1 /* $OpenBSD: cd9660_lookup.c,v 1.14 2007/06/06 17:15:13 deraadt Exp $ */
2 /* $NetBSD: cd9660_lookup.c,v 1.18 1997/05/08 16:19:59 mycroft Exp $ */
3
4 /*-
5 * Copyright (c) 1989, 1993, 1994
6 * The Regents of the University of California. All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley
9 * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension
10 * Support code is derived from software contributed to Berkeley
11 * by Atsushi Murai (amurai@spec.co.jp).
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91
38 *
39 * @(#)cd9660_lookup.c 8.5 (Berkeley) 12/5/94
40 */
41
42 #include <sys/param.h>
43 #include <sys/namei.h>
44 #include <sys/buf.h>
45 #include <sys/file.h>
46 #include <sys/vnode.h>
47 #include <sys/mount.h>
48 #include <sys/systm.h>
49 #include <sys/malloc.h>
50
51 #include <isofs/cd9660/iso.h>
52 #include <isofs/cd9660/cd9660_extern.h>
53 #include <isofs/cd9660/cd9660_node.h>
54 #include <isofs/cd9660/iso_rrip.h>
55 #include <isofs/cd9660/cd9660_rrip.h>
56
57 struct nchstats iso_nchstats;
58
59 /*
60 * Convert a component of a pathname into a pointer to a locked inode.
61 * This is a very central and rather complicated routine.
62 * If the file system is not maintained in a strict tree hierarchy,
63 * this can result in a deadlock situation (see comments in code below).
64 *
65 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
66 * whether the name is to be looked up, created, renamed, or deleted.
67 * When CREATE, RENAME, or DELETE is specified, information usable in
68 * creating, renaming, or deleting a directory entry may be calculated.
69 * If flag has LOCKPARENT or'ed into it and the target of the pathname
70 * exists, lookup returns both the target and its parent directory locked.
71 * When creating or renaming and LOCKPARENT is specified, the target may
72 * not be ".". When deleting and LOCKPARENT is specified, the target may
73 * be "."., but the caller must check to ensure it does an vrele and iput
74 * instead of two iputs.
75 *
76 * Overall outline of cd9660_lookup:
77 *
78 * check accessibility of directory
79 * look for name in cache, if found, then if at end of path
80 * and deleting or creating, drop it, else return name
81 * search for name in directory, to found or notfound
82 * notfound:
83 * if creating, return locked directory, leaving info on available slots
84 * else return error
85 * found:
86 * if at end of path and deleting, return information to allow delete
87 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target
88 * inode and return info to allow rewrite
89 * if not at end, add name to cache; if at end and neither creating
90 * nor deleting, add name to cache
91 *
92 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
93 */
94 int
95 cd9660_lookup(v)
96 void *v;
97 {
98 struct vop_lookup_args *ap = v;
99 register struct vnode *vdp; /* vnode for directory being searched */
100 register struct iso_node *dp; /* inode for directory being searched */
101 register struct iso_mnt *imp; /* file system that directory is in */
102 struct buf *bp; /* a buffer of directory entries */
103 struct iso_directory_record *ep = NULL;
104 /* the current directory entry */
105 int entryoffsetinblock; /* offset of ep in bp's buffer */
106 int saveoffset = -1; /* offset of last directory entry in dir */
107 int numdirpasses; /* strategy for directory search */
108 doff_t endsearch; /* offset to end directory search */
109 struct vnode *pdp; /* saved dp during symlink work */
110 struct vnode *tdp; /* returned by cd9660_vget_internal */
111 u_long bmask; /* block offset mask */
112 int lockparent; /* 1 => lockparent flag is set */
113 int wantparent; /* 1 => wantparent or lockparent flag */
114 int error;
115 ino_t ino = 0;
116 int reclen;
117 u_short namelen;
118 char *altname;
119 int res;
120 int assoc, len;
121 char *name;
122 struct vnode **vpp = ap->a_vpp;
123 struct componentname *cnp = ap->a_cnp;
124 struct ucred *cred = cnp->cn_cred;
125 int flags;
126 int nameiop = cnp->cn_nameiop;
127 struct proc *p = cnp->cn_proc;
128
129 cnp->cn_flags &= ~PDIRUNLOCK;
130 flags = cnp->cn_flags;
131
132 bp = NULL;
133 *vpp = NULL;
134 vdp = ap->a_dvp;
135 dp = VTOI(vdp);
136 imp = dp->i_mnt;
137 lockparent = flags & LOCKPARENT;
138 wantparent = flags & (LOCKPARENT|WANTPARENT);
139
140 /*
141 * Check accessiblity of directory.
142 */
143 if ((error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) != 0)
144 return (error);
145
146 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
147 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
148 return (EROFS);
149
150 /*
151 * We now have a segment name to search for, and a directory to search.
152 *
153 * Before tediously performing a linear scan of the directory,
154 * check the name cache to see if the directory/name pair
155 * we are looking for is known already.
156 */
157 if ((error = cache_lookup(vdp, vpp, cnp)) >= 0)
158 return (error);
159
160 len = cnp->cn_namelen;
161 name = cnp->cn_nameptr;
162 /*
163 * A leading `=' means, we are looking for an associated file
164 */
165 assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR);
166 if (assoc) {
167 len--;
168 name++;
169 }
170
171 /*
172 * If there is cached information on a previous search of
173 * this directory, pick up where we last left off.
174 * We cache only lookups as these are the most common
175 * and have the greatest payoff. Caching CREATE has little
176 * benefit as it usually must search the entire directory
177 * to determine that the entry does not exist. Caching the
178 * location of the last DELETE or RENAME has not reduced
179 * profiling time and hence has been removed in the interest
180 * of simplicity.
181 */
182 bmask = imp->im_bmask;
183 if (nameiop != LOOKUP || dp->i_diroff == 0 ||
184 dp->i_diroff > dp->i_size) {
185 entryoffsetinblock = 0;
186 dp->i_offset = 0;
187 numdirpasses = 1;
188 } else {
189 dp->i_offset = dp->i_diroff;
190 if ((entryoffsetinblock = dp->i_offset & bmask) &&
191 (error = cd9660_bufatoff(dp, (off_t)dp->i_offset, NULL,
192 &bp)))
193 return (error);
194 numdirpasses = 2;
195 iso_nchstats.ncs_2passes++;
196 }
197 endsearch = dp->i_size;
198
199 searchloop:
200 while (dp->i_offset < endsearch) {
201 /*
202 * If offset is on a block boundary,
203 * read the next directory block.
204 * Release previous if it exists.
205 */
206 if ((dp->i_offset & bmask) == 0) {
207 if (bp != NULL)
208 brelse(bp);
209 error = cd9660_bufatoff(dp, (off_t)dp->i_offset,
210 NULL, &bp);
211 if (error)
212 return (error);
213 entryoffsetinblock = 0;
214 }
215 /*
216 * Get pointer to next entry.
217 */
218 ep = (struct iso_directory_record *)
219 ((char *)bp->b_data + entryoffsetinblock);
220
221 reclen = isonum_711(ep->length);
222 if (reclen == 0) {
223 /* skip to next block, if any */
224 dp->i_offset =
225 (dp->i_offset & ~bmask) + imp->logical_block_size;
226 continue;
227 }
228
229 if (reclen < ISO_DIRECTORY_RECORD_SIZE)
230 /* illegal entry, stop */
231 break;
232
233 if (entryoffsetinblock + reclen > imp->logical_block_size)
234 /* entries are not allowed to cross boundaries */
235 break;
236
237 namelen = isonum_711(ep->name_len);
238
239 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
240 /* illegal entry, stop */
241 break;
242
243 /*
244 * Check for a name match.
245 */
246 switch (imp->iso_ftype) {
247 default:
248 if ((!(isonum_711(ep->flags)&4)) == !assoc) {
249 if ((len == 1
250 && *name == '.')
251 || (flags & ISDOTDOT)) {
252 if (namelen == 1
253 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
254 /*
255 * Save directory entry's inode number and
256 * release directory buffer.
257 */
258 dp->i_ino = isodirino(ep, imp);
259 goto found;
260 }
261 if (namelen != 1
262 || ep->name[0] != 0)
263 goto notfound;
264 } else if (!(res = isofncmp(name, len,
265 ep->name, namelen, imp->joliet_level))) {
266 if (isonum_711(ep->flags)&2)
267 ino = isodirino(ep, imp);
268 else
269 ino = dbtob(bp->b_blkno)
270 + entryoffsetinblock;
271 saveoffset = dp->i_offset;
272 } else if (ino)
273 goto foundino;
274 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */
275 else if (res < 0)
276 goto notfound;
277 else if (res > 0 && numdirpasses == 2)
278 numdirpasses++;
279 #endif
280 }
281 break;
282 case ISO_FTYPE_RRIP:
283 if (isonum_711(ep->flags)&2)
284 ino = isodirino(ep, imp);
285 else
286 ino = dbtob(bp->b_blkno) + entryoffsetinblock;
287 dp->i_ino = ino;
288 MALLOC(altname, char *, NAME_MAX, M_TEMP, M_WAITOK);
289 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
290 if (namelen == cnp->cn_namelen
291 && !bcmp(name,altname,namelen)) {
292 FREE(altname, M_TEMP);
293 goto found;
294 }
295 FREE(altname, M_TEMP);
296 ino = 0;
297 break;
298 }
299 dp->i_offset += reclen;
300 entryoffsetinblock += reclen;
301 }
302 if (ino) {
303 foundino:
304 dp->i_ino = ino;
305 if (saveoffset != dp->i_offset) {
306 if (lblkno(imp, dp->i_offset) !=
307 lblkno(imp, saveoffset)) {
308 if (bp != NULL)
309 brelse(bp);
310 if ((error = cd9660_bufatoff(dp,
311 (off_t)saveoffset, NULL, &bp)) != 0)
312 return (error);
313 }
314 entryoffsetinblock = saveoffset & bmask;
315 ep = (struct iso_directory_record *)
316 ((char *)bp->b_data + entryoffsetinblock);
317 dp->i_offset = saveoffset;
318 }
319 goto found;
320 }
321 notfound:
322 /*
323 * If we started in the middle of the directory and failed
324 * to find our target, we must check the beginning as well.
325 */
326 if (numdirpasses == 2) {
327 numdirpasses--;
328 dp->i_offset = 0;
329 endsearch = dp->i_diroff;
330 goto searchloop;
331 }
332 if (bp != NULL)
333 brelse(bp);
334
335 /*
336 * Insert name into cache (as non-existent) if appropriate.
337 */
338 if (cnp->cn_flags & MAKEENTRY)
339 cache_enter(vdp, *vpp, cnp);
340 if (nameiop == CREATE || nameiop == RENAME)
341 return (EJUSTRETURN);
342 return (ENOENT);
343
344 found:
345 if (numdirpasses == 2)
346 iso_nchstats.ncs_pass2++;
347
348 /*
349 * Found component in pathname.
350 * If the final component of path name, save information
351 * in the cache as to where the entry was found.
352 */
353 if ((flags & ISLASTCN) && nameiop == LOOKUP)
354 dp->i_diroff = dp->i_offset;
355
356 /*
357 * Step through the translation in the name. We do not `iput' the
358 * directory because we may need it again if a symbolic link
359 * is relative to the current directory. Instead we save it
360 * unlocked as "pdp". We must get the target inode before unlocking
361 * the directory to insure that the inode will not be removed
362 * before we get it. We prevent deadlock by always fetching
363 * inodes from the root, moving down the directory tree. Thus
364 * when following backward pointers ".." we must unlock the
365 * parent directory before getting the requested directory.
366 * There is a potential race condition here if both the current
367 * and parent directories are removed before the `iget' for the
368 * inode associated with ".." returns. We hope that this occurs
369 * infrequently since we cannot avoid this race condition without
370 * implementing a sophisticated deadlock detection algorithm.
371 * Note also that this simple deadlock detection scheme will not
372 * work if the file system has any hard links other than ".."
373 * that point backwards in the directory structure.
374 */
375 pdp = vdp;
376 /*
377 * If ino is different from dp->i_ino,
378 * it's a relocated directory.
379 */
380 if (flags & ISDOTDOT) {
381 brelse(bp);
382 VOP_UNLOCK(pdp, 0, p); /* race to get the inode */
383 cnp->cn_flags |= PDIRUNLOCK;
384 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
385 dp->i_ino != ino, NULL);
386 if (error) {
387 if (vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p) == 0)
388 cnp->cn_flags &= ~PDIRUNLOCK;
389 return (error);
390 }
391 if (lockparent && (flags & ISLASTCN)) {
392 if ((error = vn_lock(pdp, LK_EXCLUSIVE, p))) {
393 vput(tdp);
394 return (error);
395 }
396 cnp->cn_flags &= ~PDIRUNLOCK;
397 }
398 *vpp = tdp;
399 } else if (dp->i_number == dp->i_ino) {
400 brelse(bp);
401 VREF(vdp); /* we want ourself, ie "." */
402 *vpp = vdp;
403 } else {
404 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
405 dp->i_ino != ino, ep);
406 brelse(bp);
407 if (error)
408 return (error);
409 if (!lockparent || !(flags & ISLASTCN)) {
410 VOP_UNLOCK(pdp, 0, p);
411 cnp->cn_flags |= PDIRUNLOCK;
412 }
413 *vpp = tdp;
414 }
415
416 /*
417 * Insert name into cache if appropriate.
418 */
419 if (cnp->cn_flags & MAKEENTRY)
420 cache_enter(vdp, *vpp, cnp);
421 return (0);
422 }
423
424 /*
425 * Return buffer with the contents of block "offset" from the beginning of
426 * directory "ip". If "res" is non-zero, fill it in with a pointer to the
427 * remaining space in the directory.
428 */
429 int
430 cd9660_bufatoff(struct iso_node *ip, off_t offset, char **res,
431 struct buf **bpp)
432 {
433 struct iso_mnt *imp;
434 struct buf *bp;
435 daddr64_t lbn;
436 int bsize, error;
437 struct vnode *vp = ITOV(ip);
438
439 imp = ip->i_mnt;
440 lbn = lblkno(imp, offset);
441 bsize = blksize(imp, ip, lbn);
442
443 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
444 brelse(bp);
445 *bpp = NULL;
446 return (error);
447 }
448 if (res)
449 *res = (char *)bp->b_data + blkoff(imp, offset);
450 *bpp = bp;
451 return (0);
452 }