linux/fs/isofs/rock.c
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   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
  27struct 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
  42static 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
  52static 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
  71static 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 */
  81static 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        }
 123out:
 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 */
 133static 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 */
 192int 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);
 208repeat:
 209
 210        while (rs.len > 2) { /* There may be one byte for padding somewhere */
 211                rr = (struct rock_ridge *)rs.chr;
 212                /*
 213                 * Ignore rock ridge info if rr->len is out of range, but
 214                 * don't return -EIO because that would make the file
 215                 * invisible.
 216                 */
 217                if (rr->len < 3)
 218                        goto out;       /* Something got screwed up here */
 219                sig = isonum_721(rs.chr);
 220                if (rock_check_overflow(&rs, sig))
 221                        goto eio;
 222                rs.chr += rr->len;
 223                rs.len -= rr->len;
 224                /*
 225                 * As above, just ignore the rock ridge info if rr->len
 226                 * is bogus.
 227                 */
 228                if (rs.len < 0)
 229                        goto out;       /* Something got screwed up here */
 230
 231                switch (sig) {
 232                case SIG('R', 'R'):
 233                        if ((rr->u.RR.flags[0] & RR_NM) == 0)
 234                                goto out;
 235                        break;
 236                case SIG('S', 'P'):
 237                        if (check_sp(rr, inode))
 238                                goto out;
 239                        break;
 240                case SIG('C', 'E'):
 241                        rs.cont_extent = isonum_733(rr->u.CE.extent);
 242                        rs.cont_offset = isonum_733(rr->u.CE.offset);
 243                        rs.cont_size = isonum_733(rr->u.CE.size);
 244                        break;
 245                case SIG('N', 'M'):
 246                        if (truncate)
 247                                break;
 248                        if (rr->len < 5)
 249                                break;
 250                        /*
 251                         * If the flags are 2 or 4, this indicates '.' or '..'.
 252                         * We don't want to do anything with this, because it
 253                         * screws up the code that calls us.  We don't really
 254                         * care anyways, since we can just use the non-RR
 255                         * name.
 256                         */
 257                        if (rr->u.NM.flags & 6)
 258                                break;
 259
 260                        if (rr->u.NM.flags & ~1) {
 261                                printk("Unsupported NM flag settings (%d)\n",
 262                                        rr->u.NM.flags);
 263                                break;
 264                        }
 265                        if ((strlen(retname) + rr->len - 5) >= 254) {
 266                                truncate = 1;
 267                                break;
 268                        }
 269                        strncat(retname, rr->u.NM.name, rr->len - 5);
 270                        retnamlen += rr->len - 5;
 271                        break;
 272                case SIG('R', 'E'):
 273                        kfree(rs.buffer);
 274                        return -1;
 275                default:
 276                        break;
 277                }
 278        }
 279        ret = rock_continue(&rs);
 280        if (ret == 0)
 281                goto repeat;
 282        if (ret == 1)
 283                return retnamlen; /* If 0, this file did not have a NM field */
 284out:
 285        kfree(rs.buffer);
 286        return ret;
 287eio:
 288        ret = -EIO;
 289        goto out;
 290}
 291
 292static int
 293parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 294                                struct inode *inode, int regard_xa)
 295{
 296        int symlink_len = 0;
 297        int cnt, sig;
 298        struct inode *reloc;
 299        struct rock_ridge *rr;
 300        int rootflag;
 301        struct rock_state rs;
 302        int ret = 0;
 303
 304        if (!ISOFS_SB(inode->i_sb)->s_rock)
 305                return 0;
 306
 307        init_rock_state(&rs, inode);
 308        setup_rock_ridge(de, inode, &rs);
 309        if (regard_xa) {
 310                rs.chr += 14;
 311                rs.len -= 14;
 312                if (rs.len < 0)
 313                        rs.len = 0;
 314        }
 315
 316repeat:
 317        while (rs.len > 2) { /* There may be one byte for padding somewhere */
 318                rr = (struct rock_ridge *)rs.chr;
 319                /*
 320                 * Ignore rock ridge info if rr->len is out of range, but
 321                 * don't return -EIO because that would make the file
 322                 * invisible.
 323                 */
 324                if (rr->len < 3)
 325                        goto out;       /* Something got screwed up here */
 326                sig = isonum_721(rs.chr);
 327                if (rock_check_overflow(&rs, sig))
 328                        goto eio;
 329                rs.chr += rr->len;
 330                rs.len -= rr->len;
 331                /*
 332                 * As above, just ignore the rock ridge info if rr->len
 333                 * is bogus.
 334                 */
 335                if (rs.len < 0)
 336                        goto out;       /* Something got screwed up here */
 337
 338                switch (sig) {
 339#ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 340                case SIG('R', 'R'):
 341                        if ((rr->u.RR.flags[0] &
 342                             (RR_PX | RR_TF | RR_SL | RR_CL)) == 0)
 343                                goto out;
 344                        break;
 345#endif
 346                case SIG('S', 'P'):
 347                        if (check_sp(rr, inode))
 348                                goto out;
 349                        break;
 350                case SIG('C', 'E'):
 351                        rs.cont_extent = isonum_733(rr->u.CE.extent);
 352                        rs.cont_offset = isonum_733(rr->u.CE.offset);
 353                        rs.cont_size = isonum_733(rr->u.CE.size);
 354                        break;
 355                case SIG('E', 'R'):
 356                        ISOFS_SB(inode->i_sb)->s_rock = 1;
 357                        printk(KERN_DEBUG "ISO 9660 Extensions: ");
 358                        {
 359                                int p;
 360                                for (p = 0; p < rr->u.ER.len_id; p++)
 361                                        printk("%c", rr->u.ER.data[p]);
 362                        }
 363                        printk("\n");
 364                        break;
 365                case SIG('P', 'X'):
 366                        inode->i_mode = isonum_733(rr->u.PX.mode);
 367                        inode->i_nlink = isonum_733(rr->u.PX.n_links);
 368                        inode->i_uid = isonum_733(rr->u.PX.uid);
 369                        inode->i_gid = isonum_733(rr->u.PX.gid);
 370                        break;
 371                case SIG('P', 'N'):
 372                        {
 373                                int high, low;
 374                                high = isonum_733(rr->u.PN.dev_high);
 375                                low = isonum_733(rr->u.PN.dev_low);
 376                                /*
 377                                 * The Rock Ridge standard specifies that if
 378                                 * sizeof(dev_t) <= 4, then the high field is
 379                                 * unused, and the device number is completely
 380                                 * stored in the low field.  Some writers may
 381                                 * ignore this subtlety,
 382                                 * and as a result we test to see if the entire
 383                                 * device number is
 384                                 * stored in the low field, and use that.
 385                                 */
 386                                if ((low & ~0xff) && high == 0) {
 387                                        inode->i_rdev =
 388                                            MKDEV(low >> 8, low & 0xff);
 389                                } else {
 390                                        inode->i_rdev =
 391                                            MKDEV(high, low);
 392                                }
 393                        }
 394                        break;
 395                case SIG('T', 'F'):
 396                        /*
 397                         * Some RRIP writers incorrectly place ctime in the
 398                         * TF_CREATE field. Try to handle this correctly for
 399                         * either case.
 400                         */
 401                        /* Rock ridge never appears on a High Sierra disk */
 402                        cnt = 0;
 403                        if (rr->u.TF.flags & TF_CREATE) {
 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                        if (rr->u.TF.flags & TF_MODIFY) {
 410                                inode->i_mtime.tv_sec =
 411                                    iso_date(rr->u.TF.times[cnt++].time,
 412                                             0);
 413                                inode->i_mtime.tv_nsec = 0;
 414                        }
 415                        if (rr->u.TF.flags & TF_ACCESS) {
 416                                inode->i_atime.tv_sec =
 417                                    iso_date(rr->u.TF.times[cnt++].time,
 418                                             0);
 419                                inode->i_atime.tv_nsec = 0;
 420                        }
 421                        if (rr->u.TF.flags & TF_ATTRIBUTES) {
 422                                inode->i_ctime.tv_sec =
 423                                    iso_date(rr->u.TF.times[cnt++].time,
 424                                             0);
 425                                inode->i_ctime.tv_nsec = 0;
 426                        }
 427                        break;
 428                case SIG('S', 'L'):
 429                        {
 430                                int slen;
 431                                struct SL_component *slp;
 432                                struct SL_component *oldslp;
 433                                slen = rr->len - 5;
 434                                slp = &rr->u.SL.link;
 435                                inode->i_size = symlink_len;
 436                                while (slen > 1) {
 437                                        rootflag = 0;
 438                                        switch (slp->flags & ~1) {
 439                                        case 0:
 440                                                inode->i_size +=
 441                                                    slp->len;
 442                                                break;
 443                                        case 2:
 444                                                inode->i_size += 1;
 445                                                break;
 446                                        case 4:
 447                                                inode->i_size += 2;
 448                                                break;
 449                                        case 8:
 450                                                rootflag = 1;
 451                                                inode->i_size += 1;
 452                                                break;
 453                                        default:
 454                                                printk("Symlink component flag "
 455                                                        "not implemented\n");
 456                                        }
 457                                        slen -= slp->len + 2;
 458                                        oldslp = slp;
 459                                        slp = (struct SL_component *)
 460                                                (((char *)slp) + slp->len + 2);
 461
 462                                        if (slen < 2) {
 463                                                if (((rr->u.SL.
 464                                                      flags & 1) != 0)
 465                                                    &&
 466                                                    ((oldslp->
 467                                                      flags & 1) == 0))
 468                                                        inode->i_size +=
 469                                                            1;
 470                                                break;
 471                                        }
 472
 473                                        /*
 474                                         * If this component record isn't
 475                                         * continued, then append a '/'.
 476                                         */
 477                                        if (!rootflag
 478                                            && (oldslp->flags & 1) == 0)
 479                                                inode->i_size += 1;
 480                                }
 481                        }
 482                        symlink_len = inode->i_size;
 483                        break;
 484                case SIG('R', 'E'):
 485                        printk(KERN_WARNING "Attempt to read inode for "
 486                                        "relocated directory\n");
 487                        goto out;
 488                case SIG('C', 'L'):
 489                        ISOFS_I(inode)->i_first_extent =
 490                            isonum_733(rr->u.CL.location);
 491                        reloc =
 492                            isofs_iget(inode->i_sb,
 493                                       ISOFS_I(inode)->i_first_extent,
 494                                       0);
 495                        if (IS_ERR(reloc)) {
 496                                ret = PTR_ERR(reloc);
 497                                goto out;
 498                        }
 499                        inode->i_mode = reloc->i_mode;
 500                        inode->i_nlink = reloc->i_nlink;
 501                        inode->i_uid = reloc->i_uid;
 502                        inode->i_gid = reloc->i_gid;
 503                        inode->i_rdev = reloc->i_rdev;
 504                        inode->i_size = reloc->i_size;
 505                        inode->i_blocks = reloc->i_blocks;
 506                        inode->i_atime = reloc->i_atime;
 507                        inode->i_ctime = reloc->i_ctime;
 508                        inode->i_mtime = reloc->i_mtime;
 509                        iput(reloc);
 510                        break;
 511#ifdef CONFIG_ZISOFS
 512                case SIG('Z', 'F'): {
 513                        int algo;
 514
 515                        if (ISOFS_SB(inode->i_sb)->s_nocompress)
 516                                break;
 517                        algo = isonum_721(rr->u.ZF.algorithm);
 518                        if (algo == SIG('p', 'z')) {
 519                                int block_shift =
 520                                        isonum_711(&rr->u.ZF.parms[1]);
 521                                if (block_shift < PAGE_CACHE_SHIFT
 522                                                || block_shift > 17) {
 523                                        printk(KERN_WARNING "isofs: "
 524                                                "Can't handle ZF block "
 525                                                "size of 2^%d\n",
 526                                                block_shift);
 527                                } else {
 528                                        /*
 529                                         * Note: we don't change
 530                                         * i_blocks here
 531                                         */
 532                                        ISOFS_I(inode)->i_file_format =
 533                                                isofs_file_compressed;
 534                                        /*
 535                                         * Parameters to compression
 536                                         * algorithm (header size,
 537                                         * block size)
 538                                         */
 539                                        ISOFS_I(inode)->i_format_parm[0] =
 540                                                isonum_711(&rr->u.ZF.parms[0]);
 541                                        ISOFS_I(inode)->i_format_parm[1] =
 542                                                isonum_711(&rr->u.ZF.parms[1]);
 543                                        inode->i_size =
 544                                            isonum_733(rr->u.ZF.
 545                                                       real_size);
 546                                }
 547                        } else {
 548                                printk(KERN_WARNING
 549                                       "isofs: Unknown ZF compression "
 550                                                "algorithm: %c%c\n",
 551                                       rr->u.ZF.algorithm[0],
 552                                       rr->u.ZF.algorithm[1]);
 553                        }
 554                        break;
 555                }
 556#endif
 557                default:
 558                        break;
 559                }
 560        }
 561        ret = rock_continue(&rs);
 562        if (ret == 0)
 563                goto repeat;
 564        if (ret == 1)
 565                ret = 0;
 566out:
 567        kfree(rs.buffer);
 568        return ret;
 569eio:
 570        ret = -EIO;
 571        goto out;
 572}
 573
 574static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 575{
 576        int slen;
 577        int rootflag;
 578        struct SL_component *oldslp;
 579        struct SL_component *slp;
 580        slen = rr->len - 5;
 581        slp = &rr->u.SL.link;
 582        while (slen > 1) {
 583                rootflag = 0;
 584                switch (slp->flags & ~1) {
 585                case 0:
 586                        if (slp->len > plimit - rpnt)
 587                                return NULL;
 588                        memcpy(rpnt, slp->text, slp->len);
 589                        rpnt += slp->len;
 590                        break;
 591                case 2:
 592                        if (rpnt >= plimit)
 593                                return NULL;
 594                        *rpnt++ = '.';
 595                        break;
 596                case 4:
 597                        if (2 > plimit - rpnt)
 598                                return NULL;
 599                        *rpnt++ = '.';
 600                        *rpnt++ = '.';
 601                        break;
 602                case 8:
 603                        if (rpnt >= plimit)
 604                                return NULL;
 605                        rootflag = 1;
 606                        *rpnt++ = '/';
 607                        break;
 608                default:
 609                        printk("Symlink component flag not implemented (%d)\n",
 610                               slp->flags);
 611                }
 612                slen -= slp->len + 2;
 613                oldslp = slp;
 614                slp = (struct SL_component *)((char *)slp + slp->len + 2);
 615
 616                if (slen < 2) {
 617                        /*
 618                         * If there is another SL record, and this component
 619                         * record isn't continued, then add a slash.
 620                         */
 621                        if ((!rootflag) && (rr->u.SL.flags & 1) &&
 622                            !(oldslp->flags & 1)) {
 623                                if (rpnt >= plimit)
 624                                        return NULL;
 625                                *rpnt++ = '/';
 626                        }
 627                        break;
 628                }
 629
 630                /*
 631                 * If this component record isn't continued, then append a '/'.
 632                 */
 633                if (!rootflag && !(oldslp->flags & 1)) {
 634                        if (rpnt >= plimit)
 635                                return NULL;
 636                        *rpnt++ = '/';
 637                }
 638        }
 639        return rpnt;
 640}
 641
 642int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
 643{
 644        int result = parse_rock_ridge_inode_internal(de, inode, 0);
 645
 646        /*
 647         * if rockridge flag was reset and we didn't look for attributes
 648         * behind eventual XA attributes, have a look there
 649         */
 650        if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
 651            && (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
 652                result = parse_rock_ridge_inode_internal(de, inode, 14);
 653        }
 654        return result;
 655}
 656
 657/*
 658 * readpage() for symlinks: reads symlink contents into the page and either
 659 * makes it uptodate and returns 0 or returns error (-EIO)
 660 */
 661static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 662{
 663        struct inode *inode = page->mapping->host;
 664        struct iso_inode_info *ei = ISOFS_I(inode);
 665        char *link = kmap(page);
 666        unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 667        struct buffer_head *bh;
 668        char *rpnt = link;
 669        unsigned char *pnt;
 670        struct iso_directory_record *raw_de;
 671        unsigned long block, offset;
 672        int sig;
 673        struct rock_ridge *rr;
 674        struct rock_state rs;
 675        int ret;
 676
 677        if (!ISOFS_SB(inode->i_sb)->s_rock)
 678                goto error;
 679
 680        init_rock_state(&rs, inode);
 681        block = ei->i_iget5_block;
 682        lock_kernel();
 683        bh = sb_bread(inode->i_sb, block);
 684        if (!bh)
 685                goto out_noread;
 686
 687        offset = ei->i_iget5_offset;
 688        pnt = (unsigned char *)bh->b_data + offset;
 689
 690        raw_de = (struct iso_directory_record *)pnt;
 691
 692        /*
 693         * If we go past the end of the buffer, there is some sort of error.
 694         */
 695        if (offset + *pnt > bufsize)
 696                goto out_bad_span;
 697
 698        /*
 699         * Now test for possible Rock Ridge extensions which will override
 700         * some of these numbers in the inode structure.
 701         */
 702
 703        setup_rock_ridge(raw_de, inode, &rs);
 704
 705repeat:
 706        while (rs.len > 2) { /* There may be one byte for padding somewhere */
 707                rr = (struct rock_ridge *)rs.chr;
 708                if (rr->len < 3)
 709                        goto out;       /* Something got screwed up here */
 710                sig = isonum_721(rs.chr);
 711                if (rock_check_overflow(&rs, sig))
 712                        goto out;
 713                rs.chr += rr->len;
 714                rs.len -= rr->len;
 715                if (rs.len < 0)
 716                        goto out;       /* corrupted isofs */
 717
 718                switch (sig) {
 719                case SIG('R', 'R'):
 720                        if ((rr->u.RR.flags[0] & RR_SL) == 0)
 721                                goto out;
 722                        break;
 723                case SIG('S', 'P'):
 724                        if (check_sp(rr, inode))
 725                                goto out;
 726                        break;
 727                case SIG('S', 'L'):
 728                        rpnt = get_symlink_chunk(rpnt, rr,
 729                                                 link + (PAGE_SIZE - 1));
 730                        if (rpnt == NULL)
 731                                goto out;
 732                        break;
 733                case SIG('C', 'E'):
 734                        /* This tells is if there is a continuation record */
 735                        rs.cont_extent = isonum_733(rr->u.CE.extent);
 736                        rs.cont_offset = isonum_733(rr->u.CE.offset);
 737                        rs.cont_size = isonum_733(rr->u.CE.size);
 738                default:
 739                        break;
 740                }
 741        }
 742        ret = rock_continue(&rs);
 743        if (ret == 0)
 744                goto repeat;
 745        if (ret < 0)
 746                goto fail;
 747
 748        if (rpnt == link)
 749                goto fail;
 750        brelse(bh);
 751        *rpnt = '\0';
 752        unlock_kernel();
 753        SetPageUptodate(page);
 754        kunmap(page);
 755        unlock_page(page);
 756        return 0;
 757
 758        /* error exit from macro */
 759out:
 760        kfree(rs.buffer);
 761        goto fail;
 762out_noread:
 763        printk("unable to read i-node block");
 764        goto fail;
 765out_bad_span:
 766        printk("symlink spans iso9660 blocks\n");
 767fail:
 768        brelse(bh);
 769        unlock_kernel();
 770error:
 771        SetPageError(page);
 772        kunmap(page);
 773        unlock_page(page);
 774        return -EIO;
 775}
 776
 777const struct address_space_operations isofs_symlink_aops = {
 778        .readpage = rock_ridge_symlink_readpage
 779};
 780