[LIB]: Naive finite state machine based textsearch
A finite state machine consists of n states (struct ts_fsm_token) representing the pattern as a finite automation. The data is read sequentially on a 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 specyfing whether the pattern has to start at the first octect. 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. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Thomas Graf
David S. Miller
Родитель
df3fb93ad9
Коммит
6408f79cce
|
|
@ -0,0 +1,48 @@
|
|||
#ifndef __LINUX_TEXTSEARCH_FSM_H
|
||||
#define __LINUX_TEXTSEARCH_FSM_H
|
||||
|
||||
#include <linux/types.h>
|
||||
|
||||
enum {
|
||||
TS_FSM_SPECIFIC, /* specific character */
|
||||
TS_FSM_WILDCARD, /* any character */
|
||||
TS_FSM_DIGIT, /* isdigit() */
|
||||
TS_FSM_XDIGIT, /* isxdigit() */
|
||||
TS_FSM_PRINT, /* isprint() */
|
||||
TS_FSM_ALPHA, /* isalpha() */
|
||||
TS_FSM_ALNUM, /* isalnum() */
|
||||
TS_FSM_ASCII, /* isascii() */
|
||||
TS_FSM_CNTRL, /* iscntrl() */
|
||||
TS_FSM_GRAPH, /* isgraph() */
|
||||
TS_FSM_LOWER, /* islower() */
|
||||
TS_FSM_UPPER, /* isupper() */
|
||||
TS_FSM_PUNCT, /* ispunct() */
|
||||
TS_FSM_SPACE, /* isspace() */
|
||||
__TS_FSM_TYPE_MAX,
|
||||
};
|
||||
#define TS_FSM_TYPE_MAX (__TS_FSM_TYPE_MAX - 1)
|
||||
|
||||
enum {
|
||||
TS_FSM_SINGLE, /* 1 occurrence */
|
||||
TS_FSM_PERHAPS, /* 1 or 0 occurrence */
|
||||
TS_FSM_ANY, /* 0..n occurrences */
|
||||
TS_FSM_MULTI, /* 1..n occurrences */
|
||||
TS_FSM_HEAD_IGNORE, /* 0..n ignored occurrences at head */
|
||||
__TS_FSM_RECUR_MAX,
|
||||
};
|
||||
#define TS_FSM_RECUR_MAX (__TS_FSM_RECUR_MAX - 1)
|
||||
|
||||
/**
|
||||
* struct ts_fsm_token - state machine token (state)
|
||||
* @type: type of token
|
||||
* @recur: number of recurrences
|
||||
* @value: character value for TS_FSM_SPECIFIC
|
||||
*/
|
||||
struct ts_fsm_token
|
||||
{
|
||||
__u16 type;
|
||||
__u8 recur;
|
||||
__u8 value;
|
||||
};
|
||||
|
||||
#endif
|
||||
11
lib/Kconfig
11
lib/Kconfig
|
|
@ -80,4 +80,15 @@ config TEXTSEARCH_KMP
|
|||
To compile this code as a module, choose M here: the
|
||||
module will be called ts_kmp.
|
||||
|
||||
config TEXTSEARCH_FSM
|
||||
depends on TEXTSEARCH
|
||||
tristate "Finite state machine"
|
||||
help
|
||||
Say Y here if you want to be able to search text using a
|
||||
naive finite state machine approach implementing a subset
|
||||
of regular expressions.
|
||||
|
||||
To compile this code as a module, choose M here: the
|
||||
module will be called ts_fsm.
|
||||
|
||||
endmenu
|
||||
|
|
|
|||
|
|
@ -38,6 +38,7 @@ obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
|
|||
|
||||
lib-$(CONFIG_TEXTSEARCH) += textsearch.o
|
||||
obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o
|
||||
obj-$(CONFIG_TEXTSEARCH_FSM) += ts_fsm.o
|
||||
|
||||
hostprogs-y := gen_crc32table
|
||||
clean-files := crc32table.h
|
||||
|
|
|
|||
|
|
@ -0,0 +1,338 @@
|
|||
/*
|
||||
* lib/ts_fsm.c A naive finite state machine text search approach
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU General Public License
|
||||
* as published by the Free Software Foundation; either version
|
||||
* 2 of the License, or (at your option) any later version.
|
||||
*
|
||||
* Authors: Thomas Graf <tgraf@suug.ch>
|
||||
*
|
||||
* ==========================================================================
|
||||
*
|
||||
* A finite state machine consists of n states (struct ts_fsm_token)
|
||||
* representing the pattern as a finite automation. The data is read
|
||||
* sequentially on a 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 specyfing
|
||||
* whether the pattern has to start at the first octect. 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/config.h>
|
||||
#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 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 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,
|
||||
int gfp_mask)
|
||||
{
|
||||
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;
|
||||
|
||||
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;
|
||||
|
||||
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);
|
||||
Загрузка…
Ссылка в новой задаче