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[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  */
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  */
textsearch_next(struct ts_config * conf,struct ts_state * state)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  */
textsearch_find(struct ts_config * conf,struct ts_state * state)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  */
textsearch_get_pattern(struct ts_config * conf)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  */
textsearch_get_pattern_len(struct ts_config * conf)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 
alloc_ts_config(size_t payload,gfp_t gfp_mask)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 
ts_config_priv(struct ts_config * conf)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
180