FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_lookup.c
1 /*
2 * Copyright (c) 1982, 1986, 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
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 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
39 * $FreeBSD: src/sys/kern/vfs_lookup.c,v 1.11.4.2 1999/09/05 08:15:43 peter Exp $
40 */
41
42 #include "opt_ktrace.h"
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/syslimits.h>
47 #include <sys/time.h>
48 #include <sys/namei.h>
49 #include <sys/vnode.h>
50 #include <sys/mount.h>
51 #include <sys/errno.h>
52 #include <sys/malloc.h>
53 #include <sys/filedesc.h>
54 #include <sys/proc.h>
55
56 #ifdef KTRACE
57 #include <sys/ktrace.h>
58 #endif
59
60 /*
61 * Convert a pathname into a pointer to a locked inode.
62 *
63 * The FOLLOW flag is set when symbolic links are to be followed
64 * when they occur at the end of the name translation process.
65 * Symbolic links are always followed for all other pathname
66 * components other than the last.
67 *
68 * The segflg defines whether the name is to be copied from user
69 * space or kernel space.
70 *
71 * Overall outline of namei:
72 *
73 * copy in name
74 * get starting directory
75 * while (!done && !error) {
76 * call lookup to search path.
77 * if symbolic link, massage name in buffer and continue
78 * }
79 */
80 int
81 namei(ndp)
82 register struct nameidata *ndp;
83 {
84 register struct filedesc *fdp; /* pointer to file descriptor state */
85 register char *cp; /* pointer into pathname argument */
86 register struct vnode *dp; /* the directory we are searching */
87 struct iovec aiov; /* uio for reading symbolic links */
88 struct uio auio;
89 int error, linklen;
90 struct componentname *cnp = &ndp->ni_cnd;
91
92 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_proc->p_ucred;
93 #ifdef DIAGNOSTIC
94 if (!cnp->cn_cred || !cnp->cn_proc)
95 panic ("namei: bad cred/proc");
96 if (cnp->cn_nameiop & (~OPMASK))
97 panic ("namei: nameiop contaminated with flags");
98 if (cnp->cn_flags & OPMASK)
99 panic ("namei: flags contaminated with nameiops");
100 #endif
101 fdp = cnp->cn_proc->p_fd;
102
103 /*
104 * Get a buffer for the name to be translated, and copy the
105 * name into the buffer.
106 */
107 if ((cnp->cn_flags & HASBUF) == 0)
108 MALLOC(cnp->cn_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
109 if (ndp->ni_segflg == UIO_SYSSPACE)
110 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
111 MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
112 else
113 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
114 MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
115
116 /*
117 * Don't allow empty pathnames.
118 */
119 if (!error && *cnp->cn_pnbuf == '\0')
120 error = ENOENT;
121
122 if (error) {
123 free(cnp->cn_pnbuf, M_NAMEI);
124 ndp->ni_vp = NULL;
125 return (error);
126 }
127 ndp->ni_loopcnt = 0;
128 #ifdef KTRACE
129 if (KTRPOINT(cnp->cn_proc, KTR_NAMEI))
130 ktrnamei(cnp->cn_proc->p_tracep, cnp->cn_pnbuf);
131 #endif
132
133 /*
134 * Get starting point for the translation.
135 */
136 if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL)
137 ndp->ni_rootdir = rootvnode;
138 dp = fdp->fd_cdir;
139 VREF(dp);
140 for (;;) {
141 /*
142 * Check if root directory should replace current directory.
143 * Done at start of translation and after symbolic link.
144 */
145 cnp->cn_nameptr = cnp->cn_pnbuf;
146 if (*(cnp->cn_nameptr) == '/') {
147 vrele(dp);
148 while (*(cnp->cn_nameptr) == '/') {
149 cnp->cn_nameptr++;
150 ndp->ni_pathlen--;
151 }
152 dp = ndp->ni_rootdir;
153 VREF(dp);
154 }
155 ndp->ni_startdir = dp;
156 error = lookup(ndp);
157 if (error) {
158 FREE(cnp->cn_pnbuf, M_NAMEI);
159 return (error);
160 }
161 /*
162 * Check for symbolic link
163 */
164 if ((cnp->cn_flags & ISSYMLINK) == 0) {
165 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0)
166 FREE(cnp->cn_pnbuf, M_NAMEI);
167 else
168 cnp->cn_flags |= HASBUF;
169 return (0);
170 }
171 if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1)
172 VOP_UNLOCK(ndp->ni_dvp);
173 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
174 error = ELOOP;
175 break;
176 }
177 if (ndp->ni_pathlen > 1)
178 MALLOC(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
179 else
180 cp = cnp->cn_pnbuf;
181 aiov.iov_base = cp;
182 aiov.iov_len = MAXPATHLEN;
183 auio.uio_iov = &aiov;
184 auio.uio_iovcnt = 1;
185 auio.uio_offset = 0;
186 auio.uio_rw = UIO_READ;
187 auio.uio_segflg = UIO_SYSSPACE;
188 auio.uio_procp = (struct proc *)0;
189 auio.uio_resid = MAXPATHLEN;
190 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
191 if (error) {
192 if (ndp->ni_pathlen > 1)
193 free(cp, M_NAMEI);
194 break;
195 }
196 linklen = MAXPATHLEN - auio.uio_resid;
197 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
198 if (ndp->ni_pathlen > 1)
199 free(cp, M_NAMEI);
200 error = ENAMETOOLONG;
201 break;
202 }
203 if (ndp->ni_pathlen > 1) {
204 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
205 FREE(cnp->cn_pnbuf, M_NAMEI);
206 cnp->cn_pnbuf = cp;
207 } else
208 cnp->cn_pnbuf[linklen] = '\0';
209 ndp->ni_pathlen += linklen;
210 vput(ndp->ni_vp);
211 dp = ndp->ni_dvp;
212 }
213 FREE(cnp->cn_pnbuf, M_NAMEI);
214 vrele(ndp->ni_dvp);
215 vput(ndp->ni_vp);
216 ndp->ni_vp = NULL;
217 return (error);
218 }
219
220 /*
221 * Search a pathname.
222 * This is a very central and rather complicated routine.
223 *
224 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
225 * The starting directory is taken from ni_startdir. The pathname is
226 * descended until done, or a symbolic link is encountered. The variable
227 * ni_more is clear if the path is completed; it is set to one if a
228 * symbolic link needing interpretation is encountered.
229 *
230 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
231 * whether the name is to be looked up, created, renamed, or deleted.
232 * When CREATE, RENAME, or DELETE is specified, information usable in
233 * creating, renaming, or deleting a directory entry may be calculated.
234 * If flag has LOCKPARENT or'ed into it, the parent directory is returned
235 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
236 * returned unlocked. Otherwise the parent directory is not returned. If
237 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
238 * the target is returned locked, otherwise it is returned unlocked.
239 * When creating or renaming and LOCKPARENT is specified, the target may not
240 * be ".". When deleting and LOCKPARENT is specified, the target may be ".".
241 *
242 * Overall outline of lookup:
243 *
244 * dirloop:
245 * identify next component of name at ndp->ni_ptr
246 * handle degenerate case where name is null string
247 * if .. and crossing mount points and on mounted filesys, find parent
248 * call VOP_LOOKUP routine for next component name
249 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
250 * component vnode returned in ni_vp (if it exists), locked.
251 * if result vnode is mounted on and crossing mount points,
252 * find mounted on vnode
253 * if more components of name, do next level at dirloop
254 * return the answer in ni_vp, locked if LOCKLEAF set
255 * if LOCKPARENT set, return locked parent in ni_dvp
256 * if WANTPARENT set, return unlocked parent in ni_dvp
257 */
258 int
259 lookup(ndp)
260 register struct nameidata *ndp;
261 {
262 register char *cp; /* pointer into pathname argument */
263 register struct vnode *dp = 0; /* the directory we are searching */
264 struct vnode *tdp; /* saved dp */
265 struct mount *mp; /* mount table entry */
266 int docache; /* == 0 do not cache last component */
267 int wantparent; /* 1 => wantparent or lockparent flag */
268 int rdonly; /* lookup read-only flag bit */
269 int trailing_slash;
270 int error = 0;
271 struct componentname *cnp = &ndp->ni_cnd;
272
273 /*
274 * Setup: break out flag bits into variables.
275 */
276 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
277 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
278 if (cnp->cn_nameiop == DELETE ||
279 (wantparent && cnp->cn_nameiop != CREATE))
280 docache = 0;
281 rdonly = cnp->cn_flags & RDONLY;
282 ndp->ni_dvp = NULL;
283 cnp->cn_flags &= ~ISSYMLINK;
284 dp = ndp->ni_startdir;
285 ndp->ni_startdir = NULLVP;
286 VOP_LOCK(dp);
287
288 dirloop:
289 /*
290 * Search a new directory.
291 *
292 * The cn_hash value is for use by vfs_cache.
293 * The last component of the filename is left accessible via
294 * cnp->cn_nameptr for callers that need the name. Callers needing
295 * the name set the SAVENAME flag. When done, they assume
296 * responsibility for freeing the pathname buffer.
297 */
298 cnp->cn_consume = 0;
299 cnp->cn_hash = 0;
300 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
301 cnp->cn_hash += (unsigned char)*cp;
302 cnp->cn_namelen = cp - cnp->cn_nameptr;
303 if (cnp->cn_namelen > NAME_MAX) {
304 error = ENAMETOOLONG;
305 goto bad;
306 }
307 #ifdef NAMEI_DIAGNOSTIC
308 { char c = *cp;
309 *cp = '\0';
310 printf("{%s}: ", cnp->cn_nameptr);
311 *cp = c; }
312 #endif
313 ndp->ni_pathlen -= cnp->cn_namelen;
314 ndp->ni_next = cp;
315
316 /*
317 * Replace multiple slashes by a single slash and trailing slashes
318 * by a null. This must be done before VOP_LOOKUP() because some
319 * fs's don't know about trailing slashes. Remember if there were
320 * trailing slashes to handle symlinks, existing non-directories
321 * and non-existing files that won't be directories specially later.
322 */
323 trailing_slash = 0;
324 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
325 cp++;
326 ndp->ni_pathlen--;
327 if (*cp == '\0') {
328 trailing_slash = 1;
329 *ndp->ni_next = '\0'; /* XXX for direnter() ... */
330 }
331 }
332 ndp->ni_next = cp;
333
334 cnp->cn_flags |= MAKEENTRY;
335 if (*cp == '\0' && docache == 0)
336 cnp->cn_flags &= ~MAKEENTRY;
337 if (cnp->cn_namelen == 2 &&
338 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
339 cnp->cn_flags |= ISDOTDOT;
340 else
341 cnp->cn_flags &= ~ISDOTDOT;
342 if (*ndp->ni_next == 0)
343 cnp->cn_flags |= ISLASTCN;
344 else
345 cnp->cn_flags &= ~ISLASTCN;
346
347
348 /*
349 * Check for degenerate name (e.g. / or "")
350 * which is a way of talking about a directory,
351 * e.g. like "/." or ".".
352 */
353 if (cnp->cn_nameptr[0] == '\0') {
354 if (cnp->cn_nameiop != LOOKUP) {
355 error = EISDIR;
356 goto bad;
357 }
358 if (dp->v_type != VDIR) {
359 error = ENOTDIR;
360 goto bad;
361 }
362 if (wantparent) {
363 ndp->ni_dvp = dp;
364 VREF(dp);
365 }
366 ndp->ni_vp = dp;
367 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
368 VOP_UNLOCK(dp);
369 if (cnp->cn_flags & SAVESTART)
370 panic("lookup: SAVESTART");
371 return (0);
372 }
373
374 /*
375 * Handle "..": two special cases.
376 * 1. If at root directory (e.g. after chroot)
377 * or at absolute root directory
378 * then ignore it so can't get out.
379 * 2. If this vnode is the root of a mounted
380 * filesystem, then replace it with the
381 * vnode which was mounted on so we take the
382 * .. in the other file system.
383 */
384 if (cnp->cn_flags & ISDOTDOT) {
385 for (;;) {
386 if (dp == ndp->ni_rootdir || dp == rootvnode) {
387 ndp->ni_dvp = dp;
388 ndp->ni_vp = dp;
389 VREF(dp);
390 goto nextname;
391 }
392 if ((dp->v_flag & VROOT) == 0 ||
393 (cnp->cn_flags & NOCROSSMOUNT))
394 break;
395 tdp = dp;
396 dp = dp->v_mount->mnt_vnodecovered;
397 vput(tdp);
398 VREF(dp);
399 VOP_LOCK(dp);
400 }
401 }
402
403 /*
404 * We now have a segment name to search for, and a directory to search.
405 */
406 unionlookup:
407 ndp->ni_dvp = dp;
408 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp);
409 if (error) {
410 #ifdef DIAGNOSTIC
411 if (ndp->ni_vp != NULL)
412 panic("leaf should be empty");
413 #endif
414 #ifdef NAMEI_DIAGNOSTIC
415 printf("not found\n");
416 #endif
417 if ((error == ENOENT) &&
418 (dp->v_flag & VROOT) &&
419 (dp->v_mount->mnt_flag & MNT_UNION)) {
420 tdp = dp;
421 dp = dp->v_mount->mnt_vnodecovered;
422 vput(tdp);
423 VREF(dp);
424 VOP_LOCK(dp);
425 goto unionlookup;
426 }
427
428 if (error != EJUSTRETURN)
429 goto bad;
430 /*
431 * If creating and at end of pathname, then can consider
432 * allowing file to be created.
433 */
434 if (rdonly) {
435 error = EROFS;
436 goto bad;
437 }
438 if (*cp == '\0' && trailing_slash &&
439 !(cnp->cn_flags & WILLBEDIR)) {
440 error = ENOENT;
441 goto bad;
442 }
443 /*
444 * We return with ni_vp NULL to indicate that the entry
445 * doesn't currently exist, leaving a pointer to the
446 * (possibly locked) directory inode in ndp->ni_dvp.
447 */
448 if (cnp->cn_flags & SAVESTART) {
449 ndp->ni_startdir = ndp->ni_dvp;
450 VREF(ndp->ni_startdir);
451 }
452 return (0);
453 }
454 #ifdef NAMEI_DIAGNOSTIC
455 printf("found\n");
456 #endif
457
458 /*
459 * Take into account any additional components consumed by
460 * the underlying filesystem.
461 */
462 if (cnp->cn_consume > 0) {
463 cnp->cn_nameptr += cnp->cn_consume;
464 ndp->ni_next += cnp->cn_consume;
465 ndp->ni_pathlen -= cnp->cn_consume;
466 cnp->cn_consume = 0;
467 }
468
469 dp = ndp->ni_vp;
470
471 /*
472 * Check to see if the vnode has been mounted on;
473 * if so find the root of the mounted file system.
474 */
475 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
476 (cnp->cn_flags & NOCROSSMOUNT) == 0) {
477 if (mp->mnt_flag & MNT_MLOCK) {
478 mp->mnt_flag |= MNT_MWAIT;
479 (void) tsleep((caddr_t)mp, PVFS, "lookup", 0);
480 continue;
481 }
482 error = VFS_ROOT(dp->v_mountedhere, &tdp);
483 if (error)
484 goto bad2;
485 vput(dp);
486 ndp->ni_vp = dp = tdp;
487 }
488
489 /*
490 * Check for symbolic link
491 */
492 if ((dp->v_type == VLNK) &&
493 ((cnp->cn_flags & FOLLOW) || trailing_slash ||
494 *ndp->ni_next == '/')) {
495 cnp->cn_flags |= ISSYMLINK;
496 return (0);
497 }
498
499 /*
500 * Check for bogus trailing slashes.
501 */
502 if (trailing_slash && dp->v_type != VDIR) {
503 error = ENOTDIR;
504 goto bad2;
505 }
506
507 nextname:
508 /*
509 * Not a symbolic link. If more pathname,
510 * continue at next component, else return.
511 */
512 if (*ndp->ni_next == '/') {
513 cnp->cn_nameptr = ndp->ni_next;
514 while (*cnp->cn_nameptr == '/') {
515 cnp->cn_nameptr++;
516 ndp->ni_pathlen--;
517 }
518 vrele(ndp->ni_dvp);
519 goto dirloop;
520 }
521 /*
522 * Disallow directory write attempts on read-only file systems.
523 */
524 if (rdonly &&
525 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
526 error = EROFS;
527 goto bad2;
528 }
529 if (cnp->cn_flags & SAVESTART) {
530 ndp->ni_startdir = ndp->ni_dvp;
531 VREF(ndp->ni_startdir);
532 }
533 if (!wantparent)
534 vrele(ndp->ni_dvp);
535 if ((cnp->cn_flags & LOCKLEAF) == 0)
536 VOP_UNLOCK(dp);
537 return (0);
538
539 bad2:
540 if ((cnp->cn_flags & LOCKPARENT) && *ndp->ni_next == '\0')
541 VOP_UNLOCK(ndp->ni_dvp);
542 vrele(ndp->ni_dvp);
543 bad:
544 vput(dp);
545 ndp->ni_vp = NULL;
546 return (error);
547 }
548
549 /*
550 * relookup - lookup a path name component
551 * Used by lookup to re-aquire things.
552 */
553 int
554 relookup(dvp, vpp, cnp)
555 struct vnode *dvp, **vpp;
556 struct componentname *cnp;
557 {
558 register struct vnode *dp = 0; /* the directory we are searching */
559 int docache; /* == 0 do not cache last component */
560 int wantparent; /* 1 => wantparent or lockparent flag */
561 int rdonly; /* lookup read-only flag bit */
562 int error = 0;
563 #ifdef NAMEI_DIAGNOSTIC
564 int newhash; /* DEBUG: check name hash */
565 char *cp; /* DEBUG: check name ptr/len */
566 #endif
567
568 /*
569 * Setup: break out flag bits into variables.
570 */
571 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
572 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
573 if (cnp->cn_nameiop == DELETE ||
574 (wantparent && cnp->cn_nameiop != CREATE))
575 docache = 0;
576 rdonly = cnp->cn_flags & RDONLY;
577 cnp->cn_flags &= ~ISSYMLINK;
578 dp = dvp;
579 VOP_LOCK(dp);
580
581 /* dirloop: */
582 /*
583 * Search a new directory.
584 *
585 * The cn_hash value is for use by vfs_cache.
586 * The last component of the filename is left accessible via
587 * cnp->cn_nameptr for callers that need the name. Callers needing
588 * the name set the SAVENAME flag. When done, they assume
589 * responsibility for freeing the pathname buffer.
590 */
591 #ifdef NAMEI_DIAGNOSTIC
592 for (newhash = 0, cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
593 newhash += (unsigned char)*cp;
594 if (newhash != cnp->cn_hash)
595 panic("relookup: bad hash");
596 if (cnp->cn_namelen != cp - cnp->cn_nameptr)
597 panic ("relookup: bad len");
598 if (*cp != 0)
599 panic("relookup: not last component");
600 printf("{%s}: ", cnp->cn_nameptr);
601 #endif
602
603 /*
604 * Check for degenerate name (e.g. / or "")
605 * which is a way of talking about a directory,
606 * e.g. like "/." or ".".
607 */
608 if (cnp->cn_nameptr[0] == '\0') {
609 if (cnp->cn_nameiop != LOOKUP || wantparent) {
610 error = EISDIR;
611 goto bad;
612 }
613 if (dp->v_type != VDIR) {
614 error = ENOTDIR;
615 goto bad;
616 }
617 if (!(cnp->cn_flags & LOCKLEAF))
618 VOP_UNLOCK(dp);
619 *vpp = dp;
620 if (cnp->cn_flags & SAVESTART)
621 panic("lookup: SAVESTART");
622 return (0);
623 }
624
625 if (cnp->cn_flags & ISDOTDOT)
626 panic ("relookup: lookup on dot-dot");
627
628 /*
629 * We now have a segment name to search for, and a directory to search.
630 */
631 error = VOP_LOOKUP(dp, vpp, cnp);
632 if (error) {
633 #ifdef DIAGNOSTIC
634 if (*vpp != NULL)
635 panic("leaf should be empty");
636 #endif
637 if (error != EJUSTRETURN)
638 goto bad;
639 /*
640 * If creating and at end of pathname, then can consider
641 * allowing file to be created.
642 */
643 if (rdonly) {
644 error = EROFS;
645 goto bad;
646 }
647 /* ASSERT(dvp == ndp->ni_startdir) */
648 if (cnp->cn_flags & SAVESTART)
649 VREF(dvp);
650 /*
651 * We return with ni_vp NULL to indicate that the entry
652 * doesn't currently exist, leaving a pointer to the
653 * (possibly locked) directory inode in ndp->ni_dvp.
654 */
655 return (0);
656 }
657 dp = *vpp;
658
659 #ifdef DIAGNOSTIC
660 /*
661 * Check for symbolic link
662 */
663 if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW))
664 panic ("relookup: symlink found.\n");
665 #endif
666
667 /*
668 * Disallow directory write attempts on read-only file systems.
669 */
670 if (rdonly &&
671 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
672 error = EROFS;
673 goto bad2;
674 }
675 /* ASSERT(dvp == ndp->ni_startdir) */
676 if (cnp->cn_flags & SAVESTART)
677 VREF(dvp);
678
679 if (!wantparent)
680 vrele(dvp);
681 if ((cnp->cn_flags & LOCKLEAF) == 0)
682 VOP_UNLOCK(dp);
683 return (0);
684
685 bad2:
686 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN))
687 VOP_UNLOCK(dvp);
688 vrele(dvp);
689 bad:
690 vput(dp);
691 *vpp = NULL;
692 return (error);
693 }
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