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/stat.h>
  10 #include <linux/time.h>
  11 #include <linux/iso_fs.h>
  12 #include <linux/string.h>
  13 #include <linux/mm.h>
  14 #include <linux/slab.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/smp_lock.h>
  17 #include <linux/buffer_head.h>
  18 #include <asm/page.h>
  19
  20 #include "rock.h"
  21
  22 /* These functions are designed to read the system areas of a directory record
  23  * and extract relevant information.  There are different functions provided
  24  * depending upon what information we need at the time.  One function fills
  25  * out an inode structure, a second one extracts a filename, a third one
  26  * returns a symbolic link name, and a fourth one returns the extent number
  27  * for the file. */
  28
  29 #define SIG(A,B) ((A) | ((B) << 8)) /* isonum_721() */
  30
  31
  32 /* This is a way of ensuring that we have something in the system
  33    use fields that is compatible with Rock Ridge */
  34 #define CHECK_SP(FAIL)                          \
  35       if(rr->u.SP.magic[0] != 0xbe) FAIL;       \
  36       if(rr->u.SP.magic[1] != 0xef) FAIL;       \
  37       ISOFS_SB(inode->i_sb)->s_rock_offset=rr->u.SP.skip;
  38 /* We define a series of macros because each function must do exactly the
  39    same thing in certain places.  We use the macros to ensure that everything
  40    is done correctly */
  41
  42 #define CONTINUE_DECLS \
  43   int cont_extent = 0, cont_offset = 0, cont_size = 0;   \
  44   void *buffer = NULL
  45
  46 #define CHECK_CE                                \
  47       {cont_extent = isonum_733(rr->u.CE.extent); \
  48       cont_offset = isonum_733(rr->u.CE.offset); \
  49       cont_size = isonum_733(rr->u.CE.size);}
  50
  51 #define SETUP_ROCK_RIDGE(DE,CHR,LEN)                            \
  52   {LEN= sizeof(struct iso_directory_record) + DE->name_len[0];  \
  53   if(LEN & 1) LEN++;                                            \
  54   CHR = ((unsigned char *) DE) + LEN;                           \
  55   LEN = *((unsigned char *) DE) - LEN;                          \
  56   if (LEN<0) LEN=0;                                             \
  57   if (ISOFS_SB(inode->i_sb)->s_rock_offset!=-1)                \
  58   {                                                             \
  59      LEN-=ISOFS_SB(inode->i_sb)->s_rock_offset;                \
  60      CHR+=ISOFS_SB(inode->i_sb)->s_rock_offset;                \
  61      if (LEN<0) LEN=0;                                          \
  62   }                                                             \
  63 }
  64
  65 #define MAYBE_CONTINUE(LABEL,DEV) \
  66   {if (buffer) { kfree(buffer); buffer = NULL; } \
  67   if (cont_extent){ \
  68     int block, offset, offset1; \
  69     struct buffer_head * pbh; \
  70     buffer = kmalloc(cont_size,GFP_KERNEL); \
  71     if (!buffer) goto out; \
  72     block = cont_extent; \
  73     offset = cont_offset; \
  74     offset1 = 0; \
  75     pbh = sb_bread(DEV->i_sb, block); \
  76     if(pbh){       \
  77       if (offset > pbh->b_size || offset + cont_size > pbh->b_size){    \
  78         brelse(pbh); \
  79         goto out; \
  80       } \
  81       memcpy(buffer + offset1, pbh->b_data + offset, cont_size - offset1); \
  82       brelse(pbh); \
  83       chr = (unsigned char *) buffer; \
  84       len = cont_size; \
  85       cont_extent = 0; \
  86       cont_size = 0; \
  87       cont_offset = 0; \
  88       goto LABEL; \
  89     }    \
  90     printk("Unable to read rock-ridge attributes\n");    \
  91   }}
  92
  93 /* return length of name field; 0: not found, -1: to be ignored */
  94 int get_rock_ridge_filename(struct iso_directory_record * de,
  95                             char * retname, struct inode * inode)
  96 {
  97   int len;
  98   unsigned char * chr;
  99   CONTINUE_DECLS;
 100   int retnamlen = 0, truncate=0;
 101
 102   if (!ISOFS_SB(inode->i_sb)->s_rock) return 0;
 103   *retname = 0;
 104
 105   SETUP_ROCK_RIDGE(de, chr, len);
 106  repeat:
 107   {
 108     struct rock_ridge * rr;
 109     int sig;
 110
 111     while (len > 2){ /* There may be one byte for padding somewhere */
 112       rr = (struct rock_ridge *) chr;
 113       if (rr->len < 3) goto out; /* Something got screwed up here */
 114       sig = isonum_721(chr);
 115       chr += rr->len;
 116       len -= rr->len;
 117       if (len < 0) goto out;    /* corrupted isofs */
 118
 119       switch(sig){
 120       case SIG('R','R'):
 121         if((rr->u.RR.flags[0] & RR_NM) == 0) goto out;
 122         break;
 123       case SIG('S','P'):
 124         CHECK_SP(goto out);
 125         break;
 126       case SIG('C','E'):
 127         CHECK_CE;
 128         break;
 129       case SIG('N','M'):
 130         if (truncate) break;
 131         if (rr->len < 5) break;
 132         /*
 133          * If the flags are 2 or 4, this indicates '.' or '..'.
 134          * We don't want to do anything with this, because it
 135          * screws up the code that calls us.  We don't really
 136          * care anyways, since we can just use the non-RR
 137          * name.
 138          */
 139         if (rr->u.NM.flags & 6) {
 140           break;
 141         }
 142
 143         if (rr->u.NM.flags & ~1) {
 144           printk("Unsupported NM flag settings (%d)\n",rr->u.NM.flags);
 145           break;
 146         }
 147         if((strlen(retname) + rr->len - 5) >= 254) {
 148           truncate = 1;
 149           break;
 150         }
 151         strncat(retname, rr->u.NM.name, rr->len - 5);
 152         retnamlen += rr->len - 5;
 153         break;
 154       case SIG('R','E'):
 155         if (buffer) kfree(buffer);
 156         return -1;
 157       default:
 158         break;
 159       }
 160     }
 161   }
 162   MAYBE_CONTINUE(repeat,inode);
 163   if (buffer) kfree(buffer);
 164   return retnamlen; /* If 0, this file did not have a NM field */
 165  out:
 166   if(buffer) kfree(buffer);
 167   return 0;
 168 }
 169
 170 static int
 171 parse_rock_ridge_inode_internal(struct iso_directory_record *de,
 172                                 struct inode *inode, int regard_xa)
 173 {
 174   int len;
 175   unsigned char * chr;
 176   int symlink_len = 0;
 177   CONTINUE_DECLS;
 178
 179   if (!ISOFS_SB(inode->i_sb)->s_rock) return 0;
 180
 181   SETUP_ROCK_RIDGE(de, chr, len);
 182   if (regard_xa)
 183    {
 184      chr+=14;
 185      len-=14;
 186      if (len<0) len=0;
 187    }
 188
 189  repeat:
 190   {
 191     int cnt, sig;
 192     struct inode * reloc;
 193     struct rock_ridge * rr;
 194     int rootflag;
 195
 196     while (len > 2){ /* There may be one byte for padding somewhere */
 197       rr = (struct rock_ridge *) chr;
 198       if (rr->len < 3) goto out; /* Something got screwed up here */
 199       sig = isonum_721(chr);
 200       chr += rr->len;
 201       len -= rr->len;
 202       if (len < 0) goto out;    /* corrupted isofs */
 203
 204       switch(sig){
 205 #ifndef CONFIG_ZISOFS           /* No flag for SF or ZF */
 206       case SIG('R','R'):
 207         if((rr->u.RR.flags[0] &
 208             (RR_PX | RR_TF | RR_SL | RR_CL)) == 0) goto out;
 209         break;
 210 #endif
 211       case SIG('S','P'):
 212         CHECK_SP(goto out);
 213         break;
 214       case SIG('C','E'):
 215         CHECK_CE;
 216         break;
 217       case SIG('E','R'):
 218         ISOFS_SB(inode->i_sb)->s_rock = 1;
 219         printk(KERN_DEBUG "ISO 9660 Extensions: ");
 220         { int p;
 221           for(p=0;p<rr->u.ER.len_id;p++) printk("%c",rr->u.ER.data[p]);
 222         }
 223           printk("\n");
 224         break;
 225       case SIG('P','X'):
 226         inode->i_mode  = isonum_733(rr->u.PX.mode);
 227         inode->i_nlink = isonum_733(rr->u.PX.n_links);
 228         inode->i_uid   = isonum_733(rr->u.PX.uid);
 229         inode->i_gid   = isonum_733(rr->u.PX.gid);
 230         break;
 231       case SIG('P','N'):
 232         { int high, low;
 233           high = isonum_733(rr->u.PN.dev_high);
 234           low = isonum_733(rr->u.PN.dev_low);
 235           /*
 236            * The Rock Ridge standard specifies that if sizeof(dev_t) <= 4,
 237            * then the high field is unused, and the device number is completely
 238            * stored in the low field.  Some writers may ignore this subtlety,
 239            * and as a result we test to see if the entire device number is
 240            * stored in the low field, and use that.
 241            */
 242           if((low & ~0xff) && high == 0) {
 243             inode->i_rdev = MKDEV(low >> 8, low & 0xff);
 244           } else {
 245             inode->i_rdev = MKDEV(high, low);
 246           }
 247         }
 248         break;
 249       case SIG('T','F'):
 250         /* Some RRIP writers incorrectly place ctime in the TF_CREATE field.
 251            Try to handle this correctly for either case. */
 252         cnt = 0; /* Rock ridge never appears on a High Sierra disk */
 253         if(rr->u.TF.flags & TF_CREATE) {
 254           inode->i_ctime.tv_sec = iso_date(rr->u.TF.times[cnt++].time, 0);
 255           inode->i_ctime.tv_nsec = 0;
 256         }
 257         if(rr->u.TF.flags & TF_MODIFY) {
 258           inode->i_mtime.tv_sec = iso_date(rr->u.TF.times[cnt++].time, 0);
 259           inode->i_mtime.tv_nsec = 0;
 260         }
 261         if(rr->u.TF.flags & TF_ACCESS) {
 262           inode->i_atime.tv_sec = iso_date(rr->u.TF.times[cnt++].time, 0);
 263           inode->i_atime.tv_nsec = 0;
 264         }
 265         if(rr->u.TF.flags & TF_ATTRIBUTES) {
 266           inode->i_ctime.tv_sec = iso_date(rr->u.TF.times[cnt++].time, 0);
 267           inode->i_ctime.tv_nsec = 0;
 268         }
 269         break;
 270       case SIG('S','L'):
 271         {int slen;
 272          struct SL_component * slp;
 273          struct SL_component * oldslp;
 274          slen = rr->len - 5;
 275          slp = &rr->u.SL.link;
 276          inode->i_size = symlink_len;
 277          while (slen > 1){
 278            rootflag = 0;
 279            switch(slp->flags &~1){
 280            case 0:
 281              inode->i_size += slp->len;
 282              break;
 283            case 2:
 284              inode->i_size += 1;
 285              break;
 286            case 4:
 287              inode->i_size += 2;
 288              break;
 289            case 8:
 290              rootflag = 1;
 291              inode->i_size += 1;
 292              break;
 293            default:
 294              printk("Symlink component flag not implemented\n");
 295            }
 296            slen -= slp->len + 2;
 297            oldslp = slp;
 298            slp = (struct SL_component *) (((char *) slp) + slp->len + 2);
 299
 300            if(slen < 2) {
 301              if(    ((rr->u.SL.flags & 1) != 0)
 302                     && ((oldslp->flags & 1) == 0) ) inode->i_size += 1;
 303              break;
 304            }
 305
 306            /*
 307             * If this component record isn't continued, then append a '/'.
 308             */
 309            if (!rootflag && (oldslp->flags & 1) == 0)
 310                    inode->i_size += 1;
 311          }
 312         }
 313         symlink_len = inode->i_size;
 314         break;
 315       case SIG('R','E'):
 316         printk(KERN_WARNING "Attempt to read inode for relocated directory\n");
 317         goto out;
 318       case SIG('C','L'):
 319         ISOFS_I(inode)->i_first_extent = isonum_733(rr->u.CL.location);
 320         reloc = isofs_iget(inode->i_sb, ISOFS_I(inode)->i_first_extent, 0);
 321         if (!reloc)
 322                 goto out;
 323         inode->i_mode = reloc->i_mode;
 324         inode->i_nlink = reloc->i_nlink;
 325         inode->i_uid = reloc->i_uid;
 326         inode->i_gid = reloc->i_gid;
 327         inode->i_rdev = reloc->i_rdev;
 328         inode->i_size = reloc->i_size;
 329         inode->i_blocks = reloc->i_blocks;
 330         inode->i_atime = reloc->i_atime;
 331         inode->i_ctime = reloc->i_ctime;
 332         inode->i_mtime = reloc->i_mtime;
 333         iput(reloc);
 334         break;
 335 #ifdef CONFIG_ZISOFS
 336       case SIG('Z','F'):
 337               if ( !ISOFS_SB(inode->i_sb)->s_nocompress ) {
 338                       int algo;
 339                       algo = isonum_721(rr->u.ZF.algorithm);
 340                       if ( algo == SIG('p','z') ) {
 341                               int block_shift = isonum_711(&rr->u.ZF.parms[1]);
 342                               if ( block_shift < PAGE_CACHE_SHIFT || block_shift > 17 ) {
 343                                       printk(KERN_WARNING "isofs: Can't handle ZF block size of 2^%d\n", block_shift);
 344                               } else {
 345                                 /* Note: we don't change i_blocks here */
 346                                       ISOFS_I(inode)->i_file_format = isofs_file_compressed;
 347                                 /* Parameters to compression algorithm (header size, block size) */
 348                                       ISOFS_I(inode)->i_format_parm[0] = isonum_711(&rr->u.ZF.parms[0]);
 349                                       ISOFS_I(inode)->i_format_parm[1] = isonum_711(&rr->u.ZF.parms[1]);
 350                                       inode->i_size = isonum_733(rr->u.ZF.real_size);
 351                               }
 352                       } else {
 353                               printk(KERN_WARNING "isofs: Unknown ZF compression algorithm: %c%c\n",
 354                                      rr->u.ZF.algorithm[0], rr->u.ZF.algorithm[1]);
 355                       }
 356               }
 357               break;
 358 #endif
 359       default:
 360         break;
 361       }
 362     }
 363   }
 364   MAYBE_CONTINUE(repeat,inode);
 365  out:
 366   if(buffer) kfree(buffer);
 367   return 0;
 368 }
 369
 370 static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
 371 {
 372         int slen;
 373         int rootflag;
 374         struct SL_component *oldslp;
 375         struct SL_component *slp;
 376         slen = rr->len - 5;
 377         slp = &rr->u.SL.link;
 378         while (slen > 1) {
 379                 rootflag = 0;
 380                 switch (slp->flags & ~1) {
 381                 case 0:
 382                         if (slp->len > plimit - rpnt)
 383                                 return NULL;
 384                         memcpy(rpnt, slp->text, slp->len);
 385                         rpnt+=slp->len;
 386                         break;
 387                 case 2:
 388                         if (rpnt >= plimit)
 389                                 return NULL;
 390                         *rpnt++='.';
 391                         break;
 392                 case 4:
 393                         if (2 > plimit - rpnt)
 394                                 return NULL;
 395                         *rpnt++='.';
 396                         *rpnt++='.';
 397                         break;
 398                 case 8:
 399                         if (rpnt >= plimit)
 400                                 return NULL;
 401                         rootflag = 1;
 402                         *rpnt++='/';
 403                         break;
 404                 default:
 405                         printk("Symlink component flag not implemented (%d)\n",
 406                              slp->flags);
 407                 }
 408                 slen -= slp->len + 2;
 409                 oldslp = slp;
 410                 slp = (struct SL_component *) ((char *) slp + slp->len + 2);
 411
 412                 if (slen < 2) {
 413                         /*
 414                          * If there is another SL record, and this component
 415                          * record isn't continued, then add a slash.
 416                          */
 417                         if ((!rootflag) && (rr->u.SL.flags & 1) &&
 418                             !(oldslp->flags & 1)) {
 419                                 if (rpnt >= plimit)
 420                                         return NULL;
 421                                 *rpnt++='/';
 422                         }
 423                         break;
 424                 }
 425
 426                 /*
 427                  * If this component record isn't continued, then append a '/'.
 428                  */
 429                 if (!rootflag && !(oldslp->flags & 1)) {
 430                         if (rpnt >= plimit)
 431                                 return NULL;
 432                         *rpnt++='/';
 433                 }
 434         }
 435         return rpnt;
 436 }
 437
 438 int parse_rock_ridge_inode(struct iso_directory_record * de,
 439                            struct inode * inode)
 440 {
 441    int result=parse_rock_ridge_inode_internal(de,inode,0);
 442    /* if rockridge flag was reset and we didn't look for attributes
 443     * behind eventual XA attributes, have a look there */
 444    if ((ISOFS_SB(inode->i_sb)->s_rock_offset==-1)
 445        &&(ISOFS_SB(inode->i_sb)->s_rock==2))
 446      {
 447         result=parse_rock_ridge_inode_internal(de,inode,14);
 448      }
 449    return result;
 450 }
 451
 452 /* readpage() for symlinks: reads symlink contents into the page and either
 453    makes it uptodate and returns 0 or returns error (-EIO) */
 454
 455 static int rock_ridge_symlink_readpage(struct file *file, struct page *page)
 456 {
 457         struct inode *inode = page->mapping->host;
 458         struct iso_inode_info *ei = ISOFS_I(inode);
 459         char *link = kmap(page);
 460         unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
 461         struct buffer_head *bh;
 462         char *rpnt = link;
 463         unsigned char *pnt;
 464         struct iso_directory_record *raw_inode;
 465         CONTINUE_DECLS;
 466         unsigned long block, offset;
 467         int sig;
 468         int len;
 469         unsigned char *chr;
 470         struct rock_ridge *rr;
 471
 472         if (!ISOFS_SB(inode->i_sb)->s_rock)
 473                 goto error;
 474
 475         block = ei->i_iget5_block;
 476         lock_kernel();
 477         bh = sb_bread(inode->i_sb, block);
 478         if (!bh)
 479                 goto out_noread;
 480
 481         offset = ei->i_iget5_offset;
 482         pnt = (unsigned char *) bh->b_data + offset;
 483
 484         raw_inode = (struct iso_directory_record *) pnt;
 485
 486         /*
 487          * If we go past the end of the buffer, there is some sort of error.
 488          */
 489         if (offset + *pnt > bufsize)
 490                 goto out_bad_span;
 491
 492         /* Now test for possible Rock Ridge extensions which will override
 493            some of these numbers in the inode structure. */
 494
 495         SETUP_ROCK_RIDGE(raw_inode, chr, len);
 496
 497       repeat:
 498         while (len > 2) { /* There may be one byte for padding somewhere */
 499                 rr = (struct rock_ridge *) chr;
 500                 if (rr->len < 3)
 501                         goto out;       /* Something got screwed up here */
 502                 sig = isonum_721(chr);
 503                 chr += rr->len;
 504                 len -= rr->len;
 505                 if (len < 0)
 506                         goto out;       /* corrupted isofs */
 507
 508                 switch (sig) {
 509                 case SIG('R', 'R'):
 510                         if ((rr->u.RR.flags[0] & RR_SL) == 0)
 511                                 goto out;
 512                         break;
 513                 case SIG('S', 'P'):
 514                         CHECK_SP(goto out);
 515                         break;
 516                 case SIG('S', 'L'):
 517                         rpnt = get_symlink_chunk(rpnt, rr,
 518                                                  link + (PAGE_SIZE - 1));
 519                         if (rpnt == NULL)
 520                                 goto out;
 521                         break;
 522                 case SIG('C', 'E'):
 523                         /* This tells is if there is a continuation record */
 524                         CHECK_CE;
 525                 default:
 526                         break;
 527                 }
 528         }
 529         MAYBE_CONTINUE(repeat, inode);
 530         if (buffer)
 531                 kfree(buffer);
 532
 533         if (rpnt == link)
 534                 goto fail;
 535         brelse(bh);
 536         *rpnt = '\0';
 537         unlock_kernel();
 538         SetPageUptodate(page);
 539         kunmap(page);
 540         unlock_page(page);
 541         return 0;
 542
 543         /* error exit from macro */
 544       out:
 545         if (buffer)
 546                 kfree(buffer);
 547         goto fail;
 548       out_noread:
 549         printk("unable to read i-node block");
 550         goto fail;
 551       out_bad_span:
 552         printk("symlink spans iso9660 blocks\n");
 553       fail:
 554         brelse(bh);
 555         unlock_kernel();
 556       error:
 557         SetPageError(page);
 558         kunmap(page);
 559         unlock_page(page);
 560         return -EIO;
 561 }
 562
 563 struct address_space_operations isofs_symlink_aops = {
 564         .readpage       = rock_ridge_symlink_readpage
 565 };