/*
   * 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;
  
  	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(const struct ubifs_info *c,
  				union ubifs_key *key, ino_t inum)
  {
  	key->u32[0] = inum;
  	key->u32[1] = UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS;
  }
  
  /**
   * ino_key_init_flash - initialize on-flash inode key.
   * @c: UBIFS file-system description object
   * @k: key to initialize
   * @inum: inode number
   */
  static inline void ino_key_init_flash(const struct ubifs_info *c, void *k,
  				      ino_t inum)
  {
  	union ubifs_key *key = k;
  
  	key->j32[0] = cpu_to_le32(inum);
  	key->j32[1] = cpu_to_le32(UBIFS_INO_KEY << UBIFS_S_KEY_BLOCK_BITS);
  	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
  }
  
  /**
   * lowest_ino_key - get the lowest possible inode key.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   * @inum: inode number
   */
  static inline void lowest_ino_key(const struct ubifs_info *c,
  				union ubifs_key *key, ino_t inum)
  {
  	key->u32[0] = inum;
  	key->u32[1] = 0;
  }
  
  /**
   * highest_ino_key - get the highest possible inode key.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   * @inum: inode number
   */
  static inline void highest_ino_key(const struct ubifs_info *c,
  				union ubifs_key *key, ino_t inum)
  {
  	key->u32[0] = inum;
  	key->u32[1] = 0xffffffff;
  }
  
  /**
   * 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);
  }
  
  /**
   * dent_key_init_hash - initialize directory entry key without re-calculating
   *                      hash function.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   * @inum: parent inode number
   * @hash: direntry name hash
   */
  static inline void dent_key_init_hash(const struct ubifs_info *c,
  				      union ubifs_key *key, ino_t inum,
  				      uint32_t hash)
  {
  	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
  	key->u32[0] = inum;
  	key->u32[1] = hash | (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS);
  }
  
  /**
   * dent_key_init_flash - initialize on-flash directory entry key.
   * @c: UBIFS file-system description object
   * @k: key to initialize
   * @inum: parent inode number
   * @nm: direntry name and length
   */
  static inline void dent_key_init_flash(const struct ubifs_info *c, void *k,
  				       ino_t inum, const struct qstr *nm)
  {
  	union ubifs_key *key = k;
  	uint32_t hash = c->key_hash(nm->name, nm->len);
  
  	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
  	key->j32[0] = cpu_to_le32(inum);
  	key->j32[1] = cpu_to_le32(hash |
  				  (UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS));
  	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
  }
  
  /**
   * lowest_dent_key - get the lowest possible directory entry key.
   * @c: UBIFS file-system description object
   * @key: where to store the lowest key
   * @inum: parent inode number
   */
  static inline void lowest_dent_key(const struct ubifs_info *c,
  				   union ubifs_key *key, ino_t inum)
  {
  	key->u32[0] = inum;
  	key->u32[1] = UBIFS_DENT_KEY << UBIFS_S_KEY_HASH_BITS;
  }
  
  /**
   * xent_key_init - initialize extended attribute entry key.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   * @inum: host inode number
   * @nm: extended attribute entry name and length
   */
  static inline void xent_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_XENT_KEY << UBIFS_S_KEY_HASH_BITS);
  }
  
  /**
   * xent_key_init_flash - initialize on-flash extended attribute entry key.
   * @c: UBIFS file-system description object
   * @k: key to initialize
   * @inum: host inode number
   * @nm: extended attribute entry name and length
   */
  static inline void xent_key_init_flash(const struct ubifs_info *c, void *k,
  				       ino_t inum, const struct qstr *nm)
  {
  	union ubifs_key *key = k;
  	uint32_t hash = c->key_hash(nm->name, nm->len);
  
  	ubifs_assert(!(hash & ~UBIFS_S_KEY_HASH_MASK));
  	key->j32[0] = cpu_to_le32(inum);
  	key->j32[1] = cpu_to_le32(hash |
  				  (UBIFS_XENT_KEY << UBIFS_S_KEY_HASH_BITS));
  	memset(k + 8, 0, UBIFS_MAX_KEY_LEN - 8);
  }
  
  /**
   * lowest_xent_key - get the lowest possible extended attribute entry key.
   * @c: UBIFS file-system description object
   * @key: where to store the lowest key
   * @inum: host inode number
   */
  static inline void lowest_xent_key(const struct ubifs_info *c,
  				   union ubifs_key *key, ino_t inum)
  {
  	key->u32[0] = inum;
  	key->u32[1] = UBIFS_XENT_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(const struct ubifs_info *c,
  				 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);
  }
  
  /**
   * highest_data_key - get the highest possible data key for an inode.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   * @inum: inode number
   */
  static inline void highest_data_key(const struct ubifs_info *c,
  				   union ubifs_key *key, ino_t inum)
  {
  	data_key_init(c, key, inum, UBIFS_S_KEY_BLOCK_MASK);
  }
  
  /**
   * trun_key_init - initialize truncation node key.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   * @inum: inode number
   *
   * Note, UBIFS does not have truncation keys on the media and this function is
   * only used for purposes of replay.
   */
  static inline void trun_key_init(const struct ubifs_info *c,
  				 union ubifs_key *key, ino_t inum)
  {
  	key->u32[0] = inum;
  	key->u32[1] = UBIFS_TRUN_KEY << UBIFS_S_KEY_BLOCK_BITS;
  }
  
  /**
   * invalid_key_init - initialize invalid node key.
   * @c: UBIFS file-system description object
   * @key: key to initialize
   *
   * This is a helper function which marks a @key object as invalid.
   */
  static inline void invalid_key_init(const struct ubifs_info *c,
  				    union ubifs_key *key)
  {
  	key->u32[0] = 0xDEADBEAF;
  	key->u32[1] = UBIFS_INVALID_KEY;
  }
  
  /**
   * key_type - get key type.
   * @c: UBIFS file-system description object
   * @key: key to get type of
   */
  static inline int key_type(const struct ubifs_info *c,
  			   const union ubifs_key *key)
  {
  	return key->u32[1] >> UBIFS_S_KEY_BLOCK_BITS;
  }
  
  /**
   * key_type_flash - get type of a on-flash formatted key.
   * @c: UBIFS file-system description object
   * @k: key to get type of
   */
  static inline int key_type_flash(const struct ubifs_info *c, const void *k)
  {
  	const union ubifs_key *key = k;
  
  	return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
  }
  
  /**
   * key_inum - fetch inode number from key.
   * @c: UBIFS file-system description object
   * @k: key to fetch inode number from
   */
  static inline ino_t key_inum(const struct ubifs_info *c, const void *k)
  {
  	const union ubifs_key *key = k;
  
  	return key->u32[0];
  }
  
  /**
   * key_inum_flash - fetch inode number from an on-flash formatted key.
   * @c: UBIFS file-system description object
   * @k: key to fetch inode number from
   */
  static inline ino_t key_inum_flash(const struct ubifs_info *c, const void *k)
  {
  	const union ubifs_key *key = k;
  
  	return le32_to_cpu(key->j32[0]);
  }
  
  /**
   * key_hash - get directory entry hash.
   * @c: UBIFS file-system description object
   * @key: the key to get hash from
   */
  static inline uint32_t key_hash(const struct ubifs_info *c,
  				const union ubifs_key *key)
  {
  	return key->u32[1] & UBIFS_S_KEY_HASH_MASK;
  }
  
  /**
   * key_hash_flash - get directory entry hash from an on-flash formatted key.
   * @c: UBIFS file-system description object
   * @k: the key to get hash from
   */
  static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k)
  {
  	const union ubifs_key *key = k;
  
  	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_HASH_MASK;
  }
  
  /**
   * key_block - get data block number.
   * @c: UBIFS file-system description object
   * @key: the key to get the block number from
   */
  static inline unsigned int key_block(const struct ubifs_info *c,
  				     const union ubifs_key *key)
  {
  	return key->u32[1] & UBIFS_S_KEY_BLOCK_MASK;
  }
  
  /**
   * key_block_flash - get data block number from an on-flash formatted key.
   * @c: UBIFS file-system description object
   * @k: the key to get the block number from
   */
  static inline unsigned int key_block_flash(const struct ubifs_info *c,
  					   const void *k)
  {
  	const union ubifs_key *key = k;
  
  	return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
  }
  
  /**
   * key_read - transform a key to 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_read(const struct ubifs_info *c, const void *from,
  			    union ubifs_key *to)
  {
  	const union ubifs_key *f = from;
  
  	to->u32[0] = le32_to_cpu(f->j32[0]);
  	to->u32[1] = le32_to_cpu(f->j32[1]);
  }
  
  /**
   * 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 struct ubifs_info *c,
  			     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 struct ubifs_info *c,
  				 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]);
  }
  
  /**
   * key_copy - copy a key.
   * @c: UBIFS file-system description object
   * @from: the key to copy from
   * @to: the key to copy to
   */
  static inline void key_copy(const struct ubifs_info *c,
  			    const union ubifs_key *from, union ubifs_key *to)
  {
  	to->u64[0] = from->u64[0];
  }
  
  /**
   * 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 struct ubifs_info *c,
  			   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;
  }
  
  /**
   * keys_eq - determine if keys are equivalent.
   * @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 equal to @key2 and
   * %0 if not.
   */
  static inline int keys_eq(const struct ubifs_info *c,
  			  const union ubifs_key *key1,
  			  const union ubifs_key *key2)
  {
  	if (key1->u32[0] != key2->u32[0])
  		return 0;
  	if (key1->u32[1] != key2->u32[1])
  		return 0;
  	return 1;
  }
  
  /**
   * is_hash_key - is a key vulnerable to hash collisions.
   * @c: UBIFS file-system description object
   * @key: key
   *
   * This function returns %1 if @key is a hashed key or %0 otherwise.
   */
  static inline int is_hash_key(const struct ubifs_info *c,
  			      const union ubifs_key *key)
  {
  	int type = key_type(c, key);
  
  	return type == UBIFS_DENT_KEY || type == UBIFS_XENT_KEY;
  }
  
  /**
   * key_max_inode_size - get maximum file size allowed by current key format.
   * @c: UBIFS file-system description object
   */
  static inline unsigned long long key_max_inode_size(const struct ubifs_info *c)
  {
  	switch (c->key_fmt) {
  	case UBIFS_SIMPLE_KEY_FMT:
  		return (1ULL << UBIFS_S_KEY_BLOCK_BITS) * UBIFS_BLOCK_SIZE;
  	default:
  		return 0;
  	}
  }
  
  #endif /* !__UBIFS_KEY_H__ */