include/linux/textsearch.h

   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
  11 struct module;
  12
  13 struct 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  */
  23 struct ts_state
  24 {
  25         unsigned int            offset;
  26         char                    cb[40];
  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  */
  39 struct 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  */
  59 struct 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  */
 105 static 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  */
 124 static 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  */
 135 static 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  */
 144 static inline unsigned int textsearch_get_pattern_len(struct ts_config *conf)
 145 {
 146         return conf->ops->get_pattern_len(conf);
 147 }
 148
 149 extern int textsearch_register(struct ts_ops *);
 150 extern int textsearch_unregister(struct ts_ops *);
 151 extern struct ts_config *textsearch_prepare(const char *, const void *,
 152                                             unsigned int, gfp_t, int);
 153 extern void textsearch_destroy(struct ts_config *conf);
 154 extern 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
 162 static 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
 174 static 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