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  * invalid_key_init - initialize invalid node key.
 310  * @c: UBIFS file-system description object
 311  * @key: key to initialize
 312  *
 313  * This is a helper function which marks a @key object as invalid.
 314  */
 315 static inline void invalid_key_init(const struct ubifs_info *c,
 316                                     union ubifs_key *key)
 317 {
 318         key->u32[0] = 0xDEADBEAF;
 319         key->u32[1] = UBIFS_INVALID_KEY;
 320 }
 321
 322 /**
 323  * key_type - get key type.
 324  * @c: UBIFS file-system description object
 325  * @key: key to get type of
 326  */
 327 static inline int key_type(const struct ubifs_info *c,
 328                            const union ubifs_key *key)
 329 {
 330         return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
 331 }
 332
 333 /**
 334  * key_type_flash - get type of a on-flash formatted key.
 335  * @c: UBIFS file-system description object
 336  * @k: key to get type of
 337  */
 338 static inline int key_type_flash(const struct ubifs_info *c, const void *k)
 339 {
 340         const union ubifs_key *key = k;
 341
 342         return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
 343 }
 344
 345 /**
 346  * key_inum - fetch inode number from key.
 347  * @c: UBIFS file-system description object
 348  * @k: key to fetch inode number from
 349  */
 350 static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
 351 {
 352         const union ubifs_key *key = k;
 353
 354         return key->u32[0];
 355 }
 356
 357 /**
 358  * key_inum_flash - fetch inode number from an on-flash formatted key.
 359  * @c: UBIFS file-system description object
 360  * @k: key to fetch inode number from
 361  */
 362 static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
 363 {
 364         const union ubifs_key *key = k;
 365
 366         return le32_to_cpu(key->j32[0]);
 367 }
 368
 369 /**
 370  * key_hash - get directory entry hash.
 371  * @c: UBIFS file-system description object
 372  * @key: the key to get hash from
 373  */
 374 static inline uint32_t key_hash(const struct ubifs_info *c,
 375                                 const union ubifs_key *key)
 376 {
 377         return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
 378 }
 379
 380 /**
 381  * key_hash_flash - get directory entry hash from an on-flash formatted key.
 382  * @c: UBIFS file-system description object
 383  * @k: the key to get hash from
 384  */
 385 static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
 386 {
 387         const union ubifs_key *key = k;
 388
 389         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
 390 }
 391
 392 /**
 393  * key_block - get data block number.
 394  * @c: UBIFS file-system description object
 395  * @key: the key to get the block number from
 396  */
 397 static inline unsigned int key_block(const struct ubifs_info *c,
 398                                      const union ubifs_key *key)
 399 {
 400         return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
 401 }
 402
 403 /**
 404  * key_block_flash - get data block number from an on-flash formatted key.
 405  * @c: UBIFS file-system description object
 406  * @k: the key to get the block number from
 407  */
 408 static inline unsigned int key_block_flash(const struct ubifs_info *c,
 409                                            const void *k)
 410 {
 411         const union ubifs_key *key = k;
 412
 413         return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
 414 }
 415
 416 /**
 417  * key_read - transform a key to in-memory format.
 418  * @c: UBIFS file-system description object
 419  * @from: the key to transform
 420  * @to: the key to store the result
 421  */
 422 static inline void key_read(const struct ubifs_info *c, const void *from,
 423                             union ubifs_key *to)
 424 {
 425         const union ubifs_key *f = from;
 426
 427         to->u32[0] = le32_to_cpu(f->j32[0]);
 428         to->u32[1] = le32_to_cpu(f->j32[1]);
 429 }
 430
 431 /**
 432  * key_write - transform a key from in-memory format.
 433  * @c: UBIFS file-system description object
 434  * @from: the key to transform
 435  * @to: the key to store the result
 436  */
 437 static inline void key_write(const struct ubifs_info *c,
 438                              const union ubifs_key *from, void *to)
 439 {
 440         union ubifs_key *t = to;
 441
 442         t->j32[0] = cpu_to_le32(from->u32[0]);
 443         t->j32[1] = cpu_to_le32(from->u32[1]);
 444         memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8);
 445 }
 446
 447 /**
 448  * key_write_idx - transform a key from in-memory format for the index.
 449  * @c: UBIFS file-system description object
 450  * @from: the key to transform
 451  * @to: the key to store the result
 452  */
 453 static inline void key_write_idx(const struct ubifs_info *c,
 454                                  const union ubifs_key *from, void *to)
 455 {
 456         union ubifs_key *t = to;
 457
 458         t->j32[0] = cpu_to_le32(from->u32[0]);
 459         t->j32[1] = cpu_to_le32(from->u32[1]);
 460 }
 461
 462 /**
 463  * key_copy - copy a key.
 464  * @c: UBIFS file-system description object
 465  * @from: the key to copy from
 466  * @to: the key to copy to
 467  */
 468 static inline void key_copy(const struct ubifs_info *c,
 469                             const union ubifs_key *from, union ubifs_key *to)
 470 {
 471         to->u64[0] = from->u64[0];
 472 }
 473
 474 /**
 475  * keys_cmp - compare keys.
 476  * @c: UBIFS file-system description object
 477  * @key1: the first key to compare
 478  * @key2: the second key to compare
 479  *
 480  * This function compares 2 keys and returns %-1 if @key1 is less than
 481  * @key2, %0 if the keys are equivalent and %1 if @key1 is greater than @key2.
 482  */
 483 static inline int keys_cmp(const struct ubifs_info *c,
 484                            const union ubifs_key *key1,
 485                            const union ubifs_key *key2)
 486 {
 487         if (key1->u32[0] < key2->u32[0])
 488                 return -1;
 489         if (key1->u32[0] > key2->u32[0])
 490                 return 1;
 491         if (key1->u32[1] < key2->u32[1])
 492                 return -1;
 493         if (key1->u32[1] > key2->u32[1])
 494                 return 1;
 495
 496         return 0;
 497 }
 498
 499 /**
 500  * keys_eq - determine if keys are equivalent.
 501  * @c: UBIFS file-system description object
 502  * @key1: the first key to compare
 503  * @key2: the second key to compare
 504  *
 505  * This function compares 2 keys and returns %1 if @key1 is equal to @key2 and
 506  * %0 if not.
 507  */
 508 static inline int keys_eq(const struct ubifs_info *c,
 509                           const union ubifs_key *key1,
 510                           const union ubifs_key *key2)
 511 {
 512         if (key1->u32[0] != key2->u32[0])
 513                 return 0;
 514         if (key1->u32[1] != key2->u32[1])
 515                 return 0;
 516         return 1;
 517 }
 518
 519 /**
 520  * is_hash_key - is a key vulnerable to hash collisions.
 521  * @c: UBIFS file-system description object
 522  * @key: key
 523  *
 524  * This function returns %1 if @key is a hashed key or %0 otherwise.
 525  */
 526 static inline int is_hash_key(const struct ubifs_info *c,
 527                               const union ubifs_key *key)
 528 {
 529         int type = key_type(c, key);
 530
 531         return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
 532 }
 533
 534 /**
 535  * key_max_inode_size - get maximum file size allowed by current key format.
 536  * @c: UBIFS file-system description object
 537  */
 538 static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
 539 {
 540         switch (c->key_fmt) {
 541         case UBIFS_SIMPLE_KEY_FMT:
 542                 return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
 543         default:
 544                 return 0;
 545         }
 546 }
 547
 548 #endif /* !__UBIFS_KEY_H__ */