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                         /* Invalid length of ER tag id? */
 366                         if (rr->u.ER.len_id + offsetof(struct rock_ridge, u.ER.data) > rr->len)
 367                                 goto out;
 368                         ISOFS_SB(inode->i_sb)->s_rock = 1;
 369                         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 370                         {
 371                                 int p;
 372                                 for (p = 0; p < rr->u.ER.len_id; p++)
 373                                         printk("%c", rr->u.ER.data[p]);
 374                         }
 375                         printk("\n");
 376                         break;
 377                 case SIG('P', 'X'):
 378                         inode->i_mode = isonum_733(rr->u.PX.mode);
 379                         set_nlink(inode, isonum_733(rr->u.PX.n_links));
 380                         i_uid_write(inode, isonum_733(rr->u.PX.uid));
 381                         i_gid_write(inode, isonum_733(rr->u.PX.gid));
 382                         break;
 383                 case SIG('P', 'N'):
 384                         {
 385                                 int high, low;
 386                                 high = isonum_733(rr->u.PN.dev_high);
 387                                 low = isonum_733(rr->u.PN.dev_low);
 388                                 /*
 389                                  * The Rock Ridge standard specifies that if
 390                                  * sizeof(dev_t) <= 4, then the high field is
 391                                  * unused, and the device number is completely
 392                                  * stored in the low field.  Some writers may
 393                                  * ignore this subtlety,
 394                                  * and as a result we test to see if the entire
 395                                  * device number is
 396                                  * stored in the low field, and use that.
 397                                  */
 398                                 if ((low & ~0xff) && high == 0) {
 399                                         inode->i_rdev =
 400                                             MKDEV(low >> 8, low & 0xff);
 401                                 } else {
 402                                         inode->i_rdev =
 403                                             MKDEV(high, low);
 404                                 }
 405                         }
 406                         break;
 407                 case SIG('T', 'F'):
 408                         /*
 409                          * Some RRIP writers incorrectly place ctime in the
 410                          * TF_CREATE field. Try to handle this correctly for
 411                          * either case.
 412                          */
 413                         /* Rock ridge never appears on a High Sierra disk */
 414                         cnt = 0;
 415                         if (rr->u.TF.flags & TF_CREATE) {
 416                                 inode->i_ctime.tv_sec =
 417                                     iso_date(rr->u.TF.times[cnt++].time,
 418                                              0);
 419                                 inode->i_ctime.tv_nsec = 0;
 420                         }
 421                         if (rr->u.TF.flags & TF_MODIFY) {
 422                                 inode->i_mtime.tv_sec =
 423                                     iso_date(rr->u.TF.times[cnt++].time,
 424                                              0);
 425                                 inode->i_mtime.tv_nsec = 0;
 426                         }
 427                         if (rr->u.TF.flags & TF_ACCESS) {
 428                                 inode->i_atime.tv_sec =
 429                                     iso_date(rr->u.TF.times[cnt++].time,
 430                                              0);
 431                                 inode->i_atime.tv_nsec = 0;
 432                         }
 433                         if (rr->u.TF.flags & TF_ATTRIBUTES) {
 434                                 inode->i_ctime.tv_sec =
 435                                     iso_date(rr->u.TF.times[cnt++].time,
 436                                              0);
 437                                 inode->i_ctime.tv_nsec = 0;
 438                         }
 439                         break;
 440                 case SIG('S', 'L'):
 441                         {
 442                                 int slen;
 443                                 struct SL_component *slp;
 444                                 struct SL_component *oldslp;
 445                                 slen = rr->len - 5;
 446                                 slp = &rr->u.SL.link;
 447                                 inode->i_size = symlink_len;
 448                                 while (slen > 1) {
 449                                         rootflag = 0;
 450                                         switch (slp->flags & ~1) {
 451                                         case 0:
 452                                                 inode->i_size +=
 453                                                     slp->len;
 454                                                 break;
 455                                         case 2:
 456                                                 inode->i_size += 1;
 457                                                 break;
 458                                         case 4:
 459                                                 inode->i_size += 2;
 460                                                 break;
 461                                         case 8:
 462                                                 rootflag = 1;
 463                                                 inode->i_size += 1;
 464                                                 break;
 465                                         default:
 466                                                 printk("Symlink component flag "
 467                                                         "not implemented\n");
 468                                         }
 469                                         slen -= slp->len + 2;
 470                                         oldslp = slp;
 471                                         slp = (struct SL_component *)
 472                                                 (((char *)slp) + slp->len + 2);
 473
 474                                         if (slen < 2) {
 475                                                 if (((rr->u.SL.
 476                                                       flags & 1) != 0)
 477                                                     &&
 478                                                     ((oldslp->
 479                                                       flags & 1) == 0))
 480                                                         inode->i_size +=
 481                                                             1;
 482                                                 break;
 483                                         }
 484
 485                                         /*
 486                                          * If this component record isn't
 487                                          * continued, then append a '/'.
 488                                          */
 489                                         if (!rootflag
 490                                             && (oldslp->flags & 1) == 0)
 491                                                 inode->i_size += 1;
 492                                 }
 493                         }
 494                         symlink_len = inode->i_size;
 495                         break;
 496                 case SIG('R', 'E'):
 497                         printk(KERN_WARNING "Attempt to read inode for "
 498                                         "relocated directory\n");
 499                         goto out;
 500                 case SIG('C', 'L'):
 501                         if (flags & RR_RELOC_DE) {
 502                                 printk(KERN_ERR
 503                                        "ISOFS: Recursive directory relocation "
 504                                        "is not supported\n");
 505                                 goto eio;
 506                         }
 507                         reloc_block = isonum_733(rr->u.CL.location);
 508                         if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
 509                             ISOFS_I(inode)->i_iget5_offset == 0) {
 510                                 printk(KERN_ERR
 511                                        "ISOFS: Directory relocation points to "
 512                                        "itself\n");
 513                                 goto eio;
 514                         }
 515                         ISOFS_I(inode)->i_first_extent = reloc_block;
 516                         reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
 517                         if (IS_ERR(reloc)) {
 518                                 ret = PTR_ERR(reloc);
 519                                 goto out;
 520                         }
 521                         inode->i_mode = reloc->i_mode;
 522                         set_nlink(inode, reloc->i_nlink);
 523                         inode->i_uid = reloc->i_uid;
 524                         inode->i_gid = reloc->i_gid;
 525                         inode->i_rdev = reloc->i_rdev;
 526                         inode->i_size = reloc->i_size;
 527                         inode->i_blocks = reloc->i_blocks;
 528                         inode->i_atime = reloc->i_atime;
 529                         inode->i_ctime = reloc->i_ctime;
 530                         inode->i_mtime = reloc->i_mtime;
 531                         iput(reloc);
 532                         break;
 533 #ifdef CONFIG_ZISOFS
 534                 case SIG('Z', 'F'): {
 535                         int algo;
 536
 537                         if (ISOFS_SB(inode->i_sb)->s_nocompress)
 538                                 break;
 539                         algo = isonum_721(rr->u.ZF.algorithm);
 540                         if (algo == SIG('p', 'z')) {
 541                                 int block_shift =
 542                                         isonum_711(&rr->u.ZF.parms[1]);
 543                                 if (block_shift > 17) {
 544                                         printk(KERN_WARNING "isofs: "
 545                                                 "Can't handle ZF block "
 546                                                 "size of 2^%d\n",
 547                                                 block_shift);
 548                                 } else {
 549                                         /*
 550                                          * Note: we don't change
 551                                          * i_blocks here
 552                                          */
 553                                         ISOFS_I(inode)->i_file_format =
 554                                                 isofs_file_compressed;
 555                                         /*
 556                                          * Parameters to compression
 557                                          * algorithm (header size,
 558                                          * block size)
 559                                          */
 560                                         ISOFS_I(inode)->i_format_parm[0] =
 561                                                 isonum_711(&rr->u.ZF.parms[0]);
 562                                         ISOFS_I(inode)->i_format_parm[1] =
 563                                                 isonum_711(&rr->u.ZF.parms[1]);
 564                                         inode->i_size =
 565                                             isonum_733(rr->u.ZF.
 566                                                        real_size);
 567                                 }
 568                         } else {
 569                                 printk(KERN_WARNING
 570                                        "isofs: Unknown ZF compression "
 571                                                 "algorithm: %c%c\n",
 572                                        rr->u.ZF.algorithm[0],
 573                                        rr->u.ZF.algorithm[1]);
 574                         }
 575                         break;
 576                 }
 577 #endif
 578                 default:
 579                         break;
 580                 }
 581         }
 582         ret = rock_continue(&rs);
 583         if (ret == 0)
 584                 goto repeat;
 585         if (ret == 1)
 586                 ret = 0;
 587 out:
 588         kfree(rs.buffer);
 589         return ret;
 590 eio:
 591         ret = -EIO;
 592         goto out;
 593 }
 594
 595 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 596 {
 597         int slen;
 598         int rootflag;
 599         struct SL_component *oldslp;
 600         struct SL_component *slp;
 601         slen = rr->len - 5;
 602         slp = &rr->u.SL.link;
 603         while (slen > 1) {
 604                 rootflag = 0;
 605                 switch (slp->flags & ~1) {
 606                 case 0:
 607                         if (slp->len > plimit - rpnt)
 608                                 return NULL;
 609                         memcpy(rpnt, slp->text, slp->len);
 610                         rpnt += slp->len;
 611                         break;
 612                 case 2:
 613                         if (rpnt >= plimit)
 614                                 return NULL;
 615                         *rpnt++ = '.';
 616                         break;
 617                 case 4:
 618                         if (2 > plimit - rpnt)
 619                                 return NULL;
 620                         *rpnt++ = '.';
 621                         *rpnt++ = '.';
 622                         break;
 623                 case 8:
 624                         if (rpnt >= plimit)
 625                                 return NULL;
 626                         rootflag = 1;
 627                         *rpnt++ = '/';
 628                         break;
 629                 default:
 630                         printk("Symlink component flag not implemented (%d)\n",
 631                                slp->flags);
 632                 }
 633                 slen -= slp->len + 2;
 634                 oldslp = slp;
 635                 slp = (struct SL_component *)((char *)slp + slp->len + 2);
 636
 637                 if (slen < 2) {
 638                         /*
 639                          * If there is another SL record, and this component
 640                          * record isn't continued, then add a slash.
 641                          */
 642                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 643                             !(oldslp->flags & 1)) {
 644                                 if (rpnt >= plimit)
 645                                         return NULL;
 646                                 *rpnt++ = '/';
 647                         }
 648                         break;
 649                 }
 650
 651                 /*
 652                  * If this component record isn't continued, then append a '/'.
 653                  */
 654                 if (!rootflag && !(oldslp->flags & 1)) {
 655                         if (rpnt >= plimit)
 656                                 return NULL;
 657                         *rpnt++ = '/';
 658                 }
 659         }
 660         return rpnt;
 661 }
 662
 663 int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
 664                            int relocated)
 665 {
 666         int flags = relocated ? RR_RELOC_DE : 0;
 667         int result = parse_rock_ridge_inode_internal(de, inode, flags);
 668
 669         /*
 670          * if rockridge flag was reset and we didn't look for attributes
 671          * behind eventual XA attributes, have a look there
 672          */
 673         if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 674             && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 675                 result = parse_rock_ridge_inode_internal(de, inode,
 676                                                          flags | RR_REGARD_XA);
 677         }
 678         return result;
 679 }
 680
 681 /*
 682  * readpage() for symlinks: reads symlink contents into the page and either
 683  * makes it uptodate and returns 0 or returns error (-EIO)
 684  */
 685 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 686 {
 687         struct inode *inode = page->mapping->host;
 688         struct iso_inode_info *ei = ISOFS_I(inode);
 689         struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
 690         char *link = kmap(page);
 691         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 692         struct buffer_head *bh;
 693         char *rpnt = link;
 694         unsigned char *pnt;
 695         struct iso_directory_record *raw_de;
 696         unsigned long block, offset;
 697         int sig;
 698         struct rock_ridge *rr;
 699         struct rock_state rs;
 700         int ret;
 701
 702         if (!sbi->s_rock)
 703                 goto error;
 704
 705         init_rock_state(&rs, inode);
 706         block = ei->i_iget5_block;
 707         bh = sb_bread(inode->i_sb, block);
 708         if (!bh)
 709                 goto out_noread;
 710
 711         offset = ei->i_iget5_offset;
 712         pnt = (unsigned char *)bh->b_data + offset;
 713
 714         raw_de = (struct iso_directory_record *)pnt;
 715
 716         /*
 717          * If we go past the end of the buffer, there is some sort of error.
 718          */
 719         if (offset + *pnt > bufsize)
 720                 goto out_bad_span;
 721
 722         /*
 723          * Now test for possible Rock Ridge extensions which will override
 724          * some of these numbers in the inode structure.
 725          */
 726
 727         setup_rock_ridge(raw_de, inode, &rs);
 728
 729 repeat:
 730         while (rs.len > 2) { /* There may be one byte for padding somewhere */
 731                 rr = (struct rock_ridge *)rs.chr;
 732                 if (rr->len < 3)
 733                         goto out;       /* Something got screwed up here */
 734                 sig = isonum_721(rs.chr);
 735                 if (rock_check_overflow(&rs, sig))
 736                         goto out;
 737                 rs.chr += rr->len;
 738                 rs.len -= rr->len;
 739                 if (rs.len < 0)
 740                         goto out;       /* corrupted isofs */
 741
 742                 switch (sig) {
 743                 case SIG('R', 'R'):
 744                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 745                                 goto out;
 746                         break;
 747                 case SIG('S', 'P'):
 748                         if (check_sp(rr, inode))
 749                                 goto out;
 750                         break;
 751                 case SIG('S', 'L'):
 752                         rpnt = get_symlink_chunk(rpnt, rr,
 753                                                  link + (PAGE_SIZE - 1));
 754                         if (rpnt == NULL)
 755                                 goto out;
 756                         break;
 757                 case SIG('C', 'E'):
 758                         /* This tells is if there is a continuation record */
 759                         rs.cont_extent = isonum_733(rr->u.CE.extent);
 760                         rs.cont_offset = isonum_733(rr->u.CE.offset);
 761                         rs.cont_size = isonum_733(rr->u.CE.size);
 762                 default:
 763                         break;
 764                 }
 765         }
 766         ret = rock_continue(&rs);
 767         if (ret == 0)
 768                 goto repeat;
 769         if (ret < 0)
 770                 goto fail;
 771
 772         if (rpnt == link)
 773                 goto fail;
 774         brelse(bh);
 775         *rpnt = '\0';
 776         SetPageUptodate(page);
 777         kunmap(page);
 778         unlock_page(page);
 779         return 0;
 780
 781         /* error exit from macro */
 782 out:
 783         kfree(rs.buffer);
 784         goto fail;
 785 out_noread:
 786         printk("unable to read i-node block");
 787         goto fail;
 788 out_bad_span:
 789         printk("symlink spans iso9660 blocks\n");
 790 fail:
 791         brelse(bh);
 792 error:
 793         SetPageError(page);
 794         kunmap(page);
 795         unlock_page(page);
 796         return -EIO;
 797 }
 798
 799 const struct address_space_operations isofs_symlink_aops = {
 800         .readpage = rock_ridge_symlink_readpage
 801 };