Line data Source code
1 : /* $OpenBSD: cd9660_lookup.c,v 1.27 2018/05/02 02:24:55 visa 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/vnode.h>
46 : #include <sys/lock.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 :
56 : struct nchstats iso_nchstats;
57 :
58 : /*
59 : * Convert a component of a pathname into a pointer to a locked inode.
60 : * This is a very central and rather complicated routine.
61 : * If the file system is not maintained in a strict tree hierarchy,
62 : * this can result in a deadlock situation (see comments in code below).
63 : *
64 : * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
65 : * whether the name is to be looked up, created, renamed, or deleted.
66 : * When CREATE, RENAME, or DELETE is specified, information usable in
67 : * creating, renaming, or deleting a directory entry may be calculated.
68 : * If flag has LOCKPARENT or'ed into it and the target of the pathname
69 : * exists, lookup returns both the target and its parent directory locked.
70 : * When creating or renaming and LOCKPARENT is specified, the target may
71 : * not be ".". When deleting and LOCKPARENT is specified, the target may
72 : * be "."., but the caller must check to ensure it does an vrele and iput
73 : * instead of two iputs.
74 : *
75 : * Overall outline of cd9660_lookup:
76 : *
77 : * check accessibility of directory
78 : * look for name in cache, if found, then if at end of path
79 : * and deleting or creating, drop it, else return name
80 : * search for name in directory, to found or notfound
81 : * notfound:
82 : * if creating, return locked directory, leaving info on available slots
83 : * else return error
84 : * found:
85 : * if at end of path and deleting, return information to allow delete
86 : * if at end of path and rewriting (RENAME and LOCKPARENT), lock target
87 : * inode and return info to allow rewrite
88 : * if not at end, add name to cache; if at end and neither creating
89 : * nor deleting, add name to cache
90 : *
91 : * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
92 : */
93 : int
94 0 : cd9660_lookup(v)
95 : void *v;
96 : {
97 0 : struct vop_lookup_args *ap = v;
98 : register struct vnode *vdp; /* vnode for directory being searched */
99 : register struct iso_node *dp; /* inode for directory being searched */
100 : register struct iso_mnt *imp; /* file system that directory is in */
101 0 : struct buf *bp; /* a buffer of directory entries */
102 : struct iso_directory_record *ep = NULL;
103 : /* the current directory entry */
104 : int entryoffsetinblock; /* offset of ep in bp's buffer */
105 : int saveoffset = -1; /* offset of last directory entry in dir */
106 : int numdirpasses; /* strategy for directory search */
107 : doff_t endsearch; /* offset to end directory search */
108 : struct vnode *pdp; /* saved dp during symlink work */
109 0 : struct vnode *tdp; /* returned by cd9660_vget_internal */
110 : u_long bmask; /* block offset mask */
111 : int lockparent; /* 1 => lockparent flag is set */
112 : int error;
113 : cdino_t ino = 0;
114 : int reclen;
115 0 : u_short namelen;
116 : char *altname;
117 : int res;
118 : int assoc, len;
119 : char *name;
120 0 : struct vnode **vpp = ap->a_vpp;
121 0 : struct componentname *cnp = ap->a_cnp;
122 0 : struct ucred *cred = cnp->cn_cred;
123 : int flags;
124 0 : int nameiop = cnp->cn_nameiop;
125 :
126 0 : cnp->cn_flags &= ~PDIRUNLOCK;
127 0 : flags = cnp->cn_flags;
128 :
129 0 : bp = NULL;
130 0 : *vpp = NULL;
131 0 : vdp = ap->a_dvp;
132 0 : dp = VTOI(vdp);
133 0 : imp = dp->i_mnt;
134 0 : lockparent = flags & LOCKPARENT;
135 :
136 : /*
137 : * Check accessiblity of directory.
138 : */
139 0 : if ((error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) != 0)
140 0 : return (error);
141 :
142 0 : if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
143 0 : (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
144 0 : return (EROFS);
145 :
146 : /*
147 : * We now have a segment name to search for, and a directory to search.
148 : *
149 : * Before tediously performing a linear scan of the directory,
150 : * check the name cache to see if the directory/name pair
151 : * we are looking for is known already.
152 : */
153 0 : if ((error = cache_lookup(vdp, vpp, cnp)) >= 0)
154 0 : return (error);
155 :
156 0 : len = cnp->cn_namelen;
157 0 : name = cnp->cn_nameptr;
158 : /*
159 : * A leading `=' means, we are looking for an associated file
160 : */
161 0 : assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR);
162 0 : if (assoc) {
163 0 : len--;
164 0 : name++;
165 0 : }
166 :
167 : /*
168 : * If there is cached information on a previous search of
169 : * this directory, pick up where we last left off.
170 : * We cache only lookups as these are the most common
171 : * and have the greatest payoff. Caching CREATE has little
172 : * benefit as it usually must search the entire directory
173 : * to determine that the entry does not exist. Caching the
174 : * location of the last DELETE or RENAME has not reduced
175 : * profiling time and hence has been removed in the interest
176 : * of simplicity.
177 : */
178 0 : bmask = imp->im_bmask;
179 0 : if (nameiop != LOOKUP || dp->i_diroff == 0 ||
180 0 : dp->i_diroff > dp->i_size) {
181 : entryoffsetinblock = 0;
182 0 : dp->i_offset = 0;
183 : numdirpasses = 1;
184 0 : } else {
185 0 : dp->i_offset = dp->i_diroff;
186 0 : if ((entryoffsetinblock = dp->i_offset & bmask) &&
187 0 : (error = cd9660_bufatoff(dp, (off_t)dp->i_offset, NULL,
188 : &bp)))
189 0 : return (error);
190 : numdirpasses = 2;
191 0 : iso_nchstats.ncs_2passes++;
192 : }
193 0 : endsearch = dp->i_size;
194 :
195 : searchloop:
196 0 : while (dp->i_offset < endsearch) {
197 : /*
198 : * If offset is on a block boundary,
199 : * read the next directory block.
200 : * Release previous if it exists.
201 : */
202 0 : if ((dp->i_offset & bmask) == 0) {
203 0 : if (bp != NULL)
204 0 : brelse(bp);
205 0 : error = cd9660_bufatoff(dp, (off_t)dp->i_offset,
206 : NULL, &bp);
207 0 : if (error)
208 0 : return (error);
209 : entryoffsetinblock = 0;
210 0 : }
211 : /*
212 : * Get pointer to next entry.
213 : */
214 0 : ep = (struct iso_directory_record *)
215 0 : ((char *)bp->b_data + entryoffsetinblock);
216 :
217 0 : reclen = isonum_711(ep->length);
218 0 : if (reclen == 0) {
219 : /* skip to next block, if any */
220 0 : dp->i_offset =
221 0 : (dp->i_offset & ~bmask) + imp->logical_block_size;
222 0 : continue;
223 : }
224 :
225 0 : if (reclen < ISO_DIRECTORY_RECORD_SIZE)
226 : /* illegal entry, stop */
227 : break;
228 :
229 0 : if (entryoffsetinblock + reclen > imp->logical_block_size)
230 : /* entries are not allowed to cross boundaries */
231 : break;
232 :
233 0 : namelen = isonum_711(ep->name_len);
234 :
235 0 : if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
236 : /* illegal entry, stop */
237 : break;
238 :
239 : /*
240 : * Check for a name match.
241 : */
242 0 : switch (imp->iso_ftype) {
243 : default:
244 0 : if ((!(isonum_711(ep->flags)&4)) == !assoc) {
245 0 : if ((len == 1
246 0 : && *name == '.')
247 0 : || (flags & ISDOTDOT)) {
248 0 : if (namelen == 1
249 0 : && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
250 : /*
251 : * Save directory entry's inode number and
252 : * release directory buffer.
253 : */
254 0 : dp->i_ino = isodirino(ep, imp);
255 0 : goto found;
256 : }
257 0 : if (namelen != 1
258 0 : || ep->name[0] != 0)
259 : goto notfound;
260 0 : } else if (!(res = isofncmp(name, len,
261 0 : ep->name, namelen, imp->joliet_level))) {
262 0 : if (isonum_711(ep->flags)&2)
263 0 : ino = isodirino(ep, imp);
264 : else
265 0 : ino = dbtob(bp->b_blkno)
266 0 : + entryoffsetinblock;
267 0 : saveoffset = dp->i_offset;
268 0 : } else if (ino)
269 : goto foundino;
270 : #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */
271 : else if (res < 0)
272 : goto notfound;
273 : else if (res > 0 && numdirpasses == 2)
274 : numdirpasses++;
275 : #endif
276 : }
277 : break;
278 : case ISO_FTYPE_RRIP:
279 0 : if (isonum_711(ep->flags)&2)
280 0 : ino = isodirino(ep, imp);
281 : else
282 0 : ino = dbtob(bp->b_blkno) + entryoffsetinblock;
283 0 : dp->i_ino = ino;
284 0 : altname = malloc(NAME_MAX, M_TEMP, M_WAITOK);
285 0 : cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
286 0 : if (namelen == cnp->cn_namelen
287 0 : && !bcmp(name,altname,namelen)) {
288 0 : free(altname, M_TEMP, 0);
289 0 : goto found;
290 : }
291 0 : free(altname, M_TEMP, 0);
292 : ino = 0;
293 0 : break;
294 : }
295 0 : dp->i_offset += reclen;
296 : entryoffsetinblock += reclen;
297 : }
298 0 : if (ino) {
299 : foundino:
300 0 : dp->i_ino = ino;
301 0 : if (saveoffset != dp->i_offset) {
302 0 : if (lblkno(imp, dp->i_offset) !=
303 0 : lblkno(imp, saveoffset)) {
304 0 : if (bp != NULL)
305 0 : brelse(bp);
306 0 : if ((error = cd9660_bufatoff(dp,
307 0 : (off_t)saveoffset, NULL, &bp)) != 0)
308 0 : return (error);
309 : }
310 0 : entryoffsetinblock = saveoffset & bmask;
311 0 : ep = (struct iso_directory_record *)
312 0 : ((char *)bp->b_data + entryoffsetinblock);
313 0 : dp->i_offset = saveoffset;
314 0 : }
315 : goto found;
316 : }
317 : notfound:
318 : /*
319 : * If we started in the middle of the directory and failed
320 : * to find our target, we must check the beginning as well.
321 : */
322 0 : if (numdirpasses == 2) {
323 0 : numdirpasses--;
324 0 : dp->i_offset = 0;
325 0 : endsearch = dp->i_diroff;
326 0 : goto searchloop;
327 : }
328 0 : if (bp != NULL)
329 0 : brelse(bp);
330 :
331 : /*
332 : * Insert name into cache (as non-existent) if appropriate.
333 : */
334 0 : if (cnp->cn_flags & MAKEENTRY)
335 0 : cache_enter(vdp, *vpp, cnp);
336 0 : if (nameiop == CREATE || nameiop == RENAME)
337 0 : return (EJUSTRETURN);
338 0 : return (ENOENT);
339 :
340 : found:
341 0 : if (numdirpasses == 2)
342 0 : iso_nchstats.ncs_pass2++;
343 :
344 : /*
345 : * Found component in pathname.
346 : * If the final component of path name, save information
347 : * in the cache as to where the entry was found.
348 : */
349 0 : if ((flags & ISLASTCN) && nameiop == LOOKUP)
350 0 : dp->i_diroff = dp->i_offset;
351 :
352 : /*
353 : * Step through the translation in the name. We do not `iput' the
354 : * directory because we may need it again if a symbolic link
355 : * is relative to the current directory. Instead we save it
356 : * unlocked as "pdp". We must get the target inode before unlocking
357 : * the directory to insure that the inode will not be removed
358 : * before we get it. We prevent deadlock by always fetching
359 : * inodes from the root, moving down the directory tree. Thus
360 : * when following backward pointers ".." we must unlock the
361 : * parent directory before getting the requested directory.
362 : * There is a potential race condition here if both the current
363 : * and parent directories are removed before the `iget' for the
364 : * inode associated with ".." returns. We hope that this occurs
365 : * infrequently since we cannot avoid this race condition without
366 : * implementing a sophisticated deadlock detection algorithm.
367 : * Note also that this simple deadlock detection scheme will not
368 : * work if the file system has any hard links other than ".."
369 : * that point backwards in the directory structure.
370 : */
371 : pdp = vdp;
372 : /*
373 : * If ino is different from dp->i_ino,
374 : * it's a relocated directory.
375 : */
376 0 : if (flags & ISDOTDOT) {
377 0 : brelse(bp);
378 0 : VOP_UNLOCK(pdp); /* race to get the inode */
379 0 : cnp->cn_flags |= PDIRUNLOCK;
380 0 : error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
381 0 : dp->i_ino != ino, NULL);
382 0 : if (error) {
383 0 : if (vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY) == 0)
384 0 : cnp->cn_flags &= ~PDIRUNLOCK;
385 0 : return (error);
386 : }
387 0 : if (lockparent && (flags & ISLASTCN)) {
388 0 : if ((error = vn_lock(pdp, LK_EXCLUSIVE))) {
389 0 : vput(tdp);
390 0 : return (error);
391 : }
392 0 : cnp->cn_flags &= ~PDIRUNLOCK;
393 0 : }
394 0 : *vpp = tdp;
395 0 : } else if (dp->i_number == dp->i_ino) {
396 0 : brelse(bp);
397 0 : vref(vdp); /* we want ourself, ie "." */
398 0 : *vpp = vdp;
399 0 : } else {
400 0 : error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp,
401 0 : dp->i_ino != ino, ep);
402 0 : brelse(bp);
403 0 : if (error)
404 0 : return (error);
405 0 : if (!lockparent || !(flags & ISLASTCN)) {
406 0 : VOP_UNLOCK(pdp);
407 0 : cnp->cn_flags |= PDIRUNLOCK;
408 0 : }
409 0 : *vpp = tdp;
410 : }
411 :
412 : /*
413 : * Insert name into cache if appropriate.
414 : */
415 0 : if (cnp->cn_flags & MAKEENTRY)
416 0 : cache_enter(vdp, *vpp, cnp);
417 0 : return (0);
418 0 : }
419 :
420 : /*
421 : * Return buffer with the contents of block "offset" from the beginning of
422 : * directory "ip". If "res" is non-zero, fill it in with a pointer to the
423 : * remaining space in the directory.
424 : */
425 : int
426 0 : cd9660_bufatoff(struct iso_node *ip, off_t offset, char **res,
427 : struct buf **bpp)
428 : {
429 : struct iso_mnt *imp;
430 0 : struct buf *bp;
431 : daddr_t lbn;
432 : int bsize, error;
433 0 : struct vnode *vp = ITOV(ip);
434 :
435 0 : imp = ip->i_mnt;
436 0 : lbn = lblkno(imp, offset);
437 0 : bsize = blksize(imp, ip, lbn);
438 :
439 0 : if ((error = bread(vp, lbn, bsize, &bp)) != 0) {
440 0 : brelse(bp);
441 0 : *bpp = NULL;
442 0 : return (error);
443 : }
444 0 : if (res)
445 0 : *res = (char *)bp->b_data + blkoff(imp, offset);
446 0 : *bpp = bp;
447 0 : return (0);
448 0 : }
|
