Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/isofs/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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91 39 * @(#)cd9660_lookup.c 8.2 (Berkeley) 1/23/94 40 */ 41 42 #include <sys/cdefs.h> 43 __FBSDID("$FreeBSD: releng/5.2/sys/isofs/cd9660/cd9660_lookup.c 120492 2003-09-26 20:26:25Z fjoe $"); 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/namei.h> 48 #include <sys/bio.h> 49 #include <sys/buf.h> 50 #include <sys/vnode.h> 51 #include <sys/mount.h> 52 53 #include <isofs/cd9660/iso.h> 54 #include <isofs/cd9660/cd9660_node.h> 55 #include <isofs/cd9660/iso_rrip.h> 56 57 /* 58 * Convert a component of a pathname into a pointer to a locked inode. 59 * This is a very central and rather complicated routine. 60 * If the filesystem is not maintained in a strict tree hierarchy, 61 * this can result in a deadlock situation (see comments in code below). 62 * 63 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 64 * whether the name is to be looked up, created, renamed, or deleted. 65 * When CREATE, RENAME, or DELETE is specified, information usable in 66 * creating, renaming, or deleting a directory entry may be calculated. 67 * If flag has LOCKPARENT or'ed into it and the target of the pathname 68 * exists, lookup returns both the target and its parent directory locked. 69 * When creating or renaming and LOCKPARENT is specified, the target may 70 * not be ".". When deleting and LOCKPARENT is specified, the target may 71 * be "."., but the caller must check to ensure it does an vrele and iput 72 * instead of two iputs. 73 * 74 * Overall outline of ufs_lookup: 75 * 76 * search for name in directory, to found or notfound 77 * notfound: 78 * if creating, return locked directory, leaving info on available slots 79 * else return error 80 * found: 81 * if at end of path and deleting, return information to allow delete 82 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target 83 * inode and return info to allow rewrite 84 * if not at end, add name to cache; if at end and neither creating 85 * nor deleting, add name to cache 86 * 87 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. 88 */ 89 int 90 cd9660_lookup(ap) 91 struct vop_cachedlookup_args /* { 92 struct vnode *a_dvp; 93 struct vnode **a_vpp; 94 struct componentname *a_cnp; 95 } */ *ap; 96 { 97 register struct vnode *vdp; /* vnode for directory being searched */ 98 register struct iso_node *dp; /* inode for directory being searched */ 99 register struct iso_mnt *imp; /* filesystem that directory is in */ 100 struct buf *bp; /* a buffer of directory entries */ 101 struct iso_directory_record *ep = 0;/* the current directory entry */ 102 int entryoffsetinblock; /* offset of ep in bp's buffer */ 103 int saveoffset = 0; /* offset of last directory entry in dir */ 104 int numdirpasses; /* strategy for directory search */ 105 doff_t endsearch; /* offset to end directory search */ 106 struct vnode *pdp; /* saved dp during symlink work */ 107 struct vnode *tdp; /* returned by cd9660_vget_internal */ 108 u_long bmask; /* block offset mask */ 109 int lockparent; /* 1 => lockparent flag is set */ 110 int error; 111 ino_t ino = 0; 112 int reclen; 113 u_short namelen; 114 int isoflags; 115 char altname[NAME_MAX]; 116 int res; 117 int assoc, len; 118 char *name; 119 struct vnode **vpp = ap->a_vpp; 120 struct componentname *cnp = ap->a_cnp; 121 int flags = cnp->cn_flags; 122 int nameiop = cnp->cn_nameiop; 123 struct thread *td = cnp->cn_thread; 124 125 bp = NULL; 126 *vpp = NULL; 127 vdp = ap->a_dvp; 128 dp = VTOI(vdp); 129 imp = dp->i_mnt; 130 lockparent = flags & LOCKPARENT; 131 cnp->cn_flags &= ~PDIRUNLOCK; 132 133 /* 134 * We now have a segment name to search for, and a directory to search. 135 */ 136 137 len = cnp->cn_namelen; 138 name = cnp->cn_nameptr; 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 || dp->i_diroff == 0 || 161 dp->i_diroff > dp->i_size) { 162 entryoffsetinblock = 0; 163 dp->i_offset = 0; 164 numdirpasses = 1; 165 } else { 166 dp->i_offset = dp->i_diroff; 167 if ((entryoffsetinblock = dp->i_offset & bmask) && 168 (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp))) 169 return (error); 170 numdirpasses = 2; 171 nchstats.ncs_2passes++; 172 } 173 endsearch = dp->i_size; 174 175 searchloop: 176 while (dp->i_offset < endsearch) { 177 /* 178 * If offset is on a block boundary, 179 * read the next directory block. 180 * Release previous if it exists. 181 */ 182 if ((dp->i_offset & bmask) == 0) { 183 if (bp != NULL) 184 brelse(bp); 185 if ((error = 186 cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp)) != 0) 187 return (error); 188 entryoffsetinblock = 0; 189 } 190 /* 191 * Get pointer to next entry. 192 */ 193 ep = (struct iso_directory_record *) 194 ((char *)bp->b_data + entryoffsetinblock); 195 196 reclen = isonum_711(ep->length); 197 if (reclen == 0) { 198 /* skip to next block, if any */ 199 dp->i_offset = 200 (dp->i_offset & ~bmask) + imp->logical_block_size; 201 continue; 202 } 203 204 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 205 /* illegal entry, stop */ 206 break; 207 208 if (entryoffsetinblock + reclen > imp->logical_block_size) 209 /* entries are not allowed to cross boundaries */ 210 break; 211 212 namelen = isonum_711(ep->name_len); 213 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 214 &ep->date[6]: ep->flags); 215 216 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 217 /* illegal entry, stop */ 218 break; 219 220 /* 221 * Check for a name match. 222 */ 223 switch (imp->iso_ftype) { 224 default: 225 if (!(isoflags & 4) == !assoc) { 226 if ((len == 1 227 && *name == '.') 228 || (flags & ISDOTDOT)) { 229 if (namelen == 1 230 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 231 /* 232 * Save directory entry's inode number and 233 * release directory buffer. 234 */ 235 dp->i_ino = isodirino(ep, imp); 236 goto found; 237 } 238 if (namelen != 1 239 || ep->name[0] != 0) 240 goto notfound; 241 } else if (!(res = isofncmp(name, len, 242 ep->name, namelen, 243 imp->joliet_level, 244 imp->im_flags, 245 imp->im_d2l, 246 imp->im_l2d))) { 247 if (isoflags & 2) 248 ino = isodirino(ep, imp); 249 else 250 ino = dbtob(bp->b_blkno) 251 + entryoffsetinblock; 252 saveoffset = dp->i_offset; 253 } else if (ino) 254 goto foundino; 255 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 256 else if (res < 0) 257 goto notfound; 258 else if (res > 0 && numdirpasses == 2) 259 numdirpasses++; 260 #endif 261 } 262 break; 263 case ISO_FTYPE_RRIP: 264 if (isonum_711(ep->flags)&2) 265 ino = isodirino(ep, imp); 266 else 267 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 268 dp->i_ino = ino; 269 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 270 if (namelen == cnp->cn_namelen 271 && !bcmp(name,altname,namelen)) 272 goto found; 273 ino = 0; 274 break; 275 } 276 dp->i_offset += reclen; 277 entryoffsetinblock += reclen; 278 } 279 if (ino) { 280 foundino: 281 dp->i_ino = ino; 282 if (saveoffset != dp->i_offset) { 283 if (lblkno(imp, dp->i_offset) != 284 lblkno(imp, saveoffset)) { 285 if (bp != NULL) 286 brelse(bp); 287 if ((error = cd9660_blkatoff(vdp, 288 (off_t)saveoffset, NULL, &bp)) != 0) 289 return (error); 290 } 291 entryoffsetinblock = saveoffset & bmask; 292 ep = (struct iso_directory_record *) 293 ((char *)bp->b_data + entryoffsetinblock); 294 dp->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 dp->i_offset = 0; 306 endsearch = dp->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 = dp->i_offset; 332 333 /* 334 * Step through the translation in the name. We do not `iput' 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 `iget' 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 * If ino is different from dp->i_ino, 355 * it's a relocated directory. 356 */ 357 if (flags & ISDOTDOT) { 358 VOP_UNLOCK(pdp, 0, td); /* race to get the inode */ 359 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, 360 LK_EXCLUSIVE, &tdp, 361 dp->i_ino != ino, ep); 362 brelse(bp); 363 if (error) { 364 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, td); 365 return (error); 366 } 367 if (lockparent && (flags & ISLASTCN)) { 368 if ((error = vn_lock(pdp, LK_EXCLUSIVE, td)) != 0) { 369 cnp->cn_flags |= PDIRUNLOCK; 370 vput(tdp); 371 return (error); 372 } 373 } else 374 cnp->cn_flags |= PDIRUNLOCK; 375 *vpp = tdp; 376 } else if (dp->i_number == dp->i_ino) { 377 brelse(bp); 378 VREF(vdp); /* we want ourself, ie "." */ 379 *vpp = vdp; 380 } else { 381 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, 382 LK_EXCLUSIVE, &tdp, 383 dp->i_ino != ino, ep); 384 brelse(bp); 385 if (error) 386 return (error); 387 if (!lockparent || !(flags & ISLASTCN)) { 388 cnp->cn_flags |= PDIRUNLOCK; 389 VOP_UNLOCK(pdp, 0, td); 390 } 391 *vpp = tdp; 392 } 393 394 /* 395 * Insert name into cache if appropriate. 396 */ 397 if (cnp->cn_flags & MAKEENTRY) 398 cache_enter(vdp, *vpp, cnp); 399 return (0); 400 } 401 402 /* 403 * Return buffer with the contents of block "offset" from the beginning of 404 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 405 * remaining space in the directory. 406 */ 407 int 408 cd9660_blkatoff(vp, offset, res, bpp) 409 struct vnode *vp; 410 off_t offset; 411 char **res; 412 struct buf **bpp; 413 { 414 struct iso_node *ip; 415 register struct iso_mnt *imp; 416 struct buf *bp; 417 daddr_t lbn; 418 int bsize, bshift, error; 419 420 ip = VTOI(vp); 421 imp = ip->i_mnt; 422 lbn = lblkno(imp, offset); 423 bsize = blksize(imp, ip, lbn); 424 bshift = imp->im_bshift; 425 426 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) { 427 brelse(bp); 428 *bpp = NULL; 429 return (error); 430 } 431 432 /* 433 * We must BMAP the buffer because the directory code may use b_blkno 434 * to calculate the inode for certain types of directory entries. 435 * We could get away with not doing it before we VMIO-backed the 436 * directories because the buffers would get freed atomically with 437 * the invalidation of their data. But with VMIO-backed buffers 438 * the buffers may be freed and then later reconstituted - and the 439 * reconstituted buffer will have no knowledge of b_blkno. 440 */ 441 if (bp->b_blkno == bp->b_lblkno) { 442 bp->b_blkno = (ip->iso_start + bp->b_lblkno) << (bshift - DEV_BSHIFT); 443 } 444 445 if (res) 446 *res = (char *)bp->b_data + blkoff(imp, offset); 447 *bpp = bp; 448 return (0); 449 }
Cache object: b06cc655cc341451fabe35720abddd90
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