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 struct thread *td = cnp->cn_thread; 123 124 ep2 = ep = NULL; 125 bp = NULL; 126 *vpp = NULL; 127 vdp = ap->a_dvp; 128 dp = VTOI(vdp); 129 imp = dp->i_mnt; 130 131 /* 132 * We now have a segment name to search for, and a directory to search. 133 */ 134 ino = reclen = 0; 135 i_diroff = dp->i_diroff; 136 len = cnp->cn_namelen; 137 name = cnp->cn_nameptr; 138 139 /* 140 * A leading `=' means, we are looking for an associated file 141 */ 142 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR))) 143 { 144 len--; 145 name++; 146 } 147 148 /* 149 * If there is cached information on a previous search of 150 * this directory, pick up where we last left off. 151 * We cache only lookups as these are the most common 152 * and have the greatest payoff. Caching CREATE has little 153 * benefit as it usually must search the entire directory 154 * to determine that the entry does not exist. Caching the 155 * location of the last DELETE or RENAME has not reduced 156 * profiling time and hence has been removed in the interest 157 * of simplicity. 158 */ 159 bmask = imp->im_bmask; 160 if (nameiop != LOOKUP || i_diroff == 0 || i_diroff > dp->i_size) { 161 entryoffsetinblock = 0; 162 i_offset = 0; 163 numdirpasses = 1; 164 } else { 165 i_offset = i_diroff; 166 if ((entryoffsetinblock = i_offset & bmask) && 167 (error = cd9660_blkatoff(vdp, (off_t)i_offset, NULL, &bp))) 168 return (error); 169 numdirpasses = 2; 170 nchstats.ncs_2passes++; 171 } 172 endsearch = dp->i_size; 173 174 searchloop: 175 while (i_offset < endsearch) { 176 /* 177 * If offset is on a block boundary, 178 * read the next directory block. 179 * Release previous if it exists. 180 */ 181 if ((i_offset & bmask) == 0) { 182 if (bp != NULL) 183 brelse(bp); 184 if ((error = 185 cd9660_blkatoff(vdp, (off_t)i_offset, NULL, &bp)) != 0) 186 return (error); 187 entryoffsetinblock = 0; 188 } 189 /* 190 * Get pointer to next entry. 191 */ 192 ep = (struct iso_directory_record *) 193 ((char *)bp->b_data + entryoffsetinblock); 194 195 reclen = isonum_711(ep->length); 196 if (reclen == 0) { 197 /* skip to next block, if any */ 198 i_offset = 199 (i_offset & ~bmask) + imp->logical_block_size; 200 continue; 201 } 202 203 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 204 /* illegal entry, stop */ 205 break; 206 207 if (entryoffsetinblock + reclen > imp->logical_block_size) 208 /* entries are not allowed to cross boundaries */ 209 break; 210 211 namelen = isonum_711(ep->name_len); 212 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 213 &ep->date[6]: ep->flags); 214 215 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 216 /* illegal entry, stop */ 217 break; 218 219 /* 220 * Check for a name match. 221 */ 222 switch (imp->iso_ftype) { 223 default: 224 if (!(isoflags & 4) == !assoc) { 225 if ((len == 1 226 && *name == '.') 227 || (flags & ISDOTDOT)) { 228 if (namelen == 1 229 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 230 /* 231 * Save directory entry's inode number and 232 * release directory buffer. 233 */ 234 i_ino = isodirino(ep, imp); 235 goto found; 236 } 237 if (namelen != 1 238 || ep->name[0] != 0) 239 goto notfound; 240 } else if (!(res = isofncmp(name, len, 241 ep->name, namelen, 242 imp->joliet_level, 243 imp->im_flags, 244 imp->im_d2l, 245 imp->im_l2d))) { 246 if (isoflags & 2) 247 ino = isodirino(ep, imp); 248 else 249 ino = dbtob(bp->b_blkno) 250 + entryoffsetinblock; 251 saveoffset = i_offset; 252 } else if (ino) 253 goto foundino; 254 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 255 else if (res < 0) 256 goto notfound; 257 else if (res > 0 && numdirpasses == 2) 258 numdirpasses++; 259 #endif 260 } 261 break; 262 case ISO_FTYPE_RRIP: 263 if (isonum_711(ep->flags)&2) 264 ino = isodirino(ep, imp); 265 else 266 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 267 i_ino = ino; 268 cd9660_rrip_getname(ep, altname, &namelen, &i_ino, imp); 269 if (namelen == cnp->cn_namelen 270 && !bcmp(name,altname,namelen)) 271 goto found; 272 ino = 0; 273 break; 274 } 275 i_offset += reclen; 276 entryoffsetinblock += reclen; 277 } 278 if (ino) { 279 foundino: 280 i_ino = ino; 281 if (saveoffset != i_offset) { 282 if (lblkno(imp, i_offset) != 283 lblkno(imp, saveoffset)) { 284 if (bp != NULL) 285 brelse(bp); 286 if ((error = cd9660_blkatoff(vdp, 287 (off_t)saveoffset, NULL, &bp)) != 0) 288 return (error); 289 } 290 entryoffsetinblock = saveoffset & bmask; 291 ep = (struct iso_directory_record *) 292 ((char *)bp->b_data + entryoffsetinblock); 293 reclen = isonum_711(ep->length); 294 i_offset = saveoffset; 295 } 296 goto found; 297 } 298 notfound: 299 /* 300 * If we started in the middle of the directory and failed 301 * to find our target, we must check the beginning as well. 302 */ 303 if (numdirpasses == 2) { 304 numdirpasses--; 305 i_offset = 0; 306 endsearch = i_diroff; 307 goto searchloop; 308 } 309 if (bp != NULL) 310 brelse(bp); 311 312 /* 313 * Insert name into cache (as non-existent) if appropriate. 314 */ 315 if (cnp->cn_flags & MAKEENTRY) 316 cache_enter(vdp, *vpp, cnp); 317 if (nameiop == CREATE || nameiop == RENAME) 318 return (EROFS); 319 return (ENOENT); 320 321 found: 322 if (numdirpasses == 2) 323 nchstats.ncs_pass2++; 324 325 /* 326 * Found component in pathname. 327 * If the final component of path name, save information 328 * in the cache as to where the entry was found. 329 */ 330 if ((flags & ISLASTCN) && nameiop == LOOKUP) 331 dp->i_diroff = i_offset; 332 333 /* 334 * Step through the translation in the name. We do not `vput' the 335 * directory because we may need it again if a symbolic link 336 * is relative to the current directory. Instead we save it 337 * unlocked as "pdp". We must get the target inode before unlocking 338 * the directory to insure that the inode will not be removed 339 * before we get it. We prevent deadlock by always fetching 340 * inodes from the root, moving down the directory tree. Thus 341 * when following backward pointers ".." we must unlock the 342 * parent directory before getting the requested directory. 343 * There is a potential race condition here if both the current 344 * and parent directories are removed before the `vget' for the 345 * inode associated with ".." returns. We hope that this occurs 346 * infrequently since we cannot avoid this race condition without 347 * implementing a sophisticated deadlock detection algorithm. 348 * Note also that this simple deadlock detection scheme will not 349 * work if the filesystem has any hard links other than ".." 350 * that point backwards in the directory structure. 351 */ 352 pdp = vdp; 353 354 /* 355 * Make a copy of the directory entry for non "." lookups so 356 * we can drop the buffer before calling vget() to avoid a 357 * lock order reversal between the vnode lock and the buffer 358 * lock. 359 */ 360 if (dp->i_number != i_ino) { 361 ep2 = malloc(reclen, M_TEMP, M_WAITOK); 362 bcopy(ep, ep2, reclen); 363 ep = ep2; 364 } 365 brelse(bp); 366 367 /* 368 * If ino is different from i_ino, 369 * it's a relocated directory. 370 */ 371 if (flags & ISDOTDOT) { 372 /* 373 * Expanded copy of vn_vget_ino() so that we can use 374 * cd9660_vget_internal(). 375 */ 376 mp = pdp->v_mount; 377 ltype = VOP_ISLOCKED(pdp, td); 378 error = vfs_busy(mp, LK_NOWAIT, NULL, td); 379 if (error != 0) { 380 VOP_UNLOCK(pdp, 0, td); 381 error = vfs_busy(mp, 0, NULL, td); 382 vn_lock(pdp, ltype | LK_RETRY, td); 383 if (error) 384 return (ENOENT); 385 if (pdp->v_iflag & VI_DOOMED) { 386 vfs_unbusy(mp, td); 387 return (ENOENT); 388 } 389 } 390 VOP_UNLOCK(pdp, 0, td); 391 error = cd9660_vget_internal(vdp->v_mount, i_ino, 392 cnp->cn_lkflags, &tdp, 393 i_ino != ino, ep); 394 free(ep2, M_TEMP); 395 vfs_unbusy(mp, td); 396 vn_lock(pdp, ltype | LK_RETRY, td); 397 if (pdp->v_iflag & VI_DOOMED) { 398 if (error == 0) 399 vput(tdp); 400 error = ENOENT; 401 } 402 if (error) 403 return (error); 404 *vpp = tdp; 405 } else if (dp->i_number == i_ino) { 406 VREF(vdp); /* we want ourself, ie "." */ 407 /* 408 * When we lookup "." we still can be asked to lock it 409 * differently. 410 */ 411 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 412 if (ltype != VOP_ISLOCKED(vdp, td)) { 413 if (ltype == LK_EXCLUSIVE) 414 vn_lock(vdp, LK_UPGRADE | LK_RETRY, td); 415 else /* if (ltype == LK_SHARED) */ 416 vn_lock(vdp, LK_DOWNGRADE | LK_RETRY, td); 417 } 418 *vpp = vdp; 419 } else { 420 error = cd9660_vget_internal(vdp->v_mount, i_ino, 421 cnp->cn_lkflags, &tdp, 422 i_ino != ino, ep); 423 free(ep2, M_TEMP); 424 if (error) 425 return (error); 426 *vpp = tdp; 427 } 428 429 /* 430 * Insert name into cache if appropriate. 431 */ 432 if (cnp->cn_flags & MAKEENTRY) 433 cache_enter(vdp, *vpp, cnp); 434 return (0); 435 } 436 437 /* 438 * Return buffer with the contents of block "offset" from the beginning of 439 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 440 * remaining space in the directory. 441 */ 442 int 443 cd9660_blkatoff(vp, offset, res, bpp) 444 struct vnode *vp; 445 off_t offset; 446 char **res; 447 struct buf **bpp; 448 { 449 struct iso_node *ip; 450 struct iso_mnt *imp; 451 struct buf *bp; 452 daddr_t lbn; 453 int bsize, bshift, error; 454 455 ip = VTOI(vp); 456 imp = ip->i_mnt; 457 lbn = lblkno(imp, offset); 458 bsize = blksize(imp, ip, lbn); 459 bshift = imp->im_bshift; 460 461 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) { 462 brelse(bp); 463 *bpp = NULL; 464 return (error); 465 } 466 467 /* 468 * We must BMAP the buffer because the directory code may use b_blkno 469 * to calculate the inode for certain types of directory entries. 470 * We could get away with not doing it before we VMIO-backed the 471 * directories because the buffers would get freed atomically with 472 * the invalidation of their data. But with VMIO-backed buffers 473 * the buffers may be freed and then later reconstituted - and the 474 * reconstituted buffer will have no knowledge of b_blkno. 475 */ 476 if (bp->b_blkno == bp->b_lblkno) { 477 bp->b_blkno = (ip->iso_start + bp->b_lblkno) << (bshift - DEV_BSHIFT); 478 } 479 480 if (res) 481 *res = (char *)bp->b_data + blkoff(imp, offset); 482 *bpp = bp; 483 return (0); 484 }
Cache object: d1252d993947fb0027264f10c30f2143
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