cd9660_lookup.c revision 115542
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 * $FreeBSD: head/sys/fs/cd9660/cd9660_lookup.c 115542 2003-05-31 20:19:13Z phk $ 42 */ 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/namei.h> 47#include <sys/bio.h> 48#include <sys/buf.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 56/* 57 * Convert a component of a pathname into a pointer to a locked inode. 58 * This is a very central and rather complicated routine. 59 * If the filesystem is not maintained in a strict tree hierarchy, 60 * this can result in a deadlock situation (see comments in code below). 61 * 62 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 63 * whether the name is to be looked up, created, renamed, or deleted. 64 * When CREATE, RENAME, or DELETE is specified, information usable in 65 * creating, renaming, or deleting a directory entry may be calculated. 66 * If flag has LOCKPARENT or'ed into it and the target of the pathname 67 * exists, lookup returns both the target and its parent directory locked. 68 * When creating or renaming and LOCKPARENT is specified, the target may 69 * not be ".". When deleting and LOCKPARENT is specified, the target may 70 * be "."., but the caller must check to ensure it does an vrele and iput 71 * instead of two iputs. 72 * 73 * Overall outline of ufs_lookup: 74 * 75 * search for name in directory, to found or notfound 76 * notfound: 77 * if creating, return locked directory, leaving info on available slots 78 * else return error 79 * found: 80 * if at end of path and deleting, return information to allow delete 81 * if at end of path and rewriting (RENAME and LOCKPARENT), lock target 82 * inode and return info to allow rewrite 83 * if not at end, add name to cache; if at end and neither creating 84 * nor deleting, add name to cache 85 * 86 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. 87 */ 88int 89cd9660_lookup(ap) 90 struct vop_cachedlookup_args /* { 91 struct vnode *a_dvp; 92 struct vnode **a_vpp; 93 struct componentname *a_cnp; 94 } */ *ap; 95{ 96 register struct vnode *vdp; /* vnode for directory being searched */ 97 register struct iso_node *dp; /* inode for directory being searched */ 98 register struct iso_mnt *imp; /* filesystem that directory is in */ 99 struct buf *bp; /* a buffer of directory entries */ 100 struct iso_directory_record *ep = 0;/* the current directory entry */ 101 int entryoffsetinblock; /* offset of ep in bp's buffer */ 102 int saveoffset = 0; /* offset of last directory entry in dir */ 103 int numdirpasses; /* strategy for directory search */ 104 doff_t endsearch; /* offset to end directory search */ 105 struct vnode *pdp; /* saved dp during symlink work */ 106 struct vnode *tdp; /* returned by cd9660_vget_internal */ 107 u_long bmask; /* block offset mask */ 108 int lockparent; /* 1 => lockparent flag is set */ 109 int error; 110 ino_t ino = 0; 111 int reclen; 112 u_short namelen; 113 int isoflags; 114 char altname[NAME_MAX]; 115 int res; 116 int assoc, len; 117 char *name; 118 struct vnode **vpp = ap->a_vpp; 119 struct componentname *cnp = ap->a_cnp; 120 int flags = cnp->cn_flags; 121 int nameiop = cnp->cn_nameiop; 122 struct thread *td = cnp->cn_thread; 123 124 bp = NULL; 125 *vpp = NULL; 126 vdp = ap->a_dvp; 127 dp = VTOI(vdp); 128 imp = dp->i_mnt; 129 lockparent = flags & LOCKPARENT; 130 cnp->cn_flags &= ~PDIRUNLOCK; 131 132 /* 133 * We now have a segment name to search for, and a directory to search. 134 */ 135 136 len = cnp->cn_namelen; 137 name = cnp->cn_nameptr; 138 /* 139 * A leading `=' means, we are looking for an associated file 140 */ 141 if ((assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR))) 142 { 143 len--; 144 name++; 145 } 146 147 /* 148 * If there is cached information on a previous search of 149 * this directory, pick up where we last left off. 150 * We cache only lookups as these are the most common 151 * and have the greatest payoff. Caching CREATE has little 152 * benefit as it usually must search the entire directory 153 * to determine that the entry does not exist. Caching the 154 * location of the last DELETE or RENAME has not reduced 155 * profiling time and hence has been removed in the interest 156 * of simplicity. 157 */ 158 bmask = imp->im_bmask; 159 if (nameiop != LOOKUP || dp->i_diroff == 0 || 160 dp->i_diroff > dp->i_size) { 161 entryoffsetinblock = 0; 162 dp->i_offset = 0; 163 numdirpasses = 1; 164 } else { 165 dp->i_offset = dp->i_diroff; 166 if ((entryoffsetinblock = dp->i_offset & bmask) && 167 (error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp))) 168 return (error); 169 numdirpasses = 2; 170 nchstats.ncs_2passes++; 171 } 172 endsearch = dp->i_size; 173 174searchloop: 175 while (dp->i_offset < endsearch) { 176 /* 177 * If offset is on a block boundary, 178 * read the next directory block. 179 * Release previous if it exists. 180 */ 181 if ((dp->i_offset & bmask) == 0) { 182 if (bp != NULL) 183 brelse(bp); 184 if ((error = 185 cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp)) != 0) 186 return (error); 187 entryoffsetinblock = 0; 188 } 189 /* 190 * Get pointer to next entry. 191 */ 192 ep = (struct iso_directory_record *) 193 ((char *)bp->b_data + entryoffsetinblock); 194 195 reclen = isonum_711(ep->length); 196 if (reclen == 0) { 197 /* skip to next block, if any */ 198 dp->i_offset = 199 (dp->i_offset & ~bmask) + imp->logical_block_size; 200 continue; 201 } 202 203 if (reclen < ISO_DIRECTORY_RECORD_SIZE) 204 /* illegal entry, stop */ 205 break; 206 207 if (entryoffsetinblock + reclen > imp->logical_block_size) 208 /* entries are not allowed to cross boundaries */ 209 break; 210 211 namelen = isonum_711(ep->name_len); 212 isoflags = isonum_711(imp->iso_ftype == ISO_FTYPE_HIGH_SIERRA? 213 &ep->date[6]: ep->flags); 214 215 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) 216 /* illegal entry, stop */ 217 break; 218 219 /* 220 * Check for a name match. 221 */ 222 switch (imp->iso_ftype) { 223 default: 224 if (!(isoflags & 4) == !assoc) { 225 if ((len == 1 226 && *name == '.') 227 || (flags & ISDOTDOT)) { 228 if (namelen == 1 229 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { 230 /* 231 * Save directory entry's inode number and 232 * release directory buffer. 233 */ 234 dp->i_ino = isodirino(ep, imp); 235 goto found; 236 } 237 if (namelen != 1 238 || ep->name[0] != 0) 239 goto notfound; 240 } else if (!(res = isofncmp(name, len, ep->name, namelen, imp->joliet_level))) { 241 if (isoflags & 2) 242 ino = isodirino(ep, imp); 243 else 244 ino = dbtob(bp->b_blkno) 245 + entryoffsetinblock; 246 saveoffset = dp->i_offset; 247 } else if (ino) 248 goto foundino; 249#ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ 250 else if (res < 0) 251 goto notfound; 252 else if (res > 0 && numdirpasses == 2) 253 numdirpasses++; 254#endif 255 } 256 break; 257 case ISO_FTYPE_RRIP: 258 if (isonum_711(ep->flags)&2) 259 ino = isodirino(ep, imp); 260 else 261 ino = dbtob(bp->b_blkno) + entryoffsetinblock; 262 dp->i_ino = ino; 263 cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); 264 if (namelen == cnp->cn_namelen 265 && !bcmp(name,altname,namelen)) 266 goto found; 267 ino = 0; 268 break; 269 } 270 dp->i_offset += reclen; 271 entryoffsetinblock += reclen; 272 } 273 if (ino) { 274foundino: 275 dp->i_ino = ino; 276 if (saveoffset != dp->i_offset) { 277 if (lblkno(imp, dp->i_offset) != 278 lblkno(imp, saveoffset)) { 279 if (bp != NULL) 280 brelse(bp); 281 if ((error = cd9660_blkatoff(vdp, 282 (off_t)saveoffset, NULL, &bp)) != 0) 283 return (error); 284 } 285 entryoffsetinblock = saveoffset & bmask; 286 ep = (struct iso_directory_record *) 287 ((char *)bp->b_data + entryoffsetinblock); 288 dp->i_offset = saveoffset; 289 } 290 goto found; 291 } 292notfound: 293 /* 294 * If we started in the middle of the directory and failed 295 * to find our target, we must check the beginning as well. 296 */ 297 if (numdirpasses == 2) { 298 numdirpasses--; 299 dp->i_offset = 0; 300 endsearch = dp->i_diroff; 301 goto searchloop; 302 } 303 if (bp != NULL) 304 brelse(bp); 305 306 /* 307 * Insert name into cache (as non-existent) if appropriate. 308 */ 309 if (cnp->cn_flags & MAKEENTRY) 310 cache_enter(vdp, *vpp, cnp); 311 if (nameiop == CREATE || nameiop == RENAME) 312 return (EROFS); 313 return (ENOENT); 314 315found: 316 if (numdirpasses == 2) 317 nchstats.ncs_pass2++; 318 319 /* 320 * Found component in pathname. 321 * If the final component of path name, save information 322 * in the cache as to where the entry was found. 323 */ 324 if ((flags & ISLASTCN) && nameiop == LOOKUP) 325 dp->i_diroff = dp->i_offset; 326 327 /* 328 * Step through the translation in the name. We do not `iput' the 329 * directory because we may need it again if a symbolic link 330 * is relative to the current directory. Instead we save it 331 * unlocked as "pdp". We must get the target inode before unlocking 332 * the directory to insure that the inode will not be removed 333 * before we get it. We prevent deadlock by always fetching 334 * inodes from the root, moving down the directory tree. Thus 335 * when following backward pointers ".." we must unlock the 336 * parent directory before getting the requested directory. 337 * There is a potential race condition here if both the current 338 * and parent directories are removed before the `iget' for the 339 * inode associated with ".." returns. We hope that this occurs 340 * infrequently since we cannot avoid this race condition without 341 * implementing a sophisticated deadlock detection algorithm. 342 * Note also that this simple deadlock detection scheme will not 343 * work if the filesystem has any hard links other than ".." 344 * that point backwards in the directory structure. 345 */ 346 pdp = vdp; 347 /* 348 * If ino is different from dp->i_ino, 349 * it's a relocated directory. 350 */ 351 if (flags & ISDOTDOT) { 352 VOP_UNLOCK(pdp, 0, td); /* race to get the inode */ 353 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, 354 LK_EXCLUSIVE, &tdp, 355 dp->i_ino != ino, ep); 356 brelse(bp); 357 if (error) { 358 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, td); 359 return (error); 360 } 361 if (lockparent && (flags & ISLASTCN)) { 362 if ((error = vn_lock(pdp, LK_EXCLUSIVE, td)) != 0) { 363 cnp->cn_flags |= PDIRUNLOCK; 364 vput(tdp); 365 return (error); 366 } 367 } else 368 cnp->cn_flags |= PDIRUNLOCK; 369 *vpp = tdp; 370 } else if (dp->i_number == dp->i_ino) { 371 brelse(bp); 372 VREF(vdp); /* we want ourself, ie "." */ 373 *vpp = vdp; 374 } else { 375 error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, 376 LK_EXCLUSIVE, &tdp, 377 dp->i_ino != ino, ep); 378 brelse(bp); 379 if (error) 380 return (error); 381 if (!lockparent || !(flags & ISLASTCN)) { 382 cnp->cn_flags |= PDIRUNLOCK; 383 VOP_UNLOCK(pdp, 0, td); 384 } 385 *vpp = tdp; 386 } 387 388 /* 389 * Insert name into cache if appropriate. 390 */ 391 if (cnp->cn_flags & MAKEENTRY) 392 cache_enter(vdp, *vpp, cnp); 393 return (0); 394} 395 396/* 397 * Return buffer with the contents of block "offset" from the beginning of 398 * directory "ip". If "res" is non-zero, fill it in with a pointer to the 399 * remaining space in the directory. 400 */ 401int 402cd9660_blkatoff(vp, offset, res, bpp) 403 struct vnode *vp; 404 off_t offset; 405 char **res; 406 struct buf **bpp; 407{ 408 struct iso_node *ip; 409 register struct iso_mnt *imp; 410 struct buf *bp; 411 daddr_t lbn; 412 int bsize, error; 413 414 ip = VTOI(vp); 415 imp = ip->i_mnt; 416 lbn = lblkno(imp, offset); 417 bsize = blksize(imp, ip, lbn); 418 419 if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) { 420 brelse(bp); 421 *bpp = NULL; 422 return (error); 423 } 424 425 /* 426 * We must BMAP the buffer because the directory code may use b_blkno 427 * to calculate the inode for certain types of directory entries. 428 * We could get away with not doing it before we VMIO-backed the 429 * directories because the buffers would get freed atomically with 430 * the invalidation of their data. But with VMIO-backed buffers 431 * the buffers may be freed and then later reconstituted - and the 432 * reconstituted buffer will have no knowledge of b_blkno. 433 */ 434 if (bp->b_blkno == bp->b_lblkno) { 435 error = VOP_BMAP(vp, bp->b_lblkno, NULL, 436 &bp->b_blkno, NULL, NULL); 437 if (error) { 438 bp->b_error = error; 439 bp->b_ioflags |= BIO_ERROR; 440 brelse(bp); 441 *bpp = NULL; 442 return (error); 443 } 444 } 445 446 if (res) 447 *res = (char *)bp->b_data + blkoff(imp, offset); 448 *bpp = bp; 449 return (0); 450} 451