linux/include/linux/textsearch.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __LINUX_TEXTSEARCH_H
   3#define __LINUX_TEXTSEARCH_H
   4
   5#include <linux/types.h>
   6#include <linux/list.h>
   7#include <linux/kernel.h>
   8#include <linux/err.h>
   9#include <linux/slab.h>
  10
  11struct module;
  12
  13struct ts_config;
  14
  15#define TS_AUTOLOAD     1 /* Automatically load textsearch modules when needed */
  16#define TS_IGNORECASE   2 /* Searches string case insensitively */
  17
  18/**
  19 * struct ts_state - search state
  20 * @offset: offset for next match
  21 * @cb: control buffer, for persistent variables of get_next_block()
  22 */
  23struct ts_state
  24{
  25        unsigned int            offset;
  26        char                    cb[48];
  27};
  28
  29/**
  30 * struct ts_ops - search module operations
  31 * @name: name of search algorithm
  32 * @init: initialization function to prepare a search
  33 * @find: find the next occurrence of the pattern
  34 * @destroy: destroy algorithm specific parts of a search configuration
  35 * @get_pattern: return head of pattern
  36 * @get_pattern_len: return length of pattern
  37 * @owner: module reference to algorithm
  38 */
  39struct ts_ops
  40{
  41        const char              *name;
  42        struct ts_config *      (*init)(const void *, unsigned int, gfp_t, int);
  43        unsigned int            (*find)(struct ts_config *,
  44                                        struct ts_state *);
  45        void                    (*destroy)(struct ts_config *);
  46        void *                  (*get_pattern)(struct ts_config *);
  47        unsigned int            (*get_pattern_len)(struct ts_config *);
  48        struct module           *owner;
  49        struct list_head        list;
  50};
  51
  52/**
  53 * struct ts_config - search configuration
  54 * @ops: operations of chosen algorithm
  55 * @flags: flags
  56 * @get_next_block: callback to fetch the next block to search in
  57 * @finish: callback to finalize a search
  58 */
  59struct ts_config
  60{
  61        struct ts_ops           *ops;
  62        int                     flags;
  63
  64        /**
  65         * @get_next_block: fetch next block of data
  66         * @consumed: number of bytes consumed by the caller
  67         * @dst: destination buffer
  68         * @conf: search configuration
  69         * @state: search state
  70         *
  71         * Called repeatedly until 0 is returned. Must assign the
  72         * head of the next block of data to &*dst and return the length
  73         * of the block or 0 if at the end. consumed == 0 indicates
  74         * a new search. May store/read persistent values in state->cb.
  75         */
  76        unsigned int            (*get_next_block)(unsigned int consumed,
  77                                                  const u8 **dst,
  78                                                  struct ts_config *conf,
  79                                                  struct ts_state *state);
  80
  81        /**
  82         * @finish: finalize/clean a series of get_next_block() calls
  83         * @conf: search configuration
  84         * @state: search state
  85         *
  86         * Called after the last use of get_next_block(), may be used
  87         * to cleanup any leftovers.
  88         */
  89        void                    (*finish)(struct ts_config *conf,
  90                                          struct ts_state *state);
  91};
  92
  93/**
  94 * textsearch_next - continue searching for a pattern
  95 * @conf: search configuration
  96 * @state: search state
  97 *
  98 * Continues a search looking for more occurrences of the pattern.
  99 * textsearch_find() must be called to find the first occurrence
 100 * in order to reset the state.
 101 *
 102 * Returns the position of the next occurrence of the pattern or
 103 * UINT_MAX if not match was found.
 104 */ 
 105static inline unsigned int textsearch_next(struct ts_config *conf,
 106                                           struct ts_state *state)
 107{
 108        unsigned int ret = conf->ops->find(conf, state);
 109
 110        if (conf->finish)
 111                conf->finish(conf, state);
 112
 113        return ret;
 114}
 115
 116/**
 117 * textsearch_find - start searching for a pattern
 118 * @conf: search configuration
 119 * @state: search state
 120 *
 121 * Returns the position of first occurrence of the pattern or
 122 * UINT_MAX if no match was found.
 123 */ 
 124static inline unsigned int textsearch_find(struct ts_config *conf,
 125                                           struct ts_state *state)
 126{
 127        state->offset = 0;
 128        return textsearch_next(conf, state);
 129}
 130
 131/**
 132 * textsearch_get_pattern - return head of the pattern
 133 * @conf: search configuration
 134 */
 135static inline void *textsearch_get_pattern(struct ts_config *conf)
 136{
 137        return conf->ops->get_pattern(conf);
 138}
 139
 140/**
 141 * textsearch_get_pattern_len - return length of the pattern
 142 * @conf: search configuration
 143 */
 144static inline unsigned int textsearch_get_pattern_len(struct ts_config *conf)
 145{
 146        return conf->ops->get_pattern_len(conf);
 147}
 148
 149extern int textsearch_register(struct ts_ops *);
 150extern int textsearch_unregister(struct ts_ops *);
 151extern struct ts_config *textsearch_prepare(const char *, const void *,
 152                                            unsigned int, gfp_t, int);
 153extern void textsearch_destroy(struct ts_config *conf);
 154extern unsigned int textsearch_find_continuous(struct ts_config *,
 155                                               struct ts_state *,
 156                                               const void *, unsigned int);
 157
 158
 159#define TS_PRIV_ALIGNTO 8
 160#define TS_PRIV_ALIGN(len) (((len) + TS_PRIV_ALIGNTO-1) & ~(TS_PRIV_ALIGNTO-1))
 161
 162static inline struct ts_config *alloc_ts_config(size_t payload,
 163                                                gfp_t gfp_mask)
 164{
 165        struct ts_config *conf;
 166
 167        conf = kzalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask);
 168        if (conf == NULL)
 169                return ERR_PTR(-ENOMEM);
 170
 171        return conf;
 172}
 173
 174static inline void *ts_config_priv(struct ts_config *conf)
 175{
 176        return ((u8 *) conf + TS_PRIV_ALIGN(sizeof(struct ts_config)));
 177}
 178
 179#endif
 180
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