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 */
48static 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 */
61static 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 */
81static 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 */
96static 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 */
109static 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 */
125static 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 */
138static 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 */
152static 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 */
171static 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 */
187static 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 */
206static 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 */
220static 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 */
238static 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 */
257static 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 */
271static 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 */
286static 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 */
301static 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 */
315static 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 */
327static 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 */
338static 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 */
350static 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 */
362static 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 */
374static 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 */
385static 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 */
397static 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 */
408static 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 */
422static 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 */
437static 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 */
453static 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 */
468static 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 */
483static 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 */
508static 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 */
526static 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 */
538static 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__ */
549