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
 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 * @list: list to search
 39 */
 40struct ts_ops
 41{
 42	const char		*name;
 43	struct ts_config *	(*init)(const void *, unsigned int, gfp_t, 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 * @flags: flags
 57 * @get_next_block: callback to fetch the next block to search in
 58 * @finish: callback to finalize a search
 59 */
 60struct ts_config
 61{
 62	struct ts_ops		*ops;
 63	int 			flags;
 64
 65	/**
 66	 * @get_next_block: fetch next block of data
 67	 * @consumed: number of bytes consumed by the caller
 68	 * @dst: destination buffer
 69	 * @conf: search configuration
 70	 * @state: search state
 71	 *
 72	 * Called repeatedly until 0 is returned. Must assign the
 73	 * head of the next block of data to &*dst and return the length
 74	 * of the block or 0 if at the end. consumed == 0 indicates
 75	 * a new search. May store/read persistent values in state->cb.
 76	 */
 77	unsigned int		(*get_next_block)(unsigned int consumed,
 78						  const u8 **dst,
 79						  struct ts_config *conf,
 80						  struct ts_state *state);
 81
 82	/**
 83	 * @finish: finalize/clean a series of get_next_block() calls
 84	 * @conf: search configuration
 85	 * @state: search state
 86	 *
 87	 * Called after the last use of get_next_block(), may be used
 88	 * to cleanup any leftovers.
 89	 */
 90	void			(*finish)(struct ts_config *conf,
 91					  struct ts_state *state);
 92};
 93
 94/**
 95 * textsearch_next - continue searching for a pattern
 96 * @conf: search configuration
 97 * @state: search state
 98 *
 99 * Continues a search looking for more occurrences of the pattern.
100 * textsearch_find() must be called to find the first occurrence
101 * in order to reset the state.
102 *
103 * Returns the position of the next occurrence of the pattern or
104 * UINT_MAX if not match was found.
105 */ 
106static inline unsigned int textsearch_next(struct ts_config *conf,
107					   struct ts_state *state)
108{
109	unsigned int ret = conf->ops->find(conf, state);
110
111	if (conf->finish)
112		conf->finish(conf, state);
113
114	return ret;
115}
116
117/**
118 * textsearch_find - start searching for a pattern
119 * @conf: search configuration
120 * @state: search state
121 *
122 * Returns the position of first occurrence of the pattern or
123 * UINT_MAX if no match was found.
124 */ 
125static inline unsigned int textsearch_find(struct ts_config *conf,
126					   struct ts_state *state)
127{
128	state->offset = 0;
129	return textsearch_next(conf, state);
130}
131
132/**
133 * textsearch_get_pattern - return head of the pattern
134 * @conf: search configuration
135 */
136static inline void *textsearch_get_pattern(struct ts_config *conf)
137{
138	return conf->ops->get_pattern(conf);
139}
140
141/**
142 * textsearch_get_pattern_len - return length of the pattern
143 * @conf: search configuration
144 */
145static inline unsigned int textsearch_get_pattern_len(struct ts_config *conf)
146{
147	return conf->ops->get_pattern_len(conf);
148}
149
150extern int textsearch_register(struct ts_ops *);
151extern int textsearch_unregister(struct ts_ops *);
152extern struct ts_config *textsearch_prepare(const char *, const void *,
153					    unsigned int, gfp_t, int);
154extern void textsearch_destroy(struct ts_config *conf);
155extern unsigned int textsearch_find_continuous(struct ts_config *,
156					       struct ts_state *,
157					       const void *, unsigned int);
158
159
160#define TS_PRIV_ALIGNTO	8
161#define TS_PRIV_ALIGN(len) (((len) + TS_PRIV_ALIGNTO-1) & ~(TS_PRIV_ALIGNTO-1))
162
163static inline struct ts_config *alloc_ts_config(size_t payload,
164						gfp_t gfp_mask)
165{
166	struct ts_config *conf;
167
168	conf = kzalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask);
169	if (conf == NULL)
170		return ERR_PTR(-ENOMEM);
171
172	return conf;
173}
174
175static inline void *ts_config_priv(struct ts_config *conf)
176{
177	return ((u8 *) conf + TS_PRIV_ALIGN(sizeof(struct ts_config)));
178}
179
180#endif