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Diffstat (limited to 'ubifs-utils/mkfs.ubifs/key.h')
| -rw-r--r-- | ubifs-utils/mkfs.ubifs/key.h | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/ubifs-utils/mkfs.ubifs/key.h b/ubifs-utils/mkfs.ubifs/key.h new file mode 100644 index 0000000..d3a02d4 --- /dev/null +++ b/ubifs-utils/mkfs.ubifs/key.h @@ -0,0 +1,189 @@ +/* + * This file is part of UBIFS. + * + * Copyright (C) 2006-2008 Nokia Corporation. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program; if not, write to the Free Software Foundation, Inc., 51 + * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + * + * Authors: Artem Bityutskiy (Битюцкий Артём) + * Adrian Hunter + */ + +/* + * This header contains various key-related definitions and helper function. + * UBIFS allows several key schemes, so we access key fields only via these + * helpers. At the moment only one key scheme is supported. + * + * Simple key scheme + * ~~~~~~~~~~~~~~~~~ + * + * Keys are 64-bits long. First 32-bits are inode number (parent inode number + * in case of direntry key). Next 3 bits are node type. The last 29 bits are + * 4KiB offset in case of inode node, and direntry hash in case of a direntry + * node. We use "r5" hash borrowed from reiserfs. + */ + +#ifndef __UBIFS_KEY_H__ +#define __UBIFS_KEY_H__ + +/** + * key_mask_hash - mask a valid hash value. + * @val: value to be masked + * + * We use hash values as offset in directories, so values %0 and %1 are + * reserved for "." and "..". %2 is reserved for "end of readdir" marker. This + * function makes sure the reserved values are not used. + */ +static inline uint32_t key_mask_hash(uint32_t hash) +{ + hash &= UBIFS_S_KEY_HASH_MASK; + if (unlikely(hash <= 2)) + hash += 3; + return hash; +} + +/** + * key_r5_hash - R5 hash function (borrowed from reiserfs). + * @s: direntry name + * @len: name length + */ +static inline uint32_t key_r5_hash(const char *s, int len) +{ + uint32_t a = 0; + const signed char *str = (const signed char *)s; + + len = len; + while (*str) { + a += *str << 4; + a += *str >> 4; + a *= 11; + str++; + } + + return key_mask_hash(a); +} + +/** + * key_test_hash - testing hash function. + * @str: direntry name + * @len: name length + */ +static inline uint32_t key_test_hash(const char *str, int len) +{ + uint32_t a = 0; + + len = min_t(uint32_t, len, 4); + memcpy(&a, str, len); + return key_mask_hash(a); +} + +/** + * ino_key_init - initialize inode key. + * @c: UBIFS file-system description object + * @key: key to initialize + * @inum: inode number + */ +static inline void ino_key_init(union ubifs_key *key, ino_t inum) +{ + key->u32[0] = inum; + key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS; +} + +/** + * dent_key_init - initialize directory entry key. + * @c: UBIFS file-system description object + * @key: key to initialize + * @inum: parent inode number + * @nm: direntry name and length + */ +static inline void dent_key_init(const struct ubifs_info *c, + union ubifs_key *key, ino_t inum, + const struct qstr *nm) +{ + uint32_t hash = c->key_hash(nm->name, nm->len); + + ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK)); + key->u32[0] = inum; + key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS); +} + +/** + * data_key_init - initialize data key. + * @c: UBIFS file-system description object + * @key: key to initialize + * @inum: inode number + * @block: block number + */ +static inline void data_key_init(union ubifs_key *key, ino_t inum, + unsigned int block) +{ + ubifs_assert(!(block & ~UBIFS_S_KEY_BLOCK_MASK)); + key->u32[0] = inum; + key->u32[1] = block | (UBIFS_DATA_KEY << UBIFS_S_KEY_BLOCK_BITS); +} + +/** + * key_write - transform a key from in-memory format. + * @c: UBIFS file-system description object + * @from: the key to transform + * @to: the key to store the result + */ +static inline void key_write(const union ubifs_key *from, void *to) +{ + union ubifs_key *t = to; + + t->j32[0] = cpu_to_le32(from->u32[0]); + t->j32[1] = cpu_to_le32(from->u32[1]); + memset(to + 8, 0, UBIFS_MAX_KEY_LEN - 8); +} + +/** + * key_write_idx - transform a key from in-memory format for the index. + * @c: UBIFS file-system description object + * @from: the key to transform + * @to: the key to store the result + */ +static inline void key_write_idx(const union ubifs_key *from, void *to) +{ + union ubifs_key *t = to; + + t->j32[0] = cpu_to_le32(from->u32[0]); + t->j32[1] = cpu_to_le32(from->u32[1]); +} + +/** + * keys_cmp - compare keys. + * @c: UBIFS file-system description object + * @key1: the first key to compare + * @key2: the second key to compare + * + * This function compares 2 keys and returns %-1 if @key1 is less than + * @key2, 0 if the keys are equivalent and %1 if @key1 is greater than @key2. + */ +static inline int keys_cmp(const union ubifs_key *key1, + const union ubifs_key *key2) +{ + if (key1->u32[0] < key2->u32[0]) + return -1; + if (key1->u32[0] > key2->u32[0]) + return 1; + if (key1->u32[1] < key2->u32[1]) + return -1; + if (key1->u32[1] > key2->u32[1]) + return 1; + + return 0; +} + +#endif /* !__UBIFS_KEY_H__ */ |