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