xref: /netbsd-src/sys/miscfs/fdesc/fdesc_vnops.c (revision 82d56013d7b633d116a93943de88e08335357a7c)
1 /*	$NetBSD: fdesc_vnops.c,v 1.135 2021/05/01 15:08:14 hannken 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 1.135 2021/05/01 15:08:14 hannken 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/resourcevar.h>
51 #include <sys/socketvar.h>
52 #include <sys/filedesc.h>
53 #include <sys/vnode.h>
54 #include <sys/malloc.h>
55 #include <sys/conf.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/tty.h>
63 #include <sys/kauth.h>
64 #include <sys/atomic.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 dev_t devctty;
72 
73 #if (FD_STDIN != FD_STDOUT-1) || (FD_STDOUT != FD_STDERR-1)
74 FD_STDIN, FD_STDOUT, FD_STDERR must be a sequence n, n+1, n+2
75 #endif
76 
77 int	fdesc_lookup(void *);
78 #define	fdesc_create	genfs_eopnotsupp
79 #define	fdesc_mknod	genfs_eopnotsupp
80 int	fdesc_open(void *);
81 #define	fdesc_close	genfs_nullop
82 #define	fdesc_access	genfs_nullop
83 int	fdesc_getattr(void *);
84 int	fdesc_setattr(void *);
85 int	fdesc_read(void *);
86 int	fdesc_write(void *);
87 int	fdesc_ioctl(void *);
88 int	fdesc_poll(void *);
89 int	fdesc_kqfilter(void *);
90 #define	fdesc_mmap	genfs_eopnotsupp
91 #define	fdesc_fcntl	genfs_fcntl
92 #define	fdesc_fsync	genfs_nullop
93 #define	fdesc_seek	genfs_seek
94 #define	fdesc_remove	genfs_eopnotsupp
95 int	fdesc_link(void *);
96 #define	fdesc_rename	genfs_eopnotsupp
97 #define	fdesc_mkdir	genfs_eopnotsupp
98 #define	fdesc_rmdir	genfs_eopnotsupp
99 int	fdesc_symlink(void *);
100 int	fdesc_readdir(void *);
101 int	fdesc_readlink(void *);
102 #define	fdesc_abortop	genfs_abortop
103 int	fdesc_inactive(void *);
104 int	fdesc_reclaim(void *);
105 #define	fdesc_lock	genfs_lock
106 #define	fdesc_unlock	genfs_unlock
107 #define	fdesc_bmap	genfs_badop
108 #define	fdesc_strategy	genfs_badop
109 int	fdesc_print(void *);
110 int	fdesc_pathconf(void *);
111 #define	fdesc_islocked	genfs_islocked
112 #define	fdesc_advlock	genfs_einval
113 #define	fdesc_bwrite	genfs_eopnotsupp
114 #define fdesc_revoke	genfs_revoke
115 #define fdesc_putpages	genfs_null_putpages
116 
117 static int fdesc_attr(int, struct vattr *, kauth_cred_t);
118 
119 int (**fdesc_vnodeop_p)(void *);
120 const struct vnodeopv_entry_desc fdesc_vnodeop_entries[] = {
121 	{ &vop_default_desc, vn_default_error },
122 	{ &vop_lookup_desc, fdesc_lookup },		/* lookup */
123 	{ &vop_create_desc, fdesc_create },		/* create */
124 	{ &vop_mknod_desc, fdesc_mknod },		/* mknod */
125 	{ &vop_open_desc, fdesc_open },			/* open */
126 	{ &vop_close_desc, fdesc_close },		/* close */
127 	{ &vop_access_desc, fdesc_access },		/* access */
128 	{ &vop_accessx_desc, genfs_accessx },		/* accessx */
129 	{ &vop_getattr_desc, fdesc_getattr },		/* getattr */
130 	{ &vop_setattr_desc, fdesc_setattr },		/* setattr */
131 	{ &vop_read_desc, fdesc_read },			/* read */
132 	{ &vop_write_desc, fdesc_write },		/* write */
133 	{ &vop_fallocate_desc, genfs_eopnotsupp },	/* fallocate */
134 	{ &vop_fdiscard_desc, genfs_eopnotsupp },	/* fdiscard */
135 	{ &vop_ioctl_desc, fdesc_ioctl },		/* ioctl */
136 	{ &vop_fcntl_desc, fdesc_fcntl },		/* fcntl */
137 	{ &vop_poll_desc, fdesc_poll },			/* poll */
138 	{ &vop_kqfilter_desc, fdesc_kqfilter },		/* kqfilter */
139 	{ &vop_revoke_desc, fdesc_revoke },		/* revoke */
140 	{ &vop_mmap_desc, fdesc_mmap },			/* mmap */
141 	{ &vop_fsync_desc, fdesc_fsync },		/* fsync */
142 	{ &vop_seek_desc, fdesc_seek },			/* seek */
143 	{ &vop_remove_desc, fdesc_remove },		/* remove */
144 	{ &vop_link_desc, fdesc_link },			/* link */
145 	{ &vop_rename_desc, fdesc_rename },		/* rename */
146 	{ &vop_mkdir_desc, fdesc_mkdir },		/* mkdir */
147 	{ &vop_rmdir_desc, fdesc_rmdir },		/* rmdir */
148 	{ &vop_symlink_desc, fdesc_symlink },		/* symlink */
149 	{ &vop_readdir_desc, fdesc_readdir },		/* readdir */
150 	{ &vop_readlink_desc, fdesc_readlink },		/* readlink */
151 	{ &vop_abortop_desc, fdesc_abortop },		/* abortop */
152 	{ &vop_inactive_desc, fdesc_inactive },		/* inactive */
153 	{ &vop_reclaim_desc, fdesc_reclaim },		/* reclaim */
154 	{ &vop_lock_desc, fdesc_lock },			/* lock */
155 	{ &vop_unlock_desc, fdesc_unlock },		/* unlock */
156 	{ &vop_bmap_desc, fdesc_bmap },			/* bmap */
157 	{ &vop_strategy_desc, fdesc_strategy },		/* strategy */
158 	{ &vop_print_desc, fdesc_print },		/* print */
159 	{ &vop_islocked_desc, fdesc_islocked },		/* islocked */
160 	{ &vop_pathconf_desc, fdesc_pathconf },		/* pathconf */
161 	{ &vop_advlock_desc, fdesc_advlock },		/* advlock */
162 	{ &vop_bwrite_desc, fdesc_bwrite },		/* bwrite */
163 	{ &vop_putpages_desc, fdesc_putpages },		/* putpages */
164 	{ NULL, NULL }
165 };
166 
167 const struct vnodeopv_desc fdesc_vnodeop_opv_desc =
168 	{ &fdesc_vnodeop_p, fdesc_vnodeop_entries };
169 
170 /*
171  * Initialise cache headers
172  */
173 void
174 fdesc_init(void)
175 {
176 	int cttymajor;
177 
178 	/* locate the major number */
179 	cttymajor = devsw_name2chr("ctty", NULL, 0);
180 	devctty = makedev(cttymajor, 0);
181 }
182 
183 void
184 fdesc_done(void)
185 {
186 }
187 
188 /*
189  * vp is the current namei directory
190  * ndp is the name to locate in that directory...
191  */
192 int
193 fdesc_lookup(void *v)
194 {
195 	struct vop_lookup_v2_args /* {
196 		struct vnode * a_dvp;
197 		struct vnode ** a_vpp;
198 		struct componentname * a_cnp;
199 	} */ *ap = v;
200 	struct vnode **vpp = ap->a_vpp;
201 	struct vnode *dvp = ap->a_dvp;
202 	struct componentname *cnp = ap->a_cnp;
203 	struct lwp *l = curlwp;
204 	const char *pname = cnp->cn_nameptr;
205 	struct proc *p = l->l_proc;
206 	unsigned fd = 0;
207 	int error, ix = -1;
208 	fdtab_t *dt;
209 
210 	dt = atomic_load_consume(&curlwp->l_fd->fd_dt);
211 
212 	if (cnp->cn_namelen == 1 && *pname == '.') {
213 		*vpp = dvp;
214 		vref(dvp);
215 		return (0);
216 	}
217 
218 	switch (VTOFDESC(dvp)->fd_type) {
219 	default:
220 	case Flink:
221 	case Fdesc:
222 	case Fctty:
223 		error = ENOTDIR;
224 		goto bad;
225 
226 	case Froot:
227 		if (cnp->cn_namelen == 2 && memcmp(pname, "fd", 2) == 0) {
228 			ix = FD_DEVFD;
229 			goto good;
230 		}
231 
232 		if (cnp->cn_namelen == 3 && memcmp(pname, "tty", 3) == 0) {
233 			struct vnode *ttyvp = cttyvp(p);
234 			if (ttyvp == NULL) {
235 				error = ENXIO;
236 				goto bad;
237 			}
238 			ix = FD_CTTY;
239 			goto good;
240 		}
241 
242 		switch (cnp->cn_namelen) {
243 		case 5:
244 			if (memcmp(pname, "stdin", 5) == 0) {
245 				ix = FD_STDIN;
246 				goto good;
247 			}
248 			break;
249 		case 6:
250 			if (memcmp(pname, "stdout", 6) == 0) {
251 				ix = FD_STDOUT;
252 				goto good;
253 			} else if (memcmp(pname, "stderr", 6) == 0) {
254 				ix = FD_STDERR;
255 				goto good;
256 			}
257 			break;
258 		}
259 
260 		error = ENOENT;
261 		goto bad;
262 
263 	case Fdevfd:
264 		if (cnp->cn_namelen == 2 && memcmp(pname, "..", 2) == 0) {
265 			ix = FD_ROOT;
266 			goto good;
267 		}
268 
269 		fd = 0;
270 		while (*pname >= '0' && *pname <= '9') {
271 			fd = 10 * fd + *pname++ - '0';
272 			if (fd >= dt->dt_nfiles)
273 				break;
274 		}
275 
276 		if (*pname != '\0') {
277 			error = ENOENT;
278 			goto bad;
279 		}
280 
281 		if (fd >= dt->dt_nfiles || dt->dt_ff[fd] == NULL ||
282 		    dt->dt_ff[fd]->ff_file == NULL) {
283 			error = EBADF;
284 			goto bad;
285 		}
286 
287 		ix = FD_DESC + fd;
288 		goto good;
289 	}
290 
291 bad:
292 	*vpp = NULL;
293 	return error;
294 
295 good:
296 	KASSERT(ix != -1);
297 	error = vcache_get(dvp->v_mount, &ix, sizeof(ix), vpp);
298 	if (error)
299 		return error;
300 
301 	/*
302 	 * Prevent returning VNON nodes.
303 	 * Operation fdesc_inactive() will reset the type to VNON.
304 	 */
305 	if (ix == FD_CTTY)
306 		(*vpp)->v_type = VCHR;
307 	else if (ix >= FD_DESC)
308 		(*vpp)->v_type = VREG;
309 	KASSERT((*vpp)->v_type != VNON);
310 
311 	return 0;
312 }
313 
314 int
315 fdesc_open(void *v)
316 {
317 	struct vop_open_args /* {
318 		struct vnode *a_vp;
319 		int  a_mode;
320 		kauth_cred_t a_cred;
321 	} */ *ap = v;
322 	struct vnode *vp = ap->a_vp;
323 
324 	switch (VTOFDESC(vp)->fd_type) {
325 	case Fdesc:
326 		/*
327 		 * XXX Kludge: set dupfd to contain the value of the
328 		 * the file descriptor being sought for duplication. The error
329 		 * return ensures that the vnode for this device will be
330 		 * released by vn_open. Open will detect this special error and
331 		 * take the actions in dupfdopen.  Other callers of vn_open or
332 		 * VOP_OPEN will simply report the error.
333 		 */
334 		curlwp->l_dupfd = VTOFDESC(vp)->fd_fd;	/* XXX */
335 		return EDUPFD;
336 
337 	case Fctty:
338 		return cdev_open(devctty, ap->a_mode, 0, curlwp);
339 	case Froot:
340 	case Fdevfd:
341 	case Flink:
342 		break;
343 	}
344 
345 	return (0);
346 }
347 
348 static int
349 fdesc_attr(int fd, struct vattr *vap, kauth_cred_t cred)
350 {
351 	file_t *fp;
352 	struct stat stb;
353 	int error;
354 
355 	if ((fp = fd_getfile(fd)) == NULL)
356 		return (EBADF);
357 
358 	switch (fp->f_type) {
359 	case DTYPE_VNODE:
360 		vn_lock(fp->f_vnode, LK_SHARED | LK_RETRY);
361 		error = VOP_GETATTR(fp->f_vnode, vap, cred);
362 		VOP_UNLOCK(fp->f_vnode);
363 		if (error == 0 && vap->va_type == VDIR) {
364 			/*
365 			 * directories can cause loops in the namespace,
366 			 * so turn off the 'x' bits to avoid trouble.
367 			 */
368 			vap->va_mode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
369 		}
370 		break;
371 
372 	default:
373 		memset(&stb, 0, sizeof(stb));
374 		error = (*fp->f_ops->fo_stat)(fp, &stb);
375 		if (error)
376 			break;
377 
378 		vattr_null(vap);
379 		switch(fp->f_type) {
380 		case DTYPE_SOCKET:
381 			vap->va_type = VSOCK;
382 			break;
383 		case DTYPE_PIPE:
384 			vap->va_type = VFIFO;
385 			break;
386 		default:
387 			/* use VNON perhaps? */
388 			vap->va_type = VBAD;
389 			break;
390 		}
391 		vap->va_mode = stb.st_mode;
392 		vap->va_nlink = stb.st_nlink;
393 		vap->va_uid = stb.st_uid;
394 		vap->va_gid = stb.st_gid;
395 		vap->va_fsid = stb.st_dev;
396 		vap->va_fileid = stb.st_ino;
397 		vap->va_size = stb.st_size;
398 		vap->va_blocksize = stb.st_blksize;
399 		vap->va_atime = stb.st_atimespec;
400 		vap->va_mtime = stb.st_mtimespec;
401 		vap->va_ctime = stb.st_ctimespec;
402 		vap->va_gen = stb.st_gen;
403 		vap->va_flags = stb.st_flags;
404 		vap->va_rdev = stb.st_rdev;
405 		vap->va_bytes = stb.st_blocks * stb.st_blksize;
406 		break;
407 	}
408 
409 	fd_putfile(fd);
410 	return (error);
411 }
412 
413 int
414 fdesc_getattr(void *v)
415 {
416 	struct vop_getattr_args /* {
417 		struct vnode *a_vp;
418 		struct vattr *a_vap;
419 		kauth_cred_t a_cred;
420 		struct lwp *a_l;
421 	} */ *ap = v;
422 	struct vnode *vp = ap->a_vp;
423 	struct vattr *vap = ap->a_vap;
424 	unsigned fd;
425 	int error = 0;
426 	struct timeval tv;
427 
428 	switch (VTOFDESC(vp)->fd_type) {
429 	case Froot:
430 	case Fdevfd:
431 	case Flink:
432 	case Fctty:
433 		vattr_null(vap);
434 		vap->va_fileid = VTOFDESC(vp)->fd_ix;
435 
436 #define R_ALL (S_IRUSR|S_IRGRP|S_IROTH)
437 #define W_ALL (S_IWUSR|S_IWGRP|S_IWOTH)
438 #define X_ALL (S_IXUSR|S_IXGRP|S_IXOTH)
439 
440 		switch (VTOFDESC(vp)->fd_type) {
441 		case Flink:
442 			vap->va_mode = R_ALL|X_ALL;
443 			vap->va_type = VLNK;
444 			vap->va_rdev = 0;
445 			vap->va_nlink = 1;
446 			vap->va_size = strlen(VTOFDESC(vp)->fd_link);
447 			break;
448 
449 		case Fctty:
450 			vap->va_mode = R_ALL|W_ALL;
451 			vap->va_type = VCHR;
452 			vap->va_rdev = devctty;
453 			vap->va_nlink = 1;
454 			vap->va_size = 0;
455 			break;
456 
457 		default:
458 			vap->va_mode = R_ALL|X_ALL;
459 			vap->va_type = VDIR;
460 			vap->va_rdev = 0;
461 			vap->va_nlink = 2;
462 			vap->va_size = DEV_BSIZE;
463 			break;
464 		}
465 		vap->va_uid = 0;
466 		vap->va_gid = 0;
467 		vap->va_fsid = vp->v_mount->mnt_stat.f_fsidx.__fsid_val[0];
468 		vap->va_blocksize = DEV_BSIZE;
469 		getmicroboottime(&tv);
470 		vap->va_atime.tv_sec = tv.tv_sec;
471 		vap->va_atime.tv_nsec = 0;
472 		vap->va_mtime = vap->va_atime;
473 		vap->va_ctime = vap->va_mtime;
474 		vap->va_gen = 0;
475 		vap->va_flags = 0;
476 		vap->va_bytes = 0;
477 		break;
478 
479 	case Fdesc:
480 		fd = VTOFDESC(vp)->fd_fd;
481 		error = fdesc_attr(fd, vap, ap->a_cred);
482 		break;
483 
484 	default:
485 		panic("fdesc_getattr");
486 		break;
487 	}
488 
489 	if (error == 0)
490 		vp->v_type = vap->va_type;
491 
492 	return (error);
493 }
494 
495 int
496 fdesc_setattr(void *v)
497 {
498 	struct vop_setattr_args /* {
499 		struct vnode *a_vp;
500 		struct vattr *a_vap;
501 		kauth_cred_t a_cred;
502 	} */ *ap = v;
503 	file_t *fp;
504 	unsigned fd;
505 
506 	/*
507 	 * Can't mess with the root vnode
508 	 */
509 	switch (VTOFDESC(ap->a_vp)->fd_type) {
510 	case Fdesc:
511 		break;
512 
513 	case Fctty:
514 		return (0);
515 
516 	default:
517 		return (EACCES);
518 	}
519 
520 	fd = VTOFDESC(ap->a_vp)->fd_fd;
521 	if ((fp = fd_getfile(fd)) == NULL)
522 		return (EBADF);
523 
524 	/*
525 	 * XXX: Can't reasonably set the attr's on any types currently.
526 	 *      On vnode's this will cause truncation and socket/pipes make
527 	 *      no sense.
528 	 */
529 	fd_putfile(fd);
530 	return (0);
531 }
532 
533 
534 struct fdesc_target {
535 	ino_t ft_fileno;
536 	u_char ft_type;
537 	u_char ft_namlen;
538 	const char *ft_name;
539 } fdesc_targets[] = {
540 #define N(s) sizeof(s)-1, s
541 	{ FD_DEVFD,  DT_DIR,     N("fd")     },
542 	{ FD_STDIN,  DT_LNK,     N("stdin")  },
543 	{ FD_STDOUT, DT_LNK,     N("stdout") },
544 	{ FD_STDERR, DT_LNK,     N("stderr") },
545 	{ FD_CTTY,   DT_UNKNOWN, N("tty")    },
546 #undef N
547 #define UIO_MX _DIRENT_RECLEN((struct dirent *)NULL, sizeof("stderr") - 1)
548 };
549 static int nfdesc_targets = sizeof(fdesc_targets) / sizeof(fdesc_targets[0]);
550 
551 int
552 fdesc_readdir(void *v)
553 {
554 	struct vop_readdir_args /* {
555 		struct vnode *a_vp;
556 		struct uio *a_uio;
557 		kauth_cred_t a_cred;
558 		int *a_eofflag;
559 		off_t **a_cookies;
560 		int *a_ncookies;
561 	} */ *ap = v;
562 	struct uio *uio = ap->a_uio;
563 	struct dirent d;
564 	off_t i;
565 	int j;
566 	int error;
567 	off_t *cookies = NULL;
568 	int ncookies;
569 	fdtab_t *dt;
570 
571 	switch (VTOFDESC(ap->a_vp)->fd_type) {
572 	case Fctty:
573 		return 0;
574 
575 	case Fdesc:
576 		return ENOTDIR;
577 
578 	default:
579 		break;
580 	}
581 
582 	dt = atomic_load_consume(&curlwp->l_fd->fd_dt);
583 
584 	if (uio->uio_resid < UIO_MX)
585 		return EINVAL;
586 	if (uio->uio_offset < 0)
587 		return EINVAL;
588 
589 	error = 0;
590 	i = uio->uio_offset;
591 	(void)memset(&d, 0, UIO_MX);
592 	d.d_reclen = UIO_MX;
593 	if (ap->a_ncookies)
594 		ncookies = uio->uio_resid / UIO_MX;
595 	else
596 		ncookies = 0;
597 
598 	if (VTOFDESC(ap->a_vp)->fd_type == Froot) {
599 		struct fdesc_target *ft;
600 
601 		if (i >= nfdesc_targets)
602 			return 0;
603 
604 		if (ap->a_ncookies) {
605 			ncookies = uimin(ncookies, (nfdesc_targets - i));
606 			cookies = malloc(ncookies * sizeof(off_t),
607 			    M_TEMP, M_WAITOK);
608 			*ap->a_cookies = cookies;
609 			*ap->a_ncookies = ncookies;
610 		}
611 
612 		for (ft = &fdesc_targets[i]; uio->uio_resid >= UIO_MX &&
613 		    i < nfdesc_targets; ft++, i++) {
614 			switch (ft->ft_fileno) {
615 			case FD_CTTY:
616 				if (cttyvp(curproc) == NULL)
617 					continue;
618 				break;
619 
620 			case FD_STDIN:
621 			case FD_STDOUT:
622 			case FD_STDERR:
623 				if ((ft->ft_fileno - FD_STDIN) >=
624 				    dt->dt_nfiles)
625 					continue;
626 				if (dt->dt_ff[ft->ft_fileno - FD_STDIN]
627 				    == NULL || dt->dt_ff[ft->ft_fileno -
628 				    FD_STDIN]->ff_file == NULL)
629 					continue;
630 				break;
631 			}
632 
633 			d.d_fileno = ft->ft_fileno;
634 			d.d_namlen = ft->ft_namlen;
635 			(void)memcpy(d.d_name, ft->ft_name, ft->ft_namlen + 1);
636 			d.d_type = ft->ft_type;
637 
638 			if ((error = uiomove(&d, UIO_MX, uio)) != 0)
639 				break;
640 			if (cookies)
641 				*cookies++ = i + 1;
642 		}
643 	} else {
644 		if (ap->a_ncookies) {
645 			ncookies = uimin(ncookies, dt->dt_nfiles + 2);
646 			cookies = malloc(ncookies * sizeof(off_t),
647 			    M_TEMP, M_WAITOK);
648 			*ap->a_cookies = cookies;
649 			*ap->a_ncookies = ncookies;
650 		}
651 		for (; i - 2 < dt->dt_nfiles && uio->uio_resid >= UIO_MX; i++) {
652 			switch (i) {
653 			case 0:
654 			case 1:
655 				d.d_fileno = FD_ROOT;		/* XXX */
656 				d.d_namlen = i + 1;
657 				(void)memcpy(d.d_name, "..", d.d_namlen);
658 				d.d_name[i + 1] = '\0';
659 				d.d_type = DT_DIR;
660 				break;
661 
662 			default:
663 				j = (int)i - 2;
664 				if (dt->dt_ff[j] == NULL ||
665 				    dt->dt_ff[j]->ff_file == NULL)
666 					continue;
667 				d.d_fileno = j + FD_STDIN;
668 				d.d_namlen = snprintf(d.d_name,
669 				    sizeof(d.d_name), "%d", j);
670 				d.d_type = DT_UNKNOWN;
671 				break;
672 			}
673 
674 			if ((error = uiomove(&d, UIO_MX, uio)) != 0)
675 				break;
676 			if (cookies)
677 				*cookies++ = i + 1;
678 		}
679 	}
680 
681 	if (ap->a_ncookies && error) {
682 		free(*ap->a_cookies, M_TEMP);
683 		*ap->a_ncookies = 0;
684 		*ap->a_cookies = NULL;
685 	}
686 
687 	uio->uio_offset = i;
688 	return error;
689 }
690 
691 int
692 fdesc_readlink(void *v)
693 {
694 	struct vop_readlink_args /* {
695 		struct vnode *a_vp;
696 		struct uio *a_uio;
697 		kauth_cred_t a_cred;
698 	} */ *ap = v;
699 	struct vnode *vp = ap->a_vp;
700 	int error;
701 
702 	if (vp->v_type != VLNK)
703 		return (EPERM);
704 
705 	if (VTOFDESC(vp)->fd_type == Flink) {
706 		const char *ln = VTOFDESC(vp)->fd_link;
707 		error = uiomove(__UNCONST(ln), strlen(ln), ap->a_uio);
708 	} else {
709 		error = EOPNOTSUPP;
710 	}
711 
712 	return (error);
713 }
714 
715 int
716 fdesc_read(void *v)
717 {
718 	struct vop_read_args /* {
719 		struct vnode *a_vp;
720 		struct uio *a_uio;
721 		int  a_ioflag;
722 		kauth_cred_t a_cred;
723 	} */ *ap = v;
724 	int error = EOPNOTSUPP;
725 	struct vnode *vp = ap->a_vp;
726 
727 	switch (VTOFDESC(vp)->fd_type) {
728 	case Fctty:
729 		VOP_UNLOCK(vp);
730 		error = cdev_read(devctty, ap->a_uio, ap->a_ioflag);
731 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
732 		break;
733 
734 	default:
735 		error = EOPNOTSUPP;
736 		break;
737 	}
738 
739 	return (error);
740 }
741 
742 int
743 fdesc_write(void *v)
744 {
745 	struct vop_write_args /* {
746 		struct vnode *a_vp;
747 		struct uio *a_uio;
748 		int  a_ioflag;
749 		kauth_cred_t a_cred;
750 	} */ *ap = v;
751 	int error = EOPNOTSUPP;
752 	struct vnode *vp = ap->a_vp;
753 
754 	switch (VTOFDESC(vp)->fd_type) {
755 	case Fctty:
756 		VOP_UNLOCK(vp);
757 		error = cdev_write(devctty, ap->a_uio, ap->a_ioflag);
758 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
759 		break;
760 
761 	default:
762 		error = EOPNOTSUPP;
763 		break;
764 	}
765 
766 	return (error);
767 }
768 
769 int
770 fdesc_ioctl(void *v)
771 {
772 	struct vop_ioctl_args /* {
773 		struct vnode *a_vp;
774 		u_long a_command;
775 		void *a_data;
776 		int  a_fflag;
777 		kauth_cred_t a_cred;
778 	} */ *ap = v;
779 	int error = EOPNOTSUPP;
780 
781 	switch (VTOFDESC(ap->a_vp)->fd_type) {
782 	case Fctty:
783 		error = cdev_ioctl(devctty, ap->a_command, ap->a_data,
784 		    ap->a_fflag, curlwp);
785 		break;
786 
787 	default:
788 		error = EOPNOTSUPP;
789 		break;
790 	}
791 
792 	return (error);
793 }
794 
795 int
796 fdesc_poll(void *v)
797 {
798 	struct vop_poll_args /* {
799 		struct vnode *a_vp;
800 		int a_events;
801 	} */ *ap = v;
802 	int revents;
803 
804 	switch (VTOFDESC(ap->a_vp)->fd_type) {
805 	case Fctty:
806 		revents = cdev_poll(devctty, ap->a_events, curlwp);
807 		break;
808 
809 	default:
810 		revents = genfs_poll(v);
811 		break;
812 	}
813 
814 	return (revents);
815 }
816 
817 int
818 fdesc_kqfilter(void *v)
819 {
820 	struct vop_kqfilter_args /* {
821 		struct vnode *a_vp;
822 		struct knote *a_kn;
823 	} */ *ap = v;
824 	int error, fd;
825 	file_t *fp;
826 
827 	switch (VTOFDESC(ap->a_vp)->fd_type) {
828 	case Fctty:
829 		error = cdev_kqfilter(devctty, ap->a_kn);
830 		break;
831 
832 	case Fdesc:
833 		/* just invoke kqfilter for the underlying descriptor */
834 		fd = VTOFDESC(ap->a_vp)->fd_fd;
835 		if ((fp = fd_getfile(fd)) == NULL)
836 			return (1);
837 		error = (*fp->f_ops->fo_kqfilter)(fp, ap->a_kn);
838 		fd_putfile(fd);
839 		break;
840 
841 	default:
842 		return (genfs_kqfilter(v));
843 	}
844 
845 	return (error);
846 }
847 
848 int
849 fdesc_inactive(void *v)
850 {
851 	struct vop_inactive_v2_args /* {
852 		struct vnode *a_vp;
853 	} */ *ap = v;
854 	struct vnode *vp = ap->a_vp;
855 	struct fdescnode *fd = VTOFDESC(vp);
856 
857 	/*
858 	 * Clear out the v_type field to avoid
859 	 * nasty things happening on reclaim.
860 	 */
861 	if (fd->fd_type == Fctty || fd->fd_type == Fdesc)
862 		vp->v_type = VNON;
863 
864 	return (0);
865 }
866 
867 int
868 fdesc_reclaim(void *v)
869 {
870 	struct vop_reclaim_v2_args /* {
871 		struct vnode *a_vp;
872 	} */ *ap = v;
873 	struct vnode *vp = ap->a_vp;
874 	struct fdescnode *fd = VTOFDESC(vp);
875 
876 	VOP_UNLOCK(vp);
877 
878 	vp->v_data = NULL;
879 	kmem_free(fd, sizeof(struct fdescnode));
880 
881 	return (0);
882 }
883 
884 /*
885  * Return POSIX pathconf information applicable to special devices.
886  */
887 int
888 fdesc_pathconf(void *v)
889 {
890 	struct vop_pathconf_args /* {
891 		struct vnode *a_vp;
892 		int a_name;
893 		register_t *a_retval;
894 	} */ *ap = v;
895 
896 	switch (ap->a_name) {
897 	case _PC_LINK_MAX:
898 		*ap->a_retval = LINK_MAX;
899 		return (0);
900 	case _PC_MAX_CANON:
901 		*ap->a_retval = MAX_CANON;
902 		return (0);
903 	case _PC_MAX_INPUT:
904 		*ap->a_retval = MAX_INPUT;
905 		return (0);
906 	case _PC_PIPE_BUF:
907 		*ap->a_retval = PIPE_BUF;
908 		return (0);
909 	case _PC_CHOWN_RESTRICTED:
910 		*ap->a_retval = 1;
911 		return (0);
912 	case _PC_VDISABLE:
913 		*ap->a_retval = _POSIX_VDISABLE;
914 		return (0);
915 	case _PC_SYNC_IO:
916 		*ap->a_retval = 1;
917 		return (0);
918 	default:
919 		return genfs_pathconf(ap);
920 	}
921 	/* NOTREACHED */
922 }
923 
924 /*
925  * Print out the contents of a /dev/fd vnode.
926  */
927 /* ARGSUSED */
928 int
929 fdesc_print(void *v)
930 {
931 	printf("tag VT_NON, fdesc vnode\n");
932 	return (0);
933 }
934 
935 int
936 fdesc_link(void *v)
937 {
938 	struct vop_link_v2_args /* {
939 		struct vnode *a_dvp;
940 		struct vnode *a_vp;
941 		struct componentname *a_cnp;
942 	} */ *ap = v;
943 
944 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
945 	return (EROFS);
946 }
947 
948 int
949 fdesc_symlink(void *v)
950 {
951 	struct vop_symlink_v3_args /* {
952 		struct vnode *a_dvp;
953 		struct vnode **a_vpp;
954 		struct componentname *a_cnp;
955 		struct vattr *a_vap;
956 		char *a_target;
957 	} */ *ap = v;
958 
959 	VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
960 	return (EROFS);
961 }
962