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         int cont_loops;
  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 /* Maximum number of Rock Ridge continuation entries */
  78 #define RR_MAX_CE_ENTRIES 32
  79
  80 /*
  81  * Returns 0 if the caller should continue scanning, 1 if the scan must end
  82  * and -ve on error.
  83  */
  84 static int rock_continue(struct rock_state *rs)
  85 {
  86         int ret = 1;
  87         int blocksize = 1 << rs->inode->i_blkbits;
  88         const int min_de_size = offsetof(struct rock_ridge, u);
  89
  90         kfree(rs->buffer);
  91         rs->buffer = NULL;
  92
  93         if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
  94             (unsigned)rs->cont_size > blocksize ||
  95             (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
  96                 printk(KERN_NOTICE "rock: corrupted directory entry. "
  97                         "extent=%d, offset=%d, size=%d\n",
  98                         rs->cont_extent, rs->cont_offset, rs->cont_size);
  99                 ret = -EIO;
 100                 goto out;
 101         }
 102
 103         if (rs->cont_extent) {
 104                 struct buffer_head *bh;
 105
 106                 rs->buffer = kmalloc(rs->cont_size, GFP_KERNEL);
 107                 if (!rs->buffer) {
 108                         ret = -ENOMEM;
 109                         goto out;
 110                 }
 111                 ret = -EIO;
 112                 if (++rs->cont_loops >= RR_MAX_CE_ENTRIES)
 113                         goto out;
 114                 bh = sb_bread(rs->inode->i_sb, rs->cont_extent);
 115                 if (bh) {
 116                         memcpy(rs->buffer, bh->b_data + rs->cont_offset,
 117                                         rs->cont_size);
 118                         put_bh(bh);
 119                         rs->chr = rs->buffer;
 120                         rs->len = rs->cont_size;
 121                         rs->cont_extent = 0;
 122                         rs->cont_size = 0;
 123                         rs->cont_offset = 0;
 124                         return 0;
 125                 }
 126                 printk("Unable to read rock-ridge attributes\n");
 127         }
 128 out:
 129         kfree(rs->buffer);
 130         rs->buffer = NULL;
 131         return ret;
 132 }
 133
 134 /*
 135  * We think there's a record of type `sig' at rs->chr.  Parse the signature
 136  * and make sure that there's really room for a record of that type.
 137  */
 138 static int rock_check_overflow(struct rock_state *rs, int sig)
 139 {
 140         int len;
 141
 142         switch (sig) {
 143         case SIG('S', 'P'):
 144                 len = sizeof(struct SU_SP_s);
 145                 break;
 146         case SIG('C', 'E'):
 147                 len = sizeof(struct SU_CE_s);
 148                 break;
 149         case SIG('E', 'R'):
 150                 len = sizeof(struct SU_ER_s);
 151                 break;
 152         case SIG('R', 'R'):
 153                 len = sizeof(struct RR_RR_s);
 154                 break;
 155         case SIG('P', 'X'):
 156                 len = sizeof(struct RR_PX_s);
 157                 break;
 158         case SIG('P', 'N'):
 159                 len = sizeof(struct RR_PN_s);
 160                 break;
 161         case SIG('S', 'L'):
 162                 len = sizeof(struct RR_SL_s);
 163                 break;
 164         case SIG('N', 'M'):
 165                 len = sizeof(struct RR_NM_s);
 166                 break;
 167         case SIG('C', 'L'):
 168                 len = sizeof(struct RR_CL_s);
 169                 break;
 170         case SIG('P', 'L'):
 171                 len = sizeof(struct RR_PL_s);
 172                 break;
 173         case SIG('T', 'F'):
 174                 len = sizeof(struct RR_TF_s);
 175                 break;
 176         case SIG('Z', 'F'):
 177                 len = sizeof(struct RR_ZF_s);
 178                 break;
 179         default:
 180                 len = 0;
 181                 break;
 182         }
 183         len += offsetof(struct rock_ridge, u);
 184         if (len > rs->len) {
 185                 printk(KERN_NOTICE "rock: directory entry would overflow "
 186                                 "storage\n");
 187                 printk(KERN_NOTICE "rock: sig=0x%02x, size=%d, remaining=%d\n",
 188                                 sig, len, rs->len);
 189                 return -EIO;
 190         }
 191         return 0;
 192 }
 193
 194 /*
 195  * return length of name field; 0: not found, -1: to be ignored
 196  */
 197 int get_rock_ridge_filename(struct iso_directory_record *de,
 198                             char *retname, struct inode *inode)
 199 {
 200         struct rock_state rs;
 201         struct rock_ridge *rr;
 202         int sig;
 203         int retnamlen = 0;
 204         int truncate = 0;
 205         int ret = 0;
 206
 207         if (!ISOFS_SB(inode->i_sb)->s_rock)
 208                 return 0;
 209         *retname = 0;
 210
 211         init_rock_state(&rs, inode);
 212         setup_rock_ridge(de, inode, &rs);
 213 repeat:
 214
 215         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 216                 rr = (struct rock_ridge *)rs.chr;
 217                 /*
 218                  * Ignore rock ridge info if rr->len is out of range, but
 219                  * don't return -EIO because that would make the file
 220                  * invisible.
 221                  */
 222                 if (rr->len < 3)
 223                         goto out;       /* Something got screwed up here */
 224                 sig = isonum_721(rs.chr);
 225                 if (rock_check_overflow(&rs, sig))
 226                         goto eio;
 227                 rs.chr += rr->len;
 228                 rs.len -= rr->len;
 229                 /*
 230                  * As above, just ignore the rock ridge info if rr->len
 231                  * is bogus.
 232                  */
 233                 if (rs.len < 0)
 234                         goto out;       /* Something got screwed up here */
 235
 236                 switch (sig) {
 237                 case SIG('R', 'R'):
 238                         if ((rr->u.RR.flags[0] & RR_NM) == 0)
 239                                 goto out;
 240                         break;
 241                 case SIG('S', 'P'):
 242                         if (check_sp(rr, inode))
 243                                 goto out;
 244                         break;
 245                 case SIG('C', 'E'):
 246                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 247                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 248                         rs.cont_size = isonum_733(rr->u.CE.size);
 249                         break;
 250                 case SIG('N', 'M'):
 251                         if (truncate)
 252                                 break;
 253                         if (rr->len < 5)
 254                                 break;
 255                         /*
 256                          * If the flags are 2 or 4, this indicates '.' or '..'.
 257                          * We don't want to do anything with this, because it
 258                          * screws up the code that calls us.  We don't really
 259                          * care anyways, since we can just use the non-RR
 260                          * name.
 261                          */
 262                         if (rr->u.NM.flags & 6)
 263                                 break;
 264
 265                         if (rr->u.NM.flags & ~1) {
 266                                 printk("Unsupported NM flag settings (%d)\n",
 267                                         rr->u.NM.flags);
 268                                 break;
 269                         }
 270                         if ((strlen(retname) + rr->len - 5) >= 254) {
 271                                 truncate = 1;
 272                                 break;
 273                         }
 274                         strncat(retname, rr->u.NM.name, rr->len - 5);
 275                         retnamlen += rr->len - 5;
 276                         break;
 277                 case SIG('R', 'E'):
 278                         kfree(rs.buffer);
 279                         return -1;
 280                 default:
 281                         break;
 282                 }
 283         }
 284         ret = rock_continue(&rs);
 285         if (ret == 0)
 286                 goto repeat;
 287         if (ret == 1)
 288                 return retnamlen; /* If 0, this file did not have a NM field */
 289 out:
 290         kfree(rs.buffer);
 291         return ret;
 292 eio:
 293         ret = -EIO;
 294         goto out;
 295 }
 296
 297 #define RR_REGARD_XA 1
 298 #define RR_RELOC_DE 2
 299
 300 static int
 301 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 302                                 struct inode *inode, int flags)
 303 {
 304         int symlink_len = 0;
 305         int cnt, sig;
 306         unsigned int reloc_block;
 307         struct inode *reloc;
 308         struct rock_ridge *rr;
 309         int rootflag;
 310         struct rock_state rs;
 311         int ret = 0;
 312
 313         if (!ISOFS_SB(inode->i_sb)->s_rock)
 314                 return 0;
 315
 316         init_rock_state(&rs, inode);
 317         setup_rock_ridge(de, inode, &rs);
 318         if (flags & RR_REGARD_XA) {
 319                 rs.chr += 14;
 320                 rs.len -= 14;
 321                 if (rs.len < 0)
 322                         rs.len = 0;
 323         }
 324
 325 repeat:
 326         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 327                 rr = (struct rock_ridge *)rs.chr;
 328                 /*
 329                  * Ignore rock ridge info if rr->len is out of range, but
 330                  * don't return -EIO because that would make the file
 331                  * invisible.
 332                  */
 333                 if (rr->len < 3)
 334                         goto out;       /* Something got screwed up here */
 335                 sig = isonum_721(rs.chr);
 336                 if (rock_check_overflow(&rs, sig))
 337                         goto eio;
 338                 rs.chr += rr->len;
 339                 rs.len -= rr->len;
 340                 /*
 341                  * As above, just ignore the rock ridge info if rr->len
 342                  * is bogus.
 343                  */
 344                 if (rs.len < 0)
 345                         goto out;       /* Something got screwed up here */
 346
 347                 switch (sig) {
 348 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 349                 case SIG('R', 'R'):
 350                         if ((rr->u.RR.flags[0] &
 351                              (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 352                                 goto out;
 353                         break;
 354 #endif
 355                 case SIG('S', 'P'):
 356                         if (check_sp(rr, inode))
 357                                 goto out;
 358                         break;
 359                 case SIG('C', 'E'):
 360                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 361                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 362                         rs.cont_size = isonum_733(rr->u.CE.size);
 363                         break;
 364                 case SIG('E', 'R'):
 365                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 366                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 367                         {
 368                                 int p;
 369                                 for (p = 0; p < rr->u.ER.len_id; p++)
 370                                         printk("%c", rr->u.ER.data[p]);
 371                         }
 372                         printk("\n");
 373                         break;
 374                 case SIG('P', 'X'):
 375                         inode->i_mode = isonum_733(rr->u.PX.mode);
 376                         set_nlink(inode, isonum_733(rr->u.PX.n_links));
 377                         inode->i_uid = isonum_733(rr->u.PX.uid);
 378                         inode->i_gid = isonum_733(rr->u.PX.gid);
 379                         break;
 380                 case SIG('P', 'N'):
 381                         {
 382                                 int high, low;
 383                                 high = isonum_733(rr->u.PN.dev_high);
 384                                 low = isonum_733(rr->u.PN.dev_low);
 385                                 /*
 386                                  * The Rock Ridge standard specifies that if
 387                                  * sizeof(dev_t) <= 4, then the high field is
 388                                  * unused, and the device number is completely
 389                                  * stored in the low field.  Some writers may
 390                                  * ignore this subtlety,
 391                                  * and as a result we test to see if the entire
 392                                  * device number is
 393                                  * stored in the low field, and use that.
 394                                  */
 395                                 if ((low & ~0xff) && high == 0) {
 396                                         inode->i_rdev =
 397                                             MKDEV(low >> 8, low & 0xff);
 398                                 } else {
 399                                         inode->i_rdev =
 400                                             MKDEV(high, low);
 401                                 }
 402                         }
 403                         break;
 404                 case SIG('T', 'F'):
 405                         /*
 406                          * Some RRIP writers incorrectly place ctime in the
 407                          * TF_CREATE field. Try to handle this correctly for
 408                          * either case.
 409                          */
 410                         /* Rock ridge never appears on a High Sierra disk */
 411                         cnt = 0;
 412                         if (rr->u.TF.flags & TF_CREATE) {
 413                                 inode->i_ctime.tv_sec =
 414                                     iso_date(rr->u.TF.times[cnt++].time,
 415                                              0);
 416                                 inode->i_ctime.tv_nsec = 0;
 417                         }
 418                         if (rr->u.TF.flags & TF_MODIFY) {
 419                                 inode->i_mtime.tv_sec =
 420                                     iso_date(rr->u.TF.times[cnt++].time,
 421                                              0);
 422                                 inode->i_mtime.tv_nsec = 0;
 423                         }
 424                         if (rr->u.TF.flags & TF_ACCESS) {
 425                                 inode->i_atime.tv_sec =
 426                                     iso_date(rr->u.TF.times[cnt++].time,
 427                                              0);
 428                                 inode->i_atime.tv_nsec = 0;
 429                         }
 430                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 431                                 inode->i_ctime.tv_sec =
 432                                     iso_date(rr->u.TF.times[cnt++].time,
 433                                              0);
 434                                 inode->i_ctime.tv_nsec = 0;
 435                         }
 436                         break;
 437                 case SIG('S', 'L'):
 438                         {
 439                                 int slen;
 440                                 struct SL_component *slp;
 441                                 struct SL_component *oldslp;
 442                                 slen = rr->len - 5;
 443                                 slp = &rr->u.SL.link;
 444                                 inode->i_size = symlink_len;
 445                                 while (slen > 1) {
 446                                         rootflag = 0;
 447                                         switch (slp->flags & ~1) {
 448                                         case 0:
 449                                                 inode->i_size +=
 450                                                     slp->len;
 451                                                 break;
 452                                         case 2:
 453                                                 inode->i_size += 1;
 454                                                 break;
 455                                         case 4:
 456                                                 inode->i_size += 2;
 457                                                 break;
 458                                         case 8:
 459                                                 rootflag = 1;
 460                                                 inode->i_size += 1;
 461                                                 break;
 462                                         default:
 463                                                 printk("Symlink component flag "
 464                                                         "not implemented\n");
 465                                         }
 466                                         slen -= slp->len + 2;
 467                                         oldslp = slp;
 468                                         slp = (struct SL_component *)
 469                                                 (((char *)slp) + slp->len + 2);
 470
 471                                         if (slen < 2) {
 472                                                 if (((rr->u.SL.
 473                                                       flags & 1) != 0)
 474                                                     &&
 475                                                     ((oldslp->
 476                                                       flags & 1) == 0))
 477                                                         inode->i_size +=
 478                                                             1;
 479                                                 break;
 480                                         }
 481
 482                                         /*
 483                                          * If this component record isn't
 484                                          * continued, then append a '/'.
 485                                          */
 486                                         if (!rootflag
 487                                             && (oldslp->flags & 1) == 0)
 488                                                 inode->i_size += 1;
 489                                 }
 490                         }
 491                         symlink_len = inode->i_size;
 492                         break;
 493                 case SIG('R', 'E'):
 494                         printk(KERN_WARNING "Attempt to read inode for "
 495                                         "relocated directory\n");
 496                         goto out;
 497                 case SIG('C', 'L'):
 498                         if (flags & RR_RELOC_DE) {
 499                                 printk(KERN_ERR
 500                                        "ISOFS: Recursive directory relocation "
 501                                        "is not supported\n");
 502                                 goto eio;
 503                         }
 504                         reloc_block = isonum_733(rr->u.CL.location);
 505                         if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
 506                             ISOFS_I(inode)->i_iget5_offset == 0) {
 507                                 printk(KERN_ERR
 508                                        "ISOFS: Directory relocation points to "
 509                                        "itself\n");
 510                                 goto eio;
 511                         }
 512                         ISOFS_I(inode)->i_first_extent = reloc_block;
 513                         reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
 514                         if (IS_ERR(reloc)) {
 515                                 ret = PTR_ERR(reloc);
 516                                 goto out;
 517                         }
 518                         inode->i_mode = reloc->i_mode;
 519                         set_nlink(inode, reloc->i_nlink);
 520                         inode->i_uid = reloc->i_uid;
 521                         inode->i_gid = reloc->i_gid;
 522                         inode->i_rdev = reloc->i_rdev;
 523                         inode->i_size = reloc->i_size;
 524                         inode->i_blocks = reloc->i_blocks;
 525                         inode->i_atime = reloc->i_atime;
 526                         inode->i_ctime = reloc->i_ctime;
 527                         inode->i_mtime = reloc->i_mtime;
 528                         iput(reloc);
 529                         break;
 530 #ifdef CONFIG_ZISOFS
 531                 case SIG('Z', 'F'): {
 532                         int algo;
 533
 534                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 535                                 break;
 536                         algo = isonum_721(rr->u.ZF.algorithm);
 537                         if (algo == SIG('p', 'z')) {
 538                                 int block_shift =
 539                                         isonum_711(&rr->u.ZF.parms[1]);
 540                                 if (block_shift > 17) {
 541                                         printk(KERN_WARNING "isofs: "
 542                                                 "Can't handle ZF block "
 543                                                 "size of 2^%d\n",
 544                                                 block_shift);
 545                                 } else {
 546                                         /*
 547                                          * Note: we don't change
 548                                          * i_blocks here
 549                                          */
 550                                         ISOFS_I(inode)->i_file_format =
 551                                                 isofs_file_compressed;
 552                                         /*
 553                                          * Parameters to compression
 554                                          * algorithm (header size,
 555                                          * block size)
 556                                          */
 557                                         ISOFS_I(inode)->i_format_parm[0] =
 558                                                 isonum_711(&rr->u.ZF.parms[0]);
 559                                         ISOFS_I(inode)->i_format_parm[1] =
 560                                                 isonum_711(&rr->u.ZF.parms[1]);
 561                                         inode->i_size =
 562                                             isonum_733(rr->u.ZF.
 563                                                        real_size);
 564                                 }
 565                         } else {
 566                                 printk(KERN_WARNING
 567                                        "isofs: Unknown ZF compression "
 568                                                 "algorithm: %c%c\n",
 569                                        rr->u.ZF.algorithm[0],
 570                                        rr->u.ZF.algorithm[1]);
 571                         }
 572                         break;
 573                 }
 574 #endif
 575                 default:
 576                         break;
 577                 }
 578         }
 579         ret = rock_continue(&rs);
 580         if (ret == 0)
 581                 goto repeat;
 582         if (ret == 1)
 583                 ret = 0;
 584 out:
 585         kfree(rs.buffer);
 586         return ret;
 587 eio:
 588         ret = -EIO;
 589         goto out;
 590 }
 591
 592 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 593 {
 594         int slen;
 595         int rootflag;
 596         struct SL_component *oldslp;
 597         struct SL_component *slp;
 598         slen = rr->len - 5;
 599         slp = &rr->u.SL.link;
 600         while (slen > 1) {
 601                 rootflag = 0;
 602                 switch (slp->flags & ~1) {
 603                 case 0:
 604                         if (slp->len > plimit - rpnt)
 605                                 return NULL;
 606                         memcpy(rpnt, slp->text, slp->len);
 607                         rpnt += slp->len;
 608                         break;
 609                 case 2:
 610                         if (rpnt >= plimit)
 611                                 return NULL;
 612                         *rpnt++ = '.';
 613                         break;
 614                 case 4:
 615                         if (2 > plimit - rpnt)
 616                                 return NULL;
 617                         *rpnt++ = '.';
 618                         *rpnt++ = '.';
 619                         break;
 620                 case 8:
 621                         if (rpnt >= plimit)
 622                                 return NULL;
 623                         rootflag = 1;
 624                         *rpnt++ = '/';
 625                         break;
 626                 default:
 627                         printk("Symlink component flag not implemented (%d)\n",
 628                                slp->flags);
 629                 }
 630                 slen -= slp->len + 2;
 631                 oldslp = slp;
 632                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 633
 634                 if (slen < 2) {
 635                         /*
 636                          * If there is another SL record, and this component
 637                          * record isn't continued, then add a slash.
 638                          */
 639                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 640                             !(oldslp->flags & 1)) {
 641                                 if (rpnt >= plimit)
 642                                         return NULL;
 643                                 *rpnt++ = '/';
 644                         }
 645                         break;
 646                 }
 647
 648                 /*
 649                  * If this component record isn't continued, then append a '/'.
 650                  */
 651                 if (!rootflag && !(oldslp->flags & 1)) {
 652                         if (rpnt >= plimit)
 653                                 return NULL;
 654                         *rpnt++ = '/';
 655                 }
 656         }
 657         return rpnt;
 658 }
 659
 660 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
 661                            int relocated)
 662 {
 663         int flags = relocated ? RR_RELOC_DE : 0;
 664         int result = parse_rock_ridge_inode_internal(de, inode, flags);
 665
 666         /*
 667          * if rockridge flag was reset and we didn't look for attributes
 668          * behind eventual XA attributes, have a look there
 669          */
 670         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 671             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 672                 result = parse_rock_ridge_inode_internal(de, inode,
 673                                                          flags | RR_REGARD_XA);
 674         }
 675         return result;
 676 }
 677
 678 /*
 679  * readpage() for symlinks: reads symlink contents into the page and either
 680  * makes it uptodate and returns 0 or returns error (-EIO)
 681  */
 682 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 683 {
 684         struct inode *inode = page->mapping->host;
 685         struct iso_inode_info *ei = ISOFS_I(inode);
 686         struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
 687         char *link = kmap(page);
 688         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 689         struct buffer_head *bh;
 690         char *rpnt = link;
 691         unsigned char *pnt;
 692         struct iso_directory_record *raw_de;
 693         unsigned long block, offset;
 694         int sig;
 695         struct rock_ridge *rr;
 696         struct rock_state rs;
 697         int ret;
 698
 699         if (!sbi->s_rock)
 700                 goto error;
 701
 702         init_rock_state(&rs, inode);
 703         block = ei->i_iget5_block;
 704         bh = sb_bread(inode->i_sb, block);
 705         if (!bh)
 706                 goto out_noread;
 707
 708         offset = ei->i_iget5_offset;
 709         pnt = (unsigned char *)bh->b_data + offset;
 710
 711         raw_de = (struct iso_directory_record *)pnt;
 712
 713         /*
 714          * If we go past the end of the buffer, there is some sort of error.
 715          */
 716         if (offset + *pnt > bufsize)
 717                 goto out_bad_span;
 718
 719         /*
 720          * Now test for possible Rock Ridge extensions which will override
 721          * some of these numbers in the inode structure.
 722          */
 723
 724         setup_rock_ridge(raw_de, inode, &rs);
 725
 726 repeat:
 727         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 728                 rr = (struct rock_ridge *)rs.chr;
 729                 if (rr->len < 3)
 730                         goto out;       /* Something got screwed up here */
 731                 sig = isonum_721(rs.chr);
 732                 if (rock_check_overflow(&rs, sig))
 733                         goto out;
 734                 rs.chr += rr->len;
 735                 rs.len -= rr->len;
 736                 if (rs.len < 0)
 737                         goto out;       /* corrupted isofs */
 738
 739                 switch (sig) {
 740                 case SIG('R', 'R'):
 741                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 742                                 goto out;
 743                         break;
 744                 case SIG('S', 'P'):
 745                         if (check_sp(rr, inode))
 746                                 goto out;
 747                         break;
 748                 case SIG('S', 'L'):
 749                         rpnt = get_symlink_chunk(rpnt, rr,
 750                                                  link + (PAGE_SIZE - 1));
 751                         if (rpnt == NULL)
 752                                 goto out;
 753                         break;
 754                 case SIG('C', 'E'):
 755                         /* This tells is if there is a continuation record */
 756                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 757                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 758                         rs.cont_size = isonum_733(rr->u.CE.size);
 759                 default:
 760                         break;
 761                 }
 762         }
 763         ret = rock_continue(&rs);
 764         if (ret == 0)
 765                 goto repeat;
 766         if (ret < 0)
 767                 goto fail;
 768
 769         if (rpnt == link)
 770                 goto fail;
 771         brelse(bh);
 772         *rpnt = '\0';
 773         SetPageUptodate(page);
 774         kunmap(page);
 775         unlock_page(page);
 776         return 0;
 777
 778         /* error exit from macro */
 779 out:
 780         kfree(rs.buffer);
 781         goto fail;
 782 out_noread:
 783         printk("unable to read i-node block");
 784         goto fail;
 785 out_bad_span:
 786         printk("symlink spans iso9660 blocks\n");
 787 fail:
 788         brelse(bh);
 789 error:
 790         SetPageError(page);
 791         kunmap(page);
 792         unlock_page(page);
 793         return -EIO;
 794 }
 795
 796 const struct address_space_operations isofs_symlink_aops = {
 797         .readpage = rock_ridge_symlink_readpage
 798 };