1 /* $NetBSD: cd9660_lookup.c,v 1.30 2015/03/28 19:24:05 maxv Exp $ */
2
3 /*-
4 * Copyright (c) 1989, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley
8 * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension
9 * Support code is derived from software contributed to Berkeley
10 * by Atsushi Murai (amurai@spec.co.jp).
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91
37 *
38 * @(#)cd9660_lookup.c 8.5 (Berkeley) 5/27/95
39 */
40
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: cd9660_lookup.c,v 1.30 2015/03/28 19:24:05 maxv Exp $");
43
44 #include <sys/param.h>
45 #include <sys/namei.h>
46 #include <sys/buf.h>
47 #include <sys/file.h>
48 #include <sys/vnode.h>
49 #include <sys/mount.h>
50 #include <sys/systm.h>
51 #include <sys/kauth.h>
52
53 #include <fs/cd9660/iso.h>
54 #include <fs/cd9660/cd9660_extern.h>
55 #include <fs/cd9660/cd9660_node.h>
56 #include <fs/cd9660/iso_rrip.h>
57 #include <fs/cd9660/cd9660_rrip.h>
58 #include <fs/cd9660/cd9660_mount.h>
59
60 /*
61 * Convert a component of a pathname into a pointer to a locked inode.
62 * This is a very central and rather complicated routine.
63 * If the file system is not maintained in a strict tree hierarchy,
64 * this can result in a deadlock situation (see comments in code below).
65 *
66 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
67 * whether the name is to be looked up, created, renamed, or deleted.
68 * When CREATE, RENAME, or DELETE is specified, information usable in
69 * creating, renaming, or deleting a directory entry may be calculated.
70 * If the target of the pathname exists, lookup returns both the target
71 * and its parent directory locked.
72 * When creating or renaming, the target may * not be ".".
73 * When deleting , the target may be "."., but the caller must check
74 * to ensure it does an vrele and vput instead of two vputs.
75 *
76 * Overall outline of ufs_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), 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 int
cd9660_lookup(void * v)93 cd9660_lookup(void *v)
94 {
95 struct vop_lookup_v2_args /* {
96 struct vnode *a_dvp;
97 struct vnode **a_vpp;
98 struct componentname *a_cnp;
99 } */ *ap = v;
100 struct vnode *vdp; /* vnode for directory being searched */
101 struct iso_node *dp; /* inode for directory being searched */
102 struct iso_mnt *imp; /* file system that directory is in */
103 struct buf *bp; /* a buffer of directory entries */
104 struct iso_directory_record *ep = NULL;
105 /* the current directory entry */
106 int entryoffsetinblock; /* offset of ep in bp's buffer */
107 int saveoffset = -1; /* offset of last directory entry in dir */
108 int numdirpasses; /* strategy for directory search */
109 doff_t endsearch; /* offset to end directory search */
110 struct vnode *tdp; /* returned by vcache_get */
111 u_long bmask; /* block offset mask */
112 int error;
113 ino_t ino = 0;
114 int reclen;
115 u_short namelen;
116 char altname[ISO_MAXNAMLEN];
117 int res;
118 int assoc, len;
119 const char *name;
120 struct vnode **vpp = ap->a_vpp;
121 struct componentname *cnp = ap->a_cnp;
122 kauth_cred_t cred = cnp->cn_cred;
123 int flags;
124 int nameiop = cnp->cn_nameiop;
125
126 flags = cnp->cn_flags;
127
128 bp = NULL;
129 *vpp = NULL;
130 vdp = ap->a_dvp;
131 dp = VTOI(vdp);
132 imp = dp->i_mnt;
133
134 /*
135 * Check accessiblity of directory.
136 */
137 if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0)
138 return (error);
139
140 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
141 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
142 return (EROFS);
143
144 /*
145 * We now have a segment name to search for, and a directory to search.
146 *
147 * Before tediously performing a linear scan of the directory,
148 * check the name cache to see if the directory/name pair
149 * we are looking for is known already.
150 */
151 if (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen,
152 cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) {
153 return *vpp == NULLVP ? ENOENT : 0;
154 }
155
156 len = cnp->cn_namelen;
157 name = cnp->cn_nameptr;
158 /*
159 * A leading `=' means, we are looking for an associated file
160 */
161 assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR);
162 if (assoc) {
163 len--;
164 name++;
165 }
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 bmask = imp->im_bmask;
179 if (nameiop != LOOKUP || dp->i_diroff == 0 ||
180 dp->i_diroff > dp->i_size) {
181 entryoffsetinblock = 0;
182 dp->i_offset = 0;
183 numdirpasses = 1;
184 } else {
185 dp->i_offset = dp->i_diroff;
186 if ((entryoffsetinblock = dp->i_offset & bmask) &&
187 (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL,
188 &bp)))
189 return (error);
190 numdirpasses = 2;
191 namecache_count_2passes();
192 }
193 endsearch = dp->i_size;
194
195 searchloop:
196 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 if ((dp->i_offset & bmask) == 0) {
203 if (bp != NULL)
204 brelse(bp, 0);
205 error = cd9660_blkatoff(vdp, (off_t)dp->i_offset,
206 NULL, &bp);
207 if (error)
208 return (error);
209 entryoffsetinblock = 0;
210 }
211 /*
212 * Get pointer to next entry.
213 */
214 KASSERT(bp != NULL);
215 ep = (struct iso_directory_record *)
216 ((char *)bp->b_data + entryoffsetinblock);
217
218 reclen = isonum_711(ep->length);
219 if (reclen == 0) {
220 /* skip to next block, if any */
221 dp->i_offset =
222 (dp->i_offset & ~bmask) + imp->logical_block_size;
223 continue;
224 }
225
226 if (reclen < ISO_DIRECTORY_RECORD_SIZE)
227 /* illegal entry, stop */
228 break;
229
230 if (entryoffsetinblock + reclen > imp->logical_block_size)
231 /* entries are not allowed to cross boundaries */
232 break;
233
234 namelen = isonum_711(ep->name_len);
235
236 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
237 /* illegal entry, stop */
238 break;
239
240 /*
241 * Check for a name match.
242 */
243 switch (imp->iso_ftype) {
244 default:
245 if ((!(isonum_711(ep->flags)&4)) == !assoc) {
246 if ((len == 1
247 && *name == '.')
248 || (flags & ISDOTDOT)) {
249 if (namelen == 1
250 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
251 /*
252 * Save directory entry's inode number and
253 * release directory buffer.
254 */
255 dp->i_ino = isodirino(ep, imp);
256 goto found;
257 }
258 if (namelen != 1
259 || ep->name[0] != 0)
260 goto notfound;
261 } else if (!(res = isofncmp(name,len,
262 ep->name,namelen,
263 imp->im_joliet_level))) {
264 if (isonum_711(ep->flags)&2)
265 ino = isodirino(ep, imp);
266 else
267 ino = dbtob(bp->b_blkno)
268 + entryoffsetinblock;
269 saveoffset = dp->i_offset;
270 } else if (ino)
271 goto foundino;
272 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */
273 else if (res < 0)
274 goto notfound;
275 else if (res > 0 && numdirpasses == 2)
276 numdirpasses++;
277 #endif
278 }
279 break;
280 case ISO_FTYPE_RRIP:
281 if (isonum_711(ep->flags)&2)
282 ino = isodirino(ep, imp);
283 else
284 ino = dbtob(bp->b_blkno) + entryoffsetinblock;
285 dp->i_ino = ino;
286 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
287 if (namelen == cnp->cn_namelen) {
288 if (imp->im_flags & ISOFSMNT_RRCASEINS) {
289 if (strncasecmp(name, altname, namelen) == 0)
290 goto found;
291 } else {
292 if (memcmp(name, altname, namelen) == 0)
293 goto found;
294 }
295 }
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 (cd9660_lblkno(imp, dp->i_offset) !=
307 cd9660_lblkno(imp, saveoffset)) {
308 if (bp != NULL)
309 brelse(bp, 0);
310 if ((error = cd9660_blkatoff(vdp,
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, 0);
334
335 /*
336 * Insert name into cache (as non-existent) if appropriate.
337 */
338 cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags);
339 return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT;
340
341 found:
342 if (numdirpasses == 2)
343 namecache_count_pass2();
344 brelse(bp, 0);
345
346 /*
347 * Found component in pathname.
348 * If the final component of path name, save information
349 * in the cache as to where the entry was found.
350 */
351 if ((flags & ISLASTCN) && nameiop == LOOKUP)
352 dp->i_diroff = dp->i_offset;
353
354 if (dp->i_number == dp->i_ino) {
355 vref(vdp); /* we want ourself, ie "." */
356 *vpp = vdp;
357 } else {
358 error = vcache_get(vdp->v_mount,
359 &dp->i_ino, sizeof(dp->i_ino), &tdp);
360 if (error)
361 return (error);
362 *vpp = tdp;
363 }
364
365 /*
366 * Insert name into cache if appropriate.
367 */
368 cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags);
369
370 return 0;
371 }
372
373 /*
374 * Return buffer with the contents of block "offset" from the beginning of
375 * directory "ip". If "res" is non-zero, fill it in with a pointer to the
376 * remaining space in the directory.
377 */
378 int
cd9660_blkatoff(struct vnode * vp,off_t offset,char ** res,struct buf ** bpp)379 cd9660_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
380 {
381 struct iso_node *ip;
382 struct iso_mnt *imp;
383 struct vnode *devvp;
384 struct buf *bp;
385 daddr_t lbn;
386 int bsize, error;
387
388 ip = VTOI(vp);
389 imp = ip->i_mnt;
390 lbn = cd9660_lblkno(imp, offset);
391 bsize = cd9660_blksize(imp, ip, lbn);
392
393 if ((error = VOP_BMAP(vp, lbn, &devvp, &lbn, NULL)) != 0) {
394 *bpp = NULL;
395 return error;
396 }
397 if ((error = bread(devvp, lbn, bsize, 0, &bp)) != 0) {
398 *bpp = NULL;
399 return (error);
400 }
401 if (res)
402 *res = (char *)bp->b_data + cd9660_blkoff(imp, offset);
403 *bpp = bp;
404 return (0);
405 }
406