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 * SPDX-License-Identifier: BSD-3-Clause 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 * @(#)cd9660_lookup.c 8.2 (Berkeley) 1/23/94 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/namei.h> 46 #include <sys/bio.h> 47 #include <sys/buf.h> 48 #include <sys/vnode.h> 49 #include <sys/mount.h> 50 51 #include <fs/cd9660/iso.h> 52 #include <fs/cd9660/cd9660_node.h> 53 #include <fs/cd9660/iso_rrip.h> 54 55 struct cd9660_ino_alloc_arg { 56 cd_ino_t ino; 57 cd_ino_t i_ino; 58 struct iso_directory_record *ep; 59 }; 60 61 static int 62 cd9660_ino_alloc(struct mount *mp, void *arg, int lkflags, 63 struct vnode **vpp) 64 { 65 struct cd9660_ino_alloc_arg *dd_arg; 66 67 dd_arg = arg; 68 return (cd9660_vget_internal(mp, dd_arg->i_ino, lkflags, vpp, 69 dd_arg->i_ino != dd_arg->ino, dd_arg->ep)); 70 } 71 72 /* 73 * Convert a component of a pathname into a pointer to a locked inode. 74 * This is a very central and rather complicated routine. 75 * If the filesystem is not maintained in a strict tree hierarchy, 76 * this can result in a deadlock situation (see comments in code below). 77 * 78 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 79 * whether the name is to be looked up, created, renamed, or deleted. 80 * When CREATE, RENAME, or DELETE is specified, information usable in 81 * creating, renaming, or deleting a directory entry may be calculated. 82 * If flag has LOCKPARENT or'ed into it and the target of the pathname 83 * exists, lookup returns both the target and its parent directory locked. 84 * When creating or renaming and LOCKPARENT is specified, the target may 85 * not be ".". When deleting and LOCKPARENT is specified, the target may 86 * be "."., but the caller must check to ensure it does an vrele and iput 87 * instead of two iputs. 88 * 89 * Overall outline of ufs_lookup: 90 * 91 * search for name in directory, to found or notfound 92 * notfound: 93 * if creating, return locked directory, leaving info on available slots 94 * else return error 95 * found: 96 * if at end of path and deleting, return information to allow delete 97 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target 98 * inode and return info to allow rewrite 99 * if not at end, add name to cache; if at end and neither creating 100 * nor deleting, add name to cache 101 * 102 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. 103 */ 104 int 105 cd9660_lookup(struct vop_cachedlookup_args *ap) 106 { 107 struct vnode *vdp; /* vnode for directory being searched */ 108 struct iso_node *dp; /* inode for directory being searched */ 109 struct iso_mnt *imp; /* filesystem that directory is in */ 110 struct buf *bp; /* a buffer of directory entries */ 111 struct iso_directory_record *ep;/* the current directory entry */ 112 struct iso_directory_record *ep2;/* copy of current directory entry */ 113 int entryoffsetinblock; /* offset of ep in bp's buffer */ 114 int saveoffset = 0; /* offset of last directory entry in dir */ 115 doff_t i_diroff; /* cached i_diroff value. */ 116 doff_t i_offset; /* cached i_offset value. */ 117 int numdirpasses; /* strategy for directory search */ 118 doff_t endsearch; /* offset to end directory search */ 119 struct vnode *pdp; /* saved dp during symlink work */ 120 struct vnode *tdp; /* returned by cd9660_vget_internal */ 121 struct cd9660_ino_alloc_arg dd_arg; 122 u_long bmask; /* block offset mask */ 123 int error; 124 cd_ino_t ino, i_ino; 125 int ltype, reclen; 126 u_short namelen; 127 int isoflags; 128 char altname[NAME_MAX]; 129 int res; 130 int assoc, len; 131 char *name; 132 struct vnode **vpp = ap->a_vpp; 133 struct componentname *cnp = ap->a_cnp; 134 int flags = cnp->cn_flags; 135 int nameiop = cnp->cn_nameiop; 136 137 ep2 = ep = NULL; 138 bp = NULL; 139 *vpp = NULL; 140 vdp = ap->a_dvp; 141 dp = VTOI(vdp); 142 imp = dp->i_mnt; 143 144 /* 145 * We now have a segment name to search for, and a directory to search. 146 */ 147 ino = reclen = 0; 148 i_diroff = dp->i_diroff; 149 len = cnp->cn_namelen; 150 name = cnp->cn_nameptr; 151 152 /* 153 * A leading `=' means, we are looking for an associated file 154 */ 155 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR))) 156 { 157 len--; 158 name++; 159 } 160 161 /* 162 * If there is cached information on a previous search of 163 * this directory, pick up where we last left off. 164 * We cache only lookups as these are the most common 165 * and have the greatest payoff. Caching CREATE has little 166 * benefit as it usually must search the entire directory 167 * to determine that the entry does not exist. Caching the 168 * location of the last DELETE or RENAME has not reduced 169 * profiling time and hence has been removed in the interest 170 * of simplicity. 171 */ 172 bmask = imp->im_bmask; 173 if (nameiop != LOOKUP || i_diroff == 0 || i_diroff > dp->i_size) { 174 entryoffsetinblock = 0; 175 i_offset = 0; 176 numdirpasses = 1; 177 } else { 178 i_offset = i_diroff; 179 if ((entryoffsetinblock = i_offset & bmask) && 180 (error = cd9660_blkatoff(vdp, (off_t)i_offset, NULL, &bp))) 181 return (error); 182 numdirpasses = 2; 183 nchstats.ncs_2passes++; 184 } 185 endsearch = dp->i_size; 186 187 searchloop: 188 while (i_offset < endsearch) { 189 /* 190 * If offset is on a block boundary, 191 * read the next directory block. 192 * Release previous if it exists. 193 */ 194 if ((i_offset & bmask) == 0) { 195 if (bp != NULL) 196 brelse(bp); 197 if ((error = 198 cd9660_blkatoff(vdp, (off_t)i_offset, NULL, &bp)) != 0) 199 return (error); 200 entryoffsetinblock = 0; 201 } 202 /* 203 * Get pointer to next entry. 204 */ 205 ep = (struct iso_directory_record *) 206 ((char *)bp->b_data + entryoffsetinblock); 207 208 reclen = isonum_711(ep->length); 209 if (reclen == 0) { 210 /* skip to next block, if any */ 211 i_offset = 212 (i_offset & ~bmask) + imp->logical_block_size; 213 continue; 214 } 215 216 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 217 /* illegal entry, stop */ 218 break; 219 220 if (entryoffsetinblock + reclen > imp->logical_block_size) 221 /* entries are not allowed to cross boundaries */ 222 break; 223 224 namelen = isonum_711(ep->name_len); 225 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 226 &ep->date[6]: ep->flags); 227 228 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 229 /* illegal entry, stop */ 230 break; 231 232 /* 233 * Check for a name match. 234 */ 235 switch (imp->iso_ftype) { 236 default: 237 if (!(isoflags & 4) == !assoc) { 238 if ((len == 1 239 && *name == '.') 240 || (flags & ISDOTDOT)) { 241 if (namelen == 1 242 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 243 /* 244 * Save directory entry's inode number and 245 * release directory buffer. 246 */ 247 i_ino = isodirino(ep, imp); 248 goto found; 249 } 250 if (namelen != 1 251 || ep->name[0] != 0) 252 goto notfound; 253 } else if (!(res = isofncmp(name, len, 254 ep->name, namelen, 255 imp->joliet_level, 256 imp->im_flags, 257 imp->im_d2l, 258 imp->im_l2d))) { 259 if (isoflags & 2) 260 ino = isodirino(ep, imp); 261 else 262 ino = dbtob(bp->b_blkno) 263 + entryoffsetinblock; 264 saveoffset = i_offset; 265 } else if (ino) 266 goto foundino; 267 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 268 else if (res < 0) 269 goto notfound; 270 else if (res > 0 && numdirpasses == 2) 271 numdirpasses++; 272 #endif 273 } 274 break; 275 case ISO_FTYPE_RRIP: 276 if (isonum_711(ep->flags)&2) 277 ino = isodirino(ep, imp); 278 else 279 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 280 i_ino = ino; 281 cd9660_rrip_getname(ep, altname, &namelen, &i_ino, imp); 282 if (namelen == cnp->cn_namelen 283 && !bcmp(name,altname,namelen)) 284 goto found; 285 ino = 0; 286 break; 287 } 288 i_offset += reclen; 289 entryoffsetinblock += reclen; 290 } 291 if (ino) { 292 foundino: 293 i_ino = ino; 294 if (saveoffset != i_offset) { 295 if (lblkno(imp, i_offset) != 296 lblkno(imp, saveoffset)) { 297 if (bp != NULL) 298 brelse(bp); 299 if ((error = cd9660_blkatoff(vdp, 300 (off_t)saveoffset, NULL, &bp)) != 0) 301 return (error); 302 } 303 entryoffsetinblock = saveoffset & bmask; 304 ep = (struct iso_directory_record *) 305 ((char *)bp->b_data + entryoffsetinblock); 306 reclen = isonum_711(ep->length); 307 i_offset = saveoffset; 308 } 309 goto found; 310 } 311 notfound: 312 /* 313 * If we started in the middle of the directory and failed 314 * to find our target, we must check the beginning as well. 315 */ 316 if (numdirpasses == 2) { 317 numdirpasses--; 318 i_offset = 0; 319 endsearch = i_diroff; 320 goto searchloop; 321 } 322 if (bp != NULL) 323 brelse(bp); 324 325 /* 326 * Insert name into cache (as non-existent) if appropriate. 327 */ 328 if (cnp->cn_flags & MAKEENTRY) 329 cache_enter(vdp, *vpp, cnp); 330 if (nameiop == CREATE || nameiop == RENAME) 331 return (EROFS); 332 return (ENOENT); 333 334 found: 335 if (numdirpasses == 2) 336 nchstats.ncs_pass2++; 337 338 /* 339 * Found component in pathname. 340 * If the final component of path name, save information 341 * in the cache as to where the entry was found. 342 */ 343 if ((flags & ISLASTCN) && nameiop == LOOKUP) 344 dp->i_diroff = i_offset; 345 346 /* 347 * Step through the translation in the name. We do not `vput' the 348 * directory because we may need it again if a symbolic link 349 * is relative to the current directory. Instead we save it 350 * unlocked as "pdp". We must get the target inode before unlocking 351 * the directory to insure that the inode will not be removed 352 * before we get it. We prevent deadlock by always fetching 353 * inodes from the root, moving down the directory tree. Thus 354 * when following backward pointers ".." we must unlock the 355 * parent directory before getting the requested directory. 356 * There is a potential race condition here if both the current 357 * and parent directories are removed before the `vget' for the 358 * inode associated with ".." returns. We hope that this occurs 359 * infrequently since we cannot avoid this race condition without 360 * implementing a sophisticated deadlock detection algorithm. 361 * Note also that this simple deadlock detection scheme will not 362 * work if the filesystem has any hard links other than ".." 363 * that point backwards in the directory structure. 364 */ 365 pdp = vdp; 366 367 /* 368 * Make a copy of the directory entry for non "." lookups so 369 * we can drop the buffer before calling vget() to avoid a 370 * lock order reversal between the vnode lock and the buffer 371 * lock. 372 */ 373 if (dp->i_number != i_ino) { 374 ep2 = malloc(reclen, M_TEMP, M_WAITOK); 375 memcpy(ep2, ep, reclen); 376 ep = ep2; 377 } 378 brelse(bp); 379 380 /* 381 * If ino is different from i_ino, 382 * it's a relocated directory. 383 */ 384 if (flags & ISDOTDOT) { 385 dd_arg.ino = ino; 386 dd_arg.i_ino = i_ino; 387 dd_arg.ep = ep; 388 error = vn_vget_ino_gen(pdp, cd9660_ino_alloc, &dd_arg, 389 cnp->cn_lkflags, &tdp); 390 free(ep2, M_TEMP); 391 if (error != 0) 392 return (error); 393 *vpp = tdp; 394 } else if (dp->i_number == i_ino) { 395 VREF(vdp); /* we want ourself, ie "." */ 396 /* 397 * When we lookup "." we still can be asked to lock it 398 * differently. 399 */ 400 ltype = cnp->cn_lkflags & LK_TYPE_MASK; 401 if (ltype != VOP_ISLOCKED(vdp)) { 402 if (ltype == LK_EXCLUSIVE) 403 vn_lock(vdp, LK_UPGRADE | LK_RETRY); 404 else /* if (ltype == LK_SHARED) */ 405 vn_lock(vdp, LK_DOWNGRADE | LK_RETRY); 406 } 407 *vpp = vdp; 408 } else { 409 error = cd9660_vget_internal(vdp->v_mount, i_ino, 410 cnp->cn_lkflags, &tdp, 411 i_ino != ino, ep); 412 free(ep2, M_TEMP); 413 if (error) 414 return (error); 415 *vpp = tdp; 416 } 417 418 /* 419 * Insert name into cache if appropriate. 420 */ 421 if (cnp->cn_flags & MAKEENTRY) 422 cache_enter(vdp, *vpp, cnp); 423 return (0); 424 } 425 426 /* 427 * Return buffer with the contents of block "offset" from the beginning of 428 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 429 * remaining space in the directory. 430 */ 431 int 432 cd9660_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp) 433 { 434 struct iso_node *ip; 435 struct iso_mnt *imp; 436 struct buf *bp; 437 daddr_t lbn; 438 int bsize, bshift, error; 439 440 ip = VTOI(vp); 441 imp = ip->i_mnt; 442 lbn = lblkno(imp, offset); 443 bsize = blksize(imp, ip, lbn); 444 bshift = imp->im_bshift; 445 446 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) { 447 brelse(bp); 448 *bpp = NULL; 449 return (error); 450 } 451 452 /* 453 * We must BMAP the buffer because the directory code may use b_blkno 454 * to calculate the inode for certain types of directory entries. 455 * We could get away with not doing it before we VMIO-backed the 456 * directories because the buffers would get freed atomically with 457 * the invalidation of their data. But with VMIO-backed buffers 458 * the buffers may be freed and then later reconstituted - and the 459 * reconstituted buffer will have no knowledge of b_blkno. 460 */ 461 if (bp->b_blkno == bp->b_lblkno) { 462 bp->b_blkno = (ip->iso_start + bp->b_lblkno) << (bshift - DEV_BSHIFT); 463 } 464 465 if (res) 466 *res = (char *)bp->b_data + blkoff(imp, offset); 467 *bpp = bp; 468 return (0); 469 }
Cache object: bf3361b08866656075b1dca92ee01826
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