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_hash - initialize extended attribute entry key without
 233  *                      re-calculating hash function.
 234  * @c: UBIFS file-system description object
 235  * @key: key to initialize
 236  * @inum: host inode number
 237  * @hash: extended attribute entry name hash
 238  */
 239 static inline void xent_key_init_hash(const struct ubifs_info *c,
 240                                       union ubifs_key *key, ino_t inum,
 241                                       uint32_t hash)
 242 {
 243         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 244         key->u32[0] = inum;
 245         key->u32[1] = hash | (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
 246 }
 247
 248 /**
 249  * xent_key_init_flash - initialize on-flash extended attribute entry key.
 250  * @c: UBIFS file-system description object
 251  * @k: key to initialize
 252  * @inum: host inode number
 253  * @nm: extended attribute entry name and length
 254  */
 255 static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
 256                                        ino_t inum, const struct qstr *nm)
 257 {
 258         union ubifs_key *key = k;
 259         uint32_t hash = c->key_hash(nm->name, nm->len);
 260
 261         ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
 262         key->j32[0] = cpu_to_le32(inum);
 263         key->j32[1] = cpu_to_le32(hash |
 264                                   (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
 265         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 266 }
 267
 268 /**
 269  * lowest_xent_key - get the lowest possible extended attribute entry key.
 270  * @c: UBIFS file-system description object
 271  * @key: where to store the lowest key
 272  * @inum: host inode number
 273  */
 274 static inline void lowest_xent_key(const struct ubifs_info *c,
 275                                    union ubifs_key *key, ino_t inum)
 276 {
 277         key->u32[0] = inum;
 278         key->u32[1] = UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS;
 279 }
 280
 281 /**
 282  * data_key_init - initialize data key.
 283  * @c: UBIFS file-system description object
 284  * @key: key to initialize
 285  * @inum: inode number
 286  * @block: block number
 287  */
 288 static inline void data_key_init(const struct ubifs_info *c,
 289                                  union ubifs_key *key, ino_t inum,
 290                                  unsigned int block)
 291 {
 292         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 293         key->u32[0] = inum;
 294         key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS);
 295 }
 296
 297 /**
 298  * data_key_init_flash - initialize on-flash data key.
 299  * @c: UBIFS file-system description object
 300  * @k: key to initialize
 301  * @inum: inode number
 302  * @block: block number
 303  */
 304 static inline void data_key_init_flash(const struct ubifs_info *c, void *k,
 305                                        ino_t inum, unsigned int block)
 306 {
 307         union ubifs_key *key = k;
 308
 309         ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK));
 310         key->j32[0] = cpu_to_le32(inum);
 311         key->j32[1] = cpu_to_le32(block |
 312                                   (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS));
 313         memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 314 }
 315
 316 /**
 317  * trun_key_init - initialize truncation node key.
 318  * @c: UBIFS file-system description object
 319  * @key: key to initialize
 320  * @inum: inode number
 321  *
 322  * Note, UBIFS does not have truncation keys on the media and this function is
 323  * only used for purposes of replay.
 324  */
 325 static inline void trun_key_init(const struct ubifs_info *c,
 326                                  union ubifs_key *key, ino_t inum)
 327 {
 328         key->u32[0] = inum;
 329         key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
 330 }
 331
 332 /**
 333  * key_type - get key type.
 334  * @c: UBIFS file-system description object
 335  * @key: key to get type of
 336  */
 337 static inline int key_type(const struct ubifs_info *c,
 338                            const union ubifs_key *key)
 339 {
 340         return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 341 }
 342
 343 /**
 344  * key_type_flash - get type of a on-flash formatted key.
 345  * @c: UBIFS file-system description object
 346  * @k: key to get type of
 347  */
 348 static inline int key_type_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[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 353 }
 354
 355 /**
 356  * key_inum - fetch inode number from key.
 357  * @c: UBIFS file-system description object
 358  * @k: key to fetch inode number from
 359  */
 360 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 361 {
 362         const union ubifs_key *key = k;
 363
 364         return key->u32[0];
 365 }
 366
 367 /**
 368  * key_inum_flash - fetch inode number from an on-flash formatted key.
 369  * @c: UBIFS file-system description object
 370  * @k: key to fetch inode number from
 371  */
 372 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 373 {
 374         const union ubifs_key *key = k;
 375
 376         return le32_to_cpu(key->j32[0]);
 377 }
 378
 379 /**
 380  * key_hash - get directory entry hash.
 381  * @c: UBIFS file-system description object
 382  * @key: the key to get hash from
 383  */
 384 static inline uint32_t key_hash(const struct ubifs_info *c,
 385                                 const union ubifs_key *key)
 386 {
 387         return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 388 }
 389
 390 /**
 391  * key_hash_flash - get directory entry hash from an on-flash formatted key.
 392  * @c: UBIFS file-system description object
 393  * @k: the key to get hash from
 394  */
 395 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 396 {
 397         const union ubifs_key *key = k;
 398
 399         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 400 }
 401
 402 /**
 403  * key_block - get data block number.
 404  * @c: UBIFS file-system description object
 405  * @key: the key to get the block number from
 406  */
 407 static inline unsigned int key_block(const struct ubifs_info *c,
 408                                      const union ubifs_key *key)
 409 {
 410         return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 411 }
 412
 413 /**
 414  * key_block_flash - get data block number from an on-flash formatted key.
 415  * @c: UBIFS file-system description object
 416  * @k: the key to get the block number from
 417  */
 418 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 419                                            const void *k)
 420 {
 421         const union ubifs_key *key = k;
 422
 423         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 424 }
 425
 426 /**
 427  * key_read - transform a key to in-memory format.
 428  * @c: UBIFS file-system description object
 429  * @from: the key to transform
 430  * @to: the key to store the result
 431  */
 432 static inline void key_read(const struct ubifs_info *c, const void *from,
 433                             union ubifs_key *to)
 434 {
 435         const union ubifs_key *f = from;
 436
 437         to->u32[0] = le32_to_cpu(f->j32[0]);
 438         to->u32[1] = le32_to_cpu(f->j32[1]);
 439 }
 440
 441 /**
 442  * key_write - transform a key from in-memory format.
 443  * @c: UBIFS file-system description object
 444  * @from: the key to transform
 445  * @to: the key to store the result
 446  */
 447 static inline void key_write(const struct ubifs_info *c,
 448                              const union ubifs_key *from, void *to)
 449 {
 450         union ubifs_key *t = to;
 451
 452         t->j32[0] = cpu_to_le32(from->u32[0]);
 453         t->j32[1] = cpu_to_le32(from->u32[1]);
 454         memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 455 }
 456
 457 /**
 458  * key_write_idx - transform a key from in-memory format for the index.
 459  * @c: UBIFS file-system description object
 460  * @from: the key to transform
 461  * @to: the key to store the result
 462  */
 463 static inline void key_write_idx(const struct ubifs_info *c,
 464                                  const union ubifs_key *from, void *to)
 465 {
 466         union ubifs_key *t = to;
 467
 468         t->j32[0] = cpu_to_le32(from->u32[0]);
 469         t->j32[1] = cpu_to_le32(from->u32[1]);
 470 }
 471
 472 /**
 473  * key_copy - copy a key.
 474  * @c: UBIFS file-system description object
 475  * @from: the key to copy from
 476  * @to: the key to copy to
 477  */
 478 static inline void key_copy(const struct ubifs_info *c,
 479                             const union ubifs_key *from, union ubifs_key *to)
 480 {
 481         to->u64[0] = from->u64[0];
 482 }
 483
 484 /**
 485  * keys_cmp - compare keys.
 486  * @c: UBIFS file-system description object
 487  * @key1: the first key to compare
 488  * @key2: the second key to compare
 489  *
 490  * This function compares 2 keys and returns %-1 if @key1 is less than
 491  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
 492  */
 493 static inline int keys_cmp(const struct ubifs_info *c,
 494                            const union ubifs_key *key1,
 495                            const union ubifs_key *key2)
 496 {
 497         if (key1->u32[0] < key2->u32[0])
 498                 return -1;
 499         if (key1->u32[0] > key2->u32[0])
 500                 return 1;
 501         if (key1->u32[1] < key2->u32[1])
 502                 return -1;
 503         if (key1->u32[1] > key2->u32[1])
 504                 return 1;
 505
 506         return 0;
 507 }
 508
 509 /**
 510  * keys_eq - determine if keys are equivalent.
 511  * @c: UBIFS file-system description object
 512  * @key1: the first key to compare
 513  * @key2: the second key to compare
 514  *
 515  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
 516  * %0 if not.
 517  */
 518 static inline int keys_eq(const struct ubifs_info *c,
 519                           const union ubifs_key *key1,
 520                           const union ubifs_key *key2)
 521 {
 522         if (key1->u32[0] != key2->u32[0])
 523                 return 0;
 524         if (key1->u32[1] != key2->u32[1])
 525                 return 0;
 526         return 1;
 527 }
 528
 529 /**
 530  * is_hash_key - is a key vulnerable to hash collisions.
 531  * @c: UBIFS file-system description object
 532  * @key: key
 533  *
 534  * This function returns %1 if @key is a hashed key or %0 otherwise.
 535  */
 536 static inline int is_hash_key(const struct ubifs_info *c,
 537                               const union ubifs_key *key)
 538 {
 539         int type = key_type(c, key);
 540
 541         return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 542 }
 543
 544 /**
 545  * key_max_inode_size - get maximum file size allowed by current key format.
 546  * @c: UBIFS file-system description object
 547  */
 548 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 549 {
 550         switch (c->key_fmt) {
 551         case UBIFS_SIMPLE_KEY_FMT:
 552                 return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 553         default:
 554                 return 0;
 555         }
 556 }
 557 #endif /* !__UBIFS_KEY_H__ */