fs/minix.c

   1 /* minix.c - The minix filesystem, version 1 and 2.  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2004,2005,2006,2007,2008  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/err.h>
  21 #include <grub/file.h>
  22 #include <grub/mm.h>
  23 #include <grub/misc.h>
  24 #include <grub/disk.h>
  25 #include <grub/dl.h>
  26 #include <grub/types.h>
  27
  28 #define GRUB_MINIX_MAGIC        0x137F
  29 #define GRUB_MINIX2_MAGIC       0x2468
  30 #define GRUB_MINIX_MAGIC_30     0x138F
  31 #define GRUB_MINIX2_MAGIC_30    0x2478
  32 #define GRUB_MINIX_BSIZE        1024U
  33 #define GRUB_MINIX_LOG2_BSIZE   1
  34 #define GRUB_MINIX_ROOT_INODE   1
  35 #define GRUB_MINIX_MAX_SYMLNK_CNT       8
  36 #define GRUB_MINIX_SBLOCK       2
  37
  38 #define GRUB_MINIX_IFDIR        0040000U
  39 #define GRUB_MINIX_IFLNK        0120000U
  40
  41 #define GRUB_MINIX_INODE(data,field) (data->version == 1 ? \
  42                            data->inode.  field : data->inode2.  field)
  43 #define GRUB_MINIX_INODE_ENDIAN(data,field,bits1,bits2) (data->version == 1 ?   \
  44                         grub_le_to_cpu##bits1 (data->inode.field) :             \
  45                         grub_le_to_cpu##bits2 (data->inode2.field))
  46 #define GRUB_MINIX_INODE_SIZE(data) GRUB_MINIX_INODE_ENDIAN (data,size,16,32)
  47 #define GRUB_MINIX_INODE_MODE(data) GRUB_MINIX_INODE_ENDIAN (data,mode,16,16)
  48 #define GRUB_MINIX_INODE_DIR_ZONES(data,blk) GRUB_MINIX_INODE_ENDIAN            \
  49                                                (data,dir_zones[blk],16,32)
  50 #define GRUB_MINIX_INODE_INDIR_ZONE(data)                               \
  51                         GRUB_MINIX_INODE_ENDIAN (data,indir_zone,16,32)
  52 #define GRUB_MINIX_INODE_DINDIR_ZONE(data)                                      \
  53                         GRUB_MINIX_INODE_ENDIAN (data,double_indir_zone,16,32)
  54 #define GRUB_MINIX_INODE_BLKSZ(data) (data->version == 1 ? 2 : 4)
  55 #define GRUB_MINIX_LOG2_ZONESZ  (GRUB_MINIX_LOG2_BSIZE                          \
  56                                  + grub_le_to_cpu16 (sblock->log2_zone_size))
  57 #define GRUB_MINIX_ZONESZ       (GRUB_MINIX_BSIZE                               \
  58                                  << grub_le_to_cpu16 (sblock->log2_zone_size))
  59
  60 struct grub_minix_sblock
  61 {
  62   grub_uint16_t inode_cnt;
  63   grub_uint16_t zone_cnt;
  64   grub_uint16_t inode_bmap_size;
  65   grub_uint16_t zone_bmap_size;
  66   grub_uint16_t first_data_zone;
  67   grub_uint16_t log2_zone_size;
  68   grub_uint32_t max_file_size;
  69   grub_uint16_t magic;
  70 };
  71
  72 struct grub_minix_inode
  73 {
  74   grub_uint16_t mode;
  75   grub_uint16_t uid;
  76   grub_uint16_t size;
  77   grub_uint32_t ctime;
  78   grub_uint8_t gid;
  79   grub_uint8_t nlinks;
  80   grub_uint16_t dir_zones[7];
  81   grub_uint16_t indir_zone;
  82   grub_uint16_t double_indir_zone;
  83 };
  84
  85 struct grub_minix2_inode
  86 {
  87   grub_uint16_t mode;
  88   grub_uint16_t nlinks;
  89   grub_uint16_t uid;
  90   grub_uint16_t gid;
  91   grub_uint32_t size;
  92   grub_uint32_t atime;
  93   grub_uint32_t mtime;
  94   grub_uint32_t ctime;
  95   grub_uint32_t dir_zones[7];
  96   grub_uint32_t indir_zone;
  97   grub_uint32_t double_indir_zone;
  98   grub_uint32_t unused;
  99
 100 };
 101
 102 /* Information about a "mounted" minix filesystem.  */
 103 struct grub_minix_data
 104 {
 105   struct grub_minix_sblock sblock;
 106   struct grub_minix_inode inode;
 107   struct grub_minix2_inode inode2;
 108   int ino;
 109   int linknest;
 110   grub_disk_t disk;
 111   int version;
 112   int filename_size;
 113 };
 114
 115 #ifndef GRUB_UTIL
 116 static grub_dl_t my_mod;
 117 #endif
 118 \f
 119 static grub_err_t grub_minix_find_file (struct grub_minix_data *data,
 120                                         const char *path);
 121
 122 static int
 123 grub_minix_get_file_block (struct grub_minix_data *data, unsigned int blk)
 124 {
 125   struct grub_minix_sblock *sblock = &data->sblock;
 126   int indir;
 127
 128   auto int grub_get_indir (int, int);
 129
 130   /* Read the block pointer in ZONE, on the offset NUM.  */
 131   int grub_get_indir (int zone, int num)
 132     {
 133       if (data->version == 1)
 134         {
 135           grub_uint16_t indir16;
 136           grub_disk_read (data->disk,
 137                           zone << GRUB_MINIX_LOG2_ZONESZ,
 138                           sizeof (grub_uint16_t) * num,
 139                           sizeof (grub_uint16_t), (char *) &indir16);
 140           return grub_le_to_cpu16 (indir16);
 141         }
 142       else
 143         {
 144           grub_uint32_t indir32;
 145           grub_disk_read (data->disk,
 146                           zone << GRUB_MINIX_LOG2_ZONESZ,
 147                           sizeof (grub_uint32_t) * num,
 148                           sizeof (grub_uint32_t), (char *) &indir32);
 149           return grub_le_to_cpu32 (indir32);
 150         }
 151     }
 152
 153   /* Direct block.  */
 154   if (blk < 7)
 155     return GRUB_MINIX_INODE_DIR_ZONES (data, blk);
 156
 157   /* Indirect block.  */
 158   blk -= 7;
 159   if (blk < GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data))
 160     {
 161       indir = grub_get_indir (GRUB_MINIX_INODE_INDIR_ZONE (data), blk);
 162       return indir;
 163     }
 164
 165   /* Double indirect block.  */
 166   blk -= GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data);
 167   if (blk < (GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data))
 168       * (GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data)))
 169     {
 170       indir = grub_get_indir (GRUB_MINIX_INODE_DINDIR_ZONE (data),
 171                               blk / GRUB_MINIX_ZONESZ);
 172
 173       indir = grub_get_indir (indir, blk % GRUB_MINIX_ZONESZ);
 174
 175       return indir;
 176     }
 177
 178   /* This should never happen.  */
 179   grub_error (GRUB_ERR_OUT_OF_RANGE, "file bigger than maximum size");
 180
 181   return 0;
 182 }
 183
 184
 185 /* Read LEN bytes from the file described by DATA starting with byte
 186    POS.  Return the amount of read bytes in READ.  */
 187 static grub_ssize_t
 188 grub_minix_read_file (struct grub_minix_data *data,
 189                       void NESTED_FUNC_ATTR (*read_hook) (grub_disk_addr_t sector,
 190                                          unsigned offset, unsigned length),
 191                       int pos, grub_disk_addr_t len, char *buf)
 192 {
 193   struct grub_minix_sblock *sblock = &data->sblock;
 194   int i;
 195   int blockcnt;
 196
 197   /* Adjust len so it we can't read past the end of the file.  */
 198   if (len > GRUB_MINIX_INODE_SIZE (data))
 199     len = GRUB_MINIX_INODE_SIZE (data);
 200
 201   blockcnt = (len + pos + GRUB_MINIX_BSIZE - 1) / GRUB_MINIX_BSIZE;
 202
 203   for (i = pos / GRUB_MINIX_BSIZE; i < blockcnt; i++)
 204     {
 205       int blknr;
 206       int blockoff = pos % GRUB_MINIX_BSIZE;
 207       int blockend = GRUB_MINIX_BSIZE;
 208
 209       int skipfirst = 0;
 210
 211       blknr = grub_minix_get_file_block (data, i);
 212       if (grub_errno)
 213         return -1;
 214
 215       /* Last block.  */
 216       if (i == blockcnt - 1)
 217         {
 218           blockend = (len + pos) % GRUB_MINIX_BSIZE;
 219
 220           if (!blockend)
 221             blockend = GRUB_MINIX_BSIZE;
 222         }
 223
 224       /* First block.  */
 225       if (i == (pos / (int) GRUB_MINIX_BSIZE))
 226         {
 227           skipfirst = blockoff;
 228           blockend -= skipfirst;
 229         }
 230
 231       data->disk->read_hook = read_hook;
 232       grub_disk_read (data->disk, blknr << GRUB_MINIX_LOG2_ZONESZ,
 233                       skipfirst, blockend, buf);
 234
 235       data->disk->read_hook = 0;
 236       if (grub_errno)
 237         return -1;
 238
 239       buf += GRUB_MINIX_BSIZE - skipfirst;
 240     }
 241
 242   return len;
 243 }
 244
 245
 246 /* Read inode INO from the mounted filesystem described by DATA.  This
 247    inode is used by default now.  */
 248 static grub_err_t
 249 grub_minix_read_inode (struct grub_minix_data *data, int ino)
 250 {
 251   struct grub_minix_sblock *sblock = &data->sblock;
 252
 253   /* Block in which the inode is stored.  */
 254   int block;
 255   data->ino = ino;
 256
 257   /* The first inode in minix is inode 1.  */
 258   ino--;
 259
 260   block = ((2 + grub_le_to_cpu16 (sblock->inode_bmap_size)
 261             + grub_le_to_cpu16 (sblock->zone_bmap_size))
 262            << GRUB_MINIX_LOG2_BSIZE);
 263
 264   if (data->version == 1)
 265     {
 266       block += ino / (GRUB_DISK_SECTOR_SIZE / sizeof (struct grub_minix_inode));
 267       int offs = (ino % (GRUB_DISK_SECTOR_SIZE
 268                          / sizeof (struct grub_minix_inode))
 269                   * sizeof (struct grub_minix_inode));
 270
 271       grub_disk_read (data->disk, block, offs,
 272                       sizeof (struct grub_minix_inode), (char *) &data->inode);
 273     }
 274   else
 275     {
 276       block += ino / (GRUB_DISK_SECTOR_SIZE
 277                       / sizeof (struct grub_minix2_inode));
 278       int offs = (ino
 279                   % (GRUB_DISK_SECTOR_SIZE / sizeof (struct grub_minix2_inode))
 280                   * sizeof (struct grub_minix2_inode));
 281
 282       grub_disk_read (data->disk, block, offs,
 283                       sizeof (struct grub_minix2_inode),(char *) &data->inode2);
 284     }
 285
 286   return GRUB_ERR_NONE;
 287 }
 288
 289
 290 /* Lookup the symlink the current inode points to.  INO is the inode
 291    number of the directory the symlink is relative to.  */
 292 static grub_err_t
 293 grub_minix_lookup_symlink (struct grub_minix_data *data, int ino)
 294 {
 295   char symlink[GRUB_MINIX_INODE_SIZE (data) + 1];
 296
 297   if (++data->linknest > GRUB_MINIX_MAX_SYMLNK_CNT)
 298     return grub_error (GRUB_ERR_SYMLINK_LOOP, "too deep nesting of symlinks");
 299
 300   if (grub_minix_read_file (data, 0, 0,
 301                             GRUB_MINIX_INODE_SIZE (data), symlink) < 0)
 302     return grub_errno;
 303
 304   symlink[GRUB_MINIX_INODE_SIZE (data)] = '\0';
 305
 306   /* The symlink is an absolute path, go back to the root inode.  */
 307   if (symlink[0] == '/')
 308     ino = GRUB_MINIX_ROOT_INODE;
 309
 310   /* Now load in the old inode.  */
 311   if (grub_minix_read_inode (data, ino))
 312     return grub_errno;
 313
 314   grub_minix_find_file (data, symlink);
 315   if (grub_errno)
 316     grub_error (grub_errno, "Can not follow symlink `%s'.", symlink);
 317
 318   return grub_errno;
 319 }
 320
 321
 322 /* Find the file with the pathname PATH on the filesystem described by
 323    DATA.  */
 324 static grub_err_t
 325 grub_minix_find_file (struct grub_minix_data *data, const char *path)
 326 {
 327   char fpath[grub_strlen (path) + 1];
 328   char *name = fpath;
 329   char *next;
 330   unsigned int pos = 0;
 331   int dirino;
 332
 333   grub_strcpy (fpath, path);
 334
 335   /* Skip the first slash.  */
 336   if (name[0] == '/')
 337     {
 338       name++;
 339       if (!*name)
 340         return 0;
 341     }
 342
 343   /* Extract the actual part from the pathname.  */
 344   next = grub_strchr (name, '/');
 345   if (next)
 346     {
 347       next[0] = '\0';
 348       next++;
 349     }
 350
 351   do
 352     {
 353       grub_uint16_t ino;
 354       char filename[data->filename_size + 1];
 355
 356       if (grub_strlen (name) == 0)
 357         return GRUB_ERR_NONE;
 358
 359       if (grub_minix_read_file (data, 0, pos, sizeof (ino),
 360                                 (char *) &ino) < 0)
 361         return grub_errno;
 362       if (grub_minix_read_file (data, 0, pos + sizeof (ino),
 363                                 data->filename_size, (char *) filename)< 0)
 364         return grub_errno;
 365
 366       filename[data->filename_size] = '\0';
 367
 368       /* Check if the current direntry matches the current part of the
 369          pathname.  */
 370       if (!grub_strcmp (name, filename))
 371         {
 372           dirino = data->ino;
 373           grub_minix_read_inode (data, grub_le_to_cpu16 (ino));
 374
 375           /* Follow the symlink.  */
 376           if ((GRUB_MINIX_INODE_MODE (data)
 377                & GRUB_MINIX_IFLNK) == GRUB_MINIX_IFLNK)
 378             {
 379               grub_minix_lookup_symlink (data, dirino);
 380               if (grub_errno)
 381                 return grub_errno;
 382             }
 383
 384           if (!next)
 385             return 0;
 386
 387           pos = 0;
 388
 389           name = next;
 390           next = grub_strchr (name, '/');
 391           if (next)
 392             {
 393               next[0] = '\0';
 394               next++;
 395             }
 396
 397           if ((GRUB_MINIX_INODE_MODE (data)
 398                & GRUB_MINIX_IFDIR) != GRUB_MINIX_IFDIR)
 399             return grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
 400
 401           continue;
 402         }
 403
 404       pos += sizeof (ino) + data->filename_size;
 405     } while (pos < GRUB_MINIX_INODE_SIZE (data));
 406
 407   grub_error (GRUB_ERR_FILE_NOT_FOUND, "file not found");
 408   return grub_errno;
 409 }
 410
 411
 412 /* Mount the filesystem on the disk DISK.  */
 413 static struct grub_minix_data *
 414 grub_minix_mount (grub_disk_t disk)
 415 {
 416   struct grub_minix_data *data;
 417
 418   data = grub_malloc (sizeof (struct grub_minix_data));
 419   if (!data)
 420     return 0;
 421
 422   /* Read the superblock.  */
 423   grub_disk_read (disk, GRUB_MINIX_SBLOCK, 0,
 424                   sizeof (struct grub_minix_sblock),(char *) &data->sblock);
 425   if (grub_errno)
 426     goto fail;
 427
 428   if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX_MAGIC)
 429     {
 430       data->version = 1;
 431       data->filename_size = 14;
 432     }
 433   else if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX2_MAGIC)
 434     {
 435       data->version = 2;
 436       data->filename_size = 14;
 437     }
 438   else if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX_MAGIC_30)
 439     {
 440       data->version = 1;
 441       data->filename_size = 30;
 442     }
 443   else if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX2_MAGIC_30)
 444     {
 445       data->version = 2;
 446       data->filename_size = 30;
 447     }
 448   else
 449     goto fail;
 450
 451   data->disk = disk;
 452   data->linknest = 0;
 453
 454   return data;
 455
 456  fail:
 457   grub_free (data);
 458   grub_error (GRUB_ERR_BAD_FS, "not a minix filesystem");
 459   return 0;
 460 }
 461 \f
 462 static grub_err_t
 463 grub_minix_dir (grub_device_t device, const char *path,
 464                   int (*hook) (const char *filename, int dir))
 465 {
 466   struct grub_minix_data *data = 0;
 467   struct grub_minix_sblock *sblock;
 468   unsigned int pos = 0;
 469
 470   data = grub_minix_mount (device->disk);
 471   if (!data)
 472     return grub_errno;
 473
 474   grub_minix_read_inode (data, GRUB_MINIX_ROOT_INODE);
 475   if (grub_errno)
 476     goto fail;
 477
 478   sblock = &data->sblock;
 479
 480   grub_minix_find_file (data, path);
 481   if (grub_errno)
 482     goto fail;
 483
 484   if ((GRUB_MINIX_INODE_MODE (data) & GRUB_MINIX_IFDIR) != GRUB_MINIX_IFDIR)
 485     {
 486       grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
 487       goto fail;
 488     }
 489
 490   while (pos < GRUB_MINIX_INODE_SIZE (data))
 491     {
 492       grub_uint16_t ino;
 493       char filename[data->filename_size + 1];
 494       int dirino = data->ino;
 495
 496       if (grub_minix_read_file (data, 0, pos, sizeof (ino),
 497                                 (char *) &ino) < 0)
 498         return grub_errno;
 499
 500       if (grub_minix_read_file (data, 0, pos + sizeof (ino),
 501                                 data->filename_size,
 502                                 (char *) filename) < 0)
 503         return grub_errno;
 504       filename[data->filename_size] = '\0';
 505
 506       /* The filetype is not stored in the dirent.  Read the inode to
 507          find out the filetype.  This *REALLY* sucks.  */
 508       grub_minix_read_inode (data, grub_le_to_cpu16 (ino));
 509       if (hook (filename, ((GRUB_MINIX_INODE_MODE (data)
 510                             & GRUB_MINIX_IFDIR) == GRUB_MINIX_IFDIR)) ? 1 : 0)
 511         break;
 512
 513       /* Load the old inode back in.  */
 514       grub_minix_read_inode (data, dirino);
 515
 516       pos += sizeof (ino) + data->filename_size;
 517     }
 518
 519  fail:
 520   grub_free (data);
 521   return grub_errno;
 522 }
 523
 524
 525 /* Open a file named NAME and initialize FILE.  */
 526 static grub_err_t
 527 grub_minix_open (struct grub_file *file, const char *name)
 528 {
 529   struct grub_minix_data *data;
 530   data = grub_minix_mount (file->device->disk);
 531   if (!data)
 532     return grub_errno;
 533
 534   /* Open the inode op the root directory.  */
 535   grub_minix_read_inode (data, GRUB_MINIX_ROOT_INODE);
 536   if (grub_errno)
 537     {
 538       grub_free (data);
 539       return grub_errno;
 540     }
 541
 542   if (!name || name[0] != '/')
 543     {
 544       grub_error (GRUB_ERR_BAD_FILENAME, "bad filename");
 545       return grub_errno;
 546     }
 547
 548   /* Traverse the directory tree to the node that should be
 549      opened.  */
 550   grub_minix_find_file (data, name);
 551   if (grub_errno)
 552     {
 553       grub_free (data);
 554       return grub_errno;
 555     }
 556
 557   file->data = data;
 558   file->size = GRUB_MINIX_INODE_SIZE (data);
 559
 560   return GRUB_ERR_NONE;
 561 }
 562
 563
 564 static grub_ssize_t
 565 grub_minix_read (grub_file_t file, char *buf, grub_size_t len)
 566 {
 567   struct grub_minix_data *data =
 568     (struct grub_minix_data *) file->data;
 569
 570   return grub_minix_read_file (data, file->read_hook, file->offset, len, buf);
 571 }
 572
 573
 574 static grub_err_t
 575 grub_minix_close (grub_file_t file)
 576 {
 577   grub_free (file->data);
 578
 579   return GRUB_ERR_NONE;
 580 }
 581
 582
 583 static grub_err_t
 584 grub_minix_label (grub_device_t device __attribute ((unused)),
 585                 char **label __attribute ((unused)))
 586 {
 587   return GRUB_ERR_NONE;
 588 }
 589
 590 \f
 591 static struct grub_fs grub_minix_fs =
 592   {
 593     .name = "minix",
 594     .dir = grub_minix_dir,
 595     .open = grub_minix_open,
 596     .read = grub_minix_read,
 597     .close = grub_minix_close,
 598     .label = grub_minix_label,
 599     .next = 0
 600   };
 601
 602 GRUB_MOD_INIT(minix)
 603 {
 604   grub_fs_register (&grub_minix_fs);
 605 #ifndef GRUB_UTIL
 606   my_mod = mod;
 607 #endif
 608 }
 609
 610 GRUB_MOD_FINI(minix)
 611 {
 612   grub_fs_unregister (&grub_minix_fs);
 613 }