xref: /netbsd-src/sys/miscfs/fdesc/fdesc_vnops.c (revision 8b0f9554ff8762542c4defc4f70e1eb76fb508fa)
1 /*	$NetBSD: fdesc_vnops.c,v 1.101 2007/12/08 19:29:50 pooka 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. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *	@(#)fdesc_vnops.c	8.17 (Berkeley) 5/22/95
35  *
36  * #Id: fdesc_vnops.c,v 1.12 1993/04/06 16:17:17 jsp Exp #
37  */
38 
39 /*
40  * /dev/fd Filesystem
41  */
42 
43 #include <sys/cdefs.h>
44 __KERNEL_RCSID(0, "$NetBSD: fdesc_vnops.c,v 1.101 2007/12/08 19:29:50 pooka Exp $");
45 
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/time.h>
49 #include <sys/proc.h>
50 #include <sys/kernel.h>	/* boottime */
51 #include <sys/resourcevar.h>
52 #include <sys/socketvar.h>
53 #include <sys/filedesc.h>
54 #include <sys/vnode.h>
55 #include <sys/malloc.h>
56 #include <sys/conf.h>
57 #include <sys/file.h>
58 #include <sys/stat.h>
59 #include <sys/mount.h>
60 #include <sys/namei.h>
61 #include <sys/buf.h>
62 #include <sys/dirent.h>
63 #include <sys/tty.h>
64 #include <sys/kauth.h>
65 
66 #include <miscfs/fdesc/fdesc.h>
67 #include <miscfs/genfs/genfs.h>
68 
69 #define cttyvp(p) ((p)->p_lflag & PL_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
70 
71 #define FDL_WANT	0x01
72 #define FDL_LOCKED	0x02
73 static int fdcache_lock;
74 
75 dev_t devctty;
76 
77 #if (FD_STDIN != FD_STDOUT-1) || (FD_STDOUT != FD_STDERR-1)
78 FD_STDIN, FD_STDOUT, FD_STDERR must be a sequence n, n+1, n+2
79 #endif
80 
81 #define	NFDCACHE 4
82 
83 #define FD_NHASH(ix) \
84 	(&fdhashtbl[(ix) & fdhash])
85 LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl;
86 u_long fdhash;
87 
88 int	fdesc_lookup(void *);
89 #define	fdesc_create	genfs_eopnotsupp
90 #define	fdesc_mknod	genfs_eopnotsupp
91 int	fdesc_open(void *);
92 #define	fdesc_close	genfs_nullop
93 #define	fdesc_access	genfs_nullop
94 int	fdesc_getattr(void *);
95 int	fdesc_setattr(void *);
96 int	fdesc_read(void *);
97 int	fdesc_write(void *);
98 int	fdesc_ioctl(void *);
99 int	fdesc_poll(void *);
100 int	fdesc_kqfilter(void *);
101 #define	fdesc_mmap	genfs_eopnotsupp
102 #define	fdesc_fcntl	genfs_fcntl
103 #define	fdesc_fsync	genfs_nullop
104 #define	fdesc_seek	genfs_seek
105 #define	fdesc_remove	genfs_eopnotsupp
106 int	fdesc_link(void *);
107 #define	fdesc_rename	genfs_eopnotsupp
108 #define	fdesc_mkdir	genfs_eopnotsupp
109 #define	fdesc_rmdir	genfs_eopnotsupp
110 int	fdesc_symlink(void *);
111 int	fdesc_readdir(void *);
112 int	fdesc_readlink(void *);
113 #define	fdesc_abortop	genfs_abortop
114 int	fdesc_inactive(void *);
115 int	fdesc_reclaim(void *);
116 #define	fdesc_lock	genfs_lock
117 #define	fdesc_unlock	genfs_unlock
118 #define	fdesc_bmap	genfs_badop
119 #define	fdesc_strategy	genfs_badop
120 int	fdesc_print(void *);
121 int	fdesc_pathconf(void *);
122 #define	fdesc_islocked	genfs_islocked
123 #define	fdesc_advlock	genfs_einval
124 #define	fdesc_bwrite	genfs_eopnotsupp
125 #define fdesc_revoke	genfs_revoke
126 #define fdesc_putpages	genfs_null_putpages
127 
128 static int fdesc_attr(int, struct vattr *, kauth_cred_t, struct lwp *);
129 
130 int (**fdesc_vnodeop_p)(void *);
131 const struct vnodeopv_entry_desc fdesc_vnodeop_entries[] = {
132 	{ &vop_default_desc, vn_default_error },
133 	{ &vop_lookup_desc, fdesc_lookup },		/* lookup */
134 	{ &vop_create_desc, fdesc_create },		/* create */
135 	{ &vop_mknod_desc, fdesc_mknod },		/* mknod */
136 	{ &vop_open_desc, fdesc_open },			/* open */
137 	{ &vop_close_desc, fdesc_close },		/* close */
138 	{ &vop_access_desc, fdesc_access },		/* access */
139 	{ &vop_getattr_desc, fdesc_getattr },		/* getattr */
140 	{ &vop_setattr_desc, fdesc_setattr },		/* setattr */
141 	{ &vop_read_desc, fdesc_read },			/* read */
142 	{ &vop_write_desc, fdesc_write },		/* write */
143 	{ &vop_ioctl_desc, fdesc_ioctl },		/* ioctl */
144 	{ &vop_fcntl_desc, fdesc_fcntl },		/* fcntl */
145 	{ &vop_poll_desc, fdesc_poll },			/* poll */
146 	{ &vop_kqfilter_desc, fdesc_kqfilter },		/* kqfilter */
147 	{ &vop_revoke_desc, fdesc_revoke },		/* revoke */
148 	{ &vop_mmap_desc, fdesc_mmap },			/* mmap */
149 	{ &vop_fsync_desc, fdesc_fsync },		/* fsync */
150 	{ &vop_seek_desc, fdesc_seek },			/* seek */
151 	{ &vop_remove_desc, fdesc_remove },		/* remove */
152 	{ &vop_link_desc, fdesc_link },			/* link */
153 	{ &vop_rename_desc, fdesc_rename },		/* rename */
154 	{ &vop_mkdir_desc, fdesc_mkdir },		/* mkdir */
155 	{ &vop_rmdir_desc, fdesc_rmdir },		/* rmdir */
156 	{ &vop_symlink_desc, fdesc_symlink },		/* symlink */
157 	{ &vop_readdir_desc, fdesc_readdir },		/* readdir */
158 	{ &vop_readlink_desc, fdesc_readlink },		/* readlink */
159 	{ &vop_abortop_desc, fdesc_abortop },		/* abortop */
160 	{ &vop_inactive_desc, fdesc_inactive },		/* inactive */
161 	{ &vop_reclaim_desc, fdesc_reclaim },		/* reclaim */
162 	{ &vop_lock_desc, fdesc_lock },			/* lock */
163 	{ &vop_unlock_desc, fdesc_unlock },		/* unlock */
164 	{ &vop_bmap_desc, fdesc_bmap },			/* bmap */
165 	{ &vop_strategy_desc, fdesc_strategy },		/* strategy */
166 	{ &vop_print_desc, fdesc_print },		/* print */
167 	{ &vop_islocked_desc, fdesc_islocked },		/* islocked */
168 	{ &vop_pathconf_desc, fdesc_pathconf },		/* pathconf */
169 	{ &vop_advlock_desc, fdesc_advlock },		/* advlock */
170 	{ &vop_bwrite_desc, fdesc_bwrite },		/* bwrite */
171 	{ &vop_putpages_desc, fdesc_putpages },		/* putpages */
172 	{ NULL, NULL }
173 };
174 
175 const struct vnodeopv_desc fdesc_vnodeop_opv_desc =
176 	{ &fdesc_vnodeop_p, fdesc_vnodeop_entries };
177 
178 extern const struct cdevsw ctty_cdevsw;
179 
180 /*
181  * Initialise cache headers
182  */
183 void
184 fdesc_init()
185 {
186 	int cttymajor;
187 
188 	/* locate the major number */
189 	cttymajor = cdevsw_lookup_major(&ctty_cdevsw);
190 	devctty = makedev(cttymajor, 0);
191 	fdhashtbl = hashinit(NFDCACHE, HASH_LIST, M_CACHE, M_NOWAIT, &fdhash);
192 }
193 
194 /*
195  * Free hash table.
196  */
197 void
198 fdesc_done()
199 {
200 	hashdone(fdhashtbl, M_CACHE);
201 }
202 
203 /*
204  * Return a locked vnode of the correct type.
205  */
206 int
207 fdesc_allocvp(ftype, ix, mp, vpp)
208 	fdntype ftype;
209 	int ix;
210 	struct mount *mp;
211 	struct vnode **vpp;
212 {
213 	struct fdhashhead *fc;
214 	struct fdescnode *fd;
215 	int error = 0;
216 
217 	fc = FD_NHASH(ix);
218 loop:
219 	for (fd = fc->lh_first; fd != 0; fd = fd->fd_hash.le_next) {
220 		if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
221 			if (vget(fd->fd_vnode, LK_EXCLUSIVE))
222 				goto loop;
223 			*vpp = fd->fd_vnode;
224 			return (error);
225 		}
226 	}
227 
228 	/*
229 	 * otherwise lock the array while we call getnewvnode
230 	 * since that can block.
231 	 */
232 	if (fdcache_lock & FDL_LOCKED) {
233 		fdcache_lock |= FDL_WANT;
234 		(void) tsleep(&fdcache_lock, PINOD, "fdcache", 0);
235 		goto loop;
236 	}
237 	fdcache_lock |= FDL_LOCKED;
238 
239 	error = getnewvnode(VT_FDESC, mp, fdesc_vnodeop_p, vpp);
240 	if (error)
241 		goto out;
242 	MALLOC(fd, void *, sizeof(struct fdescnode), M_TEMP, M_WAITOK);
243 	(*vpp)->v_data = fd;
244 	fd->fd_vnode = *vpp;
245 	fd->fd_type = ftype;
246 	fd->fd_fd = -1;
247 	fd->fd_link = 0;
248 	fd->fd_ix = ix;
249 	uvm_vnp_setsize(*vpp, 0);
250 	VOP_LOCK(*vpp, LK_EXCLUSIVE);
251 	LIST_INSERT_HEAD(fc, fd, fd_hash);
252 
253 out:;
254 	fdcache_lock &= ~FDL_LOCKED;
255 
256 	if (fdcache_lock & FDL_WANT) {
257 		fdcache_lock &= ~FDL_WANT;
258 		wakeup(&fdcache_lock);
259 	}
260 
261 	return (error);
262 }
263 
264 /*
265  * vp is the current namei directory
266  * ndp is the name to locate in that directory...
267  */
268 int
269 fdesc_lookup(v)
270 	void *v;
271 {
272 	struct vop_lookup_args /* {
273 		struct vnode * a_dvp;
274 		struct vnode ** a_vpp;
275 		struct componentname * a_cnp;
276 	} */ *ap = v;
277 	struct vnode **vpp = ap->a_vpp;
278 	struct vnode *dvp = ap->a_dvp;
279 	struct componentname *cnp = ap->a_cnp;
280 	struct lwp *l = curlwp;
281 	const char *pname = cnp->cn_nameptr;
282 	struct proc *p = l->l_proc;
283 	int numfiles = p->p_fd->fd_nfiles;
284 	unsigned fd = 0;
285 	int error;
286 	struct vnode *fvp;
287 	const char *ln;
288 
289 	if (cnp->cn_namelen == 1 && *pname == '.') {
290 		*vpp = dvp;
291 		VREF(dvp);
292 		return (0);
293 	}
294 
295 	switch (VTOFDESC(dvp)->fd_type) {
296 	default:
297 	case Flink:
298 	case Fdesc:
299 	case Fctty:
300 		error = ENOTDIR;
301 		goto bad;
302 
303 	case Froot:
304 		if (cnp->cn_namelen == 2 && memcmp(pname, "fd", 2) == 0) {
305 			error = fdesc_allocvp(Fdevfd, FD_DEVFD, dvp->v_mount, &fvp);
306 			if (error)
307 				goto bad;
308 			*vpp = fvp;
309 			fvp->v_type = VDIR;
310 			goto good;
311 		}
312 
313 		if (cnp->cn_namelen == 3 && memcmp(pname, "tty", 3) == 0) {
314 			struct vnode *ttyvp = cttyvp(p);
315 			if (ttyvp == NULL) {
316 				error = ENXIO;
317 				goto bad;
318 			}
319 			error = fdesc_allocvp(Fctty, FD_CTTY, dvp->v_mount, &fvp);
320 			if (error)
321 				goto bad;
322 			*vpp = fvp;
323 			fvp->v_type = VCHR;
324 			goto good;
325 		}
326 
327 		ln = 0;
328 		switch (cnp->cn_namelen) {
329 		case 5:
330 			if (memcmp(pname, "stdin", 5) == 0) {
331 				ln = "fd/0";
332 				fd = FD_STDIN;
333 			}
334 			break;
335 		case 6:
336 			if (memcmp(pname, "stdout", 6) == 0) {
337 				ln = "fd/1";
338 				fd = FD_STDOUT;
339 			} else
340 			if (memcmp(pname, "stderr", 6) == 0) {
341 				ln = "fd/2";
342 				fd = FD_STDERR;
343 			}
344 			break;
345 		}
346 
347 		if (ln) {
348 			error = fdesc_allocvp(Flink, fd, dvp->v_mount, &fvp);
349 			if (error)
350 				goto bad;
351 			/* XXXUNCONST */
352 			VTOFDESC(fvp)->fd_link = __UNCONST(ln);
353 			*vpp = fvp;
354 			fvp->v_type = VLNK;
355 			goto good;
356 		} else {
357 			error = ENOENT;
358 			goto bad;
359 		}
360 
361 		/* FALL THROUGH */
362 
363 	case Fdevfd:
364 		if (cnp->cn_namelen == 2 && memcmp(pname, "..", 2) == 0) {
365 			VOP_UNLOCK(dvp, 0);
366 			error = fdesc_root(dvp->v_mount, vpp);
367 			vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);
368 			if (error)
369 				goto bad;
370 			return (error);
371 		}
372 
373 		fd = 0;
374 		while (*pname >= '0' && *pname <= '9') {
375 			fd = 10 * fd + *pname++ - '0';
376 			if (fd >= numfiles)
377 				break;
378 		}
379 
380 		if (*pname != '\0') {
381 			error = ENOENT;
382 			goto bad;
383 		}
384 
385 		if (fd >= numfiles || p->p_fd->fd_ofiles[fd] == NULL ||
386 		    FILE_IS_USABLE(p->p_fd->fd_ofiles[fd]) == 0) {
387 			error = EBADF;
388 			goto bad;
389 		}
390 
391 		error = fdesc_allocvp(Fdesc, FD_DESC+fd, dvp->v_mount, &fvp);
392 		if (error)
393 			goto bad;
394 		VTOFDESC(fvp)->fd_fd = fd;
395 		*vpp = fvp;
396 		goto good;
397 	}
398 
399 bad:
400 	*vpp = NULL;
401 	return (error);
402 
403 good:
404 	return (0);
405 }
406 
407 int
408 fdesc_open(v)
409 	void *v;
410 {
411 	struct vop_open_args /* {
412 		struct vnode *a_vp;
413 		int  a_mode;
414 		kauth_cred_t a_cred;
415 	} */ *ap = v;
416 	struct vnode *vp = ap->a_vp;
417 
418 	switch (VTOFDESC(vp)->fd_type) {
419 	case Fdesc:
420 		/*
421 		 * XXX Kludge: set dupfd to contain the value of the
422 		 * the file descriptor being sought for duplication. The error
423 		 * return ensures that the vnode for this device will be
424 		 * released by vn_open. Open will detect this special error and
425 		 * take the actions in dupfdopen.  Other callers of vn_open or
426 		 * VOP_OPEN will simply report the error.
427 		 */
428 		curlwp->l_dupfd = VTOFDESC(vp)->fd_fd;	/* XXX */
429 		return EDUPFD;
430 
431 	case Fctty:
432 		return cdev_open(devctty, ap->a_mode, 0, curlwp);
433 	case Froot:
434 	case Fdevfd:
435 	case Flink:
436 		break;
437 	}
438 
439 	return (0);
440 }
441 
442 static int
443 fdesc_attr(fd, vap, cred, l)
444 	int fd;
445 	struct vattr *vap;
446 	kauth_cred_t cred;
447 	struct lwp *l;
448 {
449 	struct proc *p = l->l_proc;
450 	struct filedesc *fdp = p->p_fd;
451 	struct file *fp;
452 	struct stat stb;
453 	int error;
454 
455 	if ((fp = fd_getfile(fdp, fd)) == NULL)
456 		return (EBADF);
457 
458 	switch (fp->f_type) {
459 	case DTYPE_VNODE:
460 		FILE_USE(fp);
461 		error = VOP_GETATTR((struct vnode *) fp->f_data, vap, cred);
462 		FILE_UNUSE(fp, l);
463 		if (error == 0 && vap->va_type == VDIR) {
464 			/*
465 			 * directories can cause loops in the namespace,
466 			 * so turn off the 'x' bits to avoid trouble.
467 			 */
468 			vap->va_mode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
469 		}
470 		break;
471 
472 	default:
473 		FILE_USE(fp);
474 		memset(&stb, 0, sizeof(stb));
475 		error = (*fp->f_ops->fo_stat)(fp, &stb, l);
476 		FILE_UNUSE(fp, l);
477 		if (error)
478 			break;
479 
480 		vattr_null(vap);
481 		switch(fp->f_type) {
482 		case DTYPE_SOCKET:
483 			vap->va_type = VSOCK;
484 			break;
485 		case DTYPE_PIPE:
486 			vap->va_type = VFIFO;
487 			break;
488 		default:
489 			/* use VNON perhaps? */
490 			vap->va_type = VBAD;
491 			break;
492 		}
493 		vap->va_mode = stb.st_mode;
494 		vap->va_nlink = stb.st_nlink;
495 		vap->va_uid = stb.st_uid;
496 		vap->va_gid = stb.st_gid;
497 		vap->va_fsid = stb.st_dev;
498 		vap->va_fileid = stb.st_ino;
499 		vap->va_size = stb.st_size;
500 		vap->va_blocksize = stb.st_blksize;
501 		vap->va_atime = stb.st_atimespec;
502 		vap->va_mtime = stb.st_mtimespec;
503 		vap->va_ctime = stb.st_ctimespec;
504 		vap->va_gen = stb.st_gen;
505 		vap->va_flags = stb.st_flags;
506 		vap->va_rdev = stb.st_rdev;
507 		vap->va_bytes = stb.st_blocks * stb.st_blksize;
508 		break;
509 	}
510 
511 	return (error);
512 }
513 
514 int
515 fdesc_getattr(v)
516 	void *v;
517 {
518 	struct vop_getattr_args /* {
519 		struct vnode *a_vp;
520 		struct vattr *a_vap;
521 		kauth_cred_t a_cred;
522 		struct lwp *a_l;
523 	} */ *ap = v;
524 	struct vnode *vp = ap->a_vp;
525 	struct vattr *vap = ap->a_vap;
526 	unsigned fd;
527 	int error = 0;
528 
529 	switch (VTOFDESC(vp)->fd_type) {
530 	case Froot:
531 	case Fdevfd:
532 	case Flink:
533 	case Fctty:
534 		VATTR_NULL(vap);
535 		vap->va_fileid = VTOFDESC(vp)->fd_ix;
536 
537 #define R_ALL (S_IRUSR|S_IRGRP|S_IROTH)
538 #define W_ALL (S_IWUSR|S_IWGRP|S_IWOTH)
539 #define X_ALL (S_IXUSR|S_IXGRP|S_IXOTH)
540 
541 		switch (VTOFDESC(vp)->fd_type) {
542 		case Flink:
543 			vap->va_mode = R_ALL|X_ALL;
544 			vap->va_type = VLNK;
545 			vap->va_rdev = 0;
546 			vap->va_nlink = 1;
547 			vap->va_size = strlen(VTOFDESC(vp)->fd_link);
548 			break;
549 
550 		case Fctty:
551 			vap->va_mode = R_ALL|W_ALL;
552 			vap->va_type = VCHR;
553 			vap->va_rdev = devctty;
554 			vap->va_nlink = 1;
555 			vap->va_size = 0;
556 			break;
557 
558 		default:
559 			vap->va_mode = R_ALL|X_ALL;
560 			vap->va_type = VDIR;
561 			vap->va_rdev = 0;
562 			vap->va_nlink = 2;
563 			vap->va_size = DEV_BSIZE;
564 			break;
565 		}
566 		vap->va_uid = 0;
567 		vap->va_gid = 0;
568 		vap->va_fsid = vp->v_mount->mnt_stat.f_fsidx.__fsid_val[0];
569 		vap->va_blocksize = DEV_BSIZE;
570 		vap->va_atime.tv_sec = boottime.tv_sec;
571 		vap->va_atime.tv_nsec = 0;
572 		vap->va_mtime = vap->va_atime;
573 		vap->va_ctime = vap->va_mtime;
574 		vap->va_gen = 0;
575 		vap->va_flags = 0;
576 		vap->va_bytes = 0;
577 		break;
578 
579 	case Fdesc:
580 		fd = VTOFDESC(vp)->fd_fd;
581 		error = fdesc_attr(fd, vap, ap->a_cred, curlwp);
582 		break;
583 
584 	default:
585 		panic("fdesc_getattr");
586 		break;
587 	}
588 
589 	if (error == 0)
590 		vp->v_type = vap->va_type;
591 
592 	return (error);
593 }
594 
595 int
596 fdesc_setattr(v)
597 	void *v;
598 {
599 	struct vop_setattr_args /* {
600 		struct vnode *a_vp;
601 		struct vattr *a_vap;
602 		kauth_cred_t a_cred;
603 	} */ *ap = v;
604 	struct filedesc *fdp = curlwp->l_proc->p_fd;
605 	struct file *fp;
606 	unsigned fd;
607 
608 	/*
609 	 * Can't mess with the root vnode
610 	 */
611 	switch (VTOFDESC(ap->a_vp)->fd_type) {
612 	case Fdesc:
613 		break;
614 
615 	case Fctty:
616 		return (0);
617 
618 	default:
619 		return (EACCES);
620 	}
621 
622 	fd = VTOFDESC(ap->a_vp)->fd_fd;
623 	if ((fp = fd_getfile(fdp, fd)) == NULL)
624 		return (EBADF);
625 
626 	/*
627 	 * XXX: Can't reasonably set the attr's on any types currently.
628 	 *      On vnode's this will cause truncation and socket/pipes make
629 	 *      no sense.
630 	 */
631 	mutex_exit(&fp->f_lock);
632 	return (0);
633 }
634 
635 
636 struct fdesc_target {
637 	ino_t ft_fileno;
638 	u_char ft_type;
639 	u_char ft_namlen;
640 	const char *ft_name;
641 } fdesc_targets[] = {
642 #define N(s) sizeof(s)-1, s
643 	{ FD_DEVFD,  DT_DIR,     N("fd")     },
644 	{ FD_STDIN,  DT_LNK,     N("stdin")  },
645 	{ FD_STDOUT, DT_LNK,     N("stdout") },
646 	{ FD_STDERR, DT_LNK,     N("stderr") },
647 	{ FD_CTTY,   DT_UNKNOWN, N("tty")    },
648 #undef N
649 #define UIO_MX _DIRENT_RECLEN((struct dirent *)NULL, sizeof("stderr") - 1)
650 };
651 static int nfdesc_targets = sizeof(fdesc_targets) / sizeof(fdesc_targets[0]);
652 
653 int
654 fdesc_readdir(v)
655 	void *v;
656 {
657 	struct vop_readdir_args /* {
658 		struct vnode *a_vp;
659 		struct uio *a_uio;
660 		kauth_cred_t a_cred;
661 		int *a_eofflag;
662 		off_t **a_cookies;
663 		int *a_ncookies;
664 	} */ *ap = v;
665 	struct uio *uio = ap->a_uio;
666 	struct dirent d;
667 	struct filedesc *fdp;
668 	off_t i;
669 	int j;
670 	int error;
671 	off_t *cookies = NULL;
672 	int ncookies;
673 
674 	switch (VTOFDESC(ap->a_vp)->fd_type) {
675 	case Fctty:
676 		return 0;
677 
678 	case Fdesc:
679 		return ENOTDIR;
680 
681 	default:
682 		break;
683 	}
684 
685 	fdp = curproc->p_fd;
686 
687 	if (uio->uio_resid < UIO_MX)
688 		return EINVAL;
689 	if (uio->uio_offset < 0)
690 		return EINVAL;
691 
692 	error = 0;
693 	i = uio->uio_offset;
694 	(void)memset(&d, 0, UIO_MX);
695 	d.d_reclen = UIO_MX;
696 	if (ap->a_ncookies)
697 		ncookies = uio->uio_resid / UIO_MX;
698 	else
699 		ncookies = 0;
700 
701 	if (VTOFDESC(ap->a_vp)->fd_type == Froot) {
702 		struct fdesc_target *ft;
703 
704 		if (i >= nfdesc_targets)
705 			return 0;
706 
707 		if (ap->a_ncookies) {
708 			ncookies = min(ncookies, (nfdesc_targets - i));
709 			cookies = malloc(ncookies * sizeof(off_t),
710 			    M_TEMP, M_WAITOK);
711 			*ap->a_cookies = cookies;
712 			*ap->a_ncookies = ncookies;
713 		}
714 
715 		for (ft = &fdesc_targets[i]; uio->uio_resid >= UIO_MX &&
716 		    i < nfdesc_targets; ft++, i++) {
717 			switch (ft->ft_fileno) {
718 			case FD_CTTY:
719 				if (cttyvp(curproc) == NULL)
720 					continue;
721 				break;
722 
723 			case FD_STDIN:
724 			case FD_STDOUT:
725 			case FD_STDERR:
726 				if (fdp == NULL)
727 					continue;
728 				if ((ft->ft_fileno - FD_STDIN) >=
729 				    fdp->fd_nfiles)
730 					continue;
731 				if (fdp->fd_ofiles[ft->ft_fileno - FD_STDIN]
732 				    == NULL
733 				    || FILE_IS_USABLE(
734 				    fdp->fd_ofiles[ft->ft_fileno - FD_STDIN])
735 				    == 0)
736 					continue;
737 				break;
738 			}
739 
740 			d.d_fileno = ft->ft_fileno;
741 			d.d_namlen = ft->ft_namlen;
742 			(void)memcpy(d.d_name, ft->ft_name, ft->ft_namlen + 1);
743 			d.d_type = ft->ft_type;
744 
745 			if ((error = uiomove(&d, UIO_MX, uio)) != 0)
746 				break;
747 			if (cookies)
748 				*cookies++ = i + 1;
749 		}
750 	} else {
751 		int nfdp = fdp ? fdp->fd_nfiles : 0;
752 		if (ap->a_ncookies) {
753 			ncookies = min(ncookies, nfdp + 2);
754 			cookies = malloc(ncookies * sizeof(off_t),
755 			    M_TEMP, M_WAITOK);
756 			*ap->a_cookies = cookies;
757 			*ap->a_ncookies = ncookies;
758 		}
759 		for (; i - 2 < nfdp && uio->uio_resid >= UIO_MX; i++) {
760 			switch (i) {
761 			case 0:
762 			case 1:
763 				d.d_fileno = FD_ROOT;		/* XXX */
764 				d.d_namlen = i + 1;
765 				(void)memcpy(d.d_name, "..", d.d_namlen);
766 				d.d_name[i + 1] = '\0';
767 				d.d_type = DT_DIR;
768 				break;
769 
770 			default:
771 				KASSERT(fdp != NULL);
772 				j = (int)i - 2;
773 				if (fdp == NULL || fdp->fd_ofiles[j] == NULL ||
774 				    FILE_IS_USABLE(fdp->fd_ofiles[j]) == 0)
775 					continue;
776 				d.d_fileno = j + FD_STDIN;
777 				d.d_namlen = sprintf(d.d_name, "%d", j);
778 				d.d_type = DT_UNKNOWN;
779 				break;
780 			}
781 
782 			if ((error = uiomove(&d, UIO_MX, uio)) != 0)
783 				break;
784 			if (cookies)
785 				*cookies++ = i + 1;
786 		}
787 	}
788 
789 	if (ap->a_ncookies && error) {
790 		free(*ap->a_cookies, M_TEMP);
791 		*ap->a_ncookies = 0;
792 		*ap->a_cookies = NULL;
793 	}
794 
795 	uio->uio_offset = i;
796 	return error;
797 }
798 
799 int
800 fdesc_readlink(v)
801 	void *v;
802 {
803 	struct vop_readlink_args /* {
804 		struct vnode *a_vp;
805 		struct uio *a_uio;
806 		kauth_cred_t a_cred;
807 	} */ *ap = v;
808 	struct vnode *vp = ap->a_vp;
809 	int error;
810 
811 	if (vp->v_type != VLNK)
812 		return (EPERM);
813 
814 	if (VTOFDESC(vp)->fd_type == Flink) {
815 		char *ln = VTOFDESC(vp)->fd_link;
816 		error = uiomove(ln, strlen(ln), ap->a_uio);
817 	} else {
818 		error = EOPNOTSUPP;
819 	}
820 
821 	return (error);
822 }
823 
824 int
825 fdesc_read(v)
826 	void *v;
827 {
828 	struct vop_read_args /* {
829 		struct vnode *a_vp;
830 		struct uio *a_uio;
831 		int  a_ioflag;
832 		kauth_cred_t a_cred;
833 	} */ *ap = v;
834 	int error = EOPNOTSUPP;
835 	struct vnode *vp = ap->a_vp;
836 
837 	switch (VTOFDESC(vp)->fd_type) {
838 	case Fctty:
839 		VOP_UNLOCK(vp, 0);
840 		error = cdev_read(devctty, ap->a_uio, ap->a_ioflag);
841 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
842 		break;
843 
844 	default:
845 		error = EOPNOTSUPP;
846 		break;
847 	}
848 
849 	return (error);
850 }
851 
852 int
853 fdesc_write(v)
854 	void *v;
855 {
856 	struct vop_write_args /* {
857 		struct vnode *a_vp;
858 		struct uio *a_uio;
859 		int  a_ioflag;
860 		kauth_cred_t a_cred;
861 	} */ *ap = v;
862 	int error = EOPNOTSUPP;
863 	struct vnode *vp = ap->a_vp;
864 
865 	switch (VTOFDESC(vp)->fd_type) {
866 	case Fctty:
867 		VOP_UNLOCK(vp, 0);
868 		error = cdev_write(devctty, ap->a_uio, ap->a_ioflag);
869 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
870 		break;
871 
872 	default:
873 		error = EOPNOTSUPP;
874 		break;
875 	}
876 
877 	return (error);
878 }
879 
880 int
881 fdesc_ioctl(v)
882 	void *v;
883 {
884 	struct vop_ioctl_args /* {
885 		struct vnode *a_vp;
886 		u_long a_command;
887 		void *a_data;
888 		int  a_fflag;
889 		kauth_cred_t a_cred;
890 	} */ *ap = v;
891 	int error = EOPNOTSUPP;
892 
893 	switch (VTOFDESC(ap->a_vp)->fd_type) {
894 	case Fctty:
895 		error = cdev_ioctl(devctty, ap->a_command, ap->a_data,
896 		    ap->a_fflag, curlwp);
897 		break;
898 
899 	default:
900 		error = EOPNOTSUPP;
901 		break;
902 	}
903 
904 	return (error);
905 }
906 
907 int
908 fdesc_poll(v)
909 	void *v;
910 {
911 	struct vop_poll_args /* {
912 		struct vnode *a_vp;
913 		int a_events;
914 	} */ *ap = v;
915 	int revents;
916 
917 	switch (VTOFDESC(ap->a_vp)->fd_type) {
918 	case Fctty:
919 		revents = cdev_poll(devctty, ap->a_events, curlwp);
920 		break;
921 
922 	default:
923 		revents = genfs_poll(v);
924 		break;
925 	}
926 
927 	return (revents);
928 }
929 
930 int
931 fdesc_kqfilter(v)
932 	void *v;
933 {
934 	struct vop_kqfilter_args /* {
935 		struct vnode *a_vp;
936 		struct knote *a_kn;
937 	} */ *ap = v;
938 	int error;
939 	struct proc *p;
940 	struct lwp *l;
941 	struct file *fp;
942 
943 	switch (VTOFDESC(ap->a_vp)->fd_type) {
944 	case Fctty:
945 		error = cdev_kqfilter(devctty, ap->a_kn);
946 		break;
947 
948 	case Fdesc:
949 		/* just invoke kqfilter for the underlying descriptor */
950 		l = curlwp;	/* XXX hopefully ok to use curproc here */
951 		p = l->l_proc;
952 		if ((fp = fd_getfile(p->p_fd, VTOFDESC(ap->a_vp)->fd_fd)) == NULL)
953 			return (1);
954 
955 		FILE_USE(fp);
956 		error = (*fp->f_ops->fo_kqfilter)(fp, ap->a_kn);
957 		FILE_UNUSE(fp, l);
958 		break;
959 
960 	default:
961 		return (genfs_kqfilter(v));
962 	}
963 
964 	return (error);
965 }
966 
967 int
968 fdesc_inactive(v)
969 	void *v;
970 {
971 	struct vop_inactive_args /* {
972 		struct vnode *a_vp;
973 	} */ *ap = v;
974 	struct vnode *vp = ap->a_vp;
975 
976 	/*
977 	 * Clear out the v_type field to avoid
978 	 * nasty things happening in vgone().
979 	 */
980 	VOP_UNLOCK(vp, 0);
981 	vp->v_type = VNON;
982 	return (0);
983 }
984 
985 int
986 fdesc_reclaim(v)
987 	void *v;
988 {
989 	struct vop_reclaim_args /* {
990 		struct vnode *a_vp;
991 	} */ *ap = v;
992 	struct vnode *vp = ap->a_vp;
993 	struct fdescnode *fd = VTOFDESC(vp);
994 
995 	LIST_REMOVE(fd, fd_hash);
996 	FREE(vp->v_data, M_TEMP);
997 	vp->v_data = 0;
998 
999 	return (0);
1000 }
1001 
1002 /*
1003  * Return POSIX pathconf information applicable to special devices.
1004  */
1005 int
1006 fdesc_pathconf(v)
1007 	void *v;
1008 {
1009 	struct vop_pathconf_args /* {
1010 		struct vnode *a_vp;
1011 		int a_name;
1012 		register_t *a_retval;
1013 	} */ *ap = v;
1014 
1015 	switch (ap->a_name) {
1016 	case _PC_LINK_MAX:
1017 		*ap->a_retval = LINK_MAX;
1018 		return (0);
1019 	case _PC_MAX_CANON:
1020 		*ap->a_retval = MAX_CANON;
1021 		return (0);
1022 	case _PC_MAX_INPUT:
1023 		*ap->a_retval = MAX_INPUT;
1024 		return (0);
1025 	case _PC_PIPE_BUF:
1026 		*ap->a_retval = PIPE_BUF;
1027 		return (0);
1028 	case _PC_CHOWN_RESTRICTED:
1029 		*ap->a_retval = 1;
1030 		return (0);
1031 	case _PC_VDISABLE:
1032 		*ap->a_retval = _POSIX_VDISABLE;
1033 		return (0);
1034 	case _PC_SYNC_IO:
1035 		*ap->a_retval = 1;
1036 		return (0);
1037 	default:
1038 		return (EINVAL);
1039 	}
1040 	/* NOTREACHED */
1041 }
1042 
1043 /*
1044  * Print out the contents of a /dev/fd vnode.
1045  */
1046 /* ARGSUSED */
1047 int
1048 fdesc_print(void *v)
1049 {
1050 	printf("tag VT_NON, fdesc vnode\n");
1051 	return (0);
1052 }
1053 
1054 int
1055 fdesc_link(v)
1056 	void *v;
1057 {
1058 	struct vop_link_args /* {
1059 		struct vnode *a_dvp;
1060 		struct vnode *a_vp;
1061 		struct componentname *a_cnp;
1062 	} */ *ap = v;
1063 
1064 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
1065 	vput(ap->a_dvp);
1066 	return (EROFS);
1067 }
1068 
1069 int
1070 fdesc_symlink(v)
1071 	void *v;
1072 {
1073 	struct vop_symlink_args /* {
1074 		struct vnode *a_dvp;
1075 		struct vnode **a_vpp;
1076 		struct componentname *a_cnp;
1077 		struct vattr *a_vap;
1078 		char *a_target;
1079 	} */ *ap = v;
1080 
1081 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
1082 	vput(ap->a_dvp);
1083 	return (EROFS);
1084 }
1085