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