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1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * lib/ts_fsm.c A naive finite state machine text search approach
5 * Authors: Thomas Graf <tgraf@suug.ch>
7 * ==========================================================================
9 * A finite state machine consists of n states (struct ts_fsm_token)
10 * representing the pattern as a finite automaton. The data is read
11 * sequentially on an octet basis. Every state token specifies the number
12 * of recurrences and the type of value accepted which can be either a
13 * specific character or ctype based set of characters. The available
14 * type of recurrences include 1, (0|1), [0 n], and [1 n].
16 * The algorithm differs between strict/non-strict mode specifying
17 * whether the pattern has to start at the first octet. Strict mode
18 * is enabled by default and can be disabled by inserting
19 * TS_FSM_HEAD_IGNORE as the first token in the chain.
21 * The runtime performance of the algorithm should be around O(n),
22 * however while in strict mode the average runtime can be better.
25 #include <linux/module.h>
26 #include <linux/types.h>
27 #include <linux/string.h>
28 #include <linux/ctype.h>
29 #include <linux/textsearch.h>
30 #include <linux/textsearch_fsm.h>
35 struct ts_fsm_token tokens
[0];
38 /* other values derived from ctype.h */
39 #define _A 0x100 /* ascii */
40 #define _W 0x200 /* wildcard */
42 /* Map to _ctype flags and some magic numbers */
43 static const u16 token_map
[TS_FSM_TYPE_MAX
+1] = {
44 [TS_FSM_SPECIFIC
] = 0,
45 [TS_FSM_WILDCARD
] = _W
,
52 [TS_FSM_XDIGIT
] = _D
| _X
,
53 [TS_FSM_ALPHA
] = _U
| _L
,
54 [TS_FSM_ALNUM
] = _U
| _L
| _D
,
55 [TS_FSM_PRINT
] = _P
| _U
| _L
| _D
| _SP
,
56 [TS_FSM_GRAPH
] = _P
| _U
| _L
| _D
,
60 static const u16 token_lookup_tbl
[256] = {
61 _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, /* 0- 3 */
62 _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, /* 4- 7 */
63 _W
|_A
|_C
, _W
|_A
|_C
|_S
, _W
|_A
|_C
|_S
, _W
|_A
|_C
|_S
, /* 8- 11 */
64 _W
|_A
|_C
|_S
, _W
|_A
|_C
|_S
, _W
|_A
|_C
, _W
|_A
|_C
, /* 12- 15 */
65 _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, /* 16- 19 */
66 _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, /* 20- 23 */
67 _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, /* 24- 27 */
68 _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, _W
|_A
|_C
, /* 28- 31 */
69 _W
|_A
|_S
|_SP
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, /* 32- 35 */
70 _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, /* 36- 39 */
71 _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, /* 40- 43 */
72 _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, /* 44- 47 */
73 _W
|_A
|_D
, _W
|_A
|_D
, _W
|_A
|_D
, _W
|_A
|_D
, /* 48- 51 */
74 _W
|_A
|_D
, _W
|_A
|_D
, _W
|_A
|_D
, _W
|_A
|_D
, /* 52- 55 */
75 _W
|_A
|_D
, _W
|_A
|_D
, _W
|_A
|_P
, _W
|_A
|_P
, /* 56- 59 */
76 _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, /* 60- 63 */
77 _W
|_A
|_P
, _W
|_A
|_U
|_X
, _W
|_A
|_U
|_X
, _W
|_A
|_U
|_X
, /* 64- 67 */
78 _W
|_A
|_U
|_X
, _W
|_A
|_U
|_X
, _W
|_A
|_U
|_X
, _W
|_A
|_U
, /* 68- 71 */
79 _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, /* 72- 75 */
80 _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, /* 76- 79 */
81 _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, /* 80- 83 */
82 _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, /* 84- 87 */
83 _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_U
, _W
|_A
|_P
, /* 88- 91 */
84 _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, /* 92- 95 */
85 _W
|_A
|_P
, _W
|_A
|_L
|_X
, _W
|_A
|_L
|_X
, _W
|_A
|_L
|_X
, /* 96- 99 */
86 _W
|_A
|_L
|_X
, _W
|_A
|_L
|_X
, _W
|_A
|_L
|_X
, _W
|_A
|_L
, /* 100-103 */
87 _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, /* 104-107 */
88 _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, /* 108-111 */
89 _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, /* 112-115 */
90 _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, /* 116-119 */
91 _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_L
, _W
|_A
|_P
, /* 120-123 */
92 _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_P
, _W
|_A
|_C
, /* 124-127 */
93 _W
, _W
, _W
, _W
, /* 128-131 */
94 _W
, _W
, _W
, _W
, /* 132-135 */
95 _W
, _W
, _W
, _W
, /* 136-139 */
96 _W
, _W
, _W
, _W
, /* 140-143 */
97 _W
, _W
, _W
, _W
, /* 144-147 */
98 _W
, _W
, _W
, _W
, /* 148-151 */
99 _W
, _W
, _W
, _W
, /* 152-155 */
100 _W
, _W
, _W
, _W
, /* 156-159 */
101 _W
|_S
|_SP
, _W
|_P
, _W
|_P
, _W
|_P
, /* 160-163 */
102 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 164-167 */
103 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 168-171 */
104 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 172-175 */
105 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 176-179 */
106 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 180-183 */
107 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 184-187 */
108 _W
|_P
, _W
|_P
, _W
|_P
, _W
|_P
, /* 188-191 */
109 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_U
, /* 192-195 */
110 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_U
, /* 196-199 */
111 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_U
, /* 200-203 */
112 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_U
, /* 204-207 */
113 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_U
, /* 208-211 */
114 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_P
, /* 212-215 */
115 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_U
, /* 216-219 */
116 _W
|_U
, _W
|_U
, _W
|_U
, _W
|_L
, /* 220-223 */
117 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
, /* 224-227 */
118 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
, /* 228-231 */
119 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
, /* 232-235 */
120 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
, /* 236-239 */
121 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
, /* 240-243 */
122 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_P
, /* 244-247 */
123 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
, /* 248-251 */
124 _W
|_L
, _W
|_L
, _W
|_L
, _W
|_L
}; /* 252-255 */
126 static inline int match_token(struct ts_fsm_token
*t
, u8 d
)
129 return (token_lookup_tbl
[d
] & t
->type
) != 0;
131 return t
->value
== d
;
134 static unsigned int fsm_find(struct ts_config
*conf
, struct ts_state
*state
)
136 struct ts_fsm
*fsm
= ts_config_priv(conf
);
137 struct ts_fsm_token
*cur
= NULL
, *next
;
138 unsigned int match_start
, block_idx
= 0, tok_idx
;
139 unsigned block_len
= 0, strict
, consumed
= state
->offset
;
142 #define GET_NEXT_BLOCK() \
143 ({ consumed += block_idx; \
145 block_len = conf->get_next_block(consumed, &data, conf, state); })
147 #define TOKEN_MISMATCH() \
155 #define end_of_data() unlikely(block_idx >= block_len && !GET_NEXT_BLOCK())
160 strict
= fsm
->tokens
[0].recur
!= TS_FSM_HEAD_IGNORE
;
163 match_start
= consumed
+ block_idx
;
165 for (tok_idx
= 0; tok_idx
< fsm
->ntokens
; tok_idx
++) {
166 cur
= &fsm
->tokens
[tok_idx
];
168 if (likely(tok_idx
< (fsm
->ntokens
- 1)))
169 next
= &fsm
->tokens
[tok_idx
+ 1];
173 switch (cur
->recur
) {
178 if (!match_token(cur
, data
[block_idx
]))
184 !match_token(cur
, data
[block_idx
]))
192 if (!match_token(cur
, data
[block_idx
]))
205 while (!match_token(next
, data
[block_idx
])) {
206 if (!match_token(cur
, data
[block_idx
]))
215 * Optimization: Prefer small local loop over jumping
216 * back and forth until garbage at head is munched.
218 case TS_FSM_HEAD_IGNORE
:
222 while (!match_token(next
, data
[block_idx
])) {
224 * Special case, don't start over upon
225 * a mismatch, give the user the
226 * chance to specify the type of data
227 * allowed to be ignored.
229 if (!match_token(cur
, data
[block_idx
]))
237 match_start
= consumed
+ block_idx
;
251 state
->offset
= consumed
+ block_idx
;
255 static struct ts_config
*fsm_init(const void *pattern
, unsigned int len
,
256 gfp_t gfp_mask
, int flags
)
258 int i
, err
= -EINVAL
;
259 struct ts_config
*conf
;
261 struct ts_fsm_token
*tokens
= (struct ts_fsm_token
*) pattern
;
262 unsigned int ntokens
= len
/ sizeof(*tokens
);
263 size_t priv_size
= sizeof(*fsm
) + len
;
265 if (len
% sizeof(struct ts_fsm_token
) || ntokens
< 1)
268 if (flags
& TS_IGNORECASE
)
271 for (i
= 0; i
< ntokens
; i
++) {
272 struct ts_fsm_token
*t
= &tokens
[i
];
274 if (t
->type
> TS_FSM_TYPE_MAX
|| t
->recur
> TS_FSM_RECUR_MAX
)
277 if (t
->recur
== TS_FSM_HEAD_IGNORE
&&
278 (i
!= 0 || i
== (ntokens
- 1)))
282 conf
= alloc_ts_config(priv_size
, gfp_mask
);
287 fsm
= ts_config_priv(conf
);
288 fsm
->ntokens
= ntokens
;
289 memcpy(fsm
->tokens
, pattern
, len
);
291 for (i
= 0; i
< fsm
->ntokens
; i
++) {
292 struct ts_fsm_token
*t
= &fsm
->tokens
[i
];
293 t
->type
= token_map
[t
->type
];
302 static void *fsm_get_pattern(struct ts_config
*conf
)
304 struct ts_fsm
*fsm
= ts_config_priv(conf
);
308 static unsigned int fsm_get_pattern_len(struct ts_config
*conf
)
310 struct ts_fsm
*fsm
= ts_config_priv(conf
);
311 return fsm
->ntokens
* sizeof(struct ts_fsm_token
);
314 static struct ts_ops fsm_ops
= {
318 .get_pattern
= fsm_get_pattern
,
319 .get_pattern_len
= fsm_get_pattern_len
,
320 .owner
= THIS_MODULE
,
321 .list
= LIST_HEAD_INIT(fsm_ops
.list
)
324 static int __init
init_fsm(void)
326 return textsearch_register(&fsm_ops
);
329 static void __exit
exit_fsm(void)
331 textsearch_unregister(&fsm_ops
);
334 MODULE_LICENSE("GPL");
336 module_init(init_fsm
);
337 module_exit(exit_fsm
);