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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 | // SPDX-License-Identifier: GPL-2.0-or-later /* * lib/ts_fsm.c A naive finite state machine text search approach * * Authors: Thomas Graf <tgraf@suug.ch> * * ========================================================================== * * A finite state machine consists of n states (struct ts_fsm_token) * representing the pattern as a finite automaton. The data is read * sequentially on an octet basis. Every state token specifies the number * of recurrences and the type of value accepted which can be either a * specific character or ctype based set of characters. The available * type of recurrences include 1, (0|1), [0 n], and [1 n]. * * The algorithm differs between strict/non-strict mode specifying * whether the pattern has to start at the first octet. Strict mode * is enabled by default and can be disabled by inserting * TS_FSM_HEAD_IGNORE as the first token in the chain. * * The runtime performance of the algorithm should be around O(n), * however while in strict mode the average runtime can be better. */ #include <linux/module.h> #include <linux/types.h> #include <linux/string.h> #include <linux/ctype.h> #include <linux/textsearch.h> #include <linux/textsearch_fsm.h> struct ts_fsm { unsigned int ntokens; struct ts_fsm_token tokens[0]; }; /* other values derived from ctype.h */ #define _A 0x100 /* ascii */ #define _W 0x200 /* wildcard */ /* Map to _ctype flags and some magic numbers */ static const u16 token_map[TS_FSM_TYPE_MAX+1] = { [TS_FSM_SPECIFIC] = 0, [TS_FSM_WILDCARD] = _W, [TS_FSM_CNTRL] = _C, [TS_FSM_LOWER] = _L, [TS_FSM_UPPER] = _U, [TS_FSM_PUNCT] = _P, [TS_FSM_SPACE] = _S, [TS_FSM_DIGIT] = _D, [TS_FSM_XDIGIT] = _D | _X, [TS_FSM_ALPHA] = _U | _L, [TS_FSM_ALNUM] = _U | _L | _D, [TS_FSM_PRINT] = _P | _U | _L | _D | _SP, [TS_FSM_GRAPH] = _P | _U | _L | _D, [TS_FSM_ASCII] = _A, }; static const u16 token_lookup_tbl[256] = { _W|_A|_C, _W|_A|_C, _W|_A|_C, _W|_A|_C, /* 0- 3 */ _W|_A|_C, _W|_A|_C, _W|_A|_C, _W|_A|_C, /* 4- 7 */ _W|_A|_C, _W|_A|_C|_S, _W|_A|_C|_S, _W|_A|_C|_S, /* 8- 11 */ _W|_A|_C|_S, _W|_A|_C|_S, _W|_A|_C, _W|_A|_C, /* 12- 15 */ _W|_A|_C, _W|_A|_C, _W|_A|_C, _W|_A|_C, /* 16- 19 */ _W|_A|_C, _W|_A|_C, _W|_A|_C, _W|_A|_C, /* 20- 23 */ _W|_A|_C, _W|_A|_C, _W|_A|_C, _W|_A|_C, /* 24- 27 */ _W|_A|_C, _W|_A|_C, _W|_A|_C, _W|_A|_C, /* 28- 31 */ _W|_A|_S|_SP, _W|_A|_P, _W|_A|_P, _W|_A|_P, /* 32- 35 */ _W|_A|_P, _W|_A|_P, _W|_A|_P, _W|_A|_P, /* 36- 39 */ _W|_A|_P, _W|_A|_P, _W|_A|_P, _W|_A|_P, /* 40- 43 */ _W|_A|_P, _W|_A|_P, _W|_A|_P, _W|_A|_P, /* 44- 47 */ _W|_A|_D, _W|_A|_D, _W|_A|_D, _W|_A|_D, /* 48- 51 */ _W|_A|_D, _W|_A|_D, _W|_A|_D, _W|_A|_D, /* 52- 55 */ _W|_A|_D, _W|_A|_D, _W|_A|_P, _W|_A|_P, /* 56- 59 */ _W|_A|_P, _W|_A|_P, _W|_A|_P, _W|_A|_P, /* 60- 63 */ _W|_A|_P, _W|_A|_U|_X, _W|_A|_U|_X, _W|_A|_U|_X, /* 64- 67 */ _W|_A|_U|_X, _W|_A|_U|_X, _W|_A|_U|_X, _W|_A|_U, /* 68- 71 */ _W|_A|_U, _W|_A|_U, _W|_A|_U, _W|_A|_U, /* 72- 75 */ _W|_A|_U, _W|_A|_U, _W|_A|_U, _W|_A|_U, /* 76- 79 */ _W|_A|_U, _W|_A|_U, _W|_A|_U, _W|_A|_U, /* 80- 83 */ _W|_A|_U, _W|_A|_U, _W|_A|_U, _W|_A|_U, /* 84- 87 */ _W|_A|_U, _W|_A|_U, _W|_A|_U, _W|_A|_P, /* 88- 91 */ _W|_A|_P, _W|_A|_P, _W|_A|_P, _W|_A|_P, /* 92- 95 */ _W|_A|_P, _W|_A|_L|_X, _W|_A|_L|_X, _W|_A|_L|_X, /* 96- 99 */ _W|_A|_L|_X, _W|_A|_L|_X, _W|_A|_L|_X, _W|_A|_L, /* 100-103 */ _W|_A|_L, _W|_A|_L, _W|_A|_L, _W|_A|_L, /* 104-107 */ _W|_A|_L, _W|_A|_L, _W|_A|_L, _W|_A|_L, /* 108-111 */ _W|_A|_L, _W|_A|_L, _W|_A|_L, _W|_A|_L, /* 112-115 */ _W|_A|_L, _W|_A|_L, _W|_A|_L, _W|_A|_L, /* 116-119 */ _W|_A|_L, _W|_A|_L, _W|_A|_L, _W|_A|_P, /* 120-123 */ _W|_A|_P, _W|_A|_P, _W|_A|_P, _W|_A|_C, /* 124-127 */ _W, _W, _W, _W, /* 128-131 */ _W, _W, _W, _W, /* 132-135 */ _W, _W, _W, _W, /* 136-139 */ _W, _W, _W, _W, /* 140-143 */ _W, _W, _W, _W, /* 144-147 */ _W, _W, _W, _W, /* 148-151 */ _W, _W, _W, _W, /* 152-155 */ _W, _W, _W, _W, /* 156-159 */ _W|_S|_SP, _W|_P, _W|_P, _W|_P, /* 160-163 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 164-167 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 168-171 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 172-175 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 176-179 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 180-183 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 184-187 */ _W|_P, _W|_P, _W|_P, _W|_P, /* 188-191 */ _W|_U, _W|_U, _W|_U, _W|_U, /* 192-195 */ _W|_U, _W|_U, _W|_U, _W|_U, /* 196-199 */ _W|_U, _W|_U, _W|_U, _W|_U, /* 200-203 */ _W|_U, _W|_U, _W|_U, _W|_U, /* 204-207 */ _W|_U, _W|_U, _W|_U, _W|_U, /* 208-211 */ _W|_U, _W|_U, _W|_U, _W|_P, /* 212-215 */ _W|_U, _W|_U, _W|_U, _W|_U, /* 216-219 */ _W|_U, _W|_U, _W|_U, _W|_L, /* 220-223 */ _W|_L, _W|_L, _W|_L, _W|_L, /* 224-227 */ _W|_L, _W|_L, _W|_L, _W|_L, /* 228-231 */ _W|_L, _W|_L, _W|_L, _W|_L, /* 232-235 */ _W|_L, _W|_L, _W|_L, _W|_L, /* 236-239 */ _W|_L, _W|_L, _W|_L, _W|_L, /* 240-243 */ _W|_L, _W|_L, _W|_L, _W|_P, /* 244-247 */ _W|_L, _W|_L, _W|_L, _W|_L, /* 248-251 */ _W|_L, _W|_L, _W|_L, _W|_L}; /* 252-255 */ static inline int match_token(struct ts_fsm_token *t, u8 d) { if (t->type) return (token_lookup_tbl[d] & t->type) != 0; else return t->value == d; } static unsigned int fsm_find(struct ts_config *conf, struct ts_state *state) { struct ts_fsm *fsm = ts_config_priv(conf); struct ts_fsm_token *cur = NULL, *next; unsigned int match_start, block_idx = 0, tok_idx; unsigned block_len = 0, strict, consumed = state->offset; const u8 *data; #define GET_NEXT_BLOCK() \ ({ consumed += block_idx; \ block_idx = 0; \ block_len = conf->get_next_block(consumed, &data, conf, state); }) #define TOKEN_MISMATCH() \ do { \ if (strict) \ goto no_match; \ block_idx++; \ goto startover; \ } while(0) #define end_of_data() unlikely(block_idx >= block_len && !GET_NEXT_BLOCK()) if (end_of_data()) goto no_match; strict = fsm->tokens[0].recur != TS_FSM_HEAD_IGNORE; startover: match_start = consumed + block_idx; for (tok_idx = 0; tok_idx < fsm->ntokens; tok_idx++) { cur = &fsm->tokens[tok_idx]; if (likely(tok_idx < (fsm->ntokens - 1))) next = &fsm->tokens[tok_idx + 1]; else next = NULL; switch (cur->recur) { case TS_FSM_SINGLE: if (end_of_data()) goto no_match; if (!match_token(cur, data[block_idx])) TOKEN_MISMATCH(); break; case TS_FSM_PERHAPS: if (end_of_data() || !match_token(cur, data[block_idx])) continue; break; case TS_FSM_MULTI: if (end_of_data()) goto no_match; if (!match_token(cur, data[block_idx])) TOKEN_MISMATCH(); block_idx++; /* fall through */ case TS_FSM_ANY: if (next == NULL) goto found_match; if (end_of_data()) continue; while (!match_token(next, data[block_idx])) { if (!match_token(cur, data[block_idx])) TOKEN_MISMATCH(); block_idx++; if (end_of_data()) goto no_match; } continue; /* * Optimization: Prefer small local loop over jumping * back and forth until garbage at head is munched. */ case TS_FSM_HEAD_IGNORE: if (end_of_data()) continue; while (!match_token(next, data[block_idx])) { /* * Special case, don't start over upon * a mismatch, give the user the * chance to specify the type of data * allowed to be ignored. */ if (!match_token(cur, data[block_idx])) goto no_match; block_idx++; if (end_of_data()) goto no_match; } match_start = consumed + block_idx; continue; } block_idx++; } if (end_of_data()) goto found_match; no_match: return UINT_MAX; found_match: state->offset = consumed + block_idx; return match_start; } static struct ts_config *fsm_init(const void *pattern, unsigned int len, gfp_t gfp_mask, int flags) { int i, err = -EINVAL; struct ts_config *conf; struct ts_fsm *fsm; struct ts_fsm_token *tokens = (struct ts_fsm_token *) pattern; unsigned int ntokens = len / sizeof(*tokens); size_t priv_size = sizeof(*fsm) + len; if (len % sizeof(struct ts_fsm_token) || ntokens < 1) goto errout; if (flags & TS_IGNORECASE) goto errout; for (i = 0; i < ntokens; i++) { struct ts_fsm_token *t = &tokens[i]; if (t->type > TS_FSM_TYPE_MAX || t->recur > TS_FSM_RECUR_MAX) goto errout; if (t->recur == TS_FSM_HEAD_IGNORE && (i != 0 || i == (ntokens - 1))) goto errout; } conf = alloc_ts_config(priv_size, gfp_mask); if (IS_ERR(conf)) return conf; conf->flags = flags; fsm = ts_config_priv(conf); fsm->ntokens = ntokens; memcpy(fsm->tokens, pattern, len); for (i = 0; i < fsm->ntokens; i++) { struct ts_fsm_token *t = &fsm->tokens[i]; t->type = token_map[t->type]; } return conf; errout: return ERR_PTR(err); } static void *fsm_get_pattern(struct ts_config *conf) { struct ts_fsm *fsm = ts_config_priv(conf); return fsm->tokens; } static unsigned int fsm_get_pattern_len(struct ts_config *conf) { struct ts_fsm *fsm = ts_config_priv(conf); return fsm->ntokens * sizeof(struct ts_fsm_token); } static struct ts_ops fsm_ops = { .name = "fsm", .find = fsm_find, .init = fsm_init, .get_pattern = fsm_get_pattern, .get_pattern_len = fsm_get_pattern_len, .owner = THIS_MODULE, .list = LIST_HEAD_INIT(fsm_ops.list) }; static int __init init_fsm(void) { return textsearch_register(&fsm_ops); } static void __exit exit_fsm(void) { textsearch_unregister(&fsm_ops); } MODULE_LICENSE("GPL"); module_init(init_fsm); module_exit(exit_fsm); |