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 * 40 * @(#)cd9660_lookup.c 8.2 (Berkeley) 1/23/94 41 * $Id$ 42 */ 43 44 #include <sys/param.h> 45 #include <sys/namei.h> 46 #include <sys/buf.h> 47 #include <sys/file.h> 48 #include <sys/vnode.h> 49 #include <sys/mount.h> 50 51 #include <isofs/cd9660/iso.h> 52 #include <isofs/cd9660/cd9660_node.h> 53 #include <isofs/cd9660/iso_rrip.h> 54 #include <isofs/cd9660/cd9660_rrip.h> 55 56 struct nchstats iso_nchstats; 57 58 /* 59 * Convert a component of a pathname into a pointer to a locked inode. 60 * This is a very central and rather complicated routine. 61 * If the file system is not maintained in a strict tree hierarchy, 62 * this can result in a deadlock situation (see comments in code below). 63 * 64 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 65 * whether the name is to be looked up, created, renamed, or deleted. 66 * When CREATE, RENAME, or DELETE is specified, information usable in 67 * creating, renaming, or deleting a directory entry may be calculated. 68 * If flag has LOCKPARENT or'ed into it and the target of the pathname 69 * exists, lookup returns both the target and its parent directory locked. 70 * When creating or renaming and LOCKPARENT is specified, the target may 71 * not be ".". When deleting and LOCKPARENT is specified, the target may 72 * be "."., but the caller must check to ensure it does an vrele and iput 73 * instead of two iputs. 74 * 75 * Overall outline of ufs_lookup: 76 * 77 * check accessibility of directory 78 * look for name in cache, if found, then if at end of path 79 * and deleting or creating, drop it, else return name 80 * search for name in directory, to found or notfound 81 * notfound: 82 * if creating, return locked directory, leaving info on available slots 83 * else return error 84 * found: 85 * if at end of path and deleting, return information to allow delete 86 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target 87 * inode and return info to allow rewrite 88 * if not at end, add name to cache; if at end and neither creating 89 * nor deleting, add name to cache 90 * 91 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. 92 */ 93 int 94 cd9660_lookup(ap) 95 struct vop_lookup_args /* { 96 struct vnode *a_dvp; 97 struct vnode **a_vpp; 98 struct componentname *a_cnp; 99 } */ *ap; 100 { 101 register struct vnode *vdp; /* vnode for directory being searched */ 102 register struct iso_node *dp; /* inode for directory being searched */ 103 register struct iso_mnt *imp; /* file system that directory is in */ 104 struct buf *bp; /* a buffer of directory entries */ 105 struct iso_directory_record *ep = 0;/* the current directory entry */ 106 int entryoffsetinblock; /* offset of ep in bp's buffer */ 107 int saveoffset = 0; /* offset of last directory entry in dir */ 108 int numdirpasses; /* strategy for directory search */ 109 doff_t endsearch; /* offset to end directory search */ 110 struct iso_node *pdp; /* saved dp during symlink work */ 111 struct iso_node *tdp; /* returned by iget */ 112 int lockparent; /* 1 => lockparent flag is set */ 113 int wantparent; /* 1 => wantparent or lockparent flag */ 114 int error; 115 ino_t ino = 0; 116 int reclen; 117 u_short namelen; 118 char altname[NAME_MAX]; 119 int res; 120 int assoc, len; 121 char *name; 122 struct vnode **vpp = ap->a_vpp; 123 struct componentname *cnp = ap->a_cnp; 124 struct ucred *cred = cnp->cn_cred; 125 int flags = cnp->cn_flags; 126 int nameiop = cnp->cn_nameiop; 127 128 bp = NULL; 129 *vpp = NULL; 130 vdp = ap->a_dvp; 131 dp = VTOI(vdp); 132 imp = dp->i_mnt; 133 lockparent = flags & LOCKPARENT; 134 wantparent = flags & (LOCKPARENT|WANTPARENT); 135 136 /* 137 * Check accessiblity of directory. 138 */ 139 if (vdp->v_type != VDIR) 140 return (ENOTDIR); 141 if (error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) 142 return (error); 143 144 /* 145 * We now have a segment name to search for, and a directory to search. 146 * 147 * Before tediously performing a linear scan of the directory, 148 * check the name cache to see if the directory/name pair 149 * we are looking for is known already. 150 */ 151 if (error = cache_lookup(vdp, vpp, cnp)) { 152 int vpid; /* capability number of vnode */ 153 154 if (error == ENOENT) 155 return (error); 156 #ifdef PARANOID 157 if ((vdp->v_flag & VROOT) && (flags & ISDOTDOT)) 158 panic("ufs_lookup: .. through root"); 159 #endif 160 /* 161 * Get the next vnode in the path. 162 * See comment below starting `Step through' for 163 * an explaination of the locking protocol. 164 */ 165 pdp = dp; 166 dp = VTOI(*vpp); 167 vdp = *vpp; 168 vpid = vdp->v_id; 169 if (pdp == dp) { 170 VREF(vdp); 171 error = 0; 172 } else if (flags & ISDOTDOT) { 173 ISO_IUNLOCK(pdp); 174 error = vget(vdp, 1); 175 if (!error && lockparent && (flags & ISLASTCN)) 176 ISO_ILOCK(pdp); 177 } else { 178 error = vget(vdp, 1); 179 if (!lockparent || error || !(flags & ISLASTCN)) 180 ISO_IUNLOCK(pdp); 181 } 182 /* 183 * Check that the capability number did not change 184 * while we were waiting for the lock. 185 */ 186 if (!error) { 187 if (vpid == vdp->v_id) 188 return (0); 189 iso_iput(dp); 190 if (lockparent && pdp != dp && (flags & ISLASTCN)) 191 ISO_IUNLOCK(pdp); 192 } 193 ISO_ILOCK(pdp); 194 dp = pdp; 195 vdp = ITOV(dp); 196 *vpp = NULL; 197 } 198 199 len = cnp->cn_namelen; 200 name = cnp->cn_nameptr; 201 /* 202 * A leading `=' means, we are looking for an associated file 203 */ 204 if (assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR)) { 205 len--; 206 name++; 207 } 208 209 /* 210 * If there is cached information on a previous search of 211 * this directory, pick up where we last left off. 212 * We cache only lookups as these are the most common 213 * and have the greatest payoff. Caching CREATE has little 214 * benefit as it usually must search the entire directory 215 * to determine that the entry does not exist. Caching the 216 * location of the last DELETE or RENAME has not reduced 217 * profiling time and hence has been removed in the interest 218 * of simplicity. 219 */ 220 if (nameiop != LOOKUP || dp->i_diroff == 0 || 221 dp->i_diroff > dp->i_size) { 222 entryoffsetinblock = 0; 223 dp->i_offset = 0; 224 numdirpasses = 1; 225 } else { 226 dp->i_offset = dp->i_diroff; 227 entryoffsetinblock = iso_blkoff(imp, dp->i_offset); 228 if (entryoffsetinblock != 0) { 229 if (error = iso_blkatoff(dp, dp->i_offset, &bp)) 230 return (error); 231 } 232 numdirpasses = 2; 233 iso_nchstats.ncs_2passes++; 234 } 235 endsearch = roundup(dp->i_size, imp->logical_block_size); 236 237 searchloop: 238 while (dp->i_offset < endsearch) { 239 /* 240 * If offset is on a block boundary, 241 * read the next directory block. 242 * Release previous if it exists. 243 */ 244 if (iso_blkoff(imp, dp->i_offset) == 0) { 245 if (bp != NULL) 246 brelse(bp); 247 if (error = iso_blkatoff(dp, dp->i_offset, &bp)) 248 return (error); 249 entryoffsetinblock = 0; 250 } 251 /* 252 * Get pointer to next entry. 253 */ 254 ep = (struct iso_directory_record *) 255 (bp->b_un.b_addr + entryoffsetinblock); 256 257 reclen = isonum_711 (ep->length); 258 if (reclen == 0) { 259 /* skip to next block, if any */ 260 dp->i_offset = 261 roundup(dp->i_offset, imp->logical_block_size); 262 continue; 263 } 264 265 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 266 /* illegal entry, stop */ 267 break; 268 269 if (entryoffsetinblock + reclen > imp->logical_block_size) 270 /* entries are not allowed to cross boundaries */ 271 break; 272 273 /* 274 * Check for a name match. 275 */ 276 namelen = isonum_711(ep->name_len); 277 278 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 279 /* illegal entry, stop */ 280 break; 281 282 switch (imp->iso_ftype) { 283 default: 284 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 285 if ((len == 1 286 && *name == '.') 287 || (flags & ISDOTDOT)) { 288 if (namelen == 1 289 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 290 /* 291 * Save directory entry's inode number and 292 * reclen in ndp->ni_ufs area, and release 293 * directory buffer. 294 */ 295 isodirino(&dp->i_ino,ep,imp); 296 goto found; 297 } 298 if (namelen != 1 299 || ep->name[0] != 0) 300 goto notfound; 301 } else if (!(res = isofncmp(name,len, 302 ep->name,namelen))) { 303 if (isonum_711(ep->flags)&2) 304 isodirino(&ino,ep,imp); 305 else 306 ino = dbtob(bp->b_blkno) 307 + entryoffsetinblock; 308 saveoffset = dp->i_offset; 309 } else if (ino) 310 goto foundino; 311 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 312 else if (res < 0) 313 goto notfound; 314 else if (res > 0 && numdirpasses == 2) 315 numdirpasses++; 316 #endif 317 } 318 break; 319 case ISO_FTYPE_RRIP: 320 if (isonum_711(ep->flags)&2) 321 isodirino(&ino,ep,imp); 322 else 323 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 324 dp->i_ino = ino; 325 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 326 if (namelen == cnp->cn_namelen 327 && !bcmp(name,altname,namelen)) 328 goto found; 329 ino = 0; 330 break; 331 } 332 dp->i_offset += reclen; 333 entryoffsetinblock += reclen; 334 } 335 if (ino) { 336 foundino: 337 dp->i_ino = ino; 338 if (saveoffset != dp->i_offset) { 339 if (iso_lblkno(imp,dp->i_offset) 340 != iso_lblkno(imp,saveoffset)) { 341 if (bp != NULL) 342 brelse(bp); 343 if (error = iso_blkatoff(dp, saveoffset, &bp)) 344 return (error); 345 } 346 ep = (struct iso_directory_record *)(bp->b_un.b_addr 347 + iso_blkoff(imp,saveoffset)); 348 dp->i_offset = saveoffset; 349 } 350 goto found; 351 } 352 notfound: 353 /* 354 * If we started in the middle of the directory and failed 355 * to find our target, we must check the beginning as well. 356 */ 357 if (numdirpasses == 2) { 358 numdirpasses--; 359 dp->i_offset = 0; 360 endsearch = dp->i_diroff; 361 goto searchloop; 362 } 363 if (bp != NULL) 364 brelse(bp); 365 /* 366 * Insert name into cache (as non-existent) if appropriate. 367 */ 368 if (cnp->cn_flags & MAKEENTRY) 369 cache_enter(vdp, *vpp, cnp); 370 if (nameiop == CREATE || nameiop == RENAME) 371 return (EJUSTRETURN); 372 return (ENOENT); 373 374 found: 375 if (numdirpasses == 2) 376 iso_nchstats.ncs_pass2++; 377 if (bp != NULL) 378 brelse(bp); 379 380 /* 381 * Found component in pathname. 382 * If the final component of path name, save information 383 * in the cache as to where the entry was found. 384 */ 385 if ((flags & ISLASTCN) && nameiop == LOOKUP) 386 dp->i_diroff = dp->i_offset; 387 388 /* 389 * Step through the translation in the name. We do not `iput' the 390 * directory because we may need it again if a symbolic link 391 * is relative to the current directory. Instead we save it 392 * unlocked as "pdp". We must get the target inode before unlocking 393 * the directory to insure that the inode will not be removed 394 * before we get it. We prevent deadlock by always fetching 395 * inodes from the root, moving down the directory tree. Thus 396 * when following backward pointers ".." we must unlock the 397 * parent directory before getting the requested directory. 398 * There is a potential race condition here if both the current 399 * and parent directories are removed before the `iget' for the 400 * inode associated with ".." returns. We hope that this occurs 401 * infrequently since we cannot avoid this race condition without 402 * implementing a sophisticated deadlock detection algorithm. 403 * Note also that this simple deadlock detection scheme will not 404 * work if the file system has any hard links other than ".." 405 * that point backwards in the directory structure. 406 */ 407 pdp = dp; 408 /* 409 * If ino is different from dp->i_ino, 410 * it's a relocated directory. 411 */ 412 if (flags & ISDOTDOT) { 413 ISO_IUNLOCK(pdp); /* race to get the inode */ 414 if (error = iso_iget(dp,dp->i_ino, 415 dp->i_ino != ino, 416 &tdp,ep)) { 417 ISO_ILOCK(pdp); 418 return (error); 419 } 420 if (lockparent && (flags & ISLASTCN)) 421 ISO_ILOCK(pdp); 422 *vpp = ITOV(tdp); 423 } else if (dp->i_number == dp->i_ino) { 424 VREF(vdp); /* we want ourself, ie "." */ 425 *vpp = vdp; 426 } else { 427 if (error = iso_iget(dp,dp->i_ino,dp->i_ino!=ino,&tdp,ep)) 428 return (error); 429 if (!lockparent || !(flags & ISLASTCN)) 430 ISO_IUNLOCK(pdp); 431 *vpp = ITOV(tdp); 432 } 433 434 /* 435 * Insert name into cache if appropriate. 436 */ 437 if (cnp->cn_flags & MAKEENTRY) 438 cache_enter(vdp, *vpp, cnp); 439 return (0); 440 } 441 442 /* 443 * Return buffer with contents of block "offset" 444 * from the beginning of directory "ip". If "res" 445 * is non-zero, fill it in with a pointer to the 446 * remaining space in the directory. 447 */ 448 int 449 iso_blkatoff(ip, offset, bpp) 450 struct iso_node *ip; 451 doff_t offset; 452 struct buf **bpp; 453 { 454 register struct iso_mnt *imp = ip->i_mnt; 455 daddr_t lbn = iso_lblkno(imp,offset); 456 int bsize = iso_blksize(imp,ip,lbn); 457 struct buf *bp; 458 int error; 459 460 if (error = bread(ITOV(ip),lbn,bsize,NOCRED,&bp)) { 461 brelse(bp); 462 *bpp = 0; 463 return (error); 464 } 465 *bpp = bp; 466 467 return (0); 468 } 469