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 8.5 (Berkeley) 12/05/94 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; 100 101 bp = NULL; 102 *vpp = NULL; 103 vdp = ap->a_dvp; 104 dp = VTOI(vdp); 105 imp = dp->i_mnt; 106 lockparent = flags & LOCKPARENT; 107 wantparent = flags & (LOCKPARENT|WANTPARENT); 108 109 /* 110 * Check accessiblity of directory. 111 */ 112 if (vdp->v_type != VDIR) 113 return (ENOTDIR); 114 if (error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) 115 return (error); 116 117 /* 118 * We now have a segment name to search for, and a directory to search. 119 * 120 * Before tediously performing a linear scan of the directory, 121 * check the name cache to see if the directory/name pair 122 * we are looking for is known already. 123 */ 124 if (error = cache_lookup(vdp, vpp, cnp)) { 125 int vpid; /* capability number of vnode */ 126 127 if (error == ENOENT) 128 return (error); 129 #ifdef PARANOID 130 if ((vdp->v_flag & VROOT) && (flags & ISDOTDOT)) 131 panic("cd9660_lookup: .. through root"); 132 #endif 133 /* 134 * Get the next vnode in the path. 135 * See comment below starting `Step through' for 136 * an explaination of the locking protocol. 137 */ 138 pdp = vdp; 139 dp = VTOI(*vpp); 140 vdp = *vpp; 141 vpid = vdp->v_id; 142 if (pdp == vdp) { 143 VREF(vdp); 144 error = 0; 145 } else if (flags & ISDOTDOT) { 146 VOP_UNLOCK(pdp); 147 error = vget(vdp, 1); 148 if (!error && lockparent && (flags & ISLASTCN)) 149 error = VOP_LOCK(pdp); 150 } else { 151 error = vget(vdp, 1); 152 if (!lockparent || error || !(flags & ISLASTCN)) 153 VOP_UNLOCK(pdp); 154 } 155 /* 156 * Check that the capability number did not change 157 * while we were waiting for the lock. 158 */ 159 if (!error) { 160 if (vpid == vdp->v_id) 161 return (0); 162 vput(vdp); 163 if (lockparent && pdp != vdp && (flags & ISLASTCN)) 164 VOP_UNLOCK(pdp); 165 } 166 if (error = VOP_LOCK(pdp)) 167 return (error); 168 vdp = pdp; 169 dp = VTOI(pdp); 170 *vpp = NULL; 171 } 172 173 len = cnp->cn_namelen; 174 name = cnp->cn_nameptr; 175 /* 176 * A leading `=' means, we are looking for an associated file 177 */ 178 if (assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR)) { 179 len--; 180 name++; 181 } 182 183 /* 184 * If there is cached information on a previous search of 185 * this directory, pick up where we last left off. 186 * We cache only lookups as these are the most common 187 * and have the greatest payoff. Caching CREATE has little 188 * benefit as it usually must search the entire directory 189 * to determine that the entry does not exist. Caching the 190 * location of the last DELETE or RENAME has not reduced 191 * profiling time and hence has been removed in the interest 192 * of simplicity. 193 */ 194 bmask = imp->im_bmask; 195 if (nameiop != LOOKUP || dp->i_diroff == 0 || 196 dp->i_diroff > dp->i_size) { 197 entryoffsetinblock = 0; 198 dp->i_offset = 0; 199 numdirpasses = 1; 200 } else { 201 dp->i_offset = dp->i_diroff; 202 if ((entryoffsetinblock = dp->i_offset & bmask) && 203 (error = VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp))) 204 return (error); 205 numdirpasses = 2; 206 iso_nchstats.ncs_2passes++; 207 } 208 endsearch = dp->i_size; 209 210 searchloop: 211 while (dp->i_offset < endsearch) { 212 /* 213 * If offset is on a block boundary, 214 * read the next directory block. 215 * Release previous if it exists. 216 */ 217 if ((dp->i_offset & bmask) == 0) { 218 if (bp != NULL) 219 brelse(bp); 220 if (error = 221 VOP_BLKATOFF(vdp, (off_t)dp->i_offset, NULL, &bp)) 222 return (error); 223 entryoffsetinblock = 0; 224 } 225 /* 226 * Get pointer to next entry. 227 */ 228 ep = (struct iso_directory_record *) 229 ((char *)bp->b_data + entryoffsetinblock); 230 231 reclen = isonum_711(ep->length); 232 if (reclen == 0) { 233 /* skip to next block, if any */ 234 dp->i_offset = 235 (dp->i_offset & ~bmask) + imp->logical_block_size; 236 continue; 237 } 238 239 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 240 /* illegal entry, stop */ 241 break; 242 243 if (entryoffsetinblock + reclen > imp->logical_block_size) 244 /* entries are not allowed to cross boundaries */ 245 break; 246 247 namelen = isonum_711(ep->name_len); 248 249 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 250 /* illegal entry, stop */ 251 break; 252 253 /* 254 * Check for a name match. 255 */ 256 switch (imp->iso_ftype) { 257 default: 258 if ((!(isonum_711(ep->flags)&4)) == !assoc) { 259 if ((len == 1 260 && *name == '.') 261 || (flags & ISDOTDOT)) { 262 if (namelen == 1 263 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 264 /* 265 * Save directory entry's inode number and 266 * release directory buffer. 267 */ 268 dp->i_ino = isodirino(ep, imp); 269 goto found; 270 } 271 if (namelen != 1 272 || ep->name[0] != 0) 273 goto notfound; 274 } else if (!(res = isofncmp(name,len, 275 ep->name,namelen))) { 276 if (isonum_711(ep->flags)&2) 277 ino = isodirino(ep, imp); 278 else 279 ino = dbtob(bp->b_blkno) 280 + entryoffsetinblock; 281 saveoffset = dp->i_offset; 282 } else if (ino) 283 goto foundino; 284 #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 285 else if (res < 0) 286 goto notfound; 287 else if (res > 0 && numdirpasses == 2) 288 numdirpasses++; 289 #endif 290 } 291 break; 292 case ISO_FTYPE_RRIP: 293 if (isonum_711(ep->flags)&2) 294 ino = isodirino(ep, imp); 295 else 296 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 297 dp->i_ino = ino; 298 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 299 if (namelen == cnp->cn_namelen 300 && !bcmp(name,altname,namelen)) 301 goto found; 302 ino = 0; 303 break; 304 } 305 dp->i_offset += reclen; 306 entryoffsetinblock += reclen; 307 } 308 if (ino) { 309 foundino: 310 dp->i_ino = ino; 311 if (saveoffset != dp->i_offset) { 312 if (lblkno(imp, dp->i_offset) != 313 lblkno(imp, saveoffset)) { 314 if (bp != NULL) 315 brelse(bp); 316 if (error = VOP_BLKATOFF(vdp, 317 (off_t)saveoffset, NULL, &bp)) 318 return (error); 319 } 320 entryoffsetinblock = saveoffset & bmask; 321 ep = (struct iso_directory_record *) 322 ((char *)bp->b_data + entryoffsetinblock); 323 dp->i_offset = saveoffset; 324 } 325 goto found; 326 } 327 notfound: 328 /* 329 * If we started in the middle of the directory and failed 330 * to find our target, we must check the beginning as well. 331 */ 332 if (numdirpasses == 2) { 333 numdirpasses--; 334 dp->i_offset = 0; 335 endsearch = dp->i_diroff; 336 goto searchloop; 337 } 338 if (bp != NULL) 339 brelse(bp); 340 341 /* 342 * Insert name into cache (as non-existent) if appropriate. 343 */ 344 if (cnp->cn_flags & MAKEENTRY) 345 cache_enter(vdp, *vpp, cnp); 346 if (nameiop == CREATE || nameiop == RENAME) 347 return (EJUSTRETURN); 348 return (ENOENT); 349 350 found: 351 if (numdirpasses == 2) 352 iso_nchstats.ncs_pass2++; 353 354 /* 355 * Found component in pathname. 356 * If the final component of path name, save information 357 * in the cache as to where the entry was found. 358 */ 359 if ((flags & ISLASTCN) && nameiop == LOOKUP) 360 dp->i_diroff = dp->i_offset; 361 362 /* 363 * Step through the translation in the name. We do not `iput' the 364 * directory because we may need it again if a symbolic link 365 * is relative to the current directory. Instead we save it 366 * unlocked as "pdp". We must get the target inode before unlocking 367 * the directory to insure that the inode will not be removed 368 * before we get it. We prevent deadlock by always fetching 369 * inodes from the root, moving down the directory tree. Thus 370 * when following backward pointers ".." we must unlock the 371 * parent directory before getting the requested directory. 372 * There is a potential race condition here if both the current 373 * and parent directories are removed before the `iget' for the 374 * inode associated with ".." returns. We hope that this occurs 375 * infrequently since we cannot avoid this race condition without 376 * implementing a sophisticated deadlock detection algorithm. 377 * Note also that this simple deadlock detection scheme will not 378 * work if the file system has any hard links other than ".." 379 * that point backwards in the directory structure. 380 */ 381 pdp = vdp; 382 /* 383 * If ino is different from dp->i_ino, 384 * it's a relocated directory. 385 */ 386 if (flags & ISDOTDOT) { 387 VOP_UNLOCK(pdp); /* race to get the inode */ 388 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 389 dp->i_ino != ino, ep); 390 brelse(bp); 391 if (error) { 392 VOP_LOCK(pdp); 393 return (error); 394 } 395 if (lockparent && (flags & ISLASTCN) && 396 (error = VOP_LOCK(pdp))) { 397 vput(tdp); 398 return (error); 399 } 400 *vpp = tdp; 401 } else if (dp->i_number == dp->i_ino) { 402 brelse(bp); 403 VREF(vdp); /* we want ourself, ie "." */ 404 *vpp = vdp; 405 } else { 406 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, 407 dp->i_ino != ino, ep); 408 brelse(bp); 409 if (error) 410 return (error); 411 if (!lockparent || !(flags & ISLASTCN)) 412 VOP_UNLOCK(pdp); 413 *vpp = tdp; 414 } 415 416 /* 417 * Insert name into cache if appropriate. 418 */ 419 if (cnp->cn_flags & MAKEENTRY) 420 cache_enter(vdp, *vpp, cnp); 421 return (0); 422 } 423 424 /* 425 * Return buffer with the contents of block "offset" from the beginning of 426 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 427 * remaining space in the directory. 428 */ 429 int 430 cd9660_blkatoff(ap) 431 struct vop_blkatoff_args /* { 432 struct vnode *a_vp; 433 off_t a_offset; 434 char **a_res; 435 struct buf **a_bpp; 436 } */ *ap; 437 { 438 struct iso_node *ip; 439 register struct iso_mnt *imp; 440 struct buf *bp; 441 daddr_t lbn; 442 int bsize, error; 443 444 ip = VTOI(ap->a_vp); 445 imp = ip->i_mnt; 446 lbn = lblkno(imp, ap->a_offset); 447 bsize = blksize(imp, ip, lbn); 448 449 if (error = bread(ap->a_vp, lbn, bsize, NOCRED, &bp)) { 450 brelse(bp); 451 *ap->a_bpp = NULL; 452 return (error); 453 } 454 if (ap->a_res) 455 *ap->a_res = (char *)bp->b_data + blkoff(imp, ap->a_offset); 456 *ap->a_bpp = bp; 457 return (0); 458 } 459