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 static grub_dl_t my_mod;
 116 \f
 117 static grub_err_t grub_minix_find_file (struct grub_minix_data *data,
 118                                         const char *path);
 119
 120 static int
 121 grub_minix_get_file_block (struct grub_minix_data *data, unsigned int blk)
 122 {
 123   struct grub_minix_sblock *sblock = &data->sblock;
 124   int indir;
 125
 126   auto int grub_get_indir (int, int);
 127
 128   /* Read the block pointer in ZONE, on the offset NUM.  */
 129   int grub_get_indir (int zone, int num)
 130     {
 131       if (data->version == 1)
 132         {
 133           grub_uint16_t indir16;
 134           grub_disk_read (data->disk,
 135                           zone << GRUB_MINIX_LOG2_ZONESZ,
 136                           sizeof (grub_uint16_t) * num,
 137                           sizeof (grub_uint16_t), (char *) &indir16);
 138           return grub_le_to_cpu16 (indir16);
 139         }
 140       else
 141         {
 142           grub_uint32_t indir32;
 143           grub_disk_read (data->disk,
 144                           zone << GRUB_MINIX_LOG2_ZONESZ,
 145                           sizeof (grub_uint32_t) * num,
 146                           sizeof (grub_uint32_t), (char *) &indir32);
 147           return grub_le_to_cpu32 (indir32);
 148         }
 149     }
 150
 151   /* Direct block.  */
 152   if (blk < 7)
 153     return GRUB_MINIX_INODE_DIR_ZONES (data, blk);
 154
 155   /* Indirect block.  */
 156   blk -= 7;
 157   if (blk < GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data))
 158     {
 159       indir = grub_get_indir (GRUB_MINIX_INODE_INDIR_ZONE (data), blk);
 160       return indir;
 161     }
 162
 163   /* Double indirect block.  */
 164   blk -= GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data);
 165   if (blk < (GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data))
 166       * (GRUB_MINIX_ZONESZ / GRUB_MINIX_INODE_BLKSZ (data)))
 167     {
 168       indir = grub_get_indir (GRUB_MINIX_INODE_DINDIR_ZONE (data),
 169                               blk / GRUB_MINIX_ZONESZ);
 170
 171       indir = grub_get_indir (indir, blk % GRUB_MINIX_ZONESZ);
 172
 173       return indir;
 174     }
 175
 176   /* This should never happen.  */
 177   grub_error (GRUB_ERR_OUT_OF_RANGE, "file bigger than maximum size");
 178
 179   return 0;
 180 }
 181
 182
 183 /* Read LEN bytes from the file described by DATA starting with byte
 184    POS.  Return the amount of read bytes in READ.  */
 185 static grub_ssize_t
 186 grub_minix_read_file (struct grub_minix_data *data,
 187                       void NESTED_FUNC_ATTR (*read_hook) (grub_disk_addr_t sector,
 188                                          unsigned offset, unsigned length),
 189                       int pos, grub_disk_addr_t len, char *buf)
 190 {
 191   struct grub_minix_sblock *sblock = &data->sblock;
 192   int i;
 193   int blockcnt;
 194
 195   /* Adjust len so it we can't read past the end of the file.  */
 196   if (len > GRUB_MINIX_INODE_SIZE (data))
 197     len = GRUB_MINIX_INODE_SIZE (data);
 198
 199   blockcnt = (len + pos + GRUB_MINIX_BSIZE - 1) / GRUB_MINIX_BSIZE;
 200
 201   for (i = pos / GRUB_MINIX_BSIZE; i < blockcnt; i++)
 202     {
 203       int blknr;
 204       int blockoff = pos % GRUB_MINIX_BSIZE;
 205       int blockend = GRUB_MINIX_BSIZE;
 206
 207       int skipfirst = 0;
 208
 209       blknr = grub_minix_get_file_block (data, i);
 210       if (grub_errno)
 211         return -1;
 212
 213       /* Last block.  */
 214       if (i == blockcnt - 1)
 215         {
 216           blockend = (len + pos) % GRUB_MINIX_BSIZE;
 217
 218           if (!blockend)
 219             blockend = GRUB_MINIX_BSIZE;
 220         }
 221
 222       /* First block.  */
 223       if (i == (pos / (int) GRUB_MINIX_BSIZE))
 224         {
 225           skipfirst = blockoff;
 226           blockend -= skipfirst;
 227         }
 228
 229       data->disk->read_hook = read_hook;
 230       grub_disk_read (data->disk, blknr << GRUB_MINIX_LOG2_ZONESZ,
 231                       skipfirst, blockend, buf);
 232
 233       data->disk->read_hook = 0;
 234       if (grub_errno)
 235         return -1;
 236
 237       buf += GRUB_MINIX_BSIZE - skipfirst;
 238     }
 239
 240   return len;
 241 }
 242
 243
 244 /* Read inode INO from the mounted filesystem described by DATA.  This
 245    inode is used by default now.  */
 246 static grub_err_t
 247 grub_minix_read_inode (struct grub_minix_data *data, int ino)
 248 {
 249   struct grub_minix_sblock *sblock = &data->sblock;
 250
 251   /* Block in which the inode is stored.  */
 252   int block;
 253   data->ino = ino;
 254
 255   /* The first inode in minix is inode 1.  */
 256   ino--;
 257
 258   block = ((2 + grub_le_to_cpu16 (sblock->inode_bmap_size)
 259             + grub_le_to_cpu16 (sblock->zone_bmap_size))
 260            << GRUB_MINIX_LOG2_BSIZE);
 261
 262   if (data->version == 1)
 263     {
 264       block += ino / (GRUB_DISK_SECTOR_SIZE / sizeof (struct grub_minix_inode));
 265       int offs = (ino % (GRUB_DISK_SECTOR_SIZE
 266                          / sizeof (struct grub_minix_inode))
 267                   * sizeof (struct grub_minix_inode));
 268
 269       grub_disk_read (data->disk, block, offs,
 270                       sizeof (struct grub_minix_inode), &data->inode);
 271     }
 272   else
 273     {
 274       block += ino / (GRUB_DISK_SECTOR_SIZE
 275                       / sizeof (struct grub_minix2_inode));
 276       int offs = (ino
 277                   % (GRUB_DISK_SECTOR_SIZE / sizeof (struct grub_minix2_inode))
 278                   * sizeof (struct grub_minix2_inode));
 279
 280       grub_disk_read (data->disk, block, offs,
 281                       sizeof (struct grub_minix2_inode),&data->inode2);
 282     }
 283
 284   return GRUB_ERR_NONE;
 285 }
 286
 287
 288 /* Lookup the symlink the current inode points to.  INO is the inode
 289    number of the directory the symlink is relative to.  */
 290 static grub_err_t
 291 grub_minix_lookup_symlink (struct grub_minix_data *data, int ino)
 292 {
 293   char symlink[GRUB_MINIX_INODE_SIZE (data) + 1];
 294
 295   if (++data->linknest > GRUB_MINIX_MAX_SYMLNK_CNT)
 296     return grub_error (GRUB_ERR_SYMLINK_LOOP, "too deep nesting of symlinks");
 297
 298   if (grub_minix_read_file (data, 0, 0,
 299                             GRUB_MINIX_INODE_SIZE (data), symlink) < 0)
 300     return grub_errno;
 301
 302   symlink[GRUB_MINIX_INODE_SIZE (data)] = '\0';
 303
 304   /* The symlink is an absolute path, go back to the root inode.  */
 305   if (symlink[0] == '/')
 306     ino = GRUB_MINIX_ROOT_INODE;
 307
 308   /* Now load in the old inode.  */
 309   if (grub_minix_read_inode (data, ino))
 310     return grub_errno;
 311
 312   grub_minix_find_file (data, symlink);
 313   if (grub_errno)
 314     grub_error (grub_errno, "Can not follow symlink `%s'.", symlink);
 315
 316   return grub_errno;
 317 }
 318
 319
 320 /* Find the file with the pathname PATH on the filesystem described by
 321    DATA.  */
 322 static grub_err_t
 323 grub_minix_find_file (struct grub_minix_data *data, const char *path)
 324 {
 325   char fpath[grub_strlen (path) + 1];
 326   char *name = fpath;
 327   char *next;
 328   unsigned int pos = 0;
 329   int dirino;
 330
 331   grub_strcpy (fpath, path);
 332
 333   /* Skip the first slash.  */
 334   if (name[0] == '/')
 335     {
 336       name++;
 337       if (!*name)
 338         return 0;
 339     }
 340
 341   /* Extract the actual part from the pathname.  */
 342   next = grub_strchr (name, '/');
 343   if (next)
 344     {
 345       next[0] = '\0';
 346       next++;
 347     }
 348
 349   do
 350     {
 351       grub_uint16_t ino;
 352       char filename[data->filename_size + 1];
 353
 354       if (grub_strlen (name) == 0)
 355         return GRUB_ERR_NONE;
 356
 357       if (grub_minix_read_file (data, 0, pos, sizeof (ino),
 358                                 (char *) &ino) < 0)
 359         return grub_errno;
 360       if (grub_minix_read_file (data, 0, pos + sizeof (ino),
 361                                 data->filename_size, (char *) filename)< 0)
 362         return grub_errno;
 363
 364       filename[data->filename_size] = '\0';
 365
 366       /* Check if the current direntry matches the current part of the
 367          pathname.  */
 368       if (!grub_strcmp (name, filename))
 369         {
 370           dirino = data->ino;
 371           grub_minix_read_inode (data, grub_le_to_cpu16 (ino));
 372
 373           /* Follow the symlink.  */
 374           if ((GRUB_MINIX_INODE_MODE (data)
 375                & GRUB_MINIX_IFLNK) == GRUB_MINIX_IFLNK)
 376             {
 377               grub_minix_lookup_symlink (data, dirino);
 378               if (grub_errno)
 379                 return grub_errno;
 380             }
 381
 382           if (!next)
 383             return 0;
 384
 385           pos = 0;
 386
 387           name = next;
 388           next = grub_strchr (name, '/');
 389           if (next)
 390             {
 391               next[0] = '\0';
 392               next++;
 393             }
 394
 395           if ((GRUB_MINIX_INODE_MODE (data)
 396                & GRUB_MINIX_IFDIR) != GRUB_MINIX_IFDIR)
 397             return grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
 398
 399           continue;
 400         }
 401
 402       pos += sizeof (ino) + data->filename_size;
 403     } while (pos < GRUB_MINIX_INODE_SIZE (data));
 404
 405   grub_error (GRUB_ERR_FILE_NOT_FOUND, "file not found");
 406   return grub_errno;
 407 }
 408
 409
 410 /* Mount the filesystem on the disk DISK.  */
 411 static struct grub_minix_data *
 412 grub_minix_mount (grub_disk_t disk)
 413 {
 414   struct grub_minix_data *data;
 415
 416   data = grub_malloc (sizeof (struct grub_minix_data));
 417   if (!data)
 418     return 0;
 419
 420   /* Read the superblock.  */
 421   grub_disk_read (disk, GRUB_MINIX_SBLOCK, 0,
 422                   sizeof (struct grub_minix_sblock),&data->sblock);
 423   if (grub_errno)
 424     goto fail;
 425
 426   if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX_MAGIC)
 427     {
 428       data->version = 1;
 429       data->filename_size = 14;
 430     }
 431   else if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX2_MAGIC)
 432     {
 433       data->version = 2;
 434       data->filename_size = 14;
 435     }
 436   else if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX_MAGIC_30)
 437     {
 438       data->version = 1;
 439       data->filename_size = 30;
 440     }
 441   else if (grub_le_to_cpu16 (data->sblock.magic) == GRUB_MINIX2_MAGIC_30)
 442     {
 443       data->version = 2;
 444       data->filename_size = 30;
 445     }
 446   else
 447     goto fail;
 448
 449   data->disk = disk;
 450   data->linknest = 0;
 451
 452   return data;
 453
 454  fail:
 455   grub_free (data);
 456   grub_error (GRUB_ERR_BAD_FS, "not a minix filesystem");
 457   return 0;
 458 }
 459 \f
 460 static grub_err_t
 461 grub_minix_dir (grub_device_t device, const char *path,
 462                   int (*hook) (const char *filename,
 463                                const struct grub_dirhook_info *info))
 464 {
 465   struct grub_minix_data *data = 0;
 466   struct grub_minix_sblock *sblock;
 467   unsigned int pos = 0;
 468
 469   data = grub_minix_mount (device->disk);
 470   if (!data)
 471     return grub_errno;
 472
 473   grub_minix_read_inode (data, GRUB_MINIX_ROOT_INODE);
 474   if (grub_errno)
 475     goto fail;
 476
 477   sblock = &data->sblock;
 478
 479   grub_minix_find_file (data, path);
 480   if (grub_errno)
 481     goto fail;
 482
 483   if ((GRUB_MINIX_INODE_MODE (data) & GRUB_MINIX_IFDIR) != GRUB_MINIX_IFDIR)
 484     {
 485       grub_error (GRUB_ERR_BAD_FILE_TYPE, "not a directory");
 486       goto fail;
 487     }
 488
 489   while (pos < GRUB_MINIX_INODE_SIZE (data))
 490     {
 491       grub_uint16_t ino;
 492       char filename[data->filename_size + 1];
 493       int dirino = data->ino;
 494       struct grub_dirhook_info info;
 495       grub_memset (&info, 0, sizeof (info));
 496
 497
 498       if (grub_minix_read_file (data, 0, pos, sizeof (ino),
 499                                 (char *) &ino) < 0)
 500         return grub_errno;
 501
 502       if (grub_minix_read_file (data, 0, pos + sizeof (ino),
 503                                 data->filename_size,
 504                                 (char *) filename) < 0)
 505         return grub_errno;
 506       filename[data->filename_size] = '\0';
 507
 508       /* The filetype is not stored in the dirent.  Read the inode to
 509          find out the filetype.  This *REALLY* sucks.  */
 510       grub_minix_read_inode (data, grub_le_to_cpu16 (ino));
 511       info.dir = ((GRUB_MINIX_INODE_MODE (data)
 512                    & GRUB_MINIX_IFDIR) == GRUB_MINIX_IFDIR);
 513       if (hook (filename, &info) ? 1 : 0)
 514         break;
 515
 516       /* Load the old inode back in.  */
 517       grub_minix_read_inode (data, dirino);
 518
 519       pos += sizeof (ino) + data->filename_size;
 520     }
 521
 522  fail:
 523   grub_free (data);
 524   return grub_errno;
 525 }
 526
 527
 528 /* Open a file named NAME and initialize FILE.  */
 529 static grub_err_t
 530 grub_minix_open (struct grub_file *file, const char *name)
 531 {
 532   struct grub_minix_data *data;
 533   data = grub_minix_mount (file->device->disk);
 534   if (!data)
 535     return grub_errno;
 536
 537   /* Open the inode op the root directory.  */
 538   grub_minix_read_inode (data, GRUB_MINIX_ROOT_INODE);
 539   if (grub_errno)
 540     {
 541       grub_free (data);
 542       return grub_errno;
 543     }
 544
 545   if (!name || name[0] != '/')
 546     {
 547       grub_error (GRUB_ERR_BAD_FILENAME, "bad filename");
 548       return grub_errno;
 549     }
 550
 551   /* Traverse the directory tree to the node that should be
 552      opened.  */
 553   grub_minix_find_file (data, name);
 554   if (grub_errno)
 555     {
 556       grub_free (data);
 557       return grub_errno;
 558     }
 559
 560   file->data = data;
 561   file->size = GRUB_MINIX_INODE_SIZE (data);
 562
 563   return GRUB_ERR_NONE;
 564 }
 565
 566
 567 static grub_ssize_t
 568 grub_minix_read (grub_file_t file, char *buf, grub_size_t len)
 569 {
 570   struct grub_minix_data *data =
 571     (struct grub_minix_data *) file->data;
 572
 573   return grub_minix_read_file (data, file->read_hook, file->offset, len, buf);
 574 }
 575
 576
 577 static grub_err_t
 578 grub_minix_close (grub_file_t file)
 579 {
 580   grub_free (file->data);
 581
 582   return GRUB_ERR_NONE;
 583 }
 584
 585
 586 static grub_err_t
 587 grub_minix_label (grub_device_t device __attribute ((unused)),
 588                 char **label __attribute ((unused)))
 589 {
 590   return GRUB_ERR_NONE;
 591 }
 592
 593 \f
 594 static struct grub_fs grub_minix_fs =
 595   {
 596     .name = "minix",
 597     .dir = grub_minix_dir,
 598     .open = grub_minix_open,
 599     .read = grub_minix_read,
 600     .close = grub_minix_close,
 601     .label = grub_minix_label,
 602     .next = 0
 603   };
 604
 605 GRUB_MOD_INIT(minix)
 606 {
 607   grub_fs_register (&grub_minix_fs);
 608   my_mod = mod;
 609 }
 610
 611 GRUB_MOD_FINI(minix)
 612 {
 613   grub_fs_unregister (&grub_minix_fs);
 614 }