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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339// 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[];};
/* 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++; fallthrough;
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_DESCRIPTION("naive finite state machine text search");MODULE_LICENSE("GPL");
module_init(init_fsm);module_exit(exit_fsm);