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: cd9660_lookup.c,v 1.14 1997/02/22 09:38:48 peter Exp $ 42 */ 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/namei.h> 47 #include <sys/buf.h> 48 #include <sys/file.h> 49 #include <sys/vnode.h> 50 #include <sys/mount.h> 51 52 #include <isofs/cd9660/iso.h> 53 #include <isofs/cd9660/cd9660_node.h> 54 #include <isofs/cd9660/iso_rrip.h> 55 #include <isofs/cd9660/cd9660_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 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 vnode *pdp; /* saved dp during symlink work */ 110 struct vnode *tdp; /* returned by cd9660_vget_internal */ 111 u_long bmask; /* block offset mask */ 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 int isoflags; 119 char altname[NAME_MAX]; 120 int res; 121 int assoc, len; 122 char *name; 123 struct vnode **vpp = ap->a_vpp; 124 struct componentname *cnp = ap->a_cnp; 125 struct ucred *cred = cnp->cn_cred; 126 int flags = cnp->cn_flags; 127 int nameiop = cnp->cn_nameiop; 128 struct proc *p = cnp->cn_proc; 129 130 bp = NULL; 131 *vpp = NULL; 132 vdp = ap->a_dvp; 133 dp = VTOI(vdp); 134 imp = dp->i_mnt; 135 lockparent = flags & LOCKPARENT; 136 wantparent = flags & (LOCKPARENT|WANTPARENT); 137 138 /* 139 * Check accessiblity of directory. 140 */ 141 if (vdp->v_type != VDIR) 142 return (ENOTDIR); 143 if (error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) 144 return (error); 145 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && 146 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 147 return (EROFS); 148 149 /* 150 * We now have a segment name to search for, and a directory to search. 151 * 152 * Before tediously performing a linear scan of the directory, 153 * check the name cache to see if the directory/name pair 154 * we are looking for is known already. 155 */ 156 if ((error = cache_lookup(vdp, vpp, cnp))) { 157 u_long vpid; /* capability number of vnode */ 158 159 if (error == ENOENT) 160 return (error); 161 #ifdef PARANOID 162 if ((vdp->v_flag & VROOT) && (flags & ISDOTDOT)) 163 panic("cd9660_lookup: .. through root"); 164 #endif 165 /* 166 * Get the next vnode in the path. 167 * See comment below starting `Step through' for 168 * an explaination of the locking protocol. 169 */ 170 pdp = vdp; 171 dp = VTOI(*vpp); 172 vdp = *vpp; 173 vpid = vdp->v_id; 174 if (pdp == vdp) { 175 VREF(vdp); 176 error = 0; 177 } else if (flags & ISDOTDOT) { 178 VOP_UNLOCK(pdp, 0, p); 179 error = vget(vdp, LK_EXCLUSIVE, p); 180 if (!error && lockparent && (flags & ISLASTCN)) 181 error = vn_lock(pdp, LK_EXCLUSIVE, p); 182 } else { 183 error = vget(vdp, LK_EXCLUSIVE, p); 184 if (!lockparent || error || !(flags & ISLASTCN)) 185 VOP_UNLOCK(pdp, 0, p); 186 } 187 /* 188 * Check that the capability number did not change 189 * while we were waiting for the lock. 190 */ 191 if (!error) { 192 if (vpid == vdp->v_id) 193 return (0); 194 vput(vdp); 195 if (lockparent && pdp != vdp && (flags & ISLASTCN)) 196 VOP_UNLOCK(pdp, 0, p); 197 } 198 if (error = vn_lock(pdp, LK_EXCLUSIVE, p)) 199 return (error); 200 vdp = pdp; 201 dp = VTOI(pdp); 202 *vpp = NULL; 203 } 204 205 len = cnp->cn_namelen; 206 name = cnp->cn_nameptr; 207 /* 208 * A leading `=' means, we are looking for an associated file 209 */ 210 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR))) 211 { 212 len--; 213 name++; 214 } 215 216 /* 217 * If there is cached information on a previous search of 218 * this directory, pick up where we last left off. 219 * We cache only lookups as these are the most common 220 * and have the greatest payoff. Caching CREATE has little 221 * benefit as it usually must search the entire directory 222 * to determine that the entry does not exist. Caching the 223 * location of the last DELETE or RENAME has not reduced 224 * profiling time and hence has been removed in the interest 225 * of simplicity. 226 */ 227 bmask = imp->im_bmask; 228 if (nameiop != LOOKUP || dp->i_diroff == 0 || 229 dp->i_diroff > dp->i_size) { 230 entryoffsetinblock = 0; 231 dp->i_offset = 0; 232 numdirpasses = 1; 233 } else { 234 dp->i_offset = dp->i_diroff; 235 if ((entryoffsetinblock = dp->i_offset & bmask) && 236 (error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp))) 237 return (error); 238 numdirpasses = 2; 239 nchstats.ncs_2passes++; 240 } 241 endsearch = dp->i_size; 242 243 searchloop: 244 while (dp->i_offset < endsearch) { 245 /* 246 * If offset is on a block boundary, 247 * read the next directory block. 248 * Release previous if it exists. 249 */ 250 if ((dp->i_offset & bmask) == 0) { 251 if (bp != NULL) 252 brelse(bp); 253 if (error = 254 VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)) 255 return (error); 256 entryoffsetinblock = 0; 257 } 258 /* 259 * Get pointer to next entry. 260 */ 261 ep = (struct iso_directory_record *) 262 ((char *)bp->b_data + entryoffsetinblock); 263 264 reclen = isonum_711(ep->length); 265 if (reclen == 0) { 266 /* skip to next block, if any */ 267 dp->i_offset = 268 (dp->i_offset & ~bmask) + imp->logical_block_size; 269 continue; 270 } 271 272 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 273 /* illegal entry, stop */ 274 break; 275 276 if (entryoffsetinblock + reclen > imp->logical_block_size) 277 /* entries are not allowed to cross boundaries */ 278 break; 279 280 namelen = isonum_711(ep->name_len); 281 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 282 &ep->date[6]: ep->flags); 283 284 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 285 /* illegal entry, stop */ 286 break; 287 288 /* 289 * Check for a name match. 290 */ 291 switch (imp->iso_ftype) { 292 default: 293 if (!(isoflags & 4) == !assoc) { 294 if ((len == 1 295 && *name == '.') 296 || (flags & ISDOTDOT)) { 297 if (namelen == 1 298 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 299 /* 300 * Save directory entry's inode number and 301 * release directory buffer. 302 */ 303 dp->i_ino = isodirino(ep, imp); 304 goto found; 305 } 306 if (namelen != 1 307 || ep->name[0] != 0) 308 goto notfound; 309 } else if (!(res = isofncmp(name,len, 310 ep->name,namelen))) { 311 if (isoflags & 2) 312 ino = isodirino(ep, imp); 313 else 314 ino = dbtob(bp->b_blkno) 315 + entryoffsetinblock; 316 saveoffset = dp->i_offset; 317 } else if (ino) 318 goto foundino; 319 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 320 else if (res < 0) 321 goto notfound; 322 else if (res > 0 && numdirpasses == 2) 323 numdirpasses++; 324 #endif 325 } 326 break; 327 case ISO_FTYPE_RRIP: 328 if (isonum_711(ep->flags)&2) 329 ino = isodirino(ep, imp); 330 else 331 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 332 dp->i_ino = ino; 333 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 334 if (namelen == cnp->cn_namelen 335 && !bcmp(name,altname,namelen)) 336 goto found; 337 ino = 0; 338 break; 339 } 340 dp->i_offset += reclen; 341 entryoffsetinblock += reclen; 342 } 343 if (ino) { 344 foundino: 345 dp->i_ino = ino; 346 if (saveoffset != dp->i_offset) { 347 if (lblkno(imp, dp->i_offset) != 348 lblkno(imp, saveoffset)) { 349 if (bp != NULL) 350 brelse(bp); 351 if (error = VOP_BLKATOFF(vdp, 352 (off_t)saveoffset, NULL, &bp)) 353 return (error); 354 } 355 entryoffsetinblock = saveoffset & bmask; 356 ep = (struct iso_directory_record *) 357 ((char *)bp->b_data + entryoffsetinblock); 358 dp->i_offset = saveoffset; 359 } 360 goto found; 361 } 362 notfound: 363 /* 364 * If we started in the middle of the directory and failed 365 * to find our target, we must check the beginning as well. 366 */ 367 if (numdirpasses == 2) { 368 numdirpasses--; 369 dp->i_offset = 0; 370 endsearch = dp->i_diroff; 371 goto searchloop; 372 } 373 if (bp != NULL) 374 brelse(bp); 375 376 /* 377 * Insert name into cache (as non-existent) if appropriate. 378 */ 379 if (cnp->cn_flags & MAKEENTRY) 380 cache_enter(vdp, *vpp, cnp); 381 if (nameiop == CREATE || nameiop == RENAME) 382 return (EROFS); 383 return (ENOENT); 384 385 found: 386 if (numdirpasses == 2) 387 nchstats.ncs_pass2++; 388 389 /* 390 * Found component in pathname. 391 * If the final component of path name, save information 392 * in the cache as to where the entry was found. 393 */ 394 if ((flags & ISLASTCN) && nameiop == LOOKUP) 395 dp->i_diroff = dp->i_offset; 396 397 /* 398 * Step through the translation in the name. We do not `iput' the 399 * directory because we may need it again if a symbolic link 400 * is relative to the current directory. Instead we save it 401 * unlocked as "pdp". We must get the target inode before unlocking 402 * the directory to insure that the inode will not be removed 403 * before we get it. We prevent deadlock by always fetching 404 * inodes from the root, moving down the directory tree. Thus 405 * when following backward pointers ".." we must unlock the 406 * parent directory before getting the requested directory. 407 * There is a potential race condition here if both the current 408 * and parent directories are removed before the `iget' for the 409 * inode associated with ".." returns. We hope that this occurs 410 * infrequently since we cannot avoid this race condition without 411 * implementing a sophisticated deadlock detection algorithm. 412 * Note also that this simple deadlock detection scheme will not 413 * work if the file system has any hard links other than ".." 414 * that point backwards in the directory structure. 415 */ 416 pdp = vdp; 417 /* 418 * If ino is different from dp->i_ino, 419 * it's a relocated directory. 420 */ 421 if (flags & ISDOTDOT) { 422 VOP_UNLOCK(pdp, 0, p); /* race to get the inode */ 423 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 424 dp->i_ino != ino, ep); 425 brelse(bp); 426 if (error) { 427 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p); 428 return (error); 429 } 430 if (lockparent && (flags & ISLASTCN) && 431 (error = vn_lock(pdp, LK_EXCLUSIVE, p))) { 432 vput(tdp); 433 return (error); 434 } 435 *vpp = tdp; 436 } else if (dp->i_number == dp->i_ino) { 437 brelse(bp); 438 VREF(vdp); /* we want ourself, ie "." */ 439 *vpp = vdp; 440 } else { 441 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 442 dp->i_ino != ino, ep); 443 brelse(bp); 444 if (error) 445 return (error); 446 if (!lockparent || !(flags & ISLASTCN)) 447 VOP_UNLOCK(pdp, 0, p); 448 *vpp = tdp; 449 } 450 451 /* 452 * Insert name into cache if appropriate. 453 */ 454 if (cnp->cn_flags & MAKEENTRY) 455 cache_enter(vdp, *vpp, cnp); 456 return (0); 457 } 458 459 /* 460 * Return buffer with the contents of block "offset" from the beginning of 461 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 462 * remaining space in the directory. 463 */ 464 int 465 cd9660_blkatoff(ap) 466 struct vop_blkatoff_args /* { 467 struct vnode *a_vp; 468 off_t a_offset; 469 char **a_res; 470 struct buf **a_bpp; 471 } */ *ap; 472 { 473 struct iso_node *ip; 474 register struct iso_mnt *imp; 475 struct buf *bp; 476 daddr_t lbn; 477 int bsize, error; 478 479 ip = VTOI(ap->a_vp); 480 imp = ip->i_mnt; 481 lbn = lblkno(imp, ap->a_offset); 482 bsize = blksize(imp, ip, lbn); 483 484 if (error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) { 485 brelse(bp); 486 *ap->a_bpp = NULL; 487 return (error); 488 } 489 if (ap->a_res) 490 *ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset); 491 *ap->a_bpp = bp; 492 return (0); 493 } 494