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 #ifndef __UBIFS_KEY_H__
  38 #define __UBIFS_KEY_H__
  39
  40 /**
  41  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  42  * @s: direntry name
  43  * @len: name length
  44  */
  45 static inline uint32_t key_r5_hash(const char *s, int len)
  46 {
  47         uint32_t a = 0;
  48         const signed char *str = (const signed char *)s;
  49
  50         while (*str) {
  51                 a += *str << 4;
  52                 a += *str >> 4;
  53                 a *= 11;
  54                 str++;
  55         }
  56
  57         a &= UBIFS_S_KEY_HASH_MASK;
  58
  59         /*
  60          * We use hash values as offset in directories, so values %0 and %1 are
  61          * reserved for "." and "..". %2 is reserved for "end of readdir"
  62          * marker.
  63          */
  64         if (unlikely(a >= 0 && a <= 2))
  65                 a += 3;
  66         return a;
  67 }
  68
  69 /**
  70  * key_test_hash - testing hash function.
  71  * @str: direntry name
  72  * @len: name length
  73  */
  74 static inline uint32_t key_test_hash(const char *str, int len)
  75 {
  76         uint32_t a = 0;
  77
  78         len = min_t(uint32_t, len, 4);
  79         memcpy(&a, str, len);
  80         a &= UBIFS_S_KEY_HASH_MASK;
  81         if (unlikely(a >= 0 && a <= 2))
  82                 a += 3;
  83         return a;
  84 }
  85
  86 /**
  87  * ino_key_init - initialize inode key.
  88  * @c: UBIFS file-system description object
  89  * @key: key to initialize
  90  * @inum: inode number
  91  */
  92 static inline void ino_key_init(const struct ubifs_info *c,
  93                                 union ubifs_key *key, ino_t inum)
  94 {
  95         key->u32[0] = inum;
  96         key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
  97 }
  98
  99 /**
 100  * ino_key_init_flash - initialize on-flash inode key.
 101  * @c: UBIFS file-system description object
 102  * @k: key to initialize
 103  * @inum: inode number
 104  */
 105 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
 106                                       ino_t inum)
 107 {
 108         union ubifs_key *key = k;
 109
 110         key->j32[0] = cpu_to_le32(inum);
 111         key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
 112         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 113 }
 114
 115 /**
 116  * lowest_ino_key - get the lowest possible inode key.
 117  * @c: UBIFS file-system description object
 118  * @key: key to initialize
 119  * @inum: inode number
 120  */
 121 static inline void lowest_ino_key(const struct ubifs_info *c,
 122                                 union ubifs_key *key, ino_t inum)
 123 {
 124         key->u32[0] = inum;
 125         key->u32[1] = 0;
 126 }
 127
 128 /**
 129  * highest_ino_key - get the highest possible inode key.
 130  * @c: UBIFS file-system description object
 131  * @key: key to initialize
 132  * @inum: inode number
 133  */
 134 static inline void highest_ino_key(const struct ubifs_info *c,
 135                                 union ubifs_key *key, ino_t inum)
 136 {
 137         key->u32[0] = inum;
 138         key->u32[1] = 0xffffffff;
 139 }
 140
 141 /**
 142  * dent_key_init - initialize directory entry key.
 143  * @c: UBIFS file-system description object
 144  * @key: key to initialize
 145  * @inum: parent inode number
 146  * @nm: direntry name and length
 147  */
 148 static inline void dent_key_init(const struct ubifs_info *c,
 149                                  union ubifs_key *key, ino_t inum,
 150                                  const struct qstr *nm)
 151 {
 152         uint32_t hash = c->key_hash(nm->name, nm->len);
 153
 154         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 155         key->u32[0] = inum;
 156         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 157 }
 158
 159 /**
 160  * dent_key_init_hash - initialize directory entry key without re-calculating
 161  *                      hash function.
 162  * @c: UBIFS file-system description object
 163  * @key: key to initialize
 164  * @inum: parent inode number
 165  * @hash: direntry name hash
 166  */
 167 static inline void dent_key_init_hash(const struct ubifs_info *c,
 168                                       union ubifs_key *key, ino_t inum,
 169                                       uint32_t hash)
 170 {
 171         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 172         key->u32[0] = inum;
 173         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 174 }
 175
 176 /**
 177  * dent_key_init_flash - initialize on-flash directory entry key.
 178  * @c: UBIFS file-system description object
 179  * @k: key to initialize
 180  * @inum: parent inode number
 181  * @nm: direntry name and length
 182  */
 183 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
 184                                        ino_t inum, const struct qstr *nm)
 185 {
 186         union ubifs_key *key = k;
 187         uint32_t hash = c->key_hash(nm->name, nm->len);
 188
 189         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 190         key->j32[0] = cpu_to_le32(inum);
 191         key->j32[1] = cpu_to_le32(hash |
 192                                   (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
 193         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 194 }
 195
 196 /**
 197  * lowest_dent_key - get the lowest possible directory entry key.
 198  * @c: UBIFS file-system description object
 199  * @key: where to store the lowest key
 200  * @inum: parent inode number
 201  */
 202 static inline void lowest_dent_key(const struct ubifs_info *c,
 203                                    union ubifs_key *key, ino_t inum)
 204 {
 205         key->u32[0] = inum;
 206         key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
 207 }
 208
 209 /**
 210  * xent_key_init - initialize extended attribute entry key.
 211  * @c: UBIFS file-system description object
 212  * @key: key to initialize
 213  * @inum: host inode number
 214  * @nm: extended attribute entry name and length
 215  */
 216 static inline void xent_key_init(const struct ubifs_info *c,
 217                                  union ubifs_key *key, ino_t inum,
 218                                  const struct qstr *nm)
 219 {
 220         uint32_t hash = c->key_hash(nm->name, nm->len);
 221
 222         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 223         key->u32[0] = inum;
 224         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 225 }
 226
 227 /**
 228  * xent_key_init_hash - initialize extended attribute entry key without
 229  *                      re-calculating hash function.
 230  * @c: UBIFS file-system description object
 231  * @key: key to initialize
 232  * @inum: host inode number
 233  * @hash: extended attribute entry name hash
 234  */
 235 static inline void xent_key_init_hash(const struct ubifs_info *c,
 236                                       union ubifs_key *key, ino_t inum,
 237                                       uint32_t hash)
 238 {
 239         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 240         key->u32[0] = inum;
 241         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 242 }
 243
 244 /**
 245  * xent_key_init_flash - initialize on-flash extended attribute entry key.
 246  * @c: UBIFS file-system description object
 247  * @k: key to initialize
 248  * @inum: host inode number
 249  * @nm: extended attribute entry name and length
 250  */
 251 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 252                                        ino_t inum, const struct qstr *nm)
 253 {
 254         union ubifs_key *key = k;
 255         uint32_t hash = c->key_hash(nm->name, nm->len);
 256
 257         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 258         key->j32[0] = cpu_to_le32(inum);
 259         key->j32[1] = cpu_to_le32(hash |
 260                                   (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 261         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 262 }
 263
 264 /**
 265  * lowest_xent_key - get the lowest possible extended attribute entry key.
 266  * @c: UBIFS file-system description object
 267  * @key: where to store the lowest key
 268  * @inum: host inode number
 269  */
 270 static inline void lowest_xent_key(const struct ubifs_info *c,
 271                                    union ubifs_key *key, ino_t inum)
 272 {
 273         key->u32[0] = inum;
 274         key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 275 }
 276
 277 /**
 278  * data_key_init - initialize data key.
 279  * @c: UBIFS file-system description object
 280  * @key: key to initialize
 281  * @inum: inode number
 282  * @block: block number
 283  */
 284 static inline void data_key_init(const struct ubifs_info *c,
 285                                  union ubifs_key *key, ino_t inum,
 286                                  unsigned int block)
 287 {
 288         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 289         key->u32[0] = inum;
 290         key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 291 }
 292
 293 /**
 294  * data_key_init_flash - initialize on-flash data key.
 295  * @c: UBIFS file-system description object
 296  * @k: key to initialize
 297  * @inum: inode number
 298  * @block: block number
 299  */
 300 static inline void data_key_init_flash(const struct ubifs_info *c, void *k,
 301                                        ino_t inum, unsigned int block)
 302 {
 303         union ubifs_key *key = k;
 304
 305         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 306         key->j32[0] = cpu_to_le32(inum);
 307         key->j32[1] = cpu_to_le32(block |
 308                                   (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS));
 309         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 310 }
 311
 312 /**
 313  * trun_key_init - initialize truncation node key.
 314  * @c: UBIFS file-system description object
 315  * @key: key to initialize
 316  * @inum: inode number
 317  *
 318  * Note, UBIFS does not have truncation keys on the media and this function is
 319  * only used for purposes of replay.
 320  */
 321 static inline void trun_key_init(const struct ubifs_info *c,
 322                                  union ubifs_key *key, ino_t inum)
 323 {
 324         key->u32[0] = inum;
 325         key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 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->u32[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 int 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 int 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->u32[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  * is_hash_key - is a key vulnerable to hash collisions.
 507  * @c: UBIFS file-system description object
 508  * @key: key
 509  *
 510  * This function returns %1 if @key is a hashed key or %0 otherwise.
 511  */
 512 static inline int is_hash_key(const struct ubifs_info *c,
 513                               const union ubifs_key *key)
 514 {
 515         int type = key_type(c, key);
 516
 517         return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 518 }
 519
 520 /**
 521  * key_max_inode_size - get maximum file size allowed by current key format.
 522  * @c: UBIFS file-system description object
 523  */
 524 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 525 {
 526         switch (c->key_fmt) {
 527         case UBIFS_SIMPLE_KEY_FMT:
 528                 return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 529         default:
 530                 return 0;
 531         }
 532 }
 533 #endif /* !__UBIFS_KEY_H__ */