1 /*-
2 * Copyright (c) 1989, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley
6 * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension
7 * Support code is derived from software contributed to Berkeley
8 * by Atsushi Murai (amurai@spec.co.jp).
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 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91
35 * @(#)cd9660_lookup.c 8.2 (Berkeley) 1/23/94
36 * $FreeBSD: src/sys/isofs/cd9660/cd9660_lookup.c,v 1.23.2.2 2001/11/04 06:19:47 dillon Exp $
37 */
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/proc.h>
42 #include <sys/namei.h>
43 #include <sys/buf.h>
44 #include <sys/vnode.h>
45 #include <sys/mount.h>
46
47 #include "iso.h"
48 #include "cd9660_node.h"
49 #include "iso_rrip.h"
50
51 #include <sys/buf2.h>
52
53 /*
54 * Convert a component of a pathname into a pointer to a locked inode.
55 * This is a very central and rather complicated routine.
56 * If the filesystem is not maintained in a strict tree hierarchy,
57 * this can result in a deadlock situation (see comments in code below).
58 *
59 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
60 * whether the name is to be looked up, created, renamed, or deleted.
61 * When CREATE, RENAME, or DELETE is specified, information usable in
62 * creating, renaming, or deleting a directory entry may be calculated.
63 * If flag has LOCKPARENT or'ed into it and the target of the pathname
64 * exists, lookup returns both the target and its parent directory locked.
65 * When creating or renaming and LOCKPARENT is specified, the target may
66 * not be ".". When deleting and LOCKPARENT is specified, the target may
67 * be "."., but the caller must check to ensure it does an vrele and iput
68 * instead of two iputs.
69 *
70 * Overall outline of ufs_lookup:
71 *
72 * search for name in directory, to found or notfound
73 * notfound:
74 * if creating, return locked directory, leaving info on available slots
75 * else return error
76 * found:
77 * if at end of path and deleting, return information to allow delete
78 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target
79 * inode and return info to allow rewrite
80 * if not at end, add name to cache; if at end and neither creating
81 * nor deleting, add name to cache
82 *
83 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
84 *
85 * cd9660_lookup(struct vnode *a_dvp, struct vnode **a_vpp,
86 * struct componentname *a_cnp)
87 */
88 int
cd9660_lookup(struct vop_old_lookup_args * ap)89 cd9660_lookup(struct vop_old_lookup_args *ap)
90 {
91 struct vnode *vdp; /* vnode for directory being searched */
92 struct iso_node *dp; /* inode for directory being searched */
93 struct iso_mnt *imp; /* filesystem that directory is in */
94 struct buf *bp; /* a buffer of directory entries */
95 struct iso_directory_record *ep = NULL;/* the current directory entry */
96 int entryoffsetinblock; /* offset of ep in bp's buffer */
97 int saveoffset = 0; /* offset of last directory entry in dir */
98 int numdirpasses; /* strategy for directory search */
99 doff_t endsearch; /* offset to end directory search */
100 struct vnode *pdp; /* saved dp during symlink work */
101 struct vnode *tdp; /* returned by cd9660_vget_internal */
102 u_long bmask; /* block offset mask */
103 int lockparent; /* 1 => lockparent flag is set */
104 int error;
105 ino_t ino = 0;
106 int reclen;
107 u_short namelen;
108 int isoflags;
109 char altname[NAME_MAX];
110 int res;
111 int assoc, len;
112 char *name;
113 struct vnode **vpp = ap->a_vpp;
114 struct componentname *cnp = ap->a_cnp;
115 int flags = cnp->cn_flags;
116 int nameiop = cnp->cn_nameiop;
117
118 bp = NULL;
119 *vpp = NULL;
120 vdp = ap->a_dvp;
121 dp = VTOI(vdp);
122 imp = dp->i_mnt;
123 lockparent = flags & CNP_LOCKPARENT;
124 cnp->cn_flags &= ~CNP_PDIRUNLOCK;
125
126 /*
127 * We now have a segment name to search for, and a directory to search.
128 */
129 len = cnp->cn_namelen;
130 name = cnp->cn_nameptr;
131
132 /*
133 * A leading `=' means, we are looking for an associated file
134 */
135 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR)))
136 {
137 len--;
138 name++;
139 }
140
141 /*
142 * If there is cached information on a previous search of
143 * this directory, pick up where we last left off.
144 * We cache only lookups as these are the most common
145 * and have the greatest payoff. Caching CREATE has little
146 * benefit as it usually must search the entire directory
147 * to determine that the entry does not exist. Caching the
148 * location of the last DELETE or RENAME has not reduced
149 * profiling time and hence has been removed in the interest
150 * of simplicity.
151 */
152 bmask = imp->im_bmask;
153 if (nameiop != NAMEI_LOOKUP || dp->i_diroff == 0 ||
154 dp->i_diroff > dp->i_size) {
155 entryoffsetinblock = 0;
156 dp->i_offset = 0;
157 numdirpasses = 1;
158 } else {
159 dp->i_offset = dp->i_diroff;
160 if ((entryoffsetinblock = dp->i_offset & bmask) &&
161 (error = cd9660_devblkatoff(vdp, (off_t)dp->i_offset, NULL, &bp)))
162 return (error);
163 numdirpasses = 2;
164 }
165 endsearch = dp->i_size;
166
167 searchloop:
168 while (dp->i_offset < endsearch) {
169 /*
170 * If offset is on a block boundary,
171 * read the next directory block.
172 * Release previous if it exists.
173 */
174 if ((dp->i_offset & bmask) == 0) {
175 if (bp != NULL)
176 brelse(bp);
177 if ((error =
178 cd9660_devblkatoff(vdp, (off_t)dp->i_offset, NULL, &bp)) != 0)
179 return (error);
180 entryoffsetinblock = 0;
181 }
182 /*
183 * Get pointer to next entry.
184 */
185 ep = (struct iso_directory_record *)
186 ((char *)bp->b_data + entryoffsetinblock);
187
188 reclen = isonum_711(ep->length);
189 if (reclen == 0) {
190 /* skip to next block, if any */
191 dp->i_offset =
192 (dp->i_offset & ~bmask) + imp->logical_block_size;
193 continue;
194 }
195
196 if (reclen < ISO_DIRECTORY_RECORD_SIZE)
197 /* illegal entry, stop */
198 break;
199
200 if (entryoffsetinblock + reclen > imp->logical_block_size)
201 /* entries are not allowed to cross boundaries */
202 break;
203
204 namelen = isonum_711(ep->name_len);
205 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA?
206 &ep->date[6]: ep->flags);
207
208 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
209 /* illegal entry, stop */
210 break;
211
212 /*
213 * Check for a name match.
214 */
215 switch (imp->iso_ftype) {
216 default:
217 if (!(isoflags & 4) == !assoc) {
218 if ((len == 1
219 && *name == '.')
220 || (flags & CNP_ISDOTDOT)) {
221 if (namelen == 1
222 && ep->name[0] == ((flags & CNP_ISDOTDOT) ? 1 : 0)) {
223 /*
224 * Save directory entry's inode number and
225 * release directory buffer.
226 */
227 dp->i_ino = isodirino(ep, imp);
228 goto found;
229 }
230 if (namelen != 1
231 || ep->name[0] != 0)
232 goto notfound;
233 } else if (!(res = isofncmp(name, len,
234 ep->name, namelen,
235 imp->joliet_level,
236 imp->im_flags,
237 imp->im_d2l,
238 imp->im_l2d))) {
239 if (isoflags & 2)
240 ino = isodirino(ep, imp);
241 else
242 ino = bp->b_bio1.bio_offset
243 + entryoffsetinblock;
244 saveoffset = dp->i_offset;
245 } else if (ino)
246 goto foundino;
247 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */
248 else if (res < 0)
249 goto notfound;
250 else if (res > 0 && numdirpasses == 2)
251 numdirpasses++;
252 #endif
253 }
254 break;
255 case ISO_FTYPE_RRIP:
256 if (isonum_711(ep->flags)&2)
257 ino = isodirino(ep, imp);
258 else
259 ino = bp->b_bio1.bio_offset + entryoffsetinblock;
260 dp->i_ino = ino;
261 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
262 if (namelen == cnp->cn_namelen
263 && !bcmp(name,altname,namelen))
264 goto found;
265 ino = 0;
266 break;
267 }
268 dp->i_offset += reclen;
269 entryoffsetinblock += reclen;
270 }
271 if (ino) {
272 foundino:
273 dp->i_ino = ino;
274 if (saveoffset != dp->i_offset) {
275 if (lblkno(imp, dp->i_offset) !=
276 lblkno(imp, saveoffset)) {
277 if (bp != NULL)
278 brelse(bp);
279 if ((error = cd9660_devblkatoff(vdp,
280 (off_t)saveoffset, NULL, &bp)) != 0)
281 return (error);
282 }
283 entryoffsetinblock = saveoffset & bmask;
284 ep = (struct iso_directory_record *)
285 ((char *)bp->b_data + entryoffsetinblock);
286 dp->i_offset = saveoffset;
287 }
288 goto found;
289 }
290 notfound:
291 /*
292 * If we started in the middle of the directory and failed
293 * to find our target, we must check the beginning as well.
294 */
295 if (numdirpasses == 2) {
296 numdirpasses--;
297 dp->i_offset = 0;
298 endsearch = dp->i_diroff;
299 goto searchloop;
300 }
301 if (bp != NULL)
302 brelse(bp);
303
304 if (nameiop == NAMEI_CREATE || nameiop == NAMEI_RENAME)
305 return (EROFS);
306 return (ENOENT);
307
308 found:
309 /*
310 * Found component in pathname.
311 * If the final component of path name, save information
312 * in the cache as to where the entry was found.
313 */
314 if (nameiop == NAMEI_LOOKUP)
315 dp->i_diroff = dp->i_offset;
316
317 /*
318 * Step through the translation in the name. We do not `iput' the
319 * directory because we may need it again if a symbolic link
320 * is relative to the current directory. Instead we save it
321 * unlocked as "pdp". We must get the target inode before unlocking
322 * the directory to insure that the inode will not be removed
323 * before we get it. We prevent deadlock by always fetching
324 * inodes from the root, moving down the directory tree. Thus
325 * when following backward pointers ".." we must unlock the
326 * parent directory before getting the requested directory.
327 * There is a potential race condition here if both the current
328 * and parent directories are removed before the `iget' for the
329 * inode associated with ".." returns. We hope that this occurs
330 * infrequently since we cannot avoid this race condition without
331 * implementing a sophisticated deadlock detection algorithm.
332 * Note also that this simple deadlock detection scheme will not
333 * work if the filesystem has any hard links other than ".."
334 * that point backwards in the directory structure.
335 */
336 pdp = vdp;
337
338 /*
339 * If ino is different from dp->i_ino,
340 * it's a relocated directory.
341 */
342 if (flags & CNP_ISDOTDOT) {
343 vn_unlock(pdp); /* race to get the inode */
344 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
345 dp->i_ino != ino, ep);
346 brelse(bp);
347 if (error) {
348 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY);
349 return (error);
350 }
351 if (lockparent) {
352 error = vn_lock(pdp, LK_EXCLUSIVE | LK_FAILRECLAIM);
353 if (error) {
354 cnp->cn_flags |= CNP_PDIRUNLOCK;
355 vput(tdp);
356 return (error);
357 }
358 } else
359 cnp->cn_flags |= CNP_PDIRUNLOCK;
360 *vpp = tdp;
361 } else if (dp->i_number == dp->i_ino) {
362 brelse(bp);
363 vref(vdp); /* we want ourself, ie "." */
364 *vpp = vdp;
365 } else {
366 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
367 dp->i_ino != ino, ep);
368 brelse(bp);
369 if (error)
370 return (error);
371 if (!lockparent) {
372 cnp->cn_flags |= CNP_PDIRUNLOCK;
373 vn_unlock(pdp);
374 }
375 *vpp = tdp;
376 }
377 return (0);
378 }
379
380 /*
381 * Return a buffer with the contents of block "offset" from the beginning of
382 * directory "ip". If "res" is non-zero, fill it in with a pointer to the
383 * remaining space in the directory.
384 */
385 int
cd9660_blkatoff(struct vnode * vp,off_t offset,char ** res,struct buf ** bpp)386 cd9660_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
387 {
388 struct iso_node *ip;
389 struct iso_mnt *imp;
390 struct buf *bp;
391 daddr_t lbn;
392 int bsize, error;
393
394 ip = VTOI(vp);
395 imp = ip->i_mnt;
396 lbn = lblkno(imp, offset);
397 bsize = blksize(imp, ip, lbn);
398
399 if ((error = bread(vp, lblktooff(imp, lbn), bsize, &bp)) != 0) {
400 brelse(bp);
401 *bpp = NULL;
402 return (error);
403 }
404
405 /*
406 * We must BMAP the buffer because the directory code may use
407 * bio_offset to calculate the inode for certain types of directory
408 * entries. We could get away with not doing it before we
409 * VMIO-backed the directories because the buffers would get freed
410 * atomically with the invalidation of their data. But with
411 * VMIO-backed buffers the buffers may be freed and then later
412 * reconstituted - and the reconstituted buffer will have no
413 * knowledge of bio_offset.
414 */
415 if (bp->b_bio2.bio_offset == NOOFFSET) {
416 error = VOP_BMAP(vp, bp->b_bio1.bio_offset,
417 &bp->b_bio2.bio_offset, NULL, NULL,
418 BUF_CMD_READ);
419 if (error) {
420 bp->b_error = error;
421 bp->b_flags |= B_ERROR;
422 brelse(bp);
423 *bpp = NULL;
424 return (error);
425 }
426 }
427
428 if (res)
429 *res = (char *)bp->b_data + blkoff(imp, offset);
430 *bpp = bp;
431 return (0);
432 }
433
434
435 /*
436 * Return a buffer with the contents of block "offset" from the beginning of
437 * directory "ip". If "res" is non-zero, fill it in with a pointer to the
438 * remaining space in the directory.
439 *
440 * Use the underlying device vnode rather then the passed vnode for the
441 * buffer cache operation. This allows us to access meta-data conveniently
442 * without having to instantiate a VM object for the vnode.
443 *
444 * WARNING! Callers of this routine need to be careful when accessing
445 * the bio_offset. Since this is a device buffer, the device offset will
446 * be in bio1.bio_offset, not bio2.bio_offset.
447 */
448 int
cd9660_devblkatoff(struct vnode * vp,off_t offset,char ** res,struct buf ** bpp)449 cd9660_devblkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
450 {
451 struct iso_node *ip;
452 struct iso_mnt *imp;
453 struct buf *bp;
454 daddr_t lbn;
455 off_t doffset;
456 int bsize, error;
457
458 ip = VTOI(vp);
459 imp = ip->i_mnt;
460 lbn = lblkno(imp, offset);
461 bsize = blksize(imp, ip, lbn);
462
463 error = VOP_BMAP(vp, lblktooff(imp, lbn), &doffset, NULL, NULL,
464 BUF_CMD_READ);
465 if (error)
466 return (error);
467
468 if ((error = bread(imp->im_devvp, doffset, bsize, &bp)) != 0) {
469 brelse(bp);
470 *bpp = NULL;
471 return (error);
472 }
473 if (res)
474 *res = (char *)bp->b_data + blkoff(imp, offset);
475 *bpp = bp;
476 return (0);
477 }
478