islocked	genfs_nullop
    145 int	kernfs_pathconf	__P((void *));
    146 #define	kernfs_advlock	genfs_eopnotsupp
    147 #define	kernfs_blkatoff	genfs_eopnotsupp
    148 #define	kernfs_valloc	genfs_eopnotsupp
    149 #define	kernfs_vfree	genfs_nullop
    150 #define	kernfs_truncate	genfs_eopnotsupp
    151 #define	kernfs_update	genfs_nullop
    152 #define	kernfs_bwrite	genfs_eopnotsupp
    153 
    154 int	kernfs_xread __P((struct kern_target *, int, char **, int));
    155 int	kernfs_xwrite __P((struct kern_target *, char *, int));
    156 
    157 int (**kernfs_vnodeop_p) __P((void *));
    158 struct vnodeopv_entry_desc kernfs_vnodeop_entries[] = {
    159 	{ &vop_default_desc, vn_default_error },
    160 	{ &vop_lookup_desc, kernfs_lookup },		/* lookup */
    161 	{ &vop_create_desc, kernfs_create },		/* create */
    162 	{ &vop_mknod_desc, kernfs_mknod },		/* mknod */
    163 	{ &vop_open_desc, kernfs_open },		/* open */
    164 	{ &vop_close_desc, kernfs_close },		/* close */
    165 	{ &vop_access_desc, kernfs_access },		/* access */
    166 	{ &vop_getattr_desc, kernfs_getattr },		/* getattr */
    167 	{ &vop_setattr_desc, kernfs_setattr },		/* setattr */
    168 	{ &vop_read_desc, kernfs_read },		/* read */
    169 	{ &vop_write_desc, kernfs_write },		/* write */
    170 	{ &vop_ioctl_desc, kernfs_ioctl },		/* ioctl */
    171 	{ &vop_poll_desc, kernfs_poll },		/* poll */
    172 	{ &vop_mmap_desc, kernfs_mmap },		/* mmap */
    173 	{ &vop_fsync_desc, kernfs_fsync },		/* fsync */
    174 	{ &vop_seek_desc, kernfs_seek },		/* seek */
    175 	{ &vop_remove_desc, kernfs_remove },		/* remove */
    176 	{ &vop_link_desc, kernfs_link },		/* link */
    177 	{ &vop_rename_desc, kernfs_rename },		/* rename */
    178 	{ &vop_mkdir_desc, kernfs_mkdir },		/* mkdir */
    179 	{ &vop_rmdir_desc, kernfs_rmdir },		/* rmdir */
    180 	{ &vop_symlink_desc, kernfs_symlink },		/* symlink */
    181 	{ &vop_readdir_desc, kernfs_readdir },		/* readdir */
    182 	{ &vop_readlink_desc, kernfs_readlink },	/* readlink */
    183 	{ &vop_abortop_desc, kernfs_abortop },		/* abortop */
    184 	{ &vop_inactive_desc, kernfs_inactive },	/* inactive */
    185 	{ &vop_reclaim_desc, kernfs_reclaim },		/* reclaim */
    186 	{ &vop_lock_desc, kernfs_lock },		/* lock */
    187 	{ &vop_unlock_desc, kernfs_unlock },		/* unlock */
    188 	{ &vop_bmap_desc, kernfs_bmap },		/* bmap */
    189 	{ &vop_strategy_desc, kernfs_strategy },	/* strategy */
    190 	{ &vop_print_desc, kernfs_print },		/* print */
    191 	{ &vop_islocked_desc, kernfs_islocked },	/* islocked */
    192 	{ &vop_pathconf_desc, kernfs_pathconf },	/* pathconf */
    193 	{ &vop_advlock_desc, kernfs_advlock },		/* advlock */
    194 	{ &vop_blkatoff_desc, kernfs_blkatoff },	/* blkatoff */
    195 	{ &vop_valloc_desc, kernfs_valloc },		/* valloc */
    196 	{ &vop_vfree_desc, kernfs_vfree },		/* vfree */
    197 	{ &vop_truncate_desc, kernfs_truncate },	/* truncate */
    198 	{ &vop_update_desc, kernfs_update },		/* update */
    199 	{ &vop_bwrite_desc, kernfs_bwrite },		/* bwrite */
    200 	{ (struct vnodeop_desc*)NULL, (int(*) __P((void *)))NULL }
    201 };
    202 struct vnodeopv_desc kernfs_vnodeop_opv_desc =
    203 	{ &kernfs_vnodeop_p, kernfs_vnodeop_entries };
    204 
    205 int
    206 kernfs_xread(kt, off, bufp, len)
    207 	struct kern_target *kt;
    208 	int off;
    209 	char **bufp;
    210 	int len;
    211 {
    212 
    213 	switch (kt->kt_tag) {
    214 	case KTT_TIME: {
    215 		struct timeval tv;
    216 
    217 		microtime(&tv);
    218 		sprintf(*bufp, "%ld %ld\n", tv.tv_sec, tv.tv_usec);
    219 		break;
    220 	}
    221 
    222 	case KTT_INT: {
    223 		int *ip = kt->kt_data;
    224 
    225 		sprintf(*bufp, "%d\n", *ip);
    226 		break;
    227 	}
    228 
    229 	case KTT_STRING: {
    230 		char *cp = kt->kt_data;
    231 
    232 		*bufp = cp;
    233 		break;
    234 	}
    235 
    236 	case KTT_MSGBUF: {
    237 		extern struct msgbuf *msgbufp;
    238 		long n;
    239 
    240 		if (off >= MSG_BSIZE)
    241 			return (0);
    242 		n = msgbufp->msg_bufx + off;
    243 		if (n >= MSG_BSIZE)
    244 			n -= MSG_BSIZE;
    245 		len = min(MSG_BSIZE - n, MSG_BSIZE - off);
    246 		*bufp = msgbufp->msg_bufc + n;
    247 		return (len);
    248 	}
    249 
    250 	case KTT_HOSTNAME: {
    251 		char *cp = hostname;
    252 		int xlen = hostnamelen;
    253 
    254 		if (xlen >= (len-2))
    255 			return (EINVAL);
    256 
    257 		bcopy(cp, *bufp, xlen);
    258 		(*bufp)[xlen] = '\n';
    259 		(*bufp)[xlen+1] = '\0';
    260 		break;
    261 	}
    262 
    263 	case KTT_AVENRUN:
    264 		averunnable.fscale = FSCALE;
    265 		sprintf(*bufp, "%d %d %d %ld\n",
    266 		    averunnable.ldavg[0], averunnable.ldavg[1],
    267 		    averunnable.ldavg[2], averunnable.fscale);
    268 		break;
    269 
    270 	default:
    271 		return (0);
    272 	}
    273 
    274 	len = strlen(*bufp);
    275 	if (len <= off)
    276 		return (0);
    277 	*bufp += off;
    278 	return (len - off);
    279 }
    280 
    281 int
    282 kernfs_xwrite(kt, buf, len)
    283 	struct kern_target *kt;
    284 	char *buf;
    285 	int len;
    286 {
    287 
    288 	switch (kt->kt_tag) {
    289 	case KTT_HOSTNAME:
    290 		if (buf[len-1] == '\n')
    291 			--len;
    292 		bcopy(buf, hostname, len);
    293 		hostname[len] = '\0';
    294 		hostnamelen = len;
    295 		return (0);
    296 
    297 	default:
    298 		return (EIO);
    299 	}
    300 }
    301 
    302 
    303 /*
    304  * vp is the current namei directory
    305  * ndp is the name to locate in that directory...
    306  */
    307 int
    308 kernfs_lookup(v)
    309 	void *v;
    310 {
    311 	struct vop_lookup_args /* {
    312 		struct vnode * a_dvp;
    313 		struct vnode ** a_vpp;
    314 		struct componentname * a_cnp;
    315 	} */ *ap = v;
    316 	struct componentname *cnp = ap->a_cnp;
    317 	struct vnode **vpp = ap->a_vpp;
    318 	struct vnode *dvp = ap->a_dvp;
    319 	const char *pname = cnp->cn_nameptr;
    320 	struct kern_target *kt;
    321 	struct vnode *fvp;
    322 	int error, i;
    323 
    324 #ifdef KERNFS_DIAGNOSTIC
    325 	printf("kernfs_lookup(%x)\n", ap);
    326 	printf("kernfs_lookup(dp = %x, vpp = %x, cnp = %x)\n", dvp, vpp, ap->a_cnp);
    327 	printf("kernfs_lookup(%s)\n", pname);
    328 #endif
    329 
    330 	*vpp = NULLVP;
    331 
    332 	if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
    333 		return (EROFS);
    334 
    335 	if (cnp->cn_namelen == 1 && *pname == '.') {
    336 		*vpp = dvp;
    337 		VREF(dvp);
    338 		/*VOP_LOCK(dvp);*/
    339 		return (0);
    340 	}
    341 
    342 #if 0
    343 	if (cnp->cn_namelen == 4 && bcmp(pname, "root", 4) == 0) {
    344 		*vpp = rootdir;
    345 		VREF(rootdir);
    346 		VOP_LOCK(rootdir);
    347 		return (0);
    348 	}
    349 #endif
    350 
    351 	for (kt = kern_targets, i = 0; i < nkern_targets; kt++, i++) {
    352 		if (cnp->cn_namelen == kt->kt_namlen &&
    353 		    bcmp(kt->kt_name, pname, cnp->cn_namelen) == 0)
    354 			goto found;
    355 	}
    356 
    357 #ifdef KERNFS_DIAGNOSTIC
    358 	printf("kernfs_lookup: i = %d, failed", i);
    359 #endif
    360 
    361 	return (cnp->cn_nameiop == LOOKUP ? ENOENT : EROFS);
    362 
    363 found:
    364 	if (kt->kt_tag == KTT_DEVICE) {
    365 		dev_t *dp = kt->kt_data;
    366 	loop:
    367 		if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp))
    368 			return (ENOENT);
    369 		*vpp = fvp;
    370 		if (vget(fvp, 1))
    371 			goto loop;
    372 		return (0);
    373 	}
    374 
    375 #ifdef KERNFS_DIAGNOSTIC
    376 	printf("kernfs_lookup: allocate new vnode\n");
    377 #endif
    378 	error = getnewvnode(VT_KERNFS, dvp->v_mount, kernfs_vnodeop_p, &fvp);
    379 	if (error)
    380 		return (error);
    381 
    382 	MALLOC(fvp->v_data, void *, sizeof(struct kernfs_node), M_TEMP,
    383 	    M_WAITOK);
    384 	VTOKERN(fvp)->kf_kt = kt;
    385 	fvp->v_type = kt->kt_vtype;
    386 	*vpp = fvp;
    387 
    388 #ifdef KERNFS_DIAGNOSTIC
    389 	printf("kernfs_lookup: newvp = %x\n", fvp);
    390 #endif
    391 	return (0);
    392 }
    393 
    394 int
    395 kernfs_access(v)
    396 	void *v;
    397 {
    398 	struct vop_access_args /* {
    399 		struct vnode *a_vp;
    400 		int a_mode;
    401 		struct ucred *a_cred;
    402 		struct proc *a_p;
    403 	} */ *ap = v;
    404 	struct vnode *vp = ap->a_vp;
    405 	mode_t fmode =
    406 	    (vp->v_flag & VROOT) ? DIR_MODE : VTOKERN(vp)->kf_kt->kt_mode;
    407 
    408 	return (vaccess(fmode, (uid_t)0, (gid_t)0, ap->a_mode, ap->a_cred));
    409 }
    410 
    411 int
    412 kernfs_getattr(v)
    413 	void *v;
    414 {
    415 	struct vop_getattr_args /* {
    416 		struct vnode *a_vp;
    417 		struct vattr *a_vap;
    418 		struct ucred *a_cred;
    419 		struct proc *a_p;
    420 	} */ *ap = v;
    421 	struct vnode *vp = ap->a_vp;
    422 	struct vattr *vap = ap->a_vap;
    423 	struct timeval tv;
    424 	int error = 0;
    425 	char strbuf[KSTRING], *buf;
    426 
    427 	bzero((caddr_t) vap, sizeof(*vap));
    428 	vattr_null(vap);
    429 	vap->va_uid = 0;
    430 	vap->va_gid = 0;
    431 	vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
    432 	vap->va_size = 0;
    433 	vap->va_blocksize = DEV_BSIZE;
    434 	microtime(&tv);
    435 	TIMEVAL_TO_TIMESPEC(&tv, &vap->va_atime);
    436 	vap->va_mtime = vap->va_atime;
    437 	vap->va_ctime = vap->va_ctime;
    438 	vap->va_gen = 0;
    439 	vap->va_flags = 0;
    440 	vap->va_rdev = 0;
    441 	vap->va_bytes = 0;
    442 
    443 	if (vp->v_flag & VROOT) {
    444 #ifdef KERNFS_DIAGNOSTIC
    445 		printf("kernfs_getattr: stat rootdir\n");
    446 #endif
    447 		vap->va_type = VDIR;
    448 		vap->va_mode = DIR_MODE;
    449 		vap->va_nlink = 2;
    450 		vap->va_fileid = 2;
    451 		vap->va_size = DEV_BSIZE;
    452 	} else {
    453 		struct kern_target *kt = VTOKERN(vp)->kf_kt;
    454 		int nbytes, total;
    455 #ifdef KERNFS_DIAGNOSTIC
    456 		printf("kernfs_getattr: stat target %s\n", kt->kt_name);
    457 #endif
    458 		vap->va_type = kt->kt_vtype;
    459 		vap->va_mode = kt->kt_mode;
    460 		vap->va_nlink = 1;
    461 		vap->va_fileid = 3 + (kt - kern_targets);
    462 		total = 0;
    463 		while (buf = strbuf,
    464 		       nbytes = kernfs_xread(kt, total, &buf, sizeof(strbuf)))
    465 			total += nbytes;
    466 		vap->va_size = total;
    467 	}
    468 
    469 #ifdef KERNFS_DIAGNOSTIC
    470 	printf("kernfs_getattr: return error %d\n", error);
    471 #endif
    472 	return (error);
    473 }
    474 
    475 /*ARGSUSED*/
    476 int
    477 kernfs_setattr(v)
    478 	void *v;
    479 {
    480 	/*
    481 	 * Silently ignore attribute changes.
    482 	 * This allows for open with truncate to have no
    483 	 * effect until some data is written.  I want to
    484 	 * do it this way because all writes are atomic.
    485 	 */
    486 	return (0);
    487 }
    488 
    489 int
    490 kernfs_read(v)
    491 	void *v;
    492 {
    493 	struct vop_read_args /* {
    494 		struct vnode *a_vp;
    495 		struct uio *a_uio;
    496 		int  a_ioflag;
    497 		struct ucred *a_cred;
    498 	} */ *ap = v;
    499 	struct vnode *vp = ap->a_vp;
    500 	struct uio *uio = ap->a_uio;
    501 	struct kern_target *kt;
    502 	char strbuf[KSTRING], *buf;
    503 	int off, len;
    504 	int error;
    505 
    506 	if (vp->v_type == VDIR)
    507 		return (EOPNOTSUPP);
    508 
    509 	kt = VTOKERN(vp)->kf_kt;
    510 
    511 #ifdef KERNFS_DIAGNOSTIC
    512 	printf("kern_read %s\n", kt->kt_name);
    513 #endif
    514 
    515 	off = uio->uio_offset;
    516 #if 0
    517 	while (buf = strbuf,
    518 #else
    519 	if (buf = strbuf,
    520 #endif
    521 	    len = kernfs_xread(kt, off, &buf, sizeof(strbuf))) {
    522 		if ((error = uiomove(buf, len, uio)) != 0)
    523 			return (error);
    524 		off += len;
    525 	}
    526 	return (0);
    527 }
    528 
    529 int
    530 kernfs_write(v)
    531 	void *v;
    532 {
    533 	struct vop_write_args /* {
    534 		struct vnode *a_vp;
    535 		struct uio *a_uio;
    536 		int  a_ioflag;
    537 		struct ucred *a_cred;
    538 	} */ *ap = v;
    539 	struct vnode *vp = ap->a_vp;
    540 	struct uio *uio = ap->a_uio;
    541 	struct kern_target *kt;
    542 	int error, xlen;
    543 	char strbuf[KSTRING];
    544 
    545 	if (vp->v_type == VDIR)
    546 		return (EOPNOTSUPP);
    547 
    548 	kt = VTOKERN(vp)->kf_kt;
    549 
    550 	if (uio->uio_offset != 0)
    551 		return (EINVAL);
    552 
    553 	xlen = min(uio->uio_resid, KSTRING-1);
    554 	if ((error = uiomove(strbuf, xlen, uio)) != 0)
    555 		return (error);
    556 
    557 	if (uio->uio_resid != 0)
    558 		return (EIO);
    559 
    560 	strbuf[xlen] = '\0';
    561 	xlen = strlen(strbuf);
    562 	return (kernfs_xwrite(kt, strbuf, xlen));
    563 }
    564 
    565 int
    566 kernfs_readdir(v)
    567 	void *v;
    568 {
    569 	struct vop_readdir_args /* {
    570 		struct vnode *a_vp;
    571 		struct uio *a_uio;
    572 		struct ucred *a_cred;
    573 		int *a_eofflag;
    574 		u_long *a_cookies;
    575 		int a_ncookies;
    576 	} */ *ap = v;
    577 	struct uio *uio = ap->a_uio;
    578 	struct dirent d;
    579 	struct kern_target *kt;
    580 	int i;
    581 	int error;
    582 	u_long *cookies = ap->a_cookies;
    583 	int ncookies = ap->a_ncookies;
    584 
    585 	if (ap->a_vp->v_type != VDIR)
    586 		return (ENOTDIR);
    587 
    588 	if (uio->uio_resid < UIO_MX)
    589 		return (EINVAL);
    590 	if (uio->uio_offset < 0)
    591 		return (EINVAL);
    592 
    593 	error = 0;
    594 	i = uio->uio_offset;
    595 	bzero((caddr_t)&d, UIO_MX);
    596 	d.d_reclen = UIO_MX;
    597 
    598 	for (kt = &kern_targets[i];
    599 	     uio->uio_resid >= UIO_MX && i < nkern_targets; kt++, i++) {
    600 #ifdef KERNFS_DIAGNOSTIC
    601 		printf("kernfs_readdir: i = %d\n", i);
    602 #endif
    603 
    604 		if (kt->kt_tag == KTT_DEVICE) {
    605 			dev_t *dp = kt->kt_data;
    606 			struct vnode *fvp;
    607 
    608 			if (*dp == NODEV || !vfinddev(*dp, kt->kt_vtype, &fvp))
    609 				continue;
    610 		}
    611 
    612 		d.d_fileno = i + 3;
    613 		d.d_namlen = kt->kt_namlen;
    614 		bcopy(kt->kt_name, d.d_name, kt->kt_namlen + 1);
    615 		d.d_type = kt->kt_type;
    616 
    617 		if ((error = uiomove((caddr_t)&d, UIO_MX, uio)) != 0)
    618 			break;
    619 		if (ncookies-- > 0)
    620 			*cookies++ = i + 1;
    621 	}
    622 
    623 	uio->uio_offset = i;
    624 	return (error);
    625 }
    626 
    627 int
    628 kernfs_inactive(v)
    629 	void *v;
    630 {
    631 	struct vop_inactive_args /* {
    632 		struct vnode *a_vp;
    633 	} */ *ap = v;
    634 	struct vnode *vp = ap->a_vp;
    635 
    636 #ifdef KERNFS_DIAGNOSTIC
    637 	printf("kernfs_inactive(%x)\n", vp);
    638 #endif
    639 	/*
    640 	 * Clear out the v_type field to avoid
    641 	 * nasty things happening in vgone().
    642 	 */
    643 	vp->v_type = VNON;
    644 	return (0);
    645 }
    646 
    647 int
    648 kernfs_reclaim(v)
    649 	void *v;
    650 {
    651 	struct vop_reclaim_args /* {
    652 		struct vnode *a_vp;
    653 	} */ *ap = v;
    654 	struct vnode *vp = ap->a_vp;
    655 
    656 #ifdef KERNFS_DIAGNOSTIC
    657 	printf("kernfs_reclaim(%x)\n", vp);
    658 #endif
    659 	if (vp->v_data) {
    660 		FREE(vp->v_data, M_TEMP);
    661 		vp->v_data = 0;
    662 	}
    663 	return (0);
    664 }
    665 
    666 /*
    667  * Return POSIX pathconf information applicable to special devices.
    668  */
    669 int
    670 kernfs_pathconf(v)
    671 	void *v;
    672 {
    673 	struct vop_pathconf_args /* {
    674 		struct vnode *a_vp;
    675 		int a_name;
    676 		register_t *a_retval;
    677 	} */ *ap = v;
    678 
    679 	switch (ap->a_name) {
    680 	case _PC_LINK_MAX:
    681 		*ap->a_retval = LINK_MAX;
    682 		return (0);
    683 	case _PC_MAX_CANON:
    684 		*ap->a_retval = MAX_CANON;
    685 		return (0);
    686 	case _PC_MAX_INPUT:
    687 		*ap->a_retval = MAX_INPUT;
    688 		return (0);
    689 	case _PC_PIPE_BUF:
    690 		*ap->a_retval = PIPE_BUF;
    691 		return (0);
    692 	case _PC_CHOWN_RESTRICTED:
    693 		*ap->a_retval = 1;
    694 		return (0);
    695 	case _PC_VDISABLE:
    696 		*ap->a_retval = _POSIX_VDISABLE;
    697 		return (0);
    698 	default:
    699 		return (EINVAL);
    700 	}
    701 	/* NOTREACHED */
    702 }
    703 
    704 /*
    705  * Print out the contents of a /dev/fd vnode.
    706  */
    707 /* ARGSUSED */
    708 int
    709 kernfs_print(v)
    710 	void *v;
    711 {
    712 
    713 	printf("tag VT_KERNFS, kernfs vnode\n");
    714 	return (0);
    715 }
    716 
    717 int
    718 kernfs_link(v)
    719 	void *v;
    720 {
    721 	struct vop_link_args /* {
    722 		struct vnode *a_dvp;
    723 		struct vnode *a_vp;
    724 		struct componentname *a_cnp;
    725 	} */ *ap = v;
    726 
    727 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
    728 	vput(ap->a_dvp);
    729 	return (EROFS);
    730 }
    731 
    732 int
    733 kernfs_symlink(v)
    734 	void *v;
    735 {
    736 	struct vop_symlink_args /* {
    737 		struct vnode *a_dvp;
    738 		struct vnode **a_vpp;
    739 		struct componentname *a_cnp;
    740 		struct vattr *a_vap;
    741 		char *a_target;
    742 	} */ *ap = v;
    743 
    744 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
    745 	vput(ap->a_dvp);
    746 	return (EROFS);
    747 }
    748