bsd/isofs/cd9660/cd9660_lookup.c

   1 /*
   2  * Copyright (c) 2000-2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*      $NetBSD: cd9660_lookup.c,v 1.13 1994/12/24 15:30:03 cgd Exp $   */
  23
  24 /*-
  25  * Copyright (c) 1989, 1993, 1994
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * This code is derived from software contributed to Berkeley
  29  * by Pace Willisson (pace@blitz.com).  The Rock Ridge Extension
  30  * Support code is derived from software contributed to Berkeley
  31  * by Atsushi Murai (amurai@spec.co.jp).
  32  *
  33  * Redistribution and use in source and binary forms, with or without
  34  * modification, are permitted provided that the following conditions
  35  * are met:
  36  * 1. Redistributions of source code must retain the above copyright
  37  *    notice, this list of conditions and the following disclaimer.
  38  * 2. Redistributions in binary form must reproduce the above copyright
  39  *    notice, this list of conditions and the following disclaimer in the
  40  *    documentation and/or other materials provided with the distribution.
  41  * 3. All advertising materials mentioning features or use of this software
  42  *    must display the following acknowledgement:
  43  *      This product includes software developed by the University of
  44  *      California, Berkeley and its contributors.
  45  * 4. Neither the name of the University nor the names of its contributors
  46  *    may be used to endorse or promote products derived from this software
  47  *    without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  *
  61  *      from: @(#)ufs_lookup.c  7.33 (Berkeley) 5/19/91
  62  *
  63  *      @(#)cd9660_lookup.c     8.5 (Berkeley) 12/5/94
  64  *
  65  */
  66
  67 #include <sys/param.h>
  68 #include <sys/vnode.h>
  69 #include <sys/mount.h>
  70 #include <sys/namei.h>
  71 #include <sys/buf.h>
  72 #include <sys/file.h>
  73 #include <sys/utfconv.h>
  74
  75 #include <isofs/cd9660/iso.h>
  76 #include <isofs/cd9660/cd9660_node.h>
  77 #include <isofs/cd9660/iso_rrip.h>
  78 #include <isofs/cd9660/cd9660_rrip.h>
  79
  80 struct  nchstats iso_nchstats;
  81
  82 /*
  83  * Convert a component of a pathname into a pointer to a locked inode.
  84  * This is a very central and rather complicated routine.
  85  * If the file system is not maintained in a strict tree hierarchy,
  86  * this can result in a deadlock situation (see comments in code below).
  87  *
  88  * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
  89  * whether the name is to be looked up, created, renamed, or deleted.
  90  * When CREATE, RENAME, or DELETE is specified, information usable in
  91  * creating, renaming, or deleting a directory entry may be calculated.
  92  * If flag has LOCKPARENT or'ed into it and the target of the pathname
  93  * exists, lookup returns both the target and its parent directory locked.
  94  * When creating or renaming and LOCKPARENT is specified, the target may
  95  * not be ".".  When deleting and LOCKPARENT is specified, the target may
  96  * be "."., but the caller must check to ensure it does an vrele and iput
  97  * instead of two iputs.
  98  *
  99  * Overall outline of ufs_lookup:
 100  *
 101  *      check accessibility of directory
 102  *      look for name in cache, if found, then if at end of path
 103  *        and deleting or creating, drop it, else return name
 104  *      search for name in directory, to found or notfound
 105  * notfound:
 106  *      if creating, return locked directory, leaving info on available slots
 107  *      else return error
 108  * found:
 109  *      if at end of path and deleting, return information to allow delete
 110  *      if at end of path and rewriting (RENAME and LOCKPARENT), lock target
 111  *        inode and return info to allow rewrite
 112  *      if not at end, add name to cache; if at end and neither creating
 113  *        nor deleting, add name to cache
 114  *
 115  * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
 116  */
 117 int
 118 cd9660_lookup(struct vnop_lookup_args *ap)
 119 {
 120         register struct vnode *vdp;     /* vnode for directory being searched */
 121         register struct iso_node *dp;   /* inode for directory being searched */
 122         register struct iso_mnt *imp;   /* file system that directory is in */
 123         struct buf *bp;                 /* a buffer of directory entries */
 124         struct iso_directory_record *ep = NULL;/* the current directory entry */
 125         int entryoffsetinblock;         /* offset of ep in bp's buffer */
 126         int saveoffset = 0;             /* offset of last directory entry in dir */
 127         int numdirpasses;               /* strategy for directory search */
 128         doff_t endsearch;               /* offset to end directory search */
 129         struct vnode *pdp;              /* saved dp during symlink work */
 130         struct vnode *tdp;              /* returned by cd9660_vget_internal */
 131         u_long bmask;                   /* block offset mask */
 132         int lockparent;                 /* 1 => lockparent flag is set */
 133         int wantparent;                 /* 1 => wantparent or lockparent flag */
 134         int wantassoc;
 135         int error;
 136         ino_t ino = 0;
 137         int reclen;
 138         u_short namelen;
 139         int isoflags;
 140         char altname[ISO_RRIP_NAMEMAX];
 141         int res;
 142         int len;
 143         char *name;
 144         struct vnode **vpp = ap->a_vpp;
 145         struct componentname *cnp = ap->a_cnp;
 146         int flags = cnp->cn_flags;
 147         int nameiop = cnp->cn_nameiop;
 148         vfs_context_t ctx = cnp->cn_context;
 149         struct proc *p = vfs_context_proc(ctx);
 150         size_t altlen;
 151
 152         bp = NULL;
 153         *vpp = NULL;
 154         vdp = ap->a_dvp;
 155         dp = VTOI(vdp);
 156         imp = dp->i_mnt;
 157         lockparent = flags & LOCKPARENT;
 158         wantparent = flags & (LOCKPARENT|WANTPARENT);
 159         wantassoc = 0;
 160
 161
 162         /*
 163          * We now have a segment name to search for, and a directory to search.
 164          *
 165          * Before tediously performing a linear scan of the directory,
 166          * check the name cache to see if the directory/name pair
 167          * we are looking for is known already.
 168          */
 169         if ((error = cache_lookup(vdp, vpp, cnp))) {
 170                 if (error == ENOENT)
 171                         return (error);
 172                 return (0);
 173         }
 174
 175         len = cnp->cn_namelen;
 176         name = cnp->cn_nameptr;
 177         altname[0] = '\0';
 178         /*
 179          * A "._" prefix means, we are looking for an associated file
 180          */
 181         if (imp->iso_ftype != ISO_FTYPE_RRIP &&
 182             *name == ASSOCCHAR1 && *(name+1) == ASSOCCHAR2) {
 183                 wantassoc = 1;
 184                 len -= 2;
 185                 name += 2;
 186         }
 187         /*
 188          * Decode search name into UCS-2 (Unicode)
 189          */
 190         if ((imp->iso_ftype == ISO_FTYPE_JOLIET) &&
 191             !((len == 1 && *name == '.') || (flags & ISDOTDOT))) {
 192                 int flags1 = UTF_PRECOMPOSED;
 193
 194                 if (BYTE_ORDER != BIG_ENDIAN)
 195                         flags1 |= UTF_REVERSE_ENDIAN;
 196
 197                 (void) utf8_decodestr(name, len, (u_int16_t*) altname, &altlen,
 198                                         sizeof(altname), 0, flags1);
 199                 name = altname;
 200                 len = altlen;
 201         }
 202         /*
 203          * If there is cached information on a previous search of
 204          * this directory, pick up where we last left off.
 205          * We cache only lookups as these are the most common
 206          * and have the greatest payoff. Caching CREATE has little
 207          * benefit as it usually must search the entire directory
 208          * to determine that the entry does not exist. Caching the
 209          * location of the last DELETE or RENAME has not reduced
 210          * profiling time and hence has been removed in the interest
 211          * of simplicity.
 212          */
 213         bmask = imp->im_sector_size - 1;
 214         if (nameiop != LOOKUP || dp->i_diroff == 0 ||
 215             dp->i_diroff > dp->i_size) {
 216                 entryoffsetinblock = 0;
 217                 dp->i_offset = 0;
 218                 numdirpasses = 1;
 219         } else {
 220                 dp->i_offset = dp->i_diroff;
 221
 222                 if ((entryoffsetinblock = dp->i_offset & bmask) &&
 223                     (error = cd9660_blkatoff(vdp, SECTOFF(imp, dp->i_offset), NULL, &bp)))
 224                                 return (error);
 225                 numdirpasses = 2;
 226                 iso_nchstats.ncs_2passes++;
 227         }
 228         endsearch = dp->i_size;
 229
 230 searchloop:
 231         while (dp->i_offset < endsearch) {
 232                 /*
 233                  * If offset is on a block boundary,
 234                  * read the next directory block.
 235                  * Release previous if it exists.
 236                  */
 237                 if ((dp->i_offset & bmask) == 0) {
 238                         if (bp != NULL)
 239                                 buf_brelse(bp);
 240                         if ( (error = cd9660_blkatoff(vdp, SECTOFF(imp,dp->i_offset), NULL, &bp)) )
 241                                 return (error);
 242                         entryoffsetinblock = 0;
 243                 }
 244                 /*
 245                  * Get pointer to next entry.
 246                  */
 247                 ep = (struct iso_directory_record *)
 248                         ((char *)buf_dataptr(bp) + entryoffsetinblock);
 249
 250                 reclen = isonum_711(ep->length);
 251                 if (reclen == 0) {
 252                         /* skip to next block, if any */
 253                         dp->i_offset =
 254                             (dp->i_offset & ~bmask) + imp->im_sector_size;
 255                         continue;
 256                 }
 257
 258                 if (reclen < ISO_DIRECTORY_RECORD_SIZE) {
 259                         /* illegal entry, stop */
 260                         break;
 261                 }
 262                 if (entryoffsetinblock + reclen > imp->im_sector_size) {
 263                         /* entries are not allowed to cross sector boundaries */
 264                         break;
 265                 }
 266                 namelen = isonum_711(ep->name_len);
 267                 isoflags = isonum_711(ep->flags);
 268
 269                 if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen)
 270                         /* illegal entry, stop */
 271                         break;
 272                 /*
 273                  * Check for a name match.
 274                  */
 275                 if (imp->iso_ftype == ISO_FTYPE_RRIP) {
 276                         if (isoflags & directoryBit)
 277                                 ino = isodirino(ep, imp);
 278                         else
 279                                 ino = ((daddr_t)buf_blkno(bp) << imp->im_bshift) + entryoffsetinblock;
 280                         dp->i_ino = ino;
 281                         cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp);
 282                         if (namelen == cnp->cn_namelen
 283                             && !bcmp(name,altname,namelen))
 284                                 goto found;
 285                         ino = 0;
 286                 } else {
 287                         if ((!(isoflags & associatedBit)) == !wantassoc) {
 288                                 if ((len == 1
 289                                      && *name == '.')
 290                                     || (flags & ISDOTDOT)) {
 291                                         if (namelen == 1
 292                                             && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) {
 293                                                 /*
 294                                                  * Save directory entry's inode number and
 295                                                  * release directory buffer.
 296                                                  */
 297                                                 dp->i_ino = isodirino(ep, imp);
 298                                                 goto found;
 299                                         }
 300                                         if (namelen != 1
 301                                             || ep->name[0] != 0)
 302                                                 goto notfound;
 303                                 } else if (imp->iso_ftype != ISO_FTYPE_JOLIET && !(res = isofncmp(name,len,
 304                                                             ep->name,namelen))) {
 305                                         if ( isoflags & directoryBit )
 306                                                 ino = isodirino(ep, imp);
 307                                         else
 308                                                 ino = ((daddr_t)buf_blkno(bp) << imp->im_bshift) + entryoffsetinblock;
 309                                         saveoffset = dp->i_offset;
 310                                 } else if (imp->iso_ftype == ISO_FTYPE_JOLIET && !(res = ucsfncmp((u_int16_t*)name, len,
 311                                                             (u_int16_t*) ep->name, namelen))) {
 312                                         if ( isoflags & directoryBit )
 313                                                 ino = isodirino(ep, imp);
 314                                         else
 315                                                 ino = ((daddr_t)buf_blkno(bp) << imp->im_bshift) + entryoffsetinblock;
 316                                         saveoffset = dp->i_offset;
 317                                 } else if (ino)
 318                                         goto foundino;
 319 #ifdef  NOSORTBUG       /* On some CDs directory entries are not sorted correctly */
 320                                 else if (res < 0)
 321                                         goto notfound;
 322                                 else if (res > 0 && numdirpasses == 2)
 323                                         numdirpasses++;
 324 #endif
 325                         }
 326                 }
 327                 dp->i_offset += reclen;
 328                 entryoffsetinblock += reclen;
 329         } /* endwhile */
 330
 331         if (ino) {
 332 foundino:
 333                 dp->i_ino = ino;
 334                 if (saveoffset != dp->i_offset) {
 335                         if (lblkno(imp, dp->i_offset) !=
 336                             lblkno(imp, saveoffset)) {
 337                                 if (bp != NULL)
 338                                         buf_brelse(bp);
 339                                 if ( (error = cd9660_blkatoff(vdp, SECTOFF(imp, saveoffset), NULL, &bp)) )
 340                                         return (error);
 341                         }
 342                         entryoffsetinblock = saveoffset & bmask;
 343                         ep = (struct iso_directory_record *)
 344                                 ((char *)buf_dataptr(bp) + entryoffsetinblock);
 345                         dp->i_offset = saveoffset;
 346                 }
 347                 goto found;
 348         }
 349 notfound:
 350         /*
 351          * If we started in the middle of the directory and failed
 352          * to find our target, we must check the beginning as well.
 353          */
 354         if (numdirpasses == 2) {
 355                 numdirpasses--;
 356                 dp->i_offset = 0;
 357                 endsearch = dp->i_diroff;
 358                 goto searchloop;
 359         }
 360         if (bp != NULL)
 361                 buf_brelse(bp);
 362
 363         /*
 364          * Insert name into cache (as non-existent) if appropriate.
 365          */
 366         if (cnp->cn_flags & MAKEENTRY)
 367                 cache_enter(vdp, *vpp, cnp);
 368         return (ENOENT);
 369
 370 found:
 371         if (numdirpasses == 2)
 372                 iso_nchstats.ncs_pass2++;
 373
 374         /*
 375          * Found component in pathname.
 376          * If the final component of path name, save information
 377          * in the cache as to where the entry was found.
 378          */
 379         if ((flags & ISLASTCN) && nameiop == LOOKUP)
 380                 dp->i_diroff = dp->i_offset;
 381
 382         /*
 383          * Step through the translation in the name.  We do not `iput' the
 384          * directory because we may need it again if a symbolic link
 385          * is relative to the current directory.  Instead we save it
 386          * unlocked as "pdp".  We must get the target inode before unlocking
 387          * the directory to insure that the inode will not be removed
 388          * before we get it.  We prevent deadlock by always fetching
 389          * inodes from the root, moving down the directory tree. Thus
 390          * when following backward pointers ".." we must unlock the
 391          * parent directory before getting the requested directory.
 392          * There is a potential race condition here if both the current
 393          * and parent directories are removed before the `iget' for the
 394          * inode associated with ".." returns.  We hope that this occurs
 395          * infrequently since we cannot avoid this race condition without
 396          * implementing a sophisticated deadlock detection algorithm.
 397          * Note also that this simple deadlock detection scheme will not
 398          * work if the file system has any hard links other than ".."
 399          * that point backwards in the directory structure.
 400          */
 401         pdp = vdp;
 402         /*
 403          * If ino is different from dp->i_ino,
 404          * it's a relocated directory.
 405          */
 406         if (flags & ISDOTDOT) {
 407                 error = cd9660_vget_internal(vnode_mount(vdp), dp->i_ino, &tdp, NULL, NULL,
 408                                              dp->i_ino != ino, ep, p);
 409                 VTOI(tdp)->i_parent = VTOI(pdp)->i_number;
 410                 buf_brelse(bp);
 411
 412                 *vpp = tdp;
 413         } else if (dp->i_number == dp->i_ino) {
 414                 buf_brelse(bp);
 415                 vnode_get(vdp); /* we want ourself, ie "." */
 416                 *vpp = vdp;
 417         } else {
 418                 error = cd9660_vget_internal(vnode_mount(vdp), dp->i_ino, &tdp, vdp, cnp,
 419                                              dp->i_ino != ino, ep, p);
 420                 /* save parent inode number */
 421                 VTOI(tdp)->i_parent = VTOI(pdp)->i_number;
 422                 buf_brelse(bp);
 423                 if (error)
 424                         return (error);
 425                 *vpp = tdp;
 426         }
 427         return (0);
 428 }
 429
 430
 431 /*
 432  * Return buffer with the contents of block "offset" from the beginning of
 433  * directory "ip".  If "res" is non-zero, fill it in with a pointer to the
 434  * remaining space in the directory.
 435  */
 436 int
 437 cd9660_blkatoff(vnode_t vp, off_t offset, char **res, buf_t *bpp)
 438 {
 439         struct iso_node *ip;
 440         register struct iso_mnt *imp;
 441         buf_t   bp;
 442         daddr_t lbn;
 443         int bsize, error;
 444
 445         ip = VTOI(vp);
 446         imp = ip->i_mnt;
 447         lbn = lblkno(imp, offset);
 448         bsize = blksize(imp, ip, lbn);
 449
 450         if ((bsize != imp->im_sector_size) &&
 451             (offset & (imp->im_sector_size - 1)) == 0) {
 452                 bsize = imp->im_sector_size;
 453         }
 454
 455         if ( (error = (int)buf_bread(vp, (daddr64_t)((unsigned)lbn), bsize, NOCRED, &bp)) ) {
 456                 buf_brelse(bp);
 457                 *bpp = NULL;
 458                 return (error);
 459         }
 460         if (res)
 461                 *res = (char *)buf_dataptr(bp) + blkoff(imp, offset);
 462         *bpp = bp;
 463
 464         return (0);
 465 }