1 /* $NetBSD: cd9660_lookup.c,v 1.2 2003/01/20 02:25:49 simonb Exp $ */ 2 3 /*- 4 * Copyright (c) 1989, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley 8 * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension 9 * Support code is derived from software contributed to Berkeley 10 * by Atsushi Murai (amurai@spec.co.jp). 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91 41 * 42 * @(#)cd9660_lookup.c 8.5 (Berkeley) 5/27/95 43 */ 44 45 #include <sys/cdefs.h> 46 __KERNEL_RCSID(0, "$NetBSD: cd9660_lookup.c,v 1.2 2003/01/20 02:25:49 simonb Exp $"); 47 48 #include <sys/param.h> 49 #include <sys/namei.h> 50 #include <sys/buf.h> 51 #include <sys/file.h> 52 #include <sys/vnode.h> 53 #include <sys/mount.h> 54 #include <sys/systm.h> 55 56 #include <fs/cd9660/iso.h> 57 #include <fs/cd9660/cd9660_extern.h> 58 #include <fs/cd9660/cd9660_node.h> 59 #include <fs/cd9660/iso_rrip.h> 60 #include <fs/cd9660/cd9660_rrip.h> 61 #include <fs/cd9660/cd9660_mount.h> 62 63 struct nchstats iso_nchstats; 64 65 /* 66 * Convert a component of a pathname into a pointer to a locked inode. 67 * This is a very central and rather complicated routine. 68 * If the file system is not maintained in a strict tree hierarchy, 69 * this can result in a deadlock situation (see comments in code below). 70 * 71 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 72 * whether the name is to be looked up, created, renamed, or deleted. 73 * When CREATE, RENAME, or DELETE is specified, information usable in 74 * creating, renaming, or deleting a directory entry may be calculated. 75 * If flag has LOCKPARENT or'ed into it and the target of the pathname 76 * exists, lookup returns both the target and its parent directory locked. 77 * When creating or renaming and LOCKPARENT is specified, the target may 78 * not be ".". When deleting and LOCKPARENT is specified, the target may 79 * be "."., but the caller must check to ensure it does an vrele and iput 80 * instead of two iputs. 81 * 82 * Overall outline of ufs_lookup: 83 * 84 * check accessibility of directory 85 * look for name in cache, if found, then if at end of path 86 * and deleting or creating, drop it, else return name 87 * search for name in directory, to found or notfound 88 * notfound: 89 * if creating, return locked directory, leaving info on available slots 90 * else return error 91 * found: 92 * if at end of path and deleting, return information to allow delete 93 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target 94 * inode and return info to allow rewrite 95 * if not at end, add name to cache; if at end and neither creating 96 * nor deleting, add name to cache 97 * 98 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. 99 */ 100 int 101 cd9660_lookup(v) 102 void *v; 103 { 104 struct vop_lookup_args /* { 105 struct vnode *a_dvp; 106 struct vnode **a_vpp; 107 struct componentname *a_cnp; 108 } */ *ap = v; 109 struct vnode *vdp; /* vnode for directory being searched */ 110 struct iso_node *dp; /* inode for directory being searched */ 111 struct iso_mnt *imp; /* file system that directory is in */ 112 struct buf *bp; /* a buffer of directory entries */ 113 struct iso_directory_record *ep = NULL; 114 /* the current directory entry */ 115 int entryoffsetinblock; /* offset of ep in bp's buffer */ 116 int saveoffset = -1; /* offset of last directory entry in dir */ 117 int numdirpasses; /* strategy for directory search */ 118 doff_t endsearch; /* offset to end directory search */ 119 struct vnode *pdp; /* saved dp during symlink work */ 120 struct vnode *tdp; /* returned by cd9660_vget_internal */ 121 u_long bmask; /* block offset mask */ 122 int lockparent; /* 1 => lockparent flag is set */ 123 int error; 124 ino_t ino = 0; 125 int reclen; 126 u_short namelen; 127 char altname[NAME_MAX]; 128 int res; 129 int assoc, len; 130 const char *name; 131 struct vnode **vpp = ap->a_vpp; 132 struct componentname *cnp = ap->a_cnp; 133 struct ucred *cred = cnp->cn_cred; 134 int flags; 135 int nameiop = cnp->cn_nameiop; 136 137 cnp->cn_flags &= ~PDIRUNLOCK; 138 flags = cnp->cn_flags; 139 140 bp = NULL; 141 *vpp = NULL; 142 vdp = ap->a_dvp; 143 dp = VTOI(vdp); 144 imp = dp->i_mnt; 145 lockparent = flags & LOCKPARENT; 146 147 /* 148 * Check accessiblity of directory. 149 */ 150 if ((error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) != 0) 151 return (error); 152 153 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && 154 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 155 return (EROFS); 156 157 /* 158 * We now have a segment name to search for, and a directory to search. 159 * 160 * Before tediously performing a linear scan of the directory, 161 * check the name cache to see if the directory/name pair 162 * we are looking for is known already. 163 */ 164 if ((error = cache_lookup(vdp, vpp, cnp)) >= 0) 165 return (error); 166 167 len = cnp->cn_namelen; 168 name = cnp->cn_nameptr; 169 /* 170 * A leading `=' means, we are looking for an associated file 171 */ 172 assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR); 173 if (assoc) { 174 len--; 175 name++; 176 } 177 178 /* 179 * If there is cached information on a previous search of 180 * this directory, pick up where we last left off. 181 * We cache only lookups as these are the most common 182 * and have the greatest payoff. Caching CREATE has little 183 * benefit as it usually must search the entire directory 184 * to determine that the entry does not exist. Caching the 185 * location of the last DELETE or RENAME has not reduced 186 * profiling time and hence has been removed in the interest 187 * of simplicity. 188 */ 189 bmask = imp->im_bmask; 190 if (nameiop != LOOKUP || dp->i_diroff == 0 || 191 dp->i_diroff > dp->i_size) { 192 entryoffsetinblock = 0; 193 dp->i_offset = 0; 194 numdirpasses = 1; 195 } else { 196 dp->i_offset = dp->i_diroff; 197 if ((entryoffsetinblock = dp->i_offset & bmask) && 198 (error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp))) 199 return (error); 200 numdirpasses = 2; 201 iso_nchstats.ncs_2passes++; 202 } 203 endsearch = dp->i_size; 204 205 searchloop: 206 while (dp->i_offset < endsearch) { 207 /* 208 * If offset is on a block boundary, 209 * read the next directory block. 210 * Release previous if it exists. 211 */ 212 if ((dp->i_offset & bmask) == 0) { 213 if (bp != NULL) 214 brelse(bp); 215 error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, 216 NULL, &bp); 217 if (error) 218 return (error); 219 entryoffsetinblock = 0; 220 } 221 /* 222 * Get pointer to next entry. 223 */ 224 ep = (struct iso_directory_record *) 225 ((char *)bp->b_data + entryoffsetinblock); 226 227 reclen = isonum_711(ep->length); 228 if (reclen == 0) { 229 /* skip to next block, if any */ 230 dp->i_offset = 231 (dp->i_offset & ~bmask) + imp->logical_block_size; 232 continue; 233 } 234 235 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 236 /* illegal entry, stop */ 237 break; 238 239 if (entryoffsetinblock + reclen > imp->logical_block_size) 240 /* entries are not allowed to cross boundaries */ 241 break; 242 243 namelen = isonum_711(ep->name_len); 244 245 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 246 /* illegal entry, stop */ 247 break; 248 249 /* 250 * Check for a name match. 251 */ 252 switch (imp->iso_ftype) { 253 default: 254 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 255 if ((len == 1 256 && *name == '.') 257 || (flags & ISDOTDOT)) { 258 if (namelen == 1 259 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 260 /* 261 * Save directory entry's inode number and 262 * release directory buffer. 263 */ 264 dp->i_ino = isodirino(ep, imp); 265 goto found; 266 } 267 if (namelen != 1 268 || ep->name[0] != 0) 269 goto notfound; 270 } else if (!(res = isofncmp(name,len, 271 ep->name,namelen, 272 imp->im_joliet_level))) { 273 if (isonum_711(ep->flags)&2) 274 ino = isodirino(ep, imp); 275 else 276 ino = dbtob(bp->b_blkno) 277 + entryoffsetinblock; 278 saveoffset = dp->i_offset; 279 } else if (ino) 280 goto foundino; 281 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 282 else if (res < 0) 283 goto notfound; 284 else if (res > 0 && numdirpasses == 2) 285 numdirpasses++; 286 #endif 287 } 288 break; 289 case ISO_FTYPE_RRIP: 290 if (isonum_711(ep->flags)&2) 291 ino = isodirino(ep, imp); 292 else 293 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 294 dp->i_ino = ino; 295 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 296 if (namelen == cnp->cn_namelen) { 297 if (imp->im_flags & ISOFSMNT_RRCASEINS) { 298 if (strncasecmp(name, altname, namelen) == 0) 299 goto found; 300 } else { 301 if (memcmp(name, altname, namelen) == 0) 302 goto found; 303 } 304 } 305 ino = 0; 306 break; 307 } 308 dp->i_offset += reclen; 309 entryoffsetinblock += reclen; 310 } 311 if (ino) { 312 foundino: 313 dp->i_ino = ino; 314 if (saveoffset != dp->i_offset) { 315 if (lblkno(imp, dp->i_offset) != 316 lblkno(imp, saveoffset)) { 317 if (bp != NULL) 318 brelse(bp); 319 if ((error = VOP_BLKATOFF(vdp, 320 (off_t)saveoffset, NULL, &bp)) != 0) 321 return (error); 322 } 323 entryoffsetinblock = saveoffset & bmask; 324 ep = (struct iso_directory_record *) 325 ((char *)bp->b_data + entryoffsetinblock); 326 dp->i_offset = saveoffset; 327 } 328 goto found; 329 } 330 notfound: 331 /* 332 * If we started in the middle of the directory and failed 333 * to find our target, we must check the beginning as well. 334 */ 335 if (numdirpasses == 2) { 336 numdirpasses--; 337 dp->i_offset = 0; 338 endsearch = dp->i_diroff; 339 goto searchloop; 340 } 341 if (bp != NULL) 342 brelse(bp); 343 344 /* 345 * Insert name into cache (as non-existent) if appropriate. 346 */ 347 if (cnp->cn_flags & MAKEENTRY) 348 cache_enter(vdp, *vpp, cnp); 349 if (nameiop == CREATE || nameiop == RENAME) 350 return (EROFS); 351 return (ENOENT); 352 353 found: 354 if (numdirpasses == 2) 355 iso_nchstats.ncs_pass2++; 356 357 /* 358 * Found component in pathname. 359 * If the final component of path name, save information 360 * in the cache as to where the entry was found. 361 */ 362 if ((flags & ISLASTCN) && nameiop == LOOKUP) 363 dp->i_diroff = dp->i_offset; 364 365 /* 366 * Step through the translation in the name. We do not `iput' the 367 * directory because we may need it again if a symbolic link 368 * is relative to the current directory. Instead we save it 369 * unlocked as "pdp". We must get the target inode before unlocking 370 * the directory to insure that the inode will not be removed 371 * before we get it. We prevent deadlock by always fetching 372 * inodes from the root, moving down the directory tree. Thus 373 * when following backward pointers ".." we must unlock the 374 * parent directory before getting the requested directory. 375 * There is a potential race condition here if both the current 376 * and parent directories are removed before the `iget' for the 377 * inode associated with ".." returns. We hope that this occurs 378 * infrequently since we cannot avoid this race condition without 379 * implementing a sophisticated deadlock detection algorithm. 380 * Note also that this simple deadlock detection scheme will not 381 * work if the file system has any hard links other than ".." 382 * that point backwards in the directory structure. 383 */ 384 pdp = vdp; 385 /* 386 * If ino is different from dp->i_ino, 387 * it's a relocated directory. 388 */ 389 if (flags & ISDOTDOT) { 390 VOP_UNLOCK(pdp, 0); /* race to get the inode */ 391 cnp->cn_flags |= PDIRUNLOCK; 392 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 393 dp->i_ino != ino, ep); 394 brelse(bp); 395 if (error) { 396 if (vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY) == 0) 397 cnp->cn_flags &= ~PDIRUNLOCK; 398 return (error); 399 } 400 if (lockparent && (flags & ISLASTCN)) { 401 if ((error = vn_lock(pdp, LK_EXCLUSIVE))) { 402 vput(tdp); 403 return (error); 404 } 405 cnp->cn_flags &= ~PDIRUNLOCK; 406 } 407 *vpp = tdp; 408 } else if (dp->i_number == dp->i_ino) { 409 brelse(bp); 410 VREF(vdp); /* we want ourself, ie "." */ 411 *vpp = vdp; 412 } else { 413 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 414 dp->i_ino != ino, ep); 415 brelse(bp); 416 if (error) 417 return (error); 418 if (!lockparent || !(flags & ISLASTCN)) { 419 VOP_UNLOCK(pdp, 0); 420 cnp->cn_flags |= PDIRUNLOCK; 421 } 422 *vpp = tdp; 423 } 424 425 /* 426 * Insert name into cache if appropriate. 427 */ 428 if (cnp->cn_flags & MAKEENTRY) 429 cache_enter(vdp, *vpp, cnp); 430 return (0); 431 } 432 433 /* 434 * Return buffer with the contents of block "offset" from the beginning of 435 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 436 * remaining space in the directory. 437 */ 438 int 439 cd9660_blkatoff(v) 440 void *v; 441 { 442 struct vop_blkatoff_args /* { 443 struct vnode *a_vp; 444 off_t a_offset; 445 char **a_res; 446 struct buf **a_bpp; 447 } */ *ap = v; 448 struct iso_node *ip; 449 struct iso_mnt *imp; 450 struct buf *bp; 451 daddr_t lbn; 452 int bsize, error; 453 454 ip = VTOI(ap->a_vp); 455 imp = ip->i_mnt; 456 lbn = lblkno(imp, ap->a_offset); 457 bsize = blksize(imp, ip, lbn); 458 459 if ((error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) != 0) { 460 brelse(bp); 461 *ap->a_bpp = NULL; 462 return (error); 463 } 464 if (ap->a_res) 465 *ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset); 466 *ap->a_bpp = bp; 467 return (0); 468 } 469