xref: /freebsd/sys/fs/pseudofs/pseudofs_vnops.c (revision f1c579b1ec70d6265f48b1b7059ac627ad2e0396)
1 /*-
2  * Copyright (c) 2001 Dag-Erling Co�dan Sm�rgrav
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer
10  *    in this position and unchanged.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. The name of the author may not be used to endorse or promote products
15  *    derived from this software without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include "opt_pseudofs.h"
33 
34 #include <sys/param.h>
35 #include <sys/kernel.h>
36 #include <sys/systm.h>
37 #include <sys/ctype.h>
38 #include <sys/dirent.h>
39 #include <sys/fcntl.h>
40 #include <sys/limits.h>
41 #include <sys/lock.h>
42 #include <sys/malloc.h>
43 #include <sys/mount.h>
44 #include <sys/mutex.h>
45 #include <sys/namei.h>
46 #include <sys/proc.h>
47 #include <sys/sbuf.h>
48 #include <sys/sx.h>
49 #include <sys/sysctl.h>
50 #include <sys/vnode.h>
51 
52 #include <fs/pseudofs/pseudofs.h>
53 #include <fs/pseudofs/pseudofs_internal.h>
54 
55 #ifdef PSEUDOFS_TRACE
56 static int pfs_trace;
57 SYSCTL_INT(_vfs_pfs, OID_AUTO, trace, CTLFLAG_RW, &pfs_trace, 0,
58     "enable tracing of pseudofs vnode operations");
59 
60 #define PFS_TRACE(foo) \
61 	do { \
62 		if (pfs_trace) { \
63 			printf("%s(): line %d: ", __func__, __LINE__); \
64 			printf foo ; \
65 			printf("\n"); \
66 		} \
67 	} while (0)
68 #define PFS_RETURN(err) \
69 	do { \
70 		if (pfs_trace) { \
71 			printf("%s(): line %d: returning %d\n", \
72 			    __func__, __LINE__, err); \
73 		} \
74 		return (err); \
75 	} while (0)
76 #else
77 #define PFS_TRACE(foo) \
78 	do { /* nothing */ } while (0)
79 #define PFS_RETURN(err) \
80 	return (err)
81 #endif
82 
83 /*
84  * Returns non-zero if given file is visible to given process
85  */
86 static int
87 pfs_visible(struct thread *td, struct pfs_node *pn, pid_t pid)
88 {
89 	struct proc *proc;
90 	int r;
91 
92 	PFS_TRACE(("%s (pid: %d, req: %d)",
93 	    pn->pn_name, pid, td->td_proc->p_pid));
94 
95 	if (pn->pn_flags & PFS_DISABLED)
96 		PFS_RETURN (0);
97 
98 	r = 1;
99 	if (pid != NO_PID) {
100 		if ((proc = pfind(pid)) == NULL)
101 			PFS_RETURN (0);
102 		if (p_cansee(td, proc) != 0 ||
103 		    (pn->pn_vis != NULL && !(pn->pn_vis)(td, proc, pn)))
104 			r = 0;
105 		PROC_UNLOCK(proc);
106 	}
107 	PFS_RETURN (r);
108 }
109 
110 /*
111  * Verify permissions
112  */
113 static int
114 pfs_access(struct vop_access_args *va)
115 {
116 	struct vnode *vn = va->a_vp;
117 	struct vattr vattr;
118 	int error;
119 
120 	PFS_TRACE((((struct pfs_vdata *)vn->v_data)->pvd_pn->pn_name));
121 
122 	error = VOP_GETATTR(vn, &vattr, va->a_cred, va->a_td);
123 	if (error)
124 		PFS_RETURN (error);
125 	error = vaccess(vn->v_type, vattr.va_mode, vattr.va_uid,
126 	    vattr.va_gid, va->a_mode, va->a_cred, NULL);
127 	PFS_RETURN (error);
128 }
129 
130 /*
131  * Close a file or directory
132  */
133 static int
134 pfs_close(struct vop_close_args *va)
135 {
136 	struct vnode *vn = va->a_vp;
137 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
138 	struct pfs_node *pn = pvd->pvd_pn;
139 	struct proc *proc;
140 	int error;
141 
142 	PFS_TRACE((pn->pn_name));
143 
144 	/*
145 	 * Do nothing unless this is the last close and the node has a
146 	 * last-close handler.
147 	 */
148 	if (vrefcnt(vn) > 1 || pn->pn_close == NULL)
149 		PFS_RETURN (0);
150 
151 	if (pvd->pvd_pid != NO_PID)
152 		proc = pfind(pvd->pvd_pid);
153 	else
154 		proc = NULL;
155 
156 	error = (pn->pn_close)(va->a_td, proc, pn);
157 
158 	if (proc != NULL)
159 		PROC_UNLOCK(proc);
160 
161 	PFS_RETURN (error);
162 }
163 
164 /*
165  * Get file attributes
166  */
167 static int
168 pfs_getattr(struct vop_getattr_args *va)
169 {
170 	struct vnode *vn = va->a_vp;
171 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
172 	struct pfs_node *pn = pvd->pvd_pn;
173 	struct vattr *vap = va->a_vap;
174 	struct proc *proc;
175 	int error = 0;
176 
177 	PFS_TRACE((pn->pn_name));
178 
179 	if (!pfs_visible(curthread, pn, pvd->pvd_pid))
180 		PFS_RETURN (ENOENT);
181 
182 	VATTR_NULL(vap);
183 	vap->va_type = vn->v_type;
184 	vap->va_fileid = pn->pn_fileno;
185 	vap->va_flags = 0;
186 	vap->va_blocksize = PAGE_SIZE;
187 	vap->va_bytes = vap->va_size = 0;
188 	vap->va_fsid = vn->v_mount->mnt_stat.f_fsid.val[0];
189 	vap->va_nlink = 1;
190 	nanotime(&vap->va_ctime);
191 	vap->va_atime = vap->va_mtime = vap->va_ctime;
192 
193 	switch (pn->pn_type) {
194 	case pfstype_procdir:
195 	case pfstype_root:
196 	case pfstype_dir:
197 		vap->va_mode = 0555;
198 		break;
199 	case pfstype_file:
200 	case pfstype_symlink:
201 		vap->va_mode = 0444;
202 		break;
203 	default:
204 		printf("shouldn't be here!\n");
205 		vap->va_mode = 0;
206 		break;
207 	}
208 
209 	if (pvd->pvd_pid != NO_PID) {
210 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
211 			PFS_RETURN (ENOENT);
212 		vap->va_uid = proc->p_ucred->cr_ruid;
213 		vap->va_gid = proc->p_ucred->cr_rgid;
214 		if (pn->pn_attr != NULL)
215 			error = (pn->pn_attr)(va->a_td, proc, pn, vap);
216 		PROC_UNLOCK(proc);
217 	} else {
218 		vap->va_uid = 0;
219 		vap->va_gid = 0;
220 	}
221 
222 	PFS_RETURN (error);
223 }
224 
225 /*
226  * Perform an ioctl
227  */
228 static int
229 pfs_ioctl(struct vop_ioctl_args *va)
230 {
231 	struct vnode *vn = va->a_vp;
232 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
233 	struct pfs_node *pn = pvd->pvd_pn;
234 	struct proc *proc = NULL;
235 	int error;
236 
237 	PFS_TRACE(("%s: %lx", pn->pn_name, va->a_command));
238 
239 	if (vn->v_type != VREG)
240 		PFS_RETURN (EINVAL);
241 
242 	if (pn->pn_ioctl == NULL)
243 		PFS_RETURN (ENOTTY);
244 
245 	/*
246 	 * This is necessary because process' privileges may
247 	 * have changed since the open() call.
248 	 */
249 	if (!pfs_visible(curthread, pn, pvd->pvd_pid))
250 		PFS_RETURN (EIO);
251 
252 	/* XXX duplicates bits of pfs_visible() */
253 	if (pvd->pvd_pid != NO_PID) {
254 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
255 			PFS_RETURN (EIO);
256 		_PHOLD(proc);
257 		PROC_UNLOCK(proc);
258 	}
259 
260 	error = (pn->pn_ioctl)(curthread, proc, pn, va->a_command, va->a_data);
261 
262 	if (proc != NULL)
263 		PRELE(proc);
264 
265 	PFS_RETURN (error);
266 }
267 
268 /*
269  * Perform getextattr
270  */
271 static int
272 pfs_getextattr(struct vop_getextattr_args *va)
273 {
274 	struct vnode *vn = va->a_vp;
275 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
276 	struct pfs_node *pn = pvd->pvd_pn;
277 	struct proc *proc = NULL;
278 	int error;
279 
280 	PFS_TRACE((pn->pn_name));
281 
282 	if (!pfs_visible(curthread, pn, pvd->pvd_pid))
283 		PFS_RETURN (ENOENT);
284 
285 	if (pn->pn_getextattr == NULL)
286 		PFS_RETURN (EOPNOTSUPP);
287 
288 	/*
289 	 * This is necessary because either process' privileges may
290 	 * have changed since the open() call.
291 	 */
292 	if (!pfs_visible(curthread, pn, pvd->pvd_pid))
293 		PFS_RETURN (EIO);
294 
295 	/* XXX duplicates bits of pfs_visible() */
296 	if (pvd->pvd_pid != NO_PID) {
297 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
298 			PFS_RETURN (EIO);
299 		_PHOLD(proc);
300 		PROC_UNLOCK(proc);
301 	}
302 
303 	error = (pn->pn_getextattr)(curthread, proc, pn, va->a_attrnamespace,
304 	    va->a_name, va->a_uio, va->a_size, va->a_cred);
305 
306 	if (proc != NULL)
307 		PRELE(proc);
308 
309 	PFS_RETURN (error);
310 }
311 
312 /*
313  * Look up a file or directory
314  */
315 static int
316 pfs_lookup(struct vop_cachedlookup_args *va)
317 {
318 	struct vnode *vn = va->a_dvp;
319 	struct vnode **vpp = va->a_vpp;
320 	struct componentname *cnp = va->a_cnp;
321 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
322 	struct pfs_node *pd = pvd->pvd_pn;
323 	struct pfs_node *pn, *pdn = NULL;
324 	pid_t pid = pvd->pvd_pid;
325 	char *pname;
326 	int error, i, namelen;
327 
328 	PFS_TRACE(("%.*s", (int)cnp->cn_namelen, cnp->cn_nameptr));
329 
330 	if (vn->v_type != VDIR)
331 		PFS_RETURN (ENOTDIR);
332 
333 	error = VOP_ACCESS(vn, VEXEC, cnp->cn_cred, cnp->cn_thread);
334 	if (error)
335 		PFS_RETURN (error);
336 
337 	/*
338 	 * Don't support DELETE or RENAME.  CREATE is supported so
339 	 * that O_CREAT will work, but the lookup will still fail if
340 	 * the file does not exist.
341 	 */
342 	if ((cnp->cn_flags & ISLASTCN) &&
343 	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
344 		PFS_RETURN (EOPNOTSUPP);
345 
346 	/* shortcut: check if the name is too long */
347 	if (cnp->cn_namelen >= PFS_NAMELEN)
348 		PFS_RETURN (ENOENT);
349 
350 	/* check that parent directory is visisble... */
351 	if (!pfs_visible(curthread, pd, pvd->pvd_pid))
352 		PFS_RETURN (ENOENT);
353 
354 	/* self */
355 	namelen = cnp->cn_namelen;
356 	pname = cnp->cn_nameptr;
357 	if (namelen == 1 && pname[0] == '.') {
358 		pn = pd;
359 		*vpp = vn;
360 		VREF(vn);
361 		PFS_RETURN (0);
362 	}
363 
364 	/* parent */
365 	if (cnp->cn_flags & ISDOTDOT) {
366 		if (pd->pn_type == pfstype_root)
367 			PFS_RETURN (EIO);
368 		VOP_UNLOCK(vn, 0, cnp->cn_thread);
369 		KASSERT(pd->pn_parent, ("non-root directory has no parent"));
370 		/*
371 		 * This one is tricky.  Descendents of procdir nodes
372 		 * inherit their parent's process affinity, but
373 		 * there's no easy reverse mapping.  For simplicity,
374 		 * we assume that if this node is a procdir, its
375 		 * parent isn't (which is correct as long as
376 		 * descendents of procdir nodes are never procdir
377 		 * nodes themselves)
378 		 */
379 		if (pd->pn_type == pfstype_procdir)
380 			pid = NO_PID;
381 		pn = pd->pn_parent;
382 		goto got_pnode;
383 	}
384 
385 	/* named node */
386 	for (pn = pd->pn_nodes; pn != NULL; pn = pn->pn_next)
387 		if (pn->pn_type == pfstype_procdir)
388 			pdn = pn;
389 		else if (pn->pn_name[namelen] == '\0' &&
390 		    bcmp(pname, pn->pn_name, namelen) == 0)
391 			goto got_pnode;
392 
393 	/* process dependent node */
394 	if ((pn = pdn) != NULL) {
395 		pid = 0;
396 		for (pid = 0, i = 0; i < namelen && isdigit(pname[i]); ++i)
397 			if ((pid = pid * 10 + pname[i] - '0') > PID_MAX)
398 				break;
399 		if (i == cnp->cn_namelen)
400 			goto got_pnode;
401 	}
402 
403 	PFS_RETURN (ENOENT);
404  got_pnode:
405 	if (pn != pd->pn_parent && !pn->pn_parent)
406 		pn->pn_parent = pd;
407 	if (!pfs_visible(curthread, pn, pvd->pvd_pid)) {
408 		error = ENOENT;
409 		goto failed;
410 	}
411 
412 	error = pfs_vncache_alloc(vn->v_mount, vpp, pn, pid);
413 	if (error)
414 		goto failed;
415 
416 	if (cnp->cn_flags & MAKEENTRY)
417 		cache_enter(vn, *vpp, cnp);
418 	PFS_RETURN (0);
419  failed:
420 	if (cnp->cn_flags & ISDOTDOT)
421 		vn_lock(vn, LK_EXCLUSIVE|LK_RETRY, cnp->cn_thread);
422 	PFS_RETURN(error);
423 }
424 
425 /*
426  * Open a file or directory.
427  */
428 static int
429 pfs_open(struct vop_open_args *va)
430 {
431 	struct vnode *vn = va->a_vp;
432 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
433 	struct pfs_node *pn = pvd->pvd_pn;
434 	int mode = va->a_mode;
435 
436 	PFS_TRACE(("%s (mode 0x%x)", pn->pn_name, mode));
437 
438 	/*
439 	 * check if the file is visible to the caller
440 	 *
441 	 * XXX Not sure if this is necessary, as the VFS system calls
442 	 * XXX pfs_lookup() and pfs_access() first, and pfs_lookup()
443 	 * XXX calls pfs_visible().  There's a race condition here, but
444 	 * XXX calling pfs_visible() from here doesn't really close it,
445 	 * XXX and the only consequence of that race is an EIO further
446 	 * XXX down the line.
447 	 */
448 	if (!pfs_visible(va->a_td, pn, pvd->pvd_pid))
449 		PFS_RETURN (ENOENT);
450 
451 	/* check if the requested mode is permitted */
452 	if (((mode & FREAD) && !(mode & PFS_RD)) ||
453 	    ((mode & FWRITE) && !(mode & PFS_WR)))
454 		PFS_RETURN (EPERM);
455 
456 	/* we don't support locking */
457 	if ((mode & O_SHLOCK) || (mode & O_EXLOCK))
458 		PFS_RETURN (EOPNOTSUPP);
459 
460 	PFS_RETURN (0);
461 }
462 
463 /*
464  * Read from a file
465  */
466 static int
467 pfs_read(struct vop_read_args *va)
468 {
469 	struct vnode *vn = va->a_vp;
470 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
471 	struct pfs_node *pn = pvd->pvd_pn;
472 	struct uio *uio = va->a_uio;
473 	struct proc *proc = NULL;
474 	struct sbuf *sb = NULL;
475 	int error;
476 	unsigned int buflen, offset, resid;
477 
478 	PFS_TRACE((pn->pn_name));
479 
480 	if (vn->v_type != VREG)
481 		PFS_RETURN (EINVAL);
482 
483 	if (!(pn->pn_flags & PFS_RD))
484 		PFS_RETURN (EBADF);
485 
486 	if (pn->pn_func == NULL)
487 		PFS_RETURN (EIO);
488 
489 	/*
490 	 * This is necessary because either process' privileges may
491 	 * have changed since the open() call.
492 	 */
493 	if (!pfs_visible(curthread, pn, pvd->pvd_pid))
494 		PFS_RETURN (EIO);
495 
496 	/* XXX duplicates bits of pfs_visible() */
497 	if (pvd->pvd_pid != NO_PID) {
498 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
499 			PFS_RETURN (EIO);
500 		_PHOLD(proc);
501 		PROC_UNLOCK(proc);
502 	}
503 
504 	if (pn->pn_flags & PFS_RAWRD) {
505 		error = (pn->pn_func)(curthread, proc, pn, NULL, uio);
506 		if (proc != NULL)
507 			PRELE(proc);
508 		PFS_RETURN (error);
509 	}
510 
511 	/* Beaucoup sanity checks so we don't ask for bogus allocation. */
512 	if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
513 	    (offset = uio->uio_offset) != uio->uio_offset ||
514 	    (resid = uio->uio_resid) != uio->uio_resid ||
515 	    (buflen = offset + resid) < offset || buflen > INT_MAX) {
516 		if (proc != NULL)
517 			PRELE(proc);
518 		PFS_RETURN (EINVAL);
519 	}
520 	if (buflen > MAXPHYS) {
521 		if (proc != NULL)
522 			PRELE(proc);
523 		PFS_RETURN (EIO);
524 	}
525 	sb = sbuf_new(sb, NULL, buflen, 0);
526 	if (sb == NULL) {
527 		if (proc != NULL)
528 			PRELE(proc);
529 		PFS_RETURN (EIO);
530 	}
531 
532 	error = (pn->pn_func)(curthread, proc, pn, sb, uio);
533 
534 	if (proc != NULL)
535 		PRELE(proc);
536 
537 	if (error) {
538 		sbuf_delete(sb);
539 		PFS_RETURN (error);
540 	}
541 
542 	sbuf_finish(sb);
543 	error = uiomove_frombuf(sbuf_data(sb), sbuf_len(sb), uio);
544 	sbuf_delete(sb);
545 	PFS_RETURN (error);
546 }
547 
548 /*
549  * Iterate through directory entries
550  */
551 static int
552 pfs_iterate(struct thread *td, pid_t pid, struct pfs_node *pd,
553 	    struct pfs_node **pn, struct proc **p)
554 {
555 	sx_assert(&allproc_lock, SX_LOCKED);
556  again:
557 	if (*pn == NULL) {
558 		/* first node */
559 		*pn = pd->pn_nodes;
560 	} else if ((*pn)->pn_type != pfstype_procdir) {
561 		/* next node */
562 		*pn = (*pn)->pn_next;
563 	}
564 	if (*pn != NULL && (*pn)->pn_type == pfstype_procdir) {
565 		/* next process */
566 		if (*p == NULL)
567 			*p = LIST_FIRST(&allproc);
568 		else
569 			*p = LIST_NEXT(*p, p_list);
570 		/* out of processes: next node */
571 		if (*p == NULL)
572 			*pn = (*pn)->pn_next;
573 	}
574 
575 	if ((*pn) == NULL)
576 		return (-1);
577 
578 	if (!pfs_visible(td, *pn, *p ? (*p)->p_pid : pid))
579 		goto again;
580 
581 	return (0);
582 }
583 
584 /*
585  * Return directory entries.
586  */
587 static int
588 pfs_readdir(struct vop_readdir_args *va)
589 {
590 	struct vnode *vn = va->a_vp;
591 	struct pfs_info *pi = (struct pfs_info *)vn->v_mount->mnt_data;
592 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
593 	struct pfs_node *pd = pvd->pvd_pn;
594 	pid_t pid = pvd->pvd_pid;
595 	struct pfs_node *pn;
596 	struct dirent entry;
597 	struct uio *uio;
598 	struct proc *p;
599 	off_t offset;
600 	int error, i, resid;
601 	char *buf, *ent;
602 
603 	PFS_TRACE((pd->pn_name));
604 
605 	if (vn->v_type != VDIR)
606 		PFS_RETURN (ENOTDIR);
607 	uio = va->a_uio;
608 
609 	/* check if the directory is visible to the caller */
610 	if (!pfs_visible(curthread, pd, pid))
611 		PFS_RETURN (ENOENT);
612 
613 	/* only allow reading entire entries */
614 	offset = uio->uio_offset;
615 	resid = uio->uio_resid;
616 	if (offset < 0 || offset % PFS_DELEN != 0 ||
617 	    (resid && resid < PFS_DELEN))
618 		PFS_RETURN (EINVAL);
619 	if (resid == 0)
620 		PFS_RETURN (0);
621 
622 	/* skip unwanted entries */
623 	sx_slock(&allproc_lock);
624 	for (pn = NULL, p = NULL; offset > 0; offset -= PFS_DELEN)
625 		if (pfs_iterate(curthread, pid, pd, &pn, &p) == -1) {
626 			/* nothing left... */
627 			sx_sunlock(&allproc_lock);
628 			PFS_RETURN (0);
629 		}
630 
631 	/* fill in entries */
632 	ent = buf = malloc(resid, M_IOV, M_WAITOK);
633 	entry.d_reclen = PFS_DELEN;
634 	while (pfs_iterate(curthread, pid, pd, &pn, &p) != -1 &&
635 	    resid >= PFS_DELEN) {
636 		if (!pn->pn_parent)
637 			pn->pn_parent = pd;
638 		if (!pn->pn_fileno)
639 			pfs_fileno_alloc(pi, pn);
640 		if (pid != NO_PID)
641 			entry.d_fileno = pn->pn_fileno * NO_PID + pid;
642 		else
643 			entry.d_fileno = pn->pn_fileno;
644 		/* PFS_DELEN was picked to fit PFS_NAMLEN */
645 		for (i = 0; i < PFS_NAMELEN - 1 && pn->pn_name[i] != '\0'; ++i)
646 			entry.d_name[i] = pn->pn_name[i];
647 		entry.d_name[i] = 0;
648 		entry.d_namlen = i;
649 		switch (pn->pn_type) {
650 		case pfstype_procdir:
651 			KASSERT(p != NULL,
652 			    ("reached procdir node with p == NULL"));
653 			entry.d_fileno = pn->pn_fileno * NO_PID + p->p_pid;
654 			entry.d_namlen = snprintf(entry.d_name,
655 			    PFS_NAMELEN, "%d", p->p_pid);
656 			/* fall through */
657 		case pfstype_root:
658 		case pfstype_dir:
659 		case pfstype_this:
660 		case pfstype_parent:
661 			entry.d_type = DT_DIR;
662 			break;
663 		case pfstype_file:
664 			entry.d_type = DT_REG;
665 			break;
666 		case pfstype_symlink:
667 			entry.d_type = DT_LNK;
668 			break;
669 		default:
670 			panic("%s has unexpected node type: %d", pn->pn_name, pn->pn_type);
671 		}
672 		PFS_TRACE((entry.d_name));
673 		bcopy(&entry, ent, PFS_DELEN); /* XXX waste of cycles */
674 		offset += PFS_DELEN;
675 		resid -= PFS_DELEN;
676 		ent += PFS_DELEN;
677 	}
678 	sx_sunlock(&allproc_lock);
679 	error = uiomove(buf, ent - buf, uio);
680 	free(buf, M_IOV);
681 	PFS_RETURN (error);
682 }
683 
684 /*
685  * Read a symbolic link
686  */
687 static int
688 pfs_readlink(struct vop_readlink_args *va)
689 {
690 	struct vnode *vn = va->a_vp;
691 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
692 	struct pfs_node *pn = pvd->pvd_pn;
693 	struct uio *uio = va->a_uio;
694 	struct proc *proc = NULL;
695 	char buf[MAXPATHLEN];
696 	struct sbuf sb;
697 	int error;
698 
699 	PFS_TRACE((pn->pn_name));
700 
701 	if (vn->v_type != VLNK)
702 		PFS_RETURN (EINVAL);
703 
704 	if (pn->pn_func == NULL)
705 		PFS_RETURN (EIO);
706 
707 	if (pvd->pvd_pid != NO_PID) {
708 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
709 			PFS_RETURN (EIO);
710 		_PHOLD(proc);
711 		PROC_UNLOCK(proc);
712 	}
713 
714 	/* sbuf_new() can't fail with a static buffer */
715 	sbuf_new(&sb, buf, sizeof buf, 0);
716 
717 	error = (pn->pn_func)(curthread, proc, pn, &sb, NULL);
718 
719 	if (proc != NULL)
720 		PRELE(proc);
721 
722 	if (error) {
723 		sbuf_delete(&sb);
724 		PFS_RETURN (error);
725 	}
726 
727 	sbuf_finish(&sb);
728 	error = uiomove_frombuf(sbuf_data(&sb), sbuf_len(&sb), uio);
729 	sbuf_delete(&sb);
730 	PFS_RETURN (error);
731 }
732 
733 /*
734  * Reclaim a vnode
735  */
736 static int
737 pfs_reclaim(struct vop_reclaim_args *va)
738 {
739 	PFS_TRACE((((struct pfs_vdata *)va->a_vp->v_data)->pvd_pn->pn_name));
740 
741 	return (pfs_vncache_free(va->a_vp));
742 }
743 
744 /*
745  * Set attributes
746  */
747 static int
748 pfs_setattr(struct vop_setattr_args *va)
749 {
750 	PFS_TRACE((((struct pfs_vdata *)va->a_vp->v_data)->pvd_pn->pn_name));
751 
752 	PFS_RETURN (EOPNOTSUPP);
753 }
754 
755 /*
756  * Read from a file
757  */
758 static int
759 pfs_write(struct vop_write_args *va)
760 {
761 	struct vnode *vn = va->a_vp;
762 	struct pfs_vdata *pvd = (struct pfs_vdata *)vn->v_data;
763 	struct pfs_node *pn = pvd->pvd_pn;
764 	struct uio *uio = va->a_uio;
765 	struct proc *proc = NULL;
766 	struct sbuf sb;
767 	int error;
768 
769 	PFS_TRACE((pn->pn_name));
770 
771 	if (vn->v_type != VREG)
772 		PFS_RETURN (EINVAL);
773 
774 	if (!(pn->pn_flags & PFS_WR))
775 		PFS_RETURN (EBADF);
776 
777 	if (pn->pn_func == NULL)
778 		PFS_RETURN (EIO);
779 
780 	/*
781 	 * This is necessary because either process' privileges may
782 	 * have changed since the open() call.
783 	 */
784 	if (!pfs_visible(curthread, pn, pvd->pvd_pid))
785 		PFS_RETURN (EIO);
786 
787 	/* XXX duplicates bits of pfs_visible() */
788 	if (pvd->pvd_pid != NO_PID) {
789 		if ((proc = pfind(pvd->pvd_pid)) == NULL)
790 			PFS_RETURN (EIO);
791 		_PHOLD(proc);
792 		PROC_UNLOCK(proc);
793 	}
794 
795 	if (pn->pn_flags & PFS_RAWWR) {
796 		error = (pn->pn_func)(curthread, proc, pn, NULL, uio);
797 		if (proc != NULL)
798 			PRELE(proc);
799 		PFS_RETURN (error);
800 	}
801 
802 	sbuf_uionew(&sb, uio, &error);
803 	if (error)
804 		PFS_RETURN (error);
805 
806 	error = (pn->pn_func)(curthread, proc, pn, &sb, uio);
807 
808 	if (proc != NULL)
809 		PRELE(proc);
810 
811 	sbuf_delete(&sb);
812 	PFS_RETURN (error);
813 }
814 
815 /*
816  * Vnode operations
817  */
818 struct vop_vector pfs_vnodeops = {
819 	.vop_default =		&default_vnodeops,
820 
821 	.vop_access =		pfs_access,
822 	.vop_cachedlookup =	pfs_lookup,
823 	.vop_close =		pfs_close,
824 	.vop_create =		VOP_EOPNOTSUPP,
825 	.vop_getattr =		pfs_getattr,
826 	.vop_getextattr =	pfs_getextattr,
827 	.vop_ioctl =		pfs_ioctl,
828 	.vop_link =		VOP_EOPNOTSUPP,
829 	.vop_lookup =		vfs_cache_lookup,
830 	.vop_mkdir =		VOP_EOPNOTSUPP,
831 	.vop_mknod =		VOP_EOPNOTSUPP,
832 	.vop_open =		pfs_open,
833 	.vop_read =		pfs_read,
834 	.vop_readdir =		pfs_readdir,
835 	.vop_readlink =		pfs_readlink,
836 	.vop_reclaim =		pfs_reclaim,
837 	.vop_remove =		VOP_EOPNOTSUPP,
838 	.vop_rename =		VOP_EOPNOTSUPP,
839 	.vop_rmdir =		VOP_EOPNOTSUPP,
840 	.vop_setattr =		pfs_setattr,
841 	.vop_symlink =		VOP_EOPNOTSUPP,
842 	.vop_write =		pfs_write,
843 	/* XXX I've probably forgotten a few that need VOP_EOPNOTSUPP */
844 };
845