fs/ubifs/key.h

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  * Authors: Artem Bityutskiy (Битюцкий Артём)
  20  *          Adrian Hunter
  21  */
  22
  23 /*
  24  * This header contains various key-related definitions and helper function.
  25  * UBIFS allows several key schemes, so we access key fields only via these
  26  * helpers. At the moment only one key scheme is supported.
  27  *
  28  * Simple key scheme
  29  * ~~~~~~~~~~~~~~~~~
  30  *
  31  * Keys are 64-bits long. First 32-bits are inode number (parent inode number
  32  * in case of direntry key). Next 3 bits are node type. The last 29 bits are
  33  * 4KiB offset in case of inode node, and direntry hash in case of a direntry
  34  * node. We use "r5" hash borrowed from reiserfs.
  35  */
  36
  37 /*
  38  * Lot's of the key helpers require a struct ubifs_info *c as the first parameter.
  39  * But we are not using it at all currently. That's designed for future extensions of
  40  * different c->key_format. But right now, there is only one key type, UBIFS_SIMPLE_KEY_FMT.
  41  */
  42
  43 #ifndef __UBIFS_KEY_H__
  44 #define __UBIFS_KEY_H__
  45
  46 /**
  47  * key_mask_hash - mask a valid hash value.
  48  * @val: value to be masked
  49  *
  50  * We use hash values as offset in directories, so values %0 and %1 are
  51  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
  52  * function makes sure the reserved values are not used.
  53  */
  54 static inline uint32_t key_mask_hash(uint32_t hash)
  55 {
  56         hash &= UBIFS_S_KEY_HASH_MASK;
  57         if (unlikely(hash <= 2))
  58                 hash += 3;
  59         return hash;
  60 }
  61
  62 /**
  63  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  64  * @s: direntry name
  65  * @len: name length
  66  */
  67 static inline uint32_t key_r5_hash(const char *s, int len)
  68 {
  69         uint32_t a = 0;
  70         const signed char *str = (const signed char *)s;
  71
  72         while (*str) {
  73                 a += *str << 4;
  74                 a += *str >> 4;
  75                 a *= 11;
  76                 str++;
  77         }
  78
  79         return key_mask_hash(a);
  80 }
  81
  82 /**
  83  * key_test_hash - testing hash function.
  84  * @str: direntry name
  85  * @len: name length
  86  */
  87 static inline uint32_t key_test_hash(const char *str, int len)
  88 {
  89         uint32_t a = 0;
  90
  91         len = min_t(uint32_t, len, 4);
  92         memcpy(&a, str, len);
  93         return key_mask_hash(a);
  94 }
  95
  96 /**
  97  * ino_key_init - initialize inode key.
  98  * @c: UBIFS file-system description object
  99  * @key: key to initialize
 100  * @inum: inode number
 101  */
 102 static inline void ino_key_init(const struct ubifs_info *c,
 103                                 union ubifs_key *key, ino_t inum)
 104 {
 105         key->u32[0] = inum;
 106         key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
 107 }
 108
 109 /**
 110  * ino_key_init_flash - initialize on-flash inode key.
 111  * @c: UBIFS file-system description object
 112  * @k: key to initialize
 113  * @inum: inode number
 114  */
 115 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
 116                                       ino_t inum)
 117 {
 118         union ubifs_key *key = k;
 119
 120         key->j32[0] = cpu_to_le32(inum);
 121         key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
 122         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 123 }
 124
 125 /**
 126  * lowest_ino_key - get the lowest possible inode key.
 127  * @c: UBIFS file-system description object
 128  * @key: key to initialize
 129  * @inum: inode number
 130  */
 131 static inline void lowest_ino_key(const struct ubifs_info *c,
 132                                 union ubifs_key *key, ino_t inum)
 133 {
 134         key->u32[0] = inum;
 135         key->u32[1] = 0;
 136 }
 137
 138 /**
 139  * highest_ino_key - get the highest possible inode key.
 140  * @c: UBIFS file-system description object
 141  * @key: key to initialize
 142  * @inum: inode number
 143  */
 144 static inline void highest_ino_key(const struct ubifs_info *c,
 145                                 union ubifs_key *key, ino_t inum)
 146 {
 147         key->u32[0] = inum;
 148         key->u32[1] = 0xffffffff;
 149 }
 150
 151 /**
 152  * dent_key_init - initialize directory entry key.
 153  * @c: UBIFS file-system description object
 154  * @key: key to initialize
 155  * @inum: parent inode number
 156  * @nm: direntry name and length
 157  */
 158 static inline void dent_key_init(const struct ubifs_info *c,
 159                                  union ubifs_key *key, ino_t inum,
 160                                  const struct qstr *nm)
 161 {
 162         uint32_t hash = c->key_hash(nm->name, nm->len);
 163
 164         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 165         key->u32[0] = inum;
 166         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 167 }
 168
 169 /**
 170  * dent_key_init_hash - initialize directory entry key without re-calculating
 171  *                      hash function.
 172  * @c: UBIFS file-system description object
 173  * @key: key to initialize
 174  * @inum: parent inode number
 175  * @hash: direntry name hash
 176  */
 177 static inline void dent_key_init_hash(const struct ubifs_info *c,
 178                                       union ubifs_key *key, ino_t inum,
 179                                       uint32_t hash)
 180 {
 181         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 182         key->u32[0] = inum;
 183         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 184 }
 185
 186 /**
 187  * dent_key_init_flash - initialize on-flash directory entry key.
 188  * @c: UBIFS file-system description object
 189  * @k: key to initialize
 190  * @inum: parent inode number
 191  * @nm: direntry name and length
 192  */
 193 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
 194                                        ino_t inum, const struct qstr *nm)
 195 {
 196         union ubifs_key *key = k;
 197         uint32_t hash = c->key_hash(nm->name, nm->len);
 198
 199         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 200         key->j32[0] = cpu_to_le32(inum);
 201         key->j32[1] = cpu_to_le32(hash |
 202                                   (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
 203         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 204 }
 205
 206 /**
 207  * lowest_dent_key - get the lowest possible directory entry key.
 208  * @c: UBIFS file-system description object
 209  * @key: where to store the lowest key
 210  * @inum: parent inode number
 211  */
 212 static inline void lowest_dent_key(const struct ubifs_info *c,
 213                                    union ubifs_key *key, ino_t inum)
 214 {
 215         key->u32[0] = inum;
 216         key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
 217 }
 218
 219 /**
 220  * xent_key_init - initialize extended attribute entry key.
 221  * @c: UBIFS file-system description object
 222  * @key: key to initialize
 223  * @inum: host inode number
 224  * @nm: extended attribute entry name and length
 225  */
 226 static inline void xent_key_init(const struct ubifs_info *c,
 227                                  union ubifs_key *key, ino_t inum,
 228                                  const struct qstr *nm)
 229 {
 230         uint32_t hash = c->key_hash(nm->name, nm->len);
 231
 232         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 233         key->u32[0] = inum;
 234         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 235 }
 236
 237 /**
 238  * xent_key_init_flash - initialize on-flash extended attribute entry key.
 239  * @c: UBIFS file-system description object
 240  * @k: key to initialize
 241  * @inum: host inode number
 242  * @nm: extended attribute entry name and length
 243  */
 244 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 245                                        ino_t inum, const struct qstr *nm)
 246 {
 247         union ubifs_key *key = k;
 248         uint32_t hash = c->key_hash(nm->name, nm->len);
 249
 250         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 251         key->j32[0] = cpu_to_le32(inum);
 252         key->j32[1] = cpu_to_le32(hash |
 253                                   (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 254         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 255 }
 256
 257 /**
 258  * lowest_xent_key - get the lowest possible extended attribute entry key.
 259  * @c: UBIFS file-system description object
 260  * @key: where to store the lowest key
 261  * @inum: host inode number
 262  */
 263 static inline void lowest_xent_key(const struct ubifs_info *c,
 264                                    union ubifs_key *key, ino_t inum)
 265 {
 266         key->u32[0] = inum;
 267         key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 268 }
 269
 270 /**
 271  * data_key_init - initialize data key.
 272  * @c: UBIFS file-system description object
 273  * @key: key to initialize
 274  * @inum: inode number
 275  * @block: block number
 276  */
 277 static inline void data_key_init(const struct ubifs_info *c,
 278                                  union ubifs_key *key, ino_t inum,
 279                                  unsigned int block)
 280 {
 281         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 282         key->u32[0] = inum;
 283         key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 284 }
 285
 286 /**
 287  * highest_data_key - get the highest possible data key for an inode.
 288  * @c: UBIFS file-system description object
 289  * @key: key to initialize
 290  * @inum: inode number
 291  */
 292 static inline void highest_data_key(const struct ubifs_info *c,
 293                                    union ubifs_key *key, ino_t inum)
 294 {
 295         data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
 296 }
 297
 298 /**
 299  * trun_key_init - initialize truncation node key.
 300  * @c: UBIFS file-system description object
 301  * @key: key to initialize
 302  * @inum: inode number
 303  *
 304  * Note, UBIFS does not have truncation keys on the media and this function is
 305  * only used for purposes of replay.
 306  */
 307 static inline void trun_key_init(const struct ubifs_info *c,
 308                                  union ubifs_key *key, ino_t inum)
 309 {
 310         key->u32[0] = inum;
 311         key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 312 }
 313
 314 /**
 315  * invalid_key_init - initialize invalid node key.
 316  * @c: UBIFS file-system description object
 317  * @key: key to initialize
 318  *
 319  * This is a helper function which marks a @key object as invalid.
 320  */
 321 static inline void invalid_key_init(const struct ubifs_info *c,
 322                                     union ubifs_key *key)
 323 {
 324         key->u32[0] = 0xDEADBEAF;
 325         key->u32[1] = UBIFS_INVALID_KEY;
 326 }
 327
 328 /**
 329  * key_type - get key type.
 330  * @c: UBIFS file-system description object
 331  * @key: key to get type of
 332  */
 333 static inline int key_type(const struct ubifs_info *c,
 334                            const union ubifs_key *key)
 335 {
 336         return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 337 }
 338
 339 /**
 340  * key_type_flash - get type of a on-flash formatted key.
 341  * @c: UBIFS file-system description object
 342  * @k: key to get type of
 343  */
 344 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
 345 {
 346         const union ubifs_key *key = k;
 347
 348         return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 349 }
 350
 351 /**
 352  * key_inum - fetch inode number from key.
 353  * @c: UBIFS file-system description object
 354  * @k: key to fetch inode number from
 355  */
 356 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 357 {
 358         const union ubifs_key *key = k;
 359
 360         return key->u32[0];
 361 }
 362
 363 /**
 364  * key_inum_flash - fetch inode number from an on-flash formatted key.
 365  * @c: UBIFS file-system description object
 366  * @k: key to fetch inode number from
 367  */
 368 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 369 {
 370         const union ubifs_key *key = k;
 371
 372         return le32_to_cpu(key->j32[0]);
 373 }
 374
 375 /**
 376  * key_hash - get directory entry hash.
 377  * @c: UBIFS file-system description object
 378  * @key: the key to get hash from
 379  */
 380 static inline uint32_t key_hash(const struct ubifs_info *c,
 381                                 const union ubifs_key *key)
 382 {
 383         return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 384 }
 385
 386 /**
 387  * key_hash_flash - get directory entry hash from an on-flash formatted key.
 388  * @c: UBIFS file-system description object
 389  * @k: the key to get hash from
 390  */
 391 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 392 {
 393         const union ubifs_key *key = k;
 394
 395         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 396 }
 397
 398 /**
 399  * key_block - get data block number.
 400  * @c: UBIFS file-system description object
 401  * @key: the key to get the block number from
 402  */
 403 static inline unsigned int key_block(const struct ubifs_info *c,
 404                                      const union ubifs_key *key)
 405 {
 406         return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 407 }
 408
 409 /**
 410  * key_block_flash - get data block number from an on-flash formatted key.
 411  * @c: UBIFS file-system description object
 412  * @k: the key to get the block number from
 413  */
 414 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 415                                            const void *k)
 416 {
 417         const union ubifs_key *key = k;
 418
 419         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 420 }
 421
 422 /**
 423  * key_read - transform a key to in-memory format.
 424  * @c: UBIFS file-system description object
 425  * @from: the key to transform
 426  * @to: the key to store the result
 427  */
 428 static inline void key_read(const struct ubifs_info *c, const void *from,
 429                             union ubifs_key *to)
 430 {
 431         const union ubifs_key *f = from;
 432
 433         to->u32[0] = le32_to_cpu(f->j32[0]);
 434         to->u32[1] = le32_to_cpu(f->j32[1]);
 435 }
 436
 437 /**
 438  * key_write - transform a key from in-memory format.
 439  * @c: UBIFS file-system description object
 440  * @from: the key to transform
 441  * @to: the key to store the result
 442  */
 443 static inline void key_write(const struct ubifs_info *c,
 444                              const union ubifs_key *from, void *to)
 445 {
 446         union ubifs_key *t = to;
 447
 448         t->j32[0] = cpu_to_le32(from->u32[0]);
 449         t->j32[1] = cpu_to_le32(from->u32[1]);
 450         memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 451 }
 452
 453 /**
 454  * key_write_idx - transform a key from in-memory format for the index.
 455  * @c: UBIFS file-system description object
 456  * @from: the key to transform
 457  * @to: the key to store the result
 458  */
 459 static inline void key_write_idx(const struct ubifs_info *c,
 460                                  const union ubifs_key *from, void *to)
 461 {
 462         union ubifs_key *t = to;
 463
 464         t->j32[0] = cpu_to_le32(from->u32[0]);
 465         t->j32[1] = cpu_to_le32(from->u32[1]);
 466 }
 467
 468 /**
 469  * key_copy - copy a key.
 470  * @c: UBIFS file-system description object
 471  * @from: the key to copy from
 472  * @to: the key to copy to
 473  */
 474 static inline void key_copy(const struct ubifs_info *c,
 475                             const union ubifs_key *from, union ubifs_key *to)
 476 {
 477         to->u64[0] = from->u64[0];
 478 }
 479
 480 /**
 481  * keys_cmp - compare keys.
 482  * @c: UBIFS file-system description object
 483  * @key1: the first key to compare
 484  * @key2: the second key to compare
 485  *
 486  * This function compares 2 keys and returns %-1 if @key1 is less than
 487  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
 488  */
 489 static inline int keys_cmp(const struct ubifs_info *c,
 490                            const union ubifs_key *key1,
 491                            const union ubifs_key *key2)
 492 {
 493         if (key1->u32[0] < key2->u32[0])
 494                 return -1;
 495         if (key1->u32[0] > key2->u32[0])
 496                 return 1;
 497         if (key1->u32[1] < key2->u32[1])
 498                 return -1;
 499         if (key1->u32[1] > key2->u32[1])
 500                 return 1;
 501
 502         return 0;
 503 }
 504
 505 /**
 506  * keys_eq - determine if keys are equivalent.
 507  * @c: UBIFS file-system description object
 508  * @key1: the first key to compare
 509  * @key2: the second key to compare
 510  *
 511  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
 512  * %0 if not.
 513  */
 514 static inline int keys_eq(const struct ubifs_info *c,
 515                           const union ubifs_key *key1,
 516                           const union ubifs_key *key2)
 517 {
 518         if (key1->u32[0] != key2->u32[0])
 519                 return 0;
 520         if (key1->u32[1] != key2->u32[1])
 521                 return 0;
 522         return 1;
 523 }
 524
 525 /**
 526  * is_hash_key - is a key vulnerable to hash collisions.
 527  * @c: UBIFS file-system description object
 528  * @key: key
 529  *
 530  * This function returns %1 if @key is a hashed key or %0 otherwise.
 531  */
 532 static inline int is_hash_key(const struct ubifs_info *c,
 533                               const union ubifs_key *key)
 534 {
 535         int type = key_type(c, key);
 536
 537         return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 538 }
 539
 540 /**
 541  * key_max_inode_size - get maximum file size allowed by current key format.
 542  * @c: UBIFS file-system description object
 543  */
 544 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 545 {
 546         switch (c->key_fmt) {
 547         case UBIFS_SIMPLE_KEY_FMT:
 548                 return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 549         default:
 550                 return 0;
 551         }
 552 }
 553
 554 #endif /* !__UBIFS_KEY_H__ */