1 /* $NetBSD: cd9660_lookup.c,v 1.18 2010/06/24 13:03:09 hannken 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 1.18 2010/06/24 13:03:09 hannken 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 struct nchstats iso_nchstats; 61 62 /* 63 * Convert a component of a pathname into a pointer to a locked inode. 64 * This is a very central and rather complicated routine. 65 * If the file system is not maintained in a strict tree hierarchy, 66 * this can result in a deadlock situation (see comments in code below). 67 * 68 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 69 * whether the name is to be looked up, created, renamed, or deleted. 70 * When CREATE, RENAME, or DELETE is specified, information usable in 71 * creating, renaming, or deleting a directory entry may be calculated. 72 * If the target of the pathname exists, lookup returns both the target 73 * and its parent directory locked. 74 * When creating or renaming, the target may * not be ".". 75 * When deleting , the target may be "."., but the caller must check 76 * to ensure it does an vrele and vput instead of two vputs. 77 * 78 * Overall outline of ufs_lookup: 79 * 80 * check accessibility of directory 81 * look for name in cache, if found, then if at end of path 82 * and deleting or creating, drop it, else return name 83 * search for name in directory, to found or notfound 84 * notfound: 85 * if creating, return locked directory, leaving info on available slots 86 * else return error 87 * found: 88 * if at end of path and deleting, return information to allow delete 89 * if at end of path and rewriting (RENAME), lock target 90 * inode and return info to allow rewrite 91 * if not at end, add name to cache; if at end and neither creating 92 * nor deleting, add name to cache 93 */ 94 int 95 cd9660_lookup(void *v) 96 { 97 struct vop_lookup_args /* { 98 struct vnode *a_dvp; 99 struct vnode **a_vpp; 100 struct componentname *a_cnp; 101 } */ *ap = v; 102 struct vnode *vdp; /* vnode for directory being searched */ 103 struct iso_node *dp; /* inode for directory being searched */ 104 struct iso_mnt *imp; /* file system that directory is in */ 105 struct buf *bp; /* a buffer of directory entries */ 106 struct iso_directory_record *ep = NULL; 107 /* the current directory entry */ 108 int entryoffsetinblock; /* offset of ep in bp's buffer */ 109 int saveoffset = -1; /* offset of last directory entry in dir */ 110 int numdirpasses; /* strategy for directory search */ 111 doff_t endsearch; /* offset to end directory search */ 112 struct vnode *pdp; /* saved dp during symlink work */ 113 struct vnode *tdp; /* returned by cd9660_vget_internal */ 114 u_long bmask; /* block offset mask */ 115 int error; 116 ino_t ino = 0; 117 int reclen; 118 u_short namelen; 119 char altname[NAME_MAX]; 120 int res; 121 int assoc, len; 122 const char *name; 123 struct vnode **vpp = ap->a_vpp; 124 struct componentname *cnp = ap->a_cnp; 125 kauth_cred_t cred = cnp->cn_cred; 126 int flags; 127 int nameiop = cnp->cn_nameiop; 128 129 flags = cnp->cn_flags; 130 131 bp = NULL; 132 *vpp = NULL; 133 vdp = ap->a_dvp; 134 dp = VTOI(vdp); 135 imp = dp->i_mnt; 136 137 /* 138 * Check accessiblity of directory. 139 */ 140 if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 0) 141 return (error); 142 143 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && 144 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 145 return (EROFS); 146 147 /* 148 * We now have a segment name to search for, and a directory to search. 149 * 150 * Before tediously performing a linear scan of the directory, 151 * check the name cache to see if the directory/name pair 152 * we are looking for is known already. 153 */ 154 if ((error = cache_lookup(vdp, vpp, cnp)) >= 0) 155 return (error); 156 157 len = cnp->cn_namelen; 158 name = cnp->cn_nameptr; 159 /* 160 * A leading `=' means, we are looking for an associated file 161 */ 162 assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR); 163 if (assoc) { 164 len--; 165 name++; 166 } 167 168 /* 169 * If there is cached information on a previous search of 170 * this directory, pick up where we last left off. 171 * We cache only lookups as these are the most common 172 * and have the greatest payoff. Caching CREATE has little 173 * benefit as it usually must search the entire directory 174 * to determine that the entry does not exist. Caching the 175 * location of the last DELETE or RENAME has not reduced 176 * profiling time and hence has been removed in the interest 177 * of simplicity. 178 */ 179 bmask = imp->im_bmask; 180 if (nameiop != LOOKUP || dp->i_diroff == 0 || 181 dp->i_diroff > dp->i_size) { 182 entryoffsetinblock = 0; 183 dp->i_offset = 0; 184 numdirpasses = 1; 185 } else { 186 dp->i_offset = dp->i_diroff; 187 if ((entryoffsetinblock = dp->i_offset & bmask) && 188 (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, 189 &bp))) 190 return (error); 191 numdirpasses = 2; 192 iso_nchstats.ncs_2passes++; 193 } 194 endsearch = dp->i_size; 195 196 searchloop: 197 while (dp->i_offset < endsearch) { 198 /* 199 * If offset is on a block boundary, 200 * read the next directory block. 201 * Release previous if it exists. 202 */ 203 if ((dp->i_offset & bmask) == 0) { 204 if (bp != NULL) 205 brelse(bp, 0); 206 error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, 207 NULL, &bp); 208 if (error) 209 return (error); 210 entryoffsetinblock = 0; 211 } 212 /* 213 * Get pointer to next entry. 214 */ 215 KASSERT(bp != NULL); 216 ep = (struct iso_directory_record *) 217 ((char *)bp->b_data + entryoffsetinblock); 218 219 reclen = isonum_711(ep->length); 220 if (reclen == 0) { 221 /* skip to next block, if any */ 222 dp->i_offset = 223 (dp->i_offset & ~bmask) + imp->logical_block_size; 224 continue; 225 } 226 227 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 228 /* illegal entry, stop */ 229 break; 230 231 if (entryoffsetinblock + reclen > imp->logical_block_size) 232 /* entries are not allowed to cross boundaries */ 233 break; 234 235 namelen = isonum_711(ep->name_len); 236 237 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 238 /* illegal entry, stop */ 239 break; 240 241 /* 242 * Check for a name match. 243 */ 244 switch (imp->iso_ftype) { 245 default: 246 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 247 if ((len == 1 248 && *name == '.') 249 || (flags & ISDOTDOT)) { 250 if (namelen == 1 251 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 252 /* 253 * Save directory entry's inode number and 254 * release directory buffer. 255 */ 256 dp->i_ino = isodirino(ep, imp); 257 goto found; 258 } 259 if (namelen != 1 260 || ep->name[0] != 0) 261 goto notfound; 262 } else if (!(res = isofncmp(name,len, 263 ep->name,namelen, 264 imp->im_joliet_level))) { 265 if (isonum_711(ep->flags)&2) 266 ino = isodirino(ep, imp); 267 else 268 ino = dbtob(bp->b_blkno) 269 + entryoffsetinblock; 270 saveoffset = dp->i_offset; 271 } else if (ino) 272 goto foundino; 273 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 274 else if (res < 0) 275 goto notfound; 276 else if (res > 0 && numdirpasses == 2) 277 numdirpasses++; 278 #endif 279 } 280 break; 281 case ISO_FTYPE_RRIP: 282 if (isonum_711(ep->flags)&2) 283 ino = isodirino(ep, imp); 284 else 285 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 286 dp->i_ino = ino; 287 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 288 if (namelen == cnp->cn_namelen) { 289 if (imp->im_flags & ISOFSMNT_RRCASEINS) { 290 if (strncasecmp(name, altname, namelen) == 0) 291 goto found; 292 } else { 293 if (memcmp(name, altname, namelen) == 0) 294 goto found; 295 } 296 } 297 ino = 0; 298 break; 299 } 300 dp->i_offset += reclen; 301 entryoffsetinblock += reclen; 302 } 303 if (ino) { 304 foundino: 305 dp->i_ino = ino; 306 if (saveoffset != dp->i_offset) { 307 if (lblkno(imp, dp->i_offset) != 308 lblkno(imp, saveoffset)) { 309 if (bp != NULL) 310 brelse(bp, 0); 311 if ((error = cd9660_blkatoff(vdp, 312 (off_t)saveoffset, NULL, &bp)) != 0) 313 return (error); 314 } 315 entryoffsetinblock = saveoffset & bmask; 316 ep = (struct iso_directory_record *) 317 ((char *)bp->b_data + entryoffsetinblock); 318 dp->i_offset = saveoffset; 319 } 320 goto found; 321 } 322 notfound: 323 /* 324 * If we started in the middle of the directory and failed 325 * to find our target, we must check the beginning as well. 326 */ 327 if (numdirpasses == 2) { 328 numdirpasses--; 329 dp->i_offset = 0; 330 endsearch = dp->i_diroff; 331 goto searchloop; 332 } 333 if (bp != NULL) 334 brelse(bp, 0); 335 336 /* 337 * Insert name into cache (as non-existent) if appropriate. 338 */ 339 if (cnp->cn_flags & MAKEENTRY) 340 cache_enter(vdp, *vpp, cnp); 341 if (nameiop == CREATE || nameiop == RENAME) 342 return (EROFS); 343 return (ENOENT); 344 345 found: 346 if (numdirpasses == 2) 347 iso_nchstats.ncs_pass2++; 348 349 /* 350 * Found component in pathname. 351 * If the final component of path name, save information 352 * in the cache as to where the entry was found. 353 */ 354 if ((flags & ISLASTCN) && nameiop == LOOKUP) 355 dp->i_diroff = dp->i_offset; 356 357 /* 358 * Step through the translation in the name. We do not `iput' the 359 * directory because we may need it again if a symbolic link 360 * is relative to the current directory. Instead we save it 361 * unlocked as "pdp". We must get the target inode before unlocking 362 * the directory to insure that the inode will not be removed 363 * before we get it. We prevent deadlock by always fetching 364 * inodes from the root, moving down the directory tree. Thus 365 * when following backward pointers ".." we must unlock the 366 * parent directory before getting the requested directory. 367 * There is a potential race condition here if both the current 368 * and parent directories are removed before the `iget' for the 369 * inode associated with ".." returns. We hope that this occurs 370 * infrequently since we cannot avoid this race condition without 371 * implementing a sophisticated deadlock detection algorithm. 372 * Note also that this simple deadlock detection scheme will not 373 * work if the file system has any hard links other than ".." 374 * that point backwards in the directory structure. 375 */ 376 pdp = vdp; 377 378 /* 379 * If ino is different from dp->i_ino, 380 * it's a relocated directory. 381 */ 382 brelse(bp, 0); 383 if (flags & ISDOTDOT) { 384 VOP_UNLOCK(pdp); /* race to get the inode */ 385 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 386 dp->i_ino != ino, ep); 387 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY); 388 if (error) 389 return error; 390 *vpp = tdp; 391 } else if (dp->i_number == dp->i_ino) { 392 vref(vdp); /* we want ourself, ie "." */ 393 *vpp = vdp; 394 } else { 395 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 396 dp->i_ino != ino, ep); 397 if (error) 398 return (error); 399 *vpp = tdp; 400 } 401 402 /* 403 * Insert name into cache if appropriate. 404 */ 405 if (cnp->cn_flags & MAKEENTRY) 406 cache_enter(vdp, *vpp, cnp); 407 return (0); 408 } 409 410 /* 411 * Return buffer with the contents of block "offset" from the beginning of 412 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 413 * remaining space in the directory. 414 */ 415 int 416 cd9660_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp) 417 { 418 struct iso_node *ip; 419 struct iso_mnt *imp; 420 struct buf *bp; 421 daddr_t lbn; 422 int bsize, error; 423 424 ip = VTOI(vp); 425 imp = ip->i_mnt; 426 lbn = lblkno(imp, offset); 427 bsize = blksize(imp, ip, lbn); 428 429 if ((error = bread(vp, lbn, bsize, NOCRED, 0, &bp)) != 0) { 430 brelse(bp, 0); 431 *bpp = NULL; 432 return (error); 433 } 434 if (res) 435 *res = (char *)bp->b_data + blkoff(imp, offset); 436 *bpp = bp; 437 return (0); 438 } 439