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