include/linux/textsearch.h

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