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_mask_hash - mask a valid hash value.
  42  * @val: value to be masked
  43  *
  44  * We use hash values as offset in directories, so values %0 and %1 are
  45  * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This
  46  * function makes sure the reserved values are not used.
  47  */
  48 static inline uint32_t key_mask_hash(uint32_t hash)
  49 {
  50         hash &= UBIFS_S_KEY_HASH_MASK;
  51         if (unlikely(hash <= 2))
  52                 hash += 3;
  53         return hash;
  54 }
  55
  56 /**
  57  * key_r5_hash - R5 hash function (borrowed from reiserfs).
  58  * @s: direntry name
  59  * @len: name length
  60  */
  61 static inline uint32_t key_r5_hash(const char *s, int len)
  62 {
  63         uint32_t a = 0;
  64         const signed char *str = (const signed char *)s;
  65
  66         while (*str) {
  67                 a += *str << 4;
  68                 a += *str >> 4;
  69                 a *= 11;
  70                 str++;
  71         }
  72
  73         return key_mask_hash(a);
  74 }
  75
  76 /**
  77  * key_test_hash - testing hash function.
  78  * @str: direntry name
  79  * @len: name length
  80  */
  81 static inline uint32_t key_test_hash(const char *str, int len)
  82 {
  83         uint32_t a = 0;
  84
  85         len = min_t(uint32_t, len, 4);
  86         memcpy(&a, str, len);
  87         return key_mask_hash(a);
  88 }
  89
  90 /**
  91  * ino_key_init - initialize inode key.
  92  * @c: UBIFS file-system description object
  93  * @key: key to initialize
  94  * @inum: inode number
  95  */
  96 static inline void ino_key_init(const struct ubifs_info *c,
  97                                 union ubifs_key *key, ino_t inum)
  98 {
  99         key->u32[0] = inum;
 100         key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
 101 }
 102
 103 /**
 104  * ino_key_init_flash - initialize on-flash inode key.
 105  * @c: UBIFS file-system description object
 106  * @k: key to initialize
 107  * @inum: inode number
 108  */
 109 static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
 110                                       ino_t inum)
 111 {
 112         union ubifs_key *key = k;
 113
 114         key->j32[0] = cpu_to_le32(inum);
 115         key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
 116         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 117 }
 118
 119 /**
 120  * lowest_ino_key - get the lowest possible inode key.
 121  * @c: UBIFS file-system description object
 122  * @key: key to initialize
 123  * @inum: inode number
 124  */
 125 static inline void lowest_ino_key(const struct ubifs_info *c,
 126                                 union ubifs_key *key, ino_t inum)
 127 {
 128         key->u32[0] = inum;
 129         key->u32[1] = 0;
 130 }
 131
 132 /**
 133  * highest_ino_key - get the highest possible inode key.
 134  * @c: UBIFS file-system description object
 135  * @key: key to initialize
 136  * @inum: inode number
 137  */
 138 static inline void highest_ino_key(const struct ubifs_info *c,
 139                                 union ubifs_key *key, ino_t inum)
 140 {
 141         key->u32[0] = inum;
 142         key->u32[1] = 0xffffffff;
 143 }
 144
 145 /**
 146  * dent_key_init - initialize directory entry key.
 147  * @c: UBIFS file-system description object
 148  * @key: key to initialize
 149  * @inum: parent inode number
 150  * @nm: direntry name and length
 151  */
 152 static inline void dent_key_init(const struct ubifs_info *c,
 153                                  union ubifs_key *key, ino_t inum,
 154                                  const struct qstr *nm)
 155 {
 156         uint32_t hash = c->key_hash(nm->name, nm->len);
 157
 158         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 159         key->u32[0] = inum;
 160         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 161 }
 162
 163 /**
 164  * dent_key_init_hash - initialize directory entry key without re-calculating
 165  *                      hash function.
 166  * @c: UBIFS file-system description object
 167  * @key: key to initialize
 168  * @inum: parent inode number
 169  * @hash: direntry name hash
 170  */
 171 static inline void dent_key_init_hash(const struct ubifs_info *c,
 172                                       union ubifs_key *key, ino_t inum,
 173                                       uint32_t hash)
 174 {
 175         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 176         key->u32[0] = inum;
 177         key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
 178 }
 179
 180 /**
 181  * dent_key_init_flash - initialize on-flash directory entry key.
 182  * @c: UBIFS file-system description object
 183  * @k: key to initialize
 184  * @inum: parent inode number
 185  * @nm: direntry name and length
 186  */
 187 static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
 188                                        ino_t inum, const struct qstr *nm)
 189 {
 190         union ubifs_key *key = k;
 191         uint32_t hash = c->key_hash(nm->name, nm->len);
 192
 193         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 194         key->j32[0] = cpu_to_le32(inum);
 195         key->j32[1] = cpu_to_le32(hash |
 196                                   (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
 197         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 198 }
 199
 200 /**
 201  * lowest_dent_key - get the lowest possible directory entry key.
 202  * @c: UBIFS file-system description object
 203  * @key: where to store the lowest key
 204  * @inum: parent inode number
 205  */
 206 static inline void lowest_dent_key(const struct ubifs_info *c,
 207                                    union ubifs_key *key, ino_t inum)
 208 {
 209         key->u32[0] = inum;
 210         key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
 211 }
 212
 213 /**
 214  * xent_key_init - initialize extended attribute entry key.
 215  * @c: UBIFS file-system description object
 216  * @key: key to initialize
 217  * @inum: host inode number
 218  * @nm: extended attribute entry name and length
 219  */
 220 static inline void xent_key_init(const struct ubifs_info *c,
 221                                  union ubifs_key *key, ino_t inum,
 222                                  const struct qstr *nm)
 223 {
 224         uint32_t hash = c->key_hash(nm->name, nm->len);
 225
 226         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 227         key->u32[0] = inum;
 228         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 229 }
 230
 231 /**
 232  * xent_key_init_flash - initialize on-flash extended attribute entry key.
 233  * @c: UBIFS file-system description object
 234  * @k: key to initialize
 235  * @inum: host inode number
 236  * @nm: extended attribute entry name and length
 237  */
 238 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 239                                        ino_t inum, const struct qstr *nm)
 240 {
 241         union ubifs_key *key = k;
 242         uint32_t hash = c->key_hash(nm->name, nm->len);
 243
 244         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 245         key->j32[0] = cpu_to_le32(inum);
 246         key->j32[1] = cpu_to_le32(hash |
 247                                   (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 248         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 249 }
 250
 251 /**
 252  * lowest_xent_key - get the lowest possible extended attribute entry key.
 253  * @c: UBIFS file-system description object
 254  * @key: where to store the lowest key
 255  * @inum: host inode number
 256  */
 257 static inline void lowest_xent_key(const struct ubifs_info *c,
 258                                    union ubifs_key *key, ino_t inum)
 259 {
 260         key->u32[0] = inum;
 261         key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 262 }
 263
 264 /**
 265  * data_key_init - initialize data key.
 266  * @c: UBIFS file-system description object
 267  * @key: key to initialize
 268  * @inum: inode number
 269  * @block: block number
 270  */
 271 static inline void data_key_init(const struct ubifs_info *c,
 272                                  union ubifs_key *key, ino_t inum,
 273                                  unsigned int block)
 274 {
 275         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 276         key->u32[0] = inum;
 277         key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 278 }
 279
 280 /**
 281  * highest_data_key - get the highest possible data key for an inode.
 282  * @c: UBIFS file-system description object
 283  * @key: key to initialize
 284  * @inum: inode number
 285  */
 286 static inline void highest_data_key(const struct ubifs_info *c,
 287                                    union ubifs_key *key, ino_t inum)
 288 {
 289         data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
 290 }
 291
 292 /**
 293  * trun_key_init - initialize truncation node key.
 294  * @c: UBIFS file-system description object
 295  * @key: key to initialize
 296  * @inum: inode number
 297  *
 298  * Note, UBIFS does not have truncation keys on the media and this function is
 299  * only used for purposes of replay.
 300  */
 301 static inline void trun_key_init(const struct ubifs_info *c,
 302                                  union ubifs_key *key, ino_t inum)
 303 {
 304         key->u32[0] = inum;
 305         key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 306 }
 307
 308 /**
 309  * key_type - get key type.
 310  * @c: UBIFS file-system description object
 311  * @key: key to get type of
 312  */
 313 static inline int key_type(const struct ubifs_info *c,
 314                            const union ubifs_key *key)
 315 {
 316         return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 317 }
 318
 319 /**
 320  * key_type_flash - get type of a on-flash formatted key.
 321  * @c: UBIFS file-system description object
 322  * @k: key to get type of
 323  */
 324 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
 325 {
 326         const union ubifs_key *key = k;
 327
 328         return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 329 }
 330
 331 /**
 332  * key_inum - fetch inode number from key.
 333  * @c: UBIFS file-system description object
 334  * @k: key to fetch inode number from
 335  */
 336 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 337 {
 338         const union ubifs_key *key = k;
 339
 340         return key->u32[0];
 341 }
 342
 343 /**
 344  * key_inum_flash - fetch inode number from an on-flash formatted key.
 345  * @c: UBIFS file-system description object
 346  * @k: key to fetch inode number from
 347  */
 348 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 349 {
 350         const union ubifs_key *key = k;
 351
 352         return le32_to_cpu(key->j32[0]);
 353 }
 354
 355 /**
 356  * key_hash - get directory entry hash.
 357  * @c: UBIFS file-system description object
 358  * @key: the key to get hash from
 359  */
 360 static inline uint32_t key_hash(const struct ubifs_info *c,
 361                                 const union ubifs_key *key)
 362 {
 363         return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 364 }
 365
 366 /**
 367  * key_hash_flash - get directory entry hash from an on-flash formatted key.
 368  * @c: UBIFS file-system description object
 369  * @k: the key to get hash from
 370  */
 371 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 372 {
 373         const union ubifs_key *key = k;
 374
 375         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 376 }
 377
 378 /**
 379  * key_block - get data block number.
 380  * @c: UBIFS file-system description object
 381  * @key: the key to get the block number from
 382  */
 383 static inline unsigned int key_block(const struct ubifs_info *c,
 384                                      const union ubifs_key *key)
 385 {
 386         return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 387 }
 388
 389 /**
 390  * key_block_flash - get data block number from an on-flash formatted key.
 391  * @c: UBIFS file-system description object
 392  * @k: the key to get the block number from
 393  */
 394 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 395                                            const void *k)
 396 {
 397         const union ubifs_key *key = k;
 398
 399         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 400 }
 401
 402 /**
 403  * key_read - transform a key to in-memory format.
 404  * @c: UBIFS file-system description object
 405  * @from: the key to transform
 406  * @to: the key to store the result
 407  */
 408 static inline void key_read(const struct ubifs_info *c, const void *from,
 409                             union ubifs_key *to)
 410 {
 411         const union ubifs_key *f = from;
 412
 413         to->u32[0] = le32_to_cpu(f->j32[0]);
 414         to->u32[1] = le32_to_cpu(f->j32[1]);
 415 }
 416
 417 /**
 418  * key_write - transform a key from in-memory format.
 419  * @c: UBIFS file-system description object
 420  * @from: the key to transform
 421  * @to: the key to store the result
 422  */
 423 static inline void key_write(const struct ubifs_info *c,
 424                              const union ubifs_key *from, void *to)
 425 {
 426         union ubifs_key *t = to;
 427
 428         t->j32[0] = cpu_to_le32(from->u32[0]);
 429         t->j32[1] = cpu_to_le32(from->u32[1]);
 430         memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 431 }
 432
 433 /**
 434  * key_write_idx - transform a key from in-memory format for the index.
 435  * @c: UBIFS file-system description object
 436  * @from: the key to transform
 437  * @to: the key to store the result
 438  */
 439 static inline void key_write_idx(const struct ubifs_info *c,
 440                                  const union ubifs_key *from, void *to)
 441 {
 442         union ubifs_key *t = to;
 443
 444         t->j32[0] = cpu_to_le32(from->u32[0]);
 445         t->j32[1] = cpu_to_le32(from->u32[1]);
 446 }
 447
 448 /**
 449  * key_copy - copy a key.
 450  * @c: UBIFS file-system description object
 451  * @from: the key to copy from
 452  * @to: the key to copy to
 453  */
 454 static inline void key_copy(const struct ubifs_info *c,
 455                             const union ubifs_key *from, union ubifs_key *to)
 456 {
 457         to->u64[0] = from->u64[0];
 458 }
 459
 460 /**
 461  * keys_cmp - compare keys.
 462  * @c: UBIFS file-system description object
 463  * @key1: the first key to compare
 464  * @key2: the second key to compare
 465  *
 466  * This function compares 2 keys and returns %-1 if @key1 is less than
 467  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
 468  */
 469 static inline int keys_cmp(const struct ubifs_info *c,
 470                            const union ubifs_key *key1,
 471                            const union ubifs_key *key2)
 472 {
 473         if (key1->u32[0] < key2->u32[0])
 474                 return -1;
 475         if (key1->u32[0] > key2->u32[0])
 476                 return 1;
 477         if (key1->u32[1] < key2->u32[1])
 478                 return -1;
 479         if (key1->u32[1] > key2->u32[1])
 480                 return 1;
 481
 482         return 0;
 483 }
 484
 485 /**
 486  * keys_eq - determine if keys are equivalent.
 487  * @c: UBIFS file-system description object
 488  * @key1: the first key to compare
 489  * @key2: the second key to compare
 490  *
 491  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
 492  * %0 if not.
 493  */
 494 static inline int keys_eq(const struct ubifs_info *c,
 495                           const union ubifs_key *key1,
 496                           const union ubifs_key *key2)
 497 {
 498         if (key1->u32[0] != key2->u32[0])
 499                 return 0;
 500         if (key1->u32[1] != key2->u32[1])
 501                 return 0;
 502         return 1;
 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
 534 #endif /* !__UBIFS_KEY_H__ */