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 = 0;/* the current directory entry */ 98 int entryoffsetinblock; /* offset of ep in bp's buffer */ 99 int saveoffset = 0; /* offset of last directory entry in dir */ 100 int numdirpasses; /* strategy for directory search */ 101 doff_t endsearch; /* offset to end directory search */ 102 struct vnode *pdp; /* saved dp during symlink work */ 103 struct vnode *tdp; /* returned by cd9660_vget_internal */ 104 u_long bmask; /* block offset mask */ 105 int error; 106 ino_t ino = 0, saved_ino; 107 int reclen; 108 u_short namelen; 109 int isoflags; 110 char altname[NAME_MAX]; 111 int res; 112 int assoc, len; 113 char *name; 114 struct vnode **vpp = ap->a_vpp; 115 struct componentname *cnp = ap->a_cnp; 116 int flags = cnp->cn_flags; 117 int nameiop = cnp->cn_nameiop; 118 struct thread *td = cnp->cn_thread; 119 120 bp = NULL; 121 *vpp = NULL; 122 vdp = ap->a_dvp; 123 dp = VTOI(vdp); 124 imp = dp->i_mnt; 125 126 /* 127 * We now have a segment name to search for, and a directory to search. 128 */ 129 130 len = cnp->cn_namelen; 131 name = cnp->cn_nameptr; 132 /* 133 * A leading `=' means, we are looking for an associated file 134 */ 135 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR))) 136 { 137 len--; 138 name++; 139 } 140 141 /* 142 * If there is cached information on a previous search of 143 * this directory, pick up where we last left off. 144 * We cache only lookups as these are the most common 145 * and have the greatest payoff. Caching CREATE has little 146 * benefit as it usually must search the entire directory 147 * to determine that the entry does not exist. Caching the 148 * location of the last DELETE or RENAME has not reduced 149 * profiling time and hence has been removed in the interest 150 * of simplicity. 151 */ 152 bmask = imp->im_bmask; 153 if (nameiop != LOOKUP || dp->i_diroff == 0 || 154 dp->i_diroff > dp->i_size) { 155 entryoffsetinblock = 0; 156 dp->i_offset = 0; 157 numdirpasses = 1; 158 } else { 159 dp->i_offset = dp->i_diroff; 160 if ((entryoffsetinblock = dp->i_offset & bmask) && 161 (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp))) 162 return (error); 163 numdirpasses = 2; 164 nchstats.ncs_2passes++; 165 } 166 endsearch = dp->i_size; 167 168 searchloop: 169 while (dp->i_offset < endsearch) { 170 /* 171 * If offset is on a block boundary, 172 * read the next directory block. 173 * Release previous if it exists. 174 */ 175 if ((dp->i_offset & bmask) == 0) { 176 if (bp != NULL) 177 brelse(bp); 178 if ((error = 179 cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp)) != 0) 180 return (error); 181 entryoffsetinblock = 0; 182 } 183 /* 184 * Get pointer to next entry. 185 */ 186 ep = (struct iso_directory_record *) 187 ((char *)bp->b_data + entryoffsetinblock); 188 189 reclen = isonum_711(ep->length); 190 if (reclen == 0) { 191 /* skip to next block, if any */ 192 dp->i_offset = 193 (dp->i_offset & ~bmask) + imp->logical_block_size; 194 continue; 195 } 196 197 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 198 /* illegal entry, stop */ 199 break; 200 201 if (entryoffsetinblock + reclen > imp->logical_block_size) 202 /* entries are not allowed to cross boundaries */ 203 break; 204 205 namelen = isonum_711(ep->name_len); 206 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 207 &ep->date[6]: ep->flags); 208 209 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 210 /* illegal entry, stop */ 211 break; 212 213 /* 214 * Check for a name match. 215 */ 216 switch (imp->iso_ftype) { 217 default: 218 if (!(isoflags & 4) == !assoc) { 219 if ((len == 1 220 && *name == '.') 221 || (flags & ISDOTDOT)) { 222 if (namelen == 1 223 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 224 /* 225 * Save directory entry's inode number and 226 * release directory buffer. 227 */ 228 dp->i_ino = isodirino(ep, imp); 229 goto found; 230 } 231 if (namelen != 1 232 || ep->name[0] != 0) 233 goto notfound; 234 } else if (!(res = isofncmp(name, len, 235 ep->name, namelen, 236 imp->joliet_level, 237 imp->im_flags, 238 imp->im_d2l, 239 imp->im_l2d))) { 240 if (isoflags & 2) 241 ino = isodirino(ep, imp); 242 else 243 ino = dbtob(bp->b_blkno) 244 + entryoffsetinblock; 245 saveoffset = dp->i_offset; 246 } else if (ino) 247 goto foundino; 248 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 249 else if (res < 0) 250 goto notfound; 251 else if (res > 0 && numdirpasses == 2) 252 numdirpasses++; 253 #endif 254 } 255 break; 256 case ISO_FTYPE_RRIP: 257 if (isonum_711(ep->flags)&2) 258 ino = isodirino(ep, imp); 259 else 260 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 261 dp->i_ino = ino; 262 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 263 if (namelen == cnp->cn_namelen 264 && !bcmp(name,altname,namelen)) 265 goto found; 266 ino = 0; 267 break; 268 } 269 dp->i_offset += reclen; 270 entryoffsetinblock += reclen; 271 } 272 if (ino) { 273 foundino: 274 dp->i_ino = ino; 275 if (saveoffset != dp->i_offset) { 276 if (lblkno(imp, dp->i_offset) != 277 lblkno(imp, saveoffset)) { 278 if (bp != NULL) 279 brelse(bp); 280 if ((error = cd9660_blkatoff(vdp, 281 (off_t)saveoffset, NULL, &bp)) != 0) 282 return (error); 283 } 284 entryoffsetinblock = saveoffset & bmask; 285 ep = (struct iso_directory_record *) 286 ((char *)bp->b_data + entryoffsetinblock); 287 dp->i_offset = saveoffset; 288 } 289 goto found; 290 } 291 notfound: 292 /* 293 * If we started in the middle of the directory and failed 294 * to find our target, we must check the beginning as well. 295 */ 296 if (numdirpasses == 2) { 297 numdirpasses--; 298 dp->i_offset = 0; 299 endsearch = dp->i_diroff; 300 goto searchloop; 301 } 302 if (bp != NULL) 303 brelse(bp); 304 305 /* 306 * Insert name into cache (as non-existent) if appropriate. 307 */ 308 if (cnp->cn_flags & MAKEENTRY) 309 cache_enter(vdp, *vpp, cnp); 310 if (nameiop == CREATE || nameiop == RENAME) 311 return (EROFS); 312 return (ENOENT); 313 314 found: 315 if (numdirpasses == 2) 316 nchstats.ncs_pass2++; 317 318 /* 319 * Found component in pathname. 320 * If the final component of path name, save information 321 * in the cache as to where the entry was found. 322 */ 323 if ((flags & ISLASTCN) && nameiop == LOOKUP) 324 dp->i_diroff = dp->i_offset; 325 326 /* 327 * Step through the translation in the name. We do not `iput' the 328 * directory because we may need it again if a symbolic link 329 * is relative to the current directory. Instead we save it 330 * unlocked as "pdp". We must get the target inode before unlocking 331 * the directory to insure that the inode will not be removed 332 * before we get it. We prevent deadlock by always fetching 333 * inodes from the root, moving down the directory tree. Thus 334 * when following backward pointers ".." we must unlock the 335 * parent directory before getting the requested directory. 336 * There is a potential race condition here if both the current 337 * and parent directories are removed before the `iget' for the 338 * inode associated with ".." returns. We hope that this occurs 339 * infrequently since we cannot avoid this race condition without 340 * implementing a sophisticated deadlock detection algorithm. 341 * Note also that this simple deadlock detection scheme will not 342 * work if the filesystem has any hard links other than ".." 343 * that point backwards in the directory structure. 344 */ 345 pdp = vdp; 346 /* 347 * If ino is different from dp->i_ino, 348 * it's a relocated directory. 349 */ 350 if (flags & ISDOTDOT) { 351 saved_ino = dp->i_ino; 352 VOP_UNLOCK(pdp, 0, td); /* race to get the inode */ 353 error = cd9660_vget_internal(vdp->v_mount, saved_ino, 354 LK_EXCLUSIVE, &tdp, 355 saved_ino != ino, ep); 356 brelse(bp); 357 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, td); 358 if (error) 359 return (error); 360 *vpp = tdp; 361 } else if (dp->i_number == dp->i_ino) { 362 brelse(bp); 363 VREF(vdp); /* we want ourself, ie "." */ 364 *vpp = vdp; 365 } else { 366 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, 367 LK_EXCLUSIVE, &tdp, 368 dp->i_ino != ino, ep); 369 brelse(bp); 370 if (error) 371 return (error); 372 *vpp = tdp; 373 } 374 375 /* 376 * Insert name into cache if appropriate. 377 */ 378 if (cnp->cn_flags & MAKEENTRY) 379 cache_enter(vdp, *vpp, cnp); 380 return (0); 381 } 382 383 /* 384 * Return buffer with the contents of block "offset" from the beginning of 385 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 386 * remaining space in the directory. 387 */ 388 int 389 cd9660_blkatoff(vp, offset, res, bpp) 390 struct vnode *vp; 391 off_t offset; 392 char **res; 393 struct buf **bpp; 394 { 395 struct iso_node *ip; 396 struct iso_mnt *imp; 397 struct buf *bp; 398 daddr_t lbn; 399 int bsize, bshift, error; 400 401 ip = VTOI(vp); 402 imp = ip->i_mnt; 403 lbn = lblkno(imp, offset); 404 bsize = blksize(imp, ip, lbn); 405 bshift = imp->im_bshift; 406 407 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) { 408 brelse(bp); 409 *bpp = NULL; 410 return (error); 411 } 412 413 /* 414 * We must BMAP the buffer because the directory code may use b_blkno 415 * to calculate the inode for certain types of directory entries. 416 * We could get away with not doing it before we VMIO-backed the 417 * directories because the buffers would get freed atomically with 418 * the invalidation of their data. But with VMIO-backed buffers 419 * the buffers may be freed and then later reconstituted - and the 420 * reconstituted buffer will have no knowledge of b_blkno. 421 */ 422 if (bp->b_blkno == bp->b_lblkno) { 423 bp->b_blkno = (ip->iso_start + bp->b_lblkno) << (bshift - DEV_BSHIFT); 424 } 425 426 if (res) 427 *res = (char *)bp->b_data + blkoff(imp, offset); 428 *bpp = bp; 429 return (0); 430 }
Cache object: cda388fdeb7588a9c7d8cd70563035e6
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