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 * %sccs.include.redist.c% 11 * 12 * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91 13 * 14 * @(#)cd9660_lookup.c 8.6 (Berkeley) 05/14/95 15 */ 16 17 #include <sys/param.h> 18 #include <sys/namei.h> 19 #include <sys/buf.h> 20 #include <sys/file.h> 21 #include <sys/vnode.h> 22 #include <sys/mount.h> 23 24 #include <isofs/cd9660/iso.h> 25 #include <isofs/cd9660/cd9660_node.h> 26 #include <isofs/cd9660/iso_rrip.h> 27 #include <isofs/cd9660/cd9660_rrip.h> 28 29 struct nchstats iso_nchstats; 30 31 /* 32 * Convert a component of a pathname into a pointer to a locked inode. 33 * This is a very central and rather complicated routine. 34 * If the file system is not maintained in a strict tree hierarchy, 35 * this can result in a deadlock situation (see comments in code below). 36 * 37 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 38 * whether the name is to be looked up, created, renamed, or deleted. 39 * When CREATE, RENAME, or DELETE is specified, information usable in 40 * creating, renaming, or deleting a directory entry may be calculated. 41 * If flag has LOCKPARENT or'ed into it and the target of the pathname 42 * exists, lookup returns both the target and its parent directory locked. 43 * When creating or renaming and LOCKPARENT is specified, the target may 44 * not be ".". When deleting and LOCKPARENT is specified, the target may 45 * be "."., but the caller must check to ensure it does an vrele and iput 46 * instead of two iputs. 47 * 48 * Overall outline of ufs_lookup: 49 * 50 * check accessibility of directory 51 * look for name in cache, if found, then if at end of path 52 * and deleting or creating, drop it, else return name 53 * search for name in directory, to found or notfound 54 * notfound: 55 * if creating, return locked directory, leaving info on available slots 56 * else return error 57 * found: 58 * if at end of path and deleting, return information to allow delete 59 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target 60 * inode and return info to allow rewrite 61 * if not at end, add name to cache; if at end and neither creating 62 * nor deleting, add name to cache 63 * 64 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. 65 */ 66 cd9660_lookup(ap) 67 struct vop_lookup_args /* { 68 struct vnode *a_dvp; 69 struct vnode **a_vpp; 70 struct componentname *a_cnp; 71 } */ *ap; 72 { 73 register struct vnode *vdp; /* vnode for directory being searched */ 74 register struct iso_node *dp; /* inode for directory being searched */ 75 register struct iso_mnt *imp; /* file system that directory is in */ 76 struct buf *bp; /* a buffer of directory entries */ 77 struct iso_directory_record *ep;/* the current directory entry */ 78 int entryoffsetinblock; /* offset of ep in bp's buffer */ 79 int saveoffset; /* offset of last directory entry in dir */ 80 int numdirpasses; /* strategy for directory search */ 81 doff_t endsearch; /* offset to end directory search */ 82 struct vnode *pdp; /* saved dp during symlink work */ 83 struct vnode *tdp; /* returned by cd9660_vget_internal */ 84 u_long bmask; /* block offset mask */ 85 int lockparent; /* 1 => lockparent flag is set */ 86 int wantparent; /* 1 => wantparent or lockparent flag */ 87 int error; 88 ino_t ino = 0; 89 int reclen; 90 u_short namelen; 91 char altname[NAME_MAX]; 92 int res; 93 int assoc, len; 94 char *name; 95 struct vnode **vpp = ap->a_vpp; 96 struct componentname *cnp = ap->a_cnp; 97 struct ucred *cred = cnp->cn_cred; 98 int flags = cnp->cn_flags; 99 int nameiop = cnp->cn_nameiop; 100 struct proc *p = cnp->cn_proc; 101 102 bp = NULL; 103 *vpp = NULL; 104 vdp = ap->a_dvp; 105 dp = VTOI(vdp); 106 imp = dp->i_mnt; 107 lockparent = flags & LOCKPARENT; 108 wantparent = flags & (LOCKPARENT|WANTPARENT); 109 110 /* 111 * Check accessiblity of directory. 112 */ 113 if (vdp->v_type != VDIR) 114 return (ENOTDIR); 115 if (error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) 116 return (error); 117 118 /* 119 * We now have a segment name to search for, and a directory to search. 120 * 121 * Before tediously performing a linear scan of the directory, 122 * check the name cache to see if the directory/name pair 123 * we are looking for is known already. 124 */ 125 if (error = cache_lookup(vdp, vpp, cnp)) { 126 int vpid; /* capability number of vnode */ 127 128 if (error == ENOENT) 129 return (error); 130 #ifdef PARANOID 131 if ((vdp->v_flag & VROOT) && (flags & ISDOTDOT)) 132 panic("cd9660_lookup: .. through root"); 133 #endif 134 /* 135 * Get the next vnode in the path. 136 * See comment below starting `Step through' for 137 * an explaination of the locking protocol. 138 */ 139 pdp = vdp; 140 dp = VTOI(*vpp); 141 vdp = *vpp; 142 vpid = vdp->v_id; 143 if (pdp == vdp) { 144 VREF(vdp); 145 error = 0; 146 } else if (flags & ISDOTDOT) { 147 VOP_UNLOCK(pdp, 0, p); 148 error = vget(vdp, LK_EXCLUSIVE, p); 149 if (!error && lockparent && (flags & ISLASTCN)) 150 error = vn_lock(pdp, LK_EXCLUSIVE, p); 151 } else { 152 error = vget(vdp, LK_EXCLUSIVE, p); 153 if (!lockparent || error || !(flags & ISLASTCN)) 154 VOP_UNLOCK(pdp, 0, p); 155 } 156 /* 157 * Check that the capability number did not change 158 * while we were waiting for the lock. 159 */ 160 if (!error) { 161 if (vpid == vdp->v_id) 162 return (0); 163 vput(vdp); 164 if (lockparent && pdp != vdp && (flags & ISLASTCN)) 165 VOP_UNLOCK(pdp, 0, p); 166 } 167 if (error = vn_lock(pdp, LK_EXCLUSIVE, p)) 168 return (error); 169 vdp = pdp; 170 dp = VTOI(pdp); 171 *vpp = NULL; 172 } 173 174 len = cnp->cn_namelen; 175 name = cnp->cn_nameptr; 176 /* 177 * A leading `=' means, we are looking for an associated file 178 */ 179 if (assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR)) { 180 len--; 181 name++; 182 } 183 184 /* 185 * If there is cached information on a previous search of 186 * this directory, pick up where we last left off. 187 * We cache only lookups as these are the most common 188 * and have the greatest payoff. Caching CREATE has little 189 * benefit as it usually must search the entire directory 190 * to determine that the entry does not exist. Caching the 191 * location of the last DELETE or RENAME has not reduced 192 * profiling time and hence has been removed in the interest 193 * of simplicity. 194 */ 195 bmask = imp->im_bmask; 196 if (nameiop != LOOKUP || dp->i_diroff == 0 || 197 dp->i_diroff > dp->i_size) { 198 entryoffsetinblock = 0; 199 dp->i_offset = 0; 200 numdirpasses = 1; 201 } else { 202 dp->i_offset = dp->i_diroff; 203 if ((entryoffsetinblock = dp->i_offset & bmask) && 204 (error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp))) 205 return (error); 206 numdirpasses = 2; 207 iso_nchstats.ncs_2passes++; 208 } 209 endsearch = dp->i_size; 210 211 searchloop: 212 while (dp->i_offset < endsearch) { 213 /* 214 * If offset is on a block boundary, 215 * read the next directory block. 216 * Release previous if it exists. 217 */ 218 if ((dp->i_offset & bmask) == 0) { 219 if (bp != NULL) 220 brelse(bp); 221 if (error = 222 VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)) 223 return (error); 224 entryoffsetinblock = 0; 225 } 226 /* 227 * Get pointer to next entry. 228 */ 229 ep = (struct iso_directory_record *) 230 ((char *)bp->b_data + entryoffsetinblock); 231 232 reclen = isonum_711(ep->length); 233 if (reclen == 0) { 234 /* skip to next block, if any */ 235 dp->i_offset = 236 (dp->i_offset & ~bmask) + imp->logical_block_size; 237 continue; 238 } 239 240 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 241 /* illegal entry, stop */ 242 break; 243 244 if (entryoffsetinblock + reclen > imp->logical_block_size) 245 /* entries are not allowed to cross boundaries */ 246 break; 247 248 namelen = isonum_711(ep->name_len); 249 250 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 251 /* illegal entry, stop */ 252 break; 253 254 /* 255 * Check for a name match. 256 */ 257 switch (imp->iso_ftype) { 258 default: 259 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 260 if ((len == 1 261 && *name == '.') 262 || (flags & ISDOTDOT)) { 263 if (namelen == 1 264 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 265 /* 266 * Save directory entry's inode number and 267 * release directory buffer. 268 */ 269 dp->i_ino = isodirino(ep, imp); 270 goto found; 271 } 272 if (namelen != 1 273 || ep->name[0] != 0) 274 goto notfound; 275 } else if (!(res = isofncmp(name,len, 276 ep->name,namelen))) { 277 if (isonum_711(ep->flags)&2) 278 ino = isodirino(ep, imp); 279 else 280 ino = dbtob(bp->b_blkno) 281 + entryoffsetinblock; 282 saveoffset = dp->i_offset; 283 } else if (ino) 284 goto foundino; 285 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 286 else if (res < 0) 287 goto notfound; 288 else if (res > 0 && numdirpasses == 2) 289 numdirpasses++; 290 #endif 291 } 292 break; 293 case ISO_FTYPE_RRIP: 294 if (isonum_711(ep->flags)&2) 295 ino = isodirino(ep, imp); 296 else 297 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 298 dp->i_ino = ino; 299 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 300 if (namelen == cnp->cn_namelen 301 && !bcmp(name,altname,namelen)) 302 goto found; 303 ino = 0; 304 break; 305 } 306 dp->i_offset += reclen; 307 entryoffsetinblock += reclen; 308 } 309 if (ino) { 310 foundino: 311 dp->i_ino = ino; 312 if (saveoffset != dp->i_offset) { 313 if (lblkno(imp, dp->i_offset) != 314 lblkno(imp, saveoffset)) { 315 if (bp != NULL) 316 brelse(bp); 317 if (error = VOP_BLKATOFF(vdp, 318 (off_t)saveoffset, NULL, &bp)) 319 return (error); 320 } 321 entryoffsetinblock = saveoffset & bmask; 322 ep = (struct iso_directory_record *) 323 ((char *)bp->b_data + entryoffsetinblock); 324 dp->i_offset = saveoffset; 325 } 326 goto found; 327 } 328 notfound: 329 /* 330 * If we started in the middle of the directory and failed 331 * to find our target, we must check the beginning as well. 332 */ 333 if (numdirpasses == 2) { 334 numdirpasses--; 335 dp->i_offset = 0; 336 endsearch = dp->i_diroff; 337 goto searchloop; 338 } 339 if (bp != NULL) 340 brelse(bp); 341 342 /* 343 * Insert name into cache (as non-existent) if appropriate. 344 */ 345 if (cnp->cn_flags & MAKEENTRY) 346 cache_enter(vdp, *vpp, cnp); 347 if (nameiop == CREATE || nameiop == RENAME) 348 return (EJUSTRETURN); 349 return (ENOENT); 350 351 found: 352 if (numdirpasses == 2) 353 iso_nchstats.ncs_pass2++; 354 355 /* 356 * Found component in pathname. 357 * If the final component of path name, save information 358 * in the cache as to where the entry was found. 359 */ 360 if ((flags & ISLASTCN) && nameiop == LOOKUP) 361 dp->i_diroff = dp->i_offset; 362 363 /* 364 * Step through the translation in the name. We do not `iput' the 365 * directory because we may need it again if a symbolic link 366 * is relative to the current directory. Instead we save it 367 * unlocked as "pdp". We must get the target inode before unlocking 368 * the directory to insure that the inode will not be removed 369 * before we get it. We prevent deadlock by always fetching 370 * inodes from the root, moving down the directory tree. Thus 371 * when following backward pointers ".." we must unlock the 372 * parent directory before getting the requested directory. 373 * There is a potential race condition here if both the current 374 * and parent directories are removed before the `iget' for the 375 * inode associated with ".." returns. We hope that this occurs 376 * infrequently since we cannot avoid this race condition without 377 * implementing a sophisticated deadlock detection algorithm. 378 * Note also that this simple deadlock detection scheme will not 379 * work if the file system has any hard links other than ".." 380 * that point backwards in the directory structure. 381 */ 382 pdp = vdp; 383 /* 384 * If ino is different from dp->i_ino, 385 * it's a relocated directory. 386 */ 387 if (flags & ISDOTDOT) { 388 VOP_UNLOCK(pdp, 0, p); /* race to get the inode */ 389 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 390 dp->i_ino != ino, ep); 391 brelse(bp); 392 if (error) { 393 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p); 394 return (error); 395 } 396 if (lockparent && (flags & ISLASTCN) && 397 (error = vn_lock(pdp, LK_EXCLUSIVE, p))) { 398 vput(tdp); 399 return (error); 400 } 401 *vpp = tdp; 402 } else if (dp->i_number == dp->i_ino) { 403 brelse(bp); 404 VREF(vdp); /* we want ourself, ie "." */ 405 *vpp = vdp; 406 } else { 407 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 408 dp->i_ino != ino, ep); 409 brelse(bp); 410 if (error) 411 return (error); 412 if (!lockparent || !(flags & ISLASTCN)) 413 VOP_UNLOCK(pdp, 0, p); 414 *vpp = tdp; 415 } 416 417 /* 418 * Insert name into cache if appropriate. 419 */ 420 if (cnp->cn_flags & MAKEENTRY) 421 cache_enter(vdp, *vpp, cnp); 422 return (0); 423 } 424 425 /* 426 * Return buffer with the contents of block "offset" from the beginning of 427 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 428 * remaining space in the directory. 429 */ 430 int 431 cd9660_blkatoff(ap) 432 struct vop_blkatoff_args /* { 433 struct vnode *a_vp; 434 off_t a_offset; 435 char **a_res; 436 struct buf **a_bpp; 437 } */ *ap; 438 { 439 struct iso_node *ip; 440 register struct iso_mnt *imp; 441 struct buf *bp; 442 daddr_t lbn; 443 int bsize, error; 444 445 ip = VTOI(ap->a_vp); 446 imp = ip->i_mnt; 447 lbn = lblkno(imp, ap->a_offset); 448 bsize = blksize(imp, ip, lbn); 449 450 if (error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) { 451 brelse(bp); 452 *ap->a_bpp = NULL; 453 return (error); 454 } 455 if (ap->a_res) 456 *ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset); 457 *ap->a_bpp = bp; 458 return (0); 459 } 460