Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/cd9660/cd9660_lookup.c
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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 * 4. 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 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/namei.h> 44 #include <sys/bio.h> 45 #include <sys/buf.h> 46 #include <sys/vnode.h> 47 #include <sys/mount.h> 48 49 #include <fs/cd9660/iso.h> 50 #include <fs/cd9660/cd9660_node.h> 51 #include <fs/cd9660/iso_rrip.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 int 86 cd9660_lookup(ap) 87 struct vop_cachedlookup_args /* { 88 struct vnode *a_dvp; 89 struct vnode **a_vpp; 90 struct componentname *a_cnp; 91 } */ *ap; 92 { 93 struct vnode *vdp; /* vnode for directory being searched */ 94 struct iso_node *dp; /* inode for directory being searched */ 95 struct iso_mnt *imp; /* filesystem that directory is in */ 96 struct buf *bp; /* a buffer of directory entries */ 97 struct iso_directory_record *ep;/* the current directory entry */ 98 struct iso_directory_record *ep2;/* copy of current directory entry */ 99 int entryoffsetinblock; /* offset of ep in bp's buffer */ 100 int saveoffset = 0; /* offset of last directory entry in dir */ 101 doff_t i_diroff; /* cached i_diroff value. */ 102 doff_t i_offset; /* cached i_offset value. */ 103 int numdirpasses; /* strategy for directory search */ 104 doff_t endsearch; /* offset to end directory search */ 105 struct vnode *pdp; /* saved dp during symlink work */ 106 struct vnode *tdp; /* returned by cd9660_vget_internal */ 107 u_long bmask; /* block offset mask */ 108 int error; 109 ino_t ino, i_ino; 110 int ltype, reclen; 111 u_short namelen; 112 int isoflags; 113 char altname[NAME_MAX]; 114 int res; 115 int assoc, len; 116 char *name; 117 struct mount *mp; 118 struct vnode **vpp = ap->a_vpp; 119 struct componentname *cnp = ap->a_cnp; 120 int flags = cnp->cn_flags; 121 int nameiop = cnp->cn_nameiop; 122 123 ep2 = ep = NULL; 124 bp = NULL; 125 *vpp = NULL; 126 vdp = ap->a_dvp; 127 dp = VTOI(vdp); 128 imp = dp->i_mnt; 129 130 /* 131 * We now have a segment name to search for, and a directory to search. 132 */ 133 ino = reclen = 0; 134 i_diroff = dp->i_diroff; 135 len = cnp->cn_namelen; 136 name = cnp->cn_nameptr; 137 138 /* 139 * A leading `=' means, we are looking for an associated file 140 */ 141 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR))) 142 { 143 len--; 144 name++; 145 } 146 147 /* 148 * If there is cached information on a previous search of 149 * this directory, pick up where we last left off. 150 * We cache only lookups as these are the most common 151 * and have the greatest payoff. Caching CREATE has little 152 * benefit as it usually must search the entire directory 153 * to determine that the entry does not exist. Caching the 154 * location of the last DELETE or RENAME has not reduced 155 * profiling time and hence has been removed in the interest 156 * of simplicity. 157 */ 158 bmask = imp->im_bmask; 159 if (nameiop != LOOKUP || i_diroff == 0 || i_diroff > dp->i_size) { 160 entryoffsetinblock = 0; 161 i_offset = 0; 162 numdirpasses = 1; 163 } else { 164 i_offset = i_diroff; 165 if ((entryoffsetinblock = i_offset & bmask) && 166 (error = cd9660_blkatoff(vdp, (off_t)i_offset, NULL, &bp))) 167 return (error); 168 numdirpasses = 2; 169 nchstats.ncs_2passes++; 170 } 171 endsearch = dp->i_size; 172 173 searchloop: 174 while (i_offset < endsearch) { 175 /* 176 * If offset is on a block boundary, 177 * read the next directory block. 178 * Release previous if it exists. 179 */ 180 if ((i_offset & bmask) == 0) { 181 if (bp != NULL) 182 brelse(bp); 183 if ((error = 184 cd9660_blkatoff(vdp, (off_t)i_offset, NULL, &bp)) != 0) 185 return (error); 186 entryoffsetinblock = 0; 187 } 188 /* 189 * Get pointer to next entry. 190 */ 191 ep = (struct iso_directory_record *) 192 ((char *)bp->b_data + entryoffsetinblock); 193 194 reclen = isonum_711(ep->length); 195 if (reclen == 0) { 196 /* skip to next block, if any */ 197 i_offset = 198 (i_offset & ~bmask) + imp->logical_block_size; 199 continue; 200 } 201 202 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 203 /* illegal entry, stop */ 204 break; 205 206 if (entryoffsetinblock + reclen > imp->logical_block_size) 207 /* entries are not allowed to cross boundaries */ 208 break; 209 210 namelen = isonum_711(ep->name_len); 211 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 212 &ep->date[6]: ep->flags); 213 214 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 215 /* illegal entry, stop */ 216 break; 217 218 /* 219 * Check for a name match. 220 */ 221 switch (imp->iso_ftype) { 222 default: 223 if (!(isoflags & 4) == !assoc) { 224 if ((len == 1 225 && *name == '.') 226 || (flags & ISDOTDOT)) { 227 if (namelen == 1 228 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 229 /* 230 * Save directory entry's inode number and 231 * release directory buffer. 232 */ 233 i_ino = isodirino(ep, imp); 234 goto found; 235 } 236 if (namelen != 1 237 || ep->name[0] != 0) 238 goto notfound; 239 } else if (!(res = isofncmp(name, len, 240 ep->name, namelen, 241 imp->joliet_level, 242 imp->im_flags, 243 imp->im_d2l, 244 imp->im_l2d))) { 245 if (isoflags & 2) 246 ino = isodirino(ep, imp); 247 else 248 ino = dbtob(bp->b_blkno) 249 + entryoffsetinblock; 250 saveoffset = i_offset; 251 } else if (ino) 252 goto foundino; 253 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 254 else if (res < 0) 255 goto notfound; 256 else if (res > 0 && numdirpasses == 2) 257 numdirpasses++; 258 #endif 259 } 260 break; 261 case ISO_FTYPE_RRIP: 262 if (isonum_711(ep->flags)&2) 263 ino = isodirino(ep, imp); 264 else 265 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 266 i_ino = ino; 267 cd9660_rrip_getname(ep, altname, &namelen, &i_ino, imp); 268 if (namelen == cnp->cn_namelen 269 && !bcmp(name,altname,namelen)) 270 goto found; 271 ino = 0; 272 break; 273 } 274 i_offset += reclen; 275 entryoffsetinblock += reclen; 276 } 277 if (ino) { 278 foundino: 279 i_ino = ino; 280 if (saveoffset != i_offset) { 281 if (lblkno(imp, i_offset) != 282 lblkno(imp, saveoffset)) { 283 if (bp != NULL) 284 brelse(bp); 285 if ((error = cd9660_blkatoff(vdp, 286 (off_t)saveoffset, NULL, &bp)) != 0) 287 return (error); 288 } 289 entryoffsetinblock = saveoffset & bmask; 290 ep = (struct iso_directory_record *) 291 ((char *)bp->b_data + entryoffsetinblock); 292 reclen = isonum_711(ep->length); 293 i_offset = saveoffset; 294 } 295 goto found; 296 } 297 notfound: 298 /* 299 * If we started in the middle of the directory and failed 300 * to find our target, we must check the beginning as well. 301 */ 302 if (numdirpasses == 2) { 303 numdirpasses--; 304 i_offset = 0; 305 endsearch = i_diroff; 306 goto searchloop; 307 } 308 if (bp != NULL) 309 brelse(bp); 310 311 /* 312 * Insert name into cache (as non-existent) if appropriate. 313 */ 314 if (cnp->cn_flags & MAKEENTRY) 315 cache_enter(vdp, *vpp, cnp); 316 if (nameiop == CREATE || nameiop == RENAME) 317 return (EROFS); 318 return (ENOENT); 319 320 found: 321 if (numdirpasses == 2) 322 nchstats.ncs_pass2++; 323 324 /* 325 * Found component in pathname. 326 * If the final component of path name, save information 327 * in the cache as to where the entry was found. 328 */ 329 if ((flags & ISLASTCN) && nameiop == LOOKUP) 330 dp->i_diroff = i_offset; 331 332 /* 333 * Step through the translation in the name. We do not `vput' the 334 * directory because we may need it again if a symbolic link 335 * is relative to the current directory. Instead we save it 336 * unlocked as "pdp". We must get the target inode before unlocking 337 * the directory to insure that the inode will not be removed 338 * before we get it. We prevent deadlock by always fetching 339 * inodes from the root, moving down the directory tree. Thus 340 * when following backward pointers ".." we must unlock the 341 * parent directory before getting the requested directory. 342 * There is a potential race condition here if both the current 343 * and parent directories are removed before the `vget' for the 344 * inode associated with ".." returns. We hope that this occurs 345 * infrequently since we cannot avoid this race condition without 346 * implementing a sophisticated deadlock detection algorithm. 347 * Note also that this simple deadlock detection scheme will not 348 * work if the filesystem has any hard links other than ".." 349 * that point backwards in the directory structure. 350 */ 351 pdp = vdp; 352 353 /* 354 * Make a copy of the directory entry for non "." lookups so 355 * we can drop the buffer before calling vget() to avoid a 356 * lock order reversal between the vnode lock and the buffer 357 * lock. 358 */ 359 if (dp->i_number != i_ino) { 360 ep2 = malloc(reclen, M_TEMP, M_WAITOK); 361 bcopy(ep, ep2, reclen); 362 ep = ep2; 363 } 364 brelse(bp); 365 366 /* 367 * If ino is different from i_ino, 368 * it's a relocated directory. 369 */ 370 if (flags & ISDOTDOT) { 371 /* 372 * Expanded copy of vn_vget_ino() so that we can use 373 * cd9660_vget_internal(). 374 */ 375 mp = pdp->v_mount; 376 ltype = VOP_ISLOCKED(pdp); 377 error = vfs_busy(mp, MBF_NOWAIT); 378 if (error != 0) { 379 vfs_ref(mp); 380 VOP_UNLOCK(pdp, 0); 381 error = vfs_busy(mp, 0); 382 vn_lock(pdp, ltype | LK_RETRY); 383 vfs_rel(mp); 384 if (error) 385 return (ENOENT); 386 if (pdp->v_iflag & VI_DOOMED) { 387 vfs_unbusy(mp); 388 return (ENOENT); 389 } 390 } 391 VOP_UNLOCK(pdp, 0); 392 error = cd9660_vget_internal(vdp->v_mount, i_ino, 393 cnp->cn_lkflags, &tdp, 394 i_ino != ino, ep); 395 free(ep2, M_TEMP); 396 vfs_unbusy(mp); 397 vn_lock(pdp, ltype | LK_RETRY); 398 if (pdp->v_iflag & VI_DOOMED) { 399 if (error == 0) 400 vput(tdp); 401 error = ENOENT; 402 } 403 if (error) 404 return (error); 405 *vpp = tdp; 406 } else if (dp->i_number == i_ino) { 407 VREF(vdp); /* we want ourself, ie "." */ 408 /* 409 * When we lookup "." we still can be asked to lock it 410 * differently. 411 */ 412 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 413 if (ltype != VOP_ISLOCKED(vdp)) { 414 if (ltype == LK_EXCLUSIVE) 415 vn_lock(vdp, LK_UPGRADE | LK_RETRY); 416 else /* if (ltype == LK_SHARED) */ 417 vn_lock(vdp, LK_DOWNGRADE | LK_RETRY); 418 } 419 *vpp = vdp; 420 } else { 421 error = cd9660_vget_internal(vdp->v_mount, i_ino, 422 cnp->cn_lkflags, &tdp, 423 i_ino != ino, ep); 424 free(ep2, M_TEMP); 425 if (error) 426 return (error); 427 *vpp = tdp; 428 } 429 430 /* 431 * Insert name into cache if appropriate. 432 */ 433 if (cnp->cn_flags & MAKEENTRY) 434 cache_enter(vdp, *vpp, cnp); 435 return (0); 436 } 437 438 /* 439 * Return buffer with the contents of block "offset" from the beginning of 440 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 441 * remaining space in the directory. 442 */ 443 int 444 cd9660_blkatoff(vp, offset, res, bpp) 445 struct vnode *vp; 446 off_t offset; 447 char **res; 448 struct buf **bpp; 449 { 450 struct iso_node *ip; 451 struct iso_mnt *imp; 452 struct buf *bp; 453 daddr_t lbn; 454 int bsize, bshift, error; 455 456 ip = VTOI(vp); 457 imp = ip->i_mnt; 458 lbn = lblkno(imp, offset); 459 bsize = blksize(imp, ip, lbn); 460 bshift = imp->im_bshift; 461 462 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) { 463 brelse(bp); 464 *bpp = NULL; 465 return (error); 466 } 467 468 /* 469 * We must BMAP the buffer because the directory code may use b_blkno 470 * to calculate the inode for certain types of directory entries. 471 * We could get away with not doing it before we VMIO-backed the 472 * directories because the buffers would get freed atomically with 473 * the invalidation of their data. But with VMIO-backed buffers 474 * the buffers may be freed and then later reconstituted - and the 475 * reconstituted buffer will have no knowledge of b_blkno. 476 */ 477 if (bp->b_blkno == bp->b_lblkno) { 478 bp->b_blkno = (ip->iso_start + bp->b_lblkno) << (bshift - DEV_BSHIFT); 479 } 480 481 if (res) 482 *res = (char *)bp->b_data + blkoff(imp, offset); 483 *bpp = bp; 484 return (0); 485 }
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