fs/isofs/rock.c

   1 /*
   2  *  linux/fs/isofs/rock.c
   3  *
   4  *  (C) 1992, 1993  Eric Youngdale
   5  *
   6  *  Rock Ridge Extensions to iso9660
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/pagemap.h>
  11
  12 #include "isofs.h"
  13 #include "rock.h"
  14
  15 /*
  16  * These functions are designed to read the system areas of a directory record
  17  * and extract relevant information.  There are different functions provided
  18  * depending upon what information we need at the time.  One function fills
  19  * out an inode structure, a second one extracts a filename, a third one
  20  * returns a symbolic link name, and a fourth one returns the extent number
  21  * for the file.
  22  */
  23
  24 #define SIG(A,B) ((A) | ((B) << 8))     /* isonum_721() */
  25
  26 struct rock_state {
  27         void *buffer;
  28         unsigned char *chr;
  29         int len;
  30         int cont_size;
  31         int cont_extent;
  32         int cont_offset;
  33         struct inode *inode;
  34 };
  35
  36 /*
  37  * This is a way of ensuring that we have something in the system
  38  * use fields that is compatible with Rock Ridge.  Return zero on success.
  39  */
  40
  41 static int check_sp(struct rock_ridge *rr, struct inode *inode)
  42 {
  43         if (rr->u.SP.magic[0] != 0xbe)
  44                 return -1;
  45         if (rr->u.SP.magic[1] != 0xef)
  46                 return -1;
  47         ISOFS_SB(inode->i_sb)->s_rock_offset = rr->u.SP.skip;
  48         return 0;
  49 }
  50
  51 static void setup_rock_ridge(struct iso_directory_record *de,
  52                         struct inode *inode, struct rock_state *rs)
  53 {
  54         rs->len = sizeof(struct iso_directory_record) + de->name_len[0];
  55         if (rs->len & 1)
  56                 (rs->len)++;
  57         rs->chr = (unsigned char *)de + rs->len;
  58         rs->len = *((unsigned char *)de) - rs->len;
  59         if (rs->len < 0)
  60                 rs->len = 0;
  61
  62         if (ISOFS_SB(inode->i_sb)->s_rock_offset != -1) {
  63                 rs->len -= ISOFS_SB(inode->i_sb)->s_rock_offset;
  64                 rs->chr += ISOFS_SB(inode->i_sb)->s_rock_offset;
  65                 if (rs->len < 0)
  66                         rs->len = 0;
  67         }
  68 }
  69
  70 static void init_rock_state(struct rock_state *rs, struct inode *inode)
  71 {
  72         memset(rs, 0, sizeof(*rs));
  73         rs->inode = inode;
  74 }
  75
  76 /*
  77  * Returns 0 if the caller should continue scanning, 1 if the scan must end
  78  * and -ve on error.
  79  */
  80 static int rock_continue(struct rock_state *rs)
  81 {
  82         int ret = 1;
  83         int blocksize = 1 << rs->inode->i_blkbits;
  84         const int min_de_size = offsetof(struct rock_ridge, u);
  85
  86         kfree(rs->buffer);
  87         rs->buffer = NULL;
  88
  89         if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
  90             (unsigned)rs->cont_size > blocksize ||
  91             (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
  92                 printk(KERN_NOTICE "rock: corrupted directory entry. "
  93                         "extent=%d, offset=%d, size=%d\n",
  94                         rs->cont_extent, rs->cont_offset, rs->cont_size);
  95                 ret = -EIO;
  96                 goto out;
  97         }
  98
  99         if (rs->cont_extent) {
 100                 struct buffer_head *bh;
 101
 102                 rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
 103                 if (!rs->buffer) {
 104                         ret = -ENOMEM;
 105                         goto out;
 106                 }
 107                 ret = -EIO;
 108                 bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
 109                 if (bh) {
 110                         memcpy(rs->buffer, bh->b_data + rs->cont_offset,
 111                                         rs->cont_size);
 112                         put_bh(bh);
 113                         rs->chr = rs->buffer;
 114                         rs->len = rs->cont_size;
 115                         rs->cont_extent = 0;
 116                         rs->cont_size = 0;
 117                         rs->cont_offset = 0;
 118                         return 0;
 119                 }
 120                 printk("Unable to read rock-ridge attributes\n");
 121         }
 122 out:
 123         kfree(rs->buffer);
 124         rs->buffer = NULL;
 125         return ret;
 126 }
 127
 128 /*
 129  * We think there's a record of type `sig' at rs->chr.  Parse the signature
 130  * and make sure that there's really room for a record of that type.
 131  */
 132 static int rock_check_overflow(struct rock_state *rs, int sig)
 133 {
 134         int len;
 135
 136         switch (sig) {
 137         case SIG('S', 'P'):
 138                 len = sizeof(struct SU_SP_s);
 139                 break;
 140         case SIG('C', 'E'):
 141                 len = sizeof(struct SU_CE_s);
 142                 break;
 143         case SIG('E', 'R'):
 144                 len = sizeof(struct SU_ER_s);
 145                 break;
 146         case SIG('R', 'R'):
 147                 len = sizeof(struct RR_RR_s);
 148                 break;
 149         case SIG('P', 'X'):
 150                 len = sizeof(struct RR_PX_s);
 151                 break;
 152         case SIG('P', 'N'):
 153                 len = sizeof(struct RR_PN_s);
 154                 break;
 155         case SIG('S', 'L'):
 156                 len = sizeof(struct RR_SL_s);
 157                 break;
 158         case SIG('N', 'M'):
 159                 len = sizeof(struct RR_NM_s);
 160                 break;
 161         case SIG('C', 'L'):
 162                 len = sizeof(struct RR_CL_s);
 163                 break;
 164         case SIG('P', 'L'):
 165                 len = sizeof(struct RR_PL_s);
 166                 break;
 167         case SIG('T', 'F'):
 168                 len = sizeof(struct RR_TF_s);
 169                 break;
 170         case SIG('Z', 'F'):
 171                 len = sizeof(struct RR_ZF_s);
 172                 break;
 173         default:
 174                 len = 0;
 175                 break;
 176         }
 177         len += offsetof(struct rock_ridge, u);
 178         if (len > rs->len) {
 179                 printk(KERN_NOTICE "rock: directory entry would overflow "
 180                                 "storage\n");
 181                 printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
 182                                 sig, len, rs->len);
 183                 return -EIO;
 184         }
 185         return 0;
 186 }
 187
 188 /*
 189  * return length of name field; 0: not found, -1: to be ignored
 190  */
 191 int get_rock_ridge_filename(struct iso_directory_record *de,
 192                             char *retname, struct inode *inode)
 193 {
 194         struct rock_state rs;
 195         struct rock_ridge *rr;
 196         int sig;
 197         int retnamlen = 0;
 198         int truncate = 0;
 199         int ret = 0;
 200
 201         if (!ISOFS_SB(inode->i_sb)->s_rock)
 202                 return 0;
 203         *retname = 0;
 204
 205         init_rock_state(&rs, inode);
 206         setup_rock_ridge(de, inode, &rs);
 207 repeat:
 208
 209         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 210                 rr = (struct rock_ridge *)rs.chr;
 211                 /*
 212                  * Ignore rock ridge info if rr->len is out of range, but
 213                  * don't return -EIO because that would make the file
 214                  * invisible.
 215                  */
 216                 if (rr->len < 3)
 217                         goto out;       /* Something got screwed up here */
 218                 sig = isonum_721(rs.chr);
 219                 if (rock_check_overflow(&rs, sig))
 220                         goto eio;
 221                 rs.chr += rr->len;
 222                 rs.len -= rr->len;
 223                 /*
 224                  * As above, just ignore the rock ridge info if rr->len
 225                  * is bogus.
 226                  */
 227                 if (rs.len < 0)
 228                         goto out;       /* Something got screwed up here */
 229
 230                 switch (sig) {
 231                 case SIG('R', 'R'):
 232                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
 233                                 goto out;
 234                         break;
 235                 case SIG('S', 'P'):
 236                         if (check_sp(rr, inode))
 237                                 goto out;
 238                         break;
 239                 case SIG('C', 'E'):
 240                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 241                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 242                         rs.cont_size = isonum_733(rr->u.CE.size);
 243                         break;
 244                 case SIG('N', 'M'):
 245                         if (truncate)
 246                                 break;
 247                         if (rr->len < 5)
 248                                 break;
 249                         /*
 250                          * If the flags are 2 or 4, this indicates '.' or '..'.
 251                          * We don't want to do anything with this, because it
 252                          * screws up the code that calls us.  We don't really
 253                          * care anyways, since we can just use the non-RR
 254                          * name.
 255                          */
 256                         if (rr->u.NM.flags & 6)
 257                                 break;
 258
 259                         if (rr->u.NM.flags & ~1) {
 260                                 printk("Unsupported NM flag settings (%d)\n",
 261                                         rr->u.NM.flags);
 262                                 break;
 263                         }
 264                         if ((strlen(retname) + rr->len - 5) >= 254) {
 265                                 truncate = 1;
 266                                 break;
 267                         }
 268                         strncat(retname, rr->u.NM.name, rr->len - 5);
 269                         retnamlen += rr->len - 5;
 270                         break;
 271                 case SIG('R', 'E'):
 272                         kfree(rs.buffer);
 273                         return -1;
 274                 default:
 275                         break;
 276                 }
 277         }
 278         ret = rock_continue(&rs);
 279         if (ret == 0)
 280                 goto repeat;
 281         if (ret == 1)
 282                 return retnamlen; /* If 0, this file did not have a NM field */
 283 out:
 284         kfree(rs.buffer);
 285         return ret;
 286 eio:
 287         ret = -EIO;
 288         goto out;
 289 }
 290
 291 #define RR_REGARD_XA 1
 292 #define RR_RELOC_DE 2
 293
 294 static int
 295 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 296                                 struct inode *inode, int flags)
 297 {
 298         int symlink_len = 0;
 299         int cnt, sig;
 300         unsigned int reloc_block;
 301         struct inode *reloc;
 302         struct rock_ridge *rr;
 303         int rootflag;
 304         struct rock_state rs;
 305         int ret = 0;
 306
 307         if (!ISOFS_SB(inode->i_sb)->s_rock)
 308                 return 0;
 309
 310         init_rock_state(&rs, inode);
 311         setup_rock_ridge(de, inode, &rs);
 312         if (flags & RR_REGARD_XA) {
 313                 rs.chr += 14;
 314                 rs.len -= 14;
 315                 if (rs.len < 0)
 316                         rs.len = 0;
 317         }
 318
 319 repeat:
 320         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 321                 rr = (struct rock_ridge *)rs.chr;
 322                 /*
 323                  * Ignore rock ridge info if rr->len is out of range, but
 324                  * don't return -EIO because that would make the file
 325                  * invisible.
 326                  */
 327                 if (rr->len < 3)
 328                         goto out;       /* Something got screwed up here */
 329                 sig = isonum_721(rs.chr);
 330                 if (rock_check_overflow(&rs, sig))
 331                         goto eio;
 332                 rs.chr += rr->len;
 333                 rs.len -= rr->len;
 334                 /*
 335                  * As above, just ignore the rock ridge info if rr->len
 336                  * is bogus.
 337                  */
 338                 if (rs.len < 0)
 339                         goto out;       /* Something got screwed up here */
 340
 341                 switch (sig) {
 342 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 343                 case SIG('R', 'R'):
 344                         if ((rr->u.RR.flags[0] &
 345                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 346                                 goto out;
 347                         break;
 348 #endif
 349                 case SIG('S', 'P'):
 350                         if (check_sp(rr, inode))
 351                                 goto out;
 352                         break;
 353                 case SIG('C', 'E'):
 354                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 355                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 356                         rs.cont_size = isonum_733(rr->u.CE.size);
 357                         break;
 358                 case SIG('E', 'R'):
 359                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 360                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 361                         {
 362                                 int p;
 363                                 for (p = 0; p < rr->u.ER.len_id; p++)
 364                                         printk("%c", rr->u.ER.data[p]);
 365                         }
 366                         printk("\n");
 367                         break;
 368                 case SIG('P', 'X'):
 369                         inode->i_mode = isonum_733(rr->u.PX.mode);
 370                         set_nlink(inode, isonum_733(rr->u.PX.n_links));
 371                         i_uid_write(inode, isonum_733(rr->u.PX.uid));
 372                         i_gid_write(inode, isonum_733(rr->u.PX.gid));
 373                         break;
 374                 case SIG('P', 'N'):
 375                         {
 376                                 int high, low;
 377                                 high = isonum_733(rr->u.PN.dev_high);
 378                                 low = isonum_733(rr->u.PN.dev_low);
 379                                 /*
 380                                  * The Rock Ridge standard specifies that if
 381                                  * sizeof(dev_t) <= 4, then the high field is
 382                                  * unused, and the device number is completely
 383                                  * stored in the low field.  Some writers may
 384                                  * ignore this subtlety,
 385                                  * and as a result we test to see if the entire
 386                                  * device number is
 387                                  * stored in the low field, and use that.
 388                                  */
 389                                 if ((low & ~0xff) && high == 0) {
 390                                         inode->i_rdev =
 391                                             MKDEV(low >> 8, low & 0xff);
 392                                 } else {
 393                                         inode->i_rdev =
 394                                             MKDEV(high, low);
 395                                 }
 396                         }
 397                         break;
 398                 case SIG('T', 'F'):
 399                         /*
 400                          * Some RRIP writers incorrectly place ctime in the
 401                          * TF_CREATE field. Try to handle this correctly for
 402                          * either case.
 403                          */
 404                         /* Rock ridge never appears on a High Sierra disk */
 405                         cnt = 0;
 406                         if (rr->u.TF.flags & TF_CREATE) {
 407                                 inode->i_ctime.tv_sec =
 408                                     iso_date(rr->u.TF.times[cnt++].time,
 409                                              0);
 410                                 inode->i_ctime.tv_nsec = 0;
 411                         }
 412                         if (rr->u.TF.flags & TF_MODIFY) {
 413                                 inode->i_mtime.tv_sec =
 414                                     iso_date(rr->u.TF.times[cnt++].time,
 415                                              0);
 416                                 inode->i_mtime.tv_nsec = 0;
 417                         }
 418                         if (rr->u.TF.flags & TF_ACCESS) {
 419                                 inode->i_atime.tv_sec =
 420                                     iso_date(rr->u.TF.times[cnt++].time,
 421                                              0);
 422                                 inode->i_atime.tv_nsec = 0;
 423                         }
 424                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 425                                 inode->i_ctime.tv_sec =
 426                                     iso_date(rr->u.TF.times[cnt++].time,
 427                                              0);
 428                                 inode->i_ctime.tv_nsec = 0;
 429                         }
 430                         break;
 431                 case SIG('S', 'L'):
 432                         {
 433                                 int slen;
 434                                 struct SL_component *slp;
 435                                 struct SL_component *oldslp;
 436                                 slen = rr->len - 5;
 437                                 slp = &rr->u.SL.link;
 438                                 inode->i_size = symlink_len;
 439                                 while (slen > 1) {
 440                                         rootflag = 0;
 441                                         switch (slp->flags & ~1) {
 442                                         case 0:
 443                                                 inode->i_size +=
 444                                                     slp->len;
 445                                                 break;
 446                                         case 2:
 447                                                 inode->i_size += 1;
 448                                                 break;
 449                                         case 4:
 450                                                 inode->i_size += 2;
 451                                                 break;
 452                                         case 8:
 453                                                 rootflag = 1;
 454                                                 inode->i_size += 1;
 455                                                 break;
 456                                         default:
 457                                                 printk("Symlink component flag "
 458                                                         "not implemented\n");
 459                                         }
 460                                         slen -= slp->len + 2;
 461                                         oldslp = slp;
 462                                         slp = (struct SL_component *)
 463                                                 (((char *)slp) + slp->len + 2);
 464
 465                                         if (slen < 2) {
 466                                                 if (((rr->u.SL.
 467                                                       flags & 1) != 0)
 468                                                     &&
 469                                                     ((oldslp->
 470                                                       flags & 1) == 0))
 471                                                         inode->i_size +=
 472                                                             1;
 473                                                 break;
 474                                         }
 475
 476                                         /*
 477                                          * If this component record isn't
 478                                          * continued, then append a '/'.
 479                                          */
 480                                         if (!rootflag
 481                                             && (oldslp->flags & 1) == 0)
 482                                                 inode->i_size += 1;
 483                                 }
 484                         }
 485                         symlink_len = inode->i_size;
 486                         break;
 487                 case SIG('R', 'E'):
 488                         printk(KERN_WARNING "Attempt to read inode for "
 489                                         "relocated directory\n");
 490                         goto out;
 491                 case SIG('C', 'L'):
 492                         if (flags & RR_RELOC_DE) {
 493                                 printk(KERN_ERR
 494                                        "ISOFS: Recursive directory relocation "
 495                                        "is not supported\n");
 496                                 goto eio;
 497                         }
 498                         reloc_block = isonum_733(rr->u.CL.location);
 499                         if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
 500                             ISOFS_I(inode)->i_iget5_offset == 0) {
 501                                 printk(KERN_ERR
 502                                        "ISOFS: Directory relocation points to "
 503                                        "itself\n");
 504                                 goto eio;
 505                         }
 506                         ISOFS_I(inode)->i_first_extent = reloc_block;
 507                         reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
 508                         if (IS_ERR(reloc)) {
 509                                 ret = PTR_ERR(reloc);
 510                                 goto out;
 511                         }
 512                         inode->i_mode = reloc->i_mode;
 513                         set_nlink(inode, reloc->i_nlink);
 514                         inode->i_uid = reloc->i_uid;
 515                         inode->i_gid = reloc->i_gid;
 516                         inode->i_rdev = reloc->i_rdev;
 517                         inode->i_size = reloc->i_size;
 518                         inode->i_blocks = reloc->i_blocks;
 519                         inode->i_atime = reloc->i_atime;
 520                         inode->i_ctime = reloc->i_ctime;
 521                         inode->i_mtime = reloc->i_mtime;
 522                         iput(reloc);
 523                         break;
 524 #ifdef CONFIG_ZISOFS
 525                 case SIG('Z', 'F'): {
 526                         int algo;
 527
 528                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 529                                 break;
 530                         algo = isonum_721(rr->u.ZF.algorithm);
 531                         if (algo == SIG('p', 'z')) {
 532                                 int block_shift =
 533                                         isonum_711(&rr->u.ZF.parms[1]);
 534                                 if (block_shift > 17) {
 535                                         printk(KERN_WARNING "isofs: "
 536                                                 "Can't handle ZF block "
 537                                                 "size of 2^%d\n",
 538                                                 block_shift);
 539                                 } else {
 540                                         /*
 541                                          * Note: we don't change
 542                                          * i_blocks here
 543                                          */
 544                                         ISOFS_I(inode)->i_file_format =
 545                                                 isofs_file_compressed;
 546                                         /*
 547                                          * Parameters to compression
 548                                          * algorithm (header size,
 549                                          * block size)
 550                                          */
 551                                         ISOFS_I(inode)->i_format_parm[0] =
 552                                                 isonum_711(&rr->u.ZF.parms[0]);
 553                                         ISOFS_I(inode)->i_format_parm[1] =
 554                                                 isonum_711(&rr->u.ZF.parms[1]);
 555                                         inode->i_size =
 556                                             isonum_733(rr->u.ZF.
 557                                                        real_size);
 558                                 }
 559                         } else {
 560                                 printk(KERN_WARNING
 561                                        "isofs: Unknown ZF compression "
 562                                                 "algorithm: %c%c\n",
 563                                        rr->u.ZF.algorithm[0],
 564                                        rr->u.ZF.algorithm[1]);
 565                         }
 566                         break;
 567                 }
 568 #endif
 569                 default:
 570                         break;
 571                 }
 572         }
 573         ret = rock_continue(&rs);
 574         if (ret == 0)
 575                 goto repeat;
 576         if (ret == 1)
 577                 ret = 0;
 578 out:
 579         kfree(rs.buffer);
 580         return ret;
 581 eio:
 582         ret = -EIO;
 583         goto out;
 584 }
 585
 586 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 587 {
 588         int slen;
 589         int rootflag;
 590         struct SL_component *oldslp;
 591         struct SL_component *slp;
 592         slen = rr->len - 5;
 593         slp = &rr->u.SL.link;
 594         while (slen > 1) {
 595                 rootflag = 0;
 596                 switch (slp->flags & ~1) {
 597                 case 0:
 598                         if (slp->len > plimit - rpnt)
 599                                 return NULL;
 600                         memcpy(rpnt, slp->text, slp->len);
 601                         rpnt += slp->len;
 602                         break;
 603                 case 2:
 604                         if (rpnt >= plimit)
 605                                 return NULL;
 606                         *rpnt++ = '.';
 607                         break;
 608                 case 4:
 609                         if (2 > plimit - rpnt)
 610                                 return NULL;
 611                         *rpnt++ = '.';
 612                         *rpnt++ = '.';
 613                         break;
 614                 case 8:
 615                         if (rpnt >= plimit)
 616                                 return NULL;
 617                         rootflag = 1;
 618                         *rpnt++ = '/';
 619                         break;
 620                 default:
 621                         printk("Symlink component flag not implemented (%d)\n",
 622                                slp->flags);
 623                 }
 624                 slen -= slp->len + 2;
 625                 oldslp = slp;
 626                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 627
 628                 if (slen < 2) {
 629                         /*
 630                          * If there is another SL record, and this component
 631                          * record isn't continued, then add a slash.
 632                          */
 633                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 634                             !(oldslp->flags & 1)) {
 635                                 if (rpnt >= plimit)
 636                                         return NULL;
 637                                 *rpnt++ = '/';
 638                         }
 639                         break;
 640                 }
 641
 642                 /*
 643                  * If this component record isn't continued, then append a '/'.
 644                  */
 645                 if (!rootflag && !(oldslp->flags & 1)) {
 646                         if (rpnt >= plimit)
 647                                 return NULL;
 648                         *rpnt++ = '/';
 649                 }
 650         }
 651         return rpnt;
 652 }
 653
 654 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
 655                            int relocated)
 656 {
 657         int flags = relocated ? RR_RELOC_DE : 0;
 658         int result = parse_rock_ridge_inode_internal(de, inode, flags);
 659
 660         /*
 661          * if rockridge flag was reset and we didn't look for attributes
 662          * behind eventual XA attributes, have a look there
 663          */
 664         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 665             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 666                 result = parse_rock_ridge_inode_internal(de, inode,
 667                                                          flags | RR_REGARD_XA);
 668         }
 669         return result;
 670 }
 671
 672 /*
 673  * readpage() for symlinks: reads symlink contents into the page and either
 674  * makes it uptodate and returns 0 or returns error (-EIO)
 675  */
 676 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 677 {
 678         struct inode *inode = page->mapping->host;
 679         struct iso_inode_info *ei = ISOFS_I(inode);
 680         struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
 681         char *link = kmap(page);
 682         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 683         struct buffer_head *bh;
 684         char *rpnt = link;
 685         unsigned char *pnt;
 686         struct iso_directory_record *raw_de;
 687         unsigned long block, offset;
 688         int sig;
 689         struct rock_ridge *rr;
 690         struct rock_state rs;
 691         int ret;
 692
 693         if (!sbi->s_rock)
 694                 goto error;
 695
 696         init_rock_state(&rs, inode);
 697         block = ei->i_iget5_block;
 698         bh = sb_bread(inode->i_sb, block);
 699         if (!bh)
 700                 goto out_noread;
 701
 702         offset = ei->i_iget5_offset;
 703         pnt = (unsigned char *)bh->b_data + offset;
 704
 705         raw_de = (struct iso_directory_record *)pnt;
 706
 707         /*
 708          * If we go past the end of the buffer, there is some sort of error.
 709          */
 710         if (offset + *pnt > bufsize)
 711                 goto out_bad_span;
 712
 713         /*
 714          * Now test for possible Rock Ridge extensions which will override
 715          * some of these numbers in the inode structure.
 716          */
 717
 718         setup_rock_ridge(raw_de, inode, &rs);
 719
 720 repeat:
 721         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 722                 rr = (struct rock_ridge *)rs.chr;
 723                 if (rr->len < 3)
 724                         goto out;       /* Something got screwed up here */
 725                 sig = isonum_721(rs.chr);
 726                 if (rock_check_overflow(&rs, sig))
 727                         goto out;
 728                 rs.chr += rr->len;
 729                 rs.len -= rr->len;
 730                 if (rs.len < 0)
 731                         goto out;       /* corrupted isofs */
 732
 733                 switch (sig) {
 734                 case SIG('R', 'R'):
 735                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 736                                 goto out;
 737                         break;
 738                 case SIG('S', 'P'):
 739                         if (check_sp(rr, inode))
 740                                 goto out;
 741                         break;
 742                 case SIG('S', 'L'):
 743                         rpnt = get_symlink_chunk(rpnt, rr,
 744                                                  link + (PAGE_SIZE - 1));
 745                         if (rpnt == NULL)
 746                                 goto out;
 747                         break;
 748                 case SIG('C', 'E'):
 749                         /* This tells is if there is a continuation record */
 750                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 751                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 752                         rs.cont_size = isonum_733(rr->u.CE.size);
 753                 default:
 754                         break;
 755                 }
 756         }
 757         ret = rock_continue(&rs);
 758         if (ret == 0)
 759                 goto repeat;
 760         if (ret < 0)
 761                 goto fail;
 762
 763         if (rpnt == link)
 764                 goto fail;
 765         brelse(bh);
 766         *rpnt = '\0';
 767         SetPageUptodate(page);
 768         kunmap(page);
 769         unlock_page(page);
 770         return 0;
 771
 772         /* error exit from macro */
 773 out:
 774         kfree(rs.buffer);
 775         goto fail;
 776 out_noread:
 777         printk("unable to read i-node block");
 778         goto fail;
 779 out_bad_span:
 780         printk("symlink spans iso9660 blocks\n");
 781 fail:
 782         brelse(bh);
 783 error:
 784         SetPageError(page);
 785         kunmap(page);
 786         unlock_page(page);
 787         return -EIO;
 788 }
 789
 790 const struct address_space_operations isofs_symlink_aops = {
 791         .readpage = rock_ridge_symlink_readpage
 792 };