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 8.7 (Berkeley) 05/27/95 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 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && 118 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 119 return (EROFS); 120 121 /* 122 * We now have a segment name to search for, and a directory to search. 123 * 124 * Before tediously performing a linear scan of the directory, 125 * check the name cache to see if the directory/name pair 126 * we are looking for is known already. 127 */ 128 if (error = cache_lookup(vdp, vpp, cnp)) { 129 int vpid; /* capability number of vnode */ 130 131 if (error == ENOENT) 132 return (error); 133 #ifdef PARANOID 134 if ((vdp->v_flag & VROOT) && (flags & ISDOTDOT)) 135 panic("cd9660_lookup: .. through root"); 136 #endif 137 /* 138 * Get the next vnode in the path. 139 * See comment below starting `Step through' for 140 * an explaination of the locking protocol. 141 */ 142 pdp = vdp; 143 dp = VTOI(*vpp); 144 vdp = *vpp; 145 vpid = vdp->v_id; 146 if (pdp == vdp) { 147 VREF(vdp); 148 error = 0; 149 } else if (flags & ISDOTDOT) { 150 VOP_UNLOCK(pdp, 0, p); 151 error = vget(vdp, LK_EXCLUSIVE, p); 152 if (!error && lockparent && (flags & ISLASTCN)) 153 error = vn_lock(pdp, LK_EXCLUSIVE, p); 154 } else { 155 error = vget(vdp, LK_EXCLUSIVE, p); 156 if (!lockparent || error || !(flags & ISLASTCN)) 157 VOP_UNLOCK(pdp, 0, p); 158 } 159 /* 160 * Check that the capability number did not change 161 * while we were waiting for the lock. 162 */ 163 if (!error) { 164 if (vpid == vdp->v_id) 165 return (0); 166 vput(vdp); 167 if (lockparent && pdp != vdp && (flags & ISLASTCN)) 168 VOP_UNLOCK(pdp, 0, p); 169 } 170 if (error = vn_lock(pdp, LK_EXCLUSIVE, p)) 171 return (error); 172 vdp = pdp; 173 dp = VTOI(pdp); 174 *vpp = NULL; 175 } 176 177 len = cnp->cn_namelen; 178 name = cnp->cn_nameptr; 179 /* 180 * A leading `=' means, we are looking for an associated file 181 */ 182 if (assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR)) { 183 len--; 184 name++; 185 } 186 187 /* 188 * If there is cached information on a previous search of 189 * this directory, pick up where we last left off. 190 * We cache only lookups as these are the most common 191 * and have the greatest payoff. Caching CREATE has little 192 * benefit as it usually must search the entire directory 193 * to determine that the entry does not exist. Caching the 194 * location of the last DELETE or RENAME has not reduced 195 * profiling time and hence has been removed in the interest 196 * of simplicity. 197 */ 198 bmask = imp->im_bmask; 199 if (nameiop != LOOKUP || dp->i_diroff == 0 || 200 dp->i_diroff > dp->i_size) { 201 entryoffsetinblock = 0; 202 dp->i_offset = 0; 203 numdirpasses = 1; 204 } else { 205 dp->i_offset = dp->i_diroff; 206 if ((entryoffsetinblock = dp->i_offset & bmask) && 207 (error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp))) 208 return (error); 209 numdirpasses = 2; 210 iso_nchstats.ncs_2passes++; 211 } 212 endsearch = dp->i_size; 213 214 searchloop: 215 while (dp->i_offset < endsearch) { 216 /* 217 * If offset is on a block boundary, 218 * read the next directory block. 219 * Release previous if it exists. 220 */ 221 if ((dp->i_offset & bmask) == 0) { 222 if (bp != NULL) 223 brelse(bp); 224 if (error = 225 VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)) 226 return (error); 227 entryoffsetinblock = 0; 228 } 229 /* 230 * Get pointer to next entry. 231 */ 232 ep = (struct iso_directory_record *) 233 ((char *)bp->b_data + entryoffsetinblock); 234 235 reclen = isonum_711(ep->length); 236 if (reclen == 0) { 237 /* skip to next block, if any */ 238 dp->i_offset = 239 (dp->i_offset & ~bmask) + imp->logical_block_size; 240 continue; 241 } 242 243 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 244 /* illegal entry, stop */ 245 break; 246 247 if (entryoffsetinblock + reclen > imp->logical_block_size) 248 /* entries are not allowed to cross boundaries */ 249 break; 250 251 namelen = isonum_711(ep->name_len); 252 253 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 254 /* illegal entry, stop */ 255 break; 256 257 /* 258 * Check for a name match. 259 */ 260 switch (imp->iso_ftype) { 261 default: 262 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 263 if ((len == 1 264 && *name == '.') 265 || (flags & ISDOTDOT)) { 266 if (namelen == 1 267 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 268 /* 269 * Save directory entry's inode number and 270 * release directory buffer. 271 */ 272 dp->i_ino = isodirino(ep, imp); 273 goto found; 274 } 275 if (namelen != 1 276 || ep->name[0] != 0) 277 goto notfound; 278 } else if (!(res = isofncmp(name,len, 279 ep->name,namelen))) { 280 if (isonum_711(ep->flags)&2) 281 ino = isodirino(ep, imp); 282 else 283 ino = dbtob(bp->b_blkno) 284 + entryoffsetinblock; 285 saveoffset = dp->i_offset; 286 } else if (ino) 287 goto foundino; 288 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 289 else if (res < 0) 290 goto notfound; 291 else if (res > 0 && numdirpasses == 2) 292 numdirpasses++; 293 #endif 294 } 295 break; 296 case ISO_FTYPE_RRIP: 297 if (isonum_711(ep->flags)&2) 298 ino = isodirino(ep, imp); 299 else 300 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 301 dp->i_ino = ino; 302 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 303 if (namelen == cnp->cn_namelen 304 && !bcmp(name,altname,namelen)) 305 goto found; 306 ino = 0; 307 break; 308 } 309 dp->i_offset += reclen; 310 entryoffsetinblock += reclen; 311 } 312 if (ino) { 313 foundino: 314 dp->i_ino = ino; 315 if (saveoffset != dp->i_offset) { 316 if (lblkno(imp, dp->i_offset) != 317 lblkno(imp, saveoffset)) { 318 if (bp != NULL) 319 brelse(bp); 320 if (error = VOP_BLKATOFF(vdp, 321 (off_t)saveoffset, NULL, &bp)) 322 return (error); 323 } 324 entryoffsetinblock = saveoffset & bmask; 325 ep = (struct iso_directory_record *) 326 ((char *)bp->b_data + entryoffsetinblock); 327 dp->i_offset = saveoffset; 328 } 329 goto found; 330 } 331 notfound: 332 /* 333 * If we started in the middle of the directory and failed 334 * to find our target, we must check the beginning as well. 335 */ 336 if (numdirpasses == 2) { 337 numdirpasses--; 338 dp->i_offset = 0; 339 endsearch = dp->i_diroff; 340 goto searchloop; 341 } 342 if (bp != NULL) 343 brelse(bp); 344 345 /* 346 * Insert name into cache (as non-existent) if appropriate. 347 */ 348 if (cnp->cn_flags & MAKEENTRY) 349 cache_enter(vdp, *vpp, cnp); 350 if (nameiop == CREATE || nameiop == RENAME) 351 return (EROFS); 352 return (ENOENT); 353 354 found: 355 if (numdirpasses == 2) 356 iso_nchstats.ncs_pass2++; 357 358 /* 359 * Found component in pathname. 360 * If the final component of path name, save information 361 * in the cache as to where the entry was found. 362 */ 363 if ((flags & ISLASTCN) && nameiop == LOOKUP) 364 dp->i_diroff = dp->i_offset; 365 366 /* 367 * Step through the translation in the name. We do not `iput' the 368 * directory because we may need it again if a symbolic link 369 * is relative to the current directory. Instead we save it 370 * unlocked as "pdp". We must get the target inode before unlocking 371 * the directory to insure that the inode will not be removed 372 * before we get it. We prevent deadlock by always fetching 373 * inodes from the root, moving down the directory tree. Thus 374 * when following backward pointers ".." we must unlock the 375 * parent directory before getting the requested directory. 376 * There is a potential race condition here if both the current 377 * and parent directories are removed before the `iget' for the 378 * inode associated with ".." returns. We hope that this occurs 379 * infrequently since we cannot avoid this race condition without 380 * implementing a sophisticated deadlock detection algorithm. 381 * Note also that this simple deadlock detection scheme will not 382 * work if the file system has any hard links other than ".." 383 * that point backwards in the directory structure. 384 */ 385 pdp = vdp; 386 /* 387 * If ino is different from dp->i_ino, 388 * it's a relocated directory. 389 */ 390 if (flags & ISDOTDOT) { 391 VOP_UNLOCK(pdp, 0, p); /* race to get the inode */ 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 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p); 397 return (error); 398 } 399 if (lockparent && (flags & ISLASTCN) && 400 (error = vn_lock(pdp, LK_EXCLUSIVE, p))) { 401 vput(tdp); 402 return (error); 403 } 404 *vpp = tdp; 405 } else if (dp->i_number == dp->i_ino) { 406 brelse(bp); 407 VREF(vdp); /* we want ourself, ie "." */ 408 *vpp = vdp; 409 } else { 410 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 411 dp->i_ino != ino, ep); 412 brelse(bp); 413 if (error) 414 return (error); 415 if (!lockparent || !(flags & ISLASTCN)) 416 VOP_UNLOCK(pdp, 0, p); 417 *vpp = tdp; 418 } 419 420 /* 421 * Insert name into cache if appropriate. 422 */ 423 if (cnp->cn_flags & MAKEENTRY) 424 cache_enter(vdp, *vpp, cnp); 425 return (0); 426 } 427 428 /* 429 * Return buffer with the contents of block "offset" from the beginning of 430 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 431 * remaining space in the directory. 432 */ 433 int 434 cd9660_blkatoff(ap) 435 struct vop_blkatoff_args /* { 436 struct vnode *a_vp; 437 off_t a_offset; 438 char **a_res; 439 struct buf **a_bpp; 440 } */ *ap; 441 { 442 struct iso_node *ip; 443 register struct iso_mnt *imp; 444 struct buf *bp; 445 daddr_t lbn; 446 int bsize, error; 447 448 ip = VTOI(ap->a_vp); 449 imp = ip->i_mnt; 450 lbn = lblkno(imp, ap->a_offset); 451 bsize = blksize(imp, ip, lbn); 452 453 if (error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) { 454 brelse(bp); 455 *ap->a_bpp = NULL; 456 return (error); 457 } 458 if (ap->a_res) 459 *ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset); 460 *ap->a_bpp = bp; 461 return (0); 462 } 463