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