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kernel/linux-imx6_3.14.28/security/selinux/ss/hashtab.h 2.45 KB
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  /*
   * A hash table (hashtab) maintains associations between
   * key values and datum values.  The type of the key values
   * and the type of the datum values is arbitrary.  The
   * functions for hash computation and key comparison are
   * provided by the creator of the table.
   *
   * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
   */
  #ifndef _SS_HASHTAB_H_
  #define _SS_HASHTAB_H_
  
  #define HASHTAB_MAX_NODES	0xffffffff
  
  struct hashtab_node {
  	void *key;
  	void *datum;
  	struct hashtab_node *next;
  };
  
  struct hashtab {
  	struct hashtab_node **htable;	/* hash table */
  	u32 size;			/* number of slots in hash table */
  	u32 nel;			/* number of elements in hash table */
  	u32 (*hash_value)(struct hashtab *h, const void *key);
  					/* hash function */
  	int (*keycmp)(struct hashtab *h, const void *key1, const void *key2);
  					/* key comparison function */
  };
  
  struct hashtab_info {
  	u32 slots_used;
  	u32 max_chain_len;
  };
  
  /*
   * Creates a new hash table with the specified characteristics.
   *
   * Returns NULL if insufficent space is available or
   * the new hash table otherwise.
   */
  struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
  			       int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
  			       u32 size);
  
  /*
   * Inserts the specified (key, datum) pair into the specified hash table.
   *
   * Returns -ENOMEM on memory allocation error,
   * -EEXIST if there is already an entry with the same key,
   * -EINVAL for general errors or
    0 otherwise.
   */
  int hashtab_insert(struct hashtab *h, void *k, void *d);
  
  /*
   * Searches for the entry with the specified key in the hash table.
   *
   * Returns NULL if no entry has the specified key or
   * the datum of the entry otherwise.
   */
  void *hashtab_search(struct hashtab *h, const void *k);
  
  /*
   * Destroys the specified hash table.
   */
  void hashtab_destroy(struct hashtab *h);
  
  /*
   * Applies the specified apply function to (key,datum,args)
   * for each entry in the specified hash table.
   *
   * The order in which the function is applied to the entries
   * is dependent upon the internal structure of the hash table.
   *
   * If apply returns a non-zero status, then hashtab_map will cease
   * iterating through the hash table and will propagate the error
   * return to its caller.
   */
  int hashtab_map(struct hashtab *h,
  		int (*apply)(void *k, void *d, void *args),
  		void *args);
  
  /* Fill info with some hash table statistics */
  void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
  
  #endif	/* _SS_HASHTAB_H */