cregit-Linux how code gets into the kernel

Release 4.9 lib/ts_fsm.c

Directory: lib
/*
 * 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 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; }

Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf43100.00%1100.00%
Total43100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf408100.00%1100.00%
Total408100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf25292.99%133.33%
joonwoo parkjoonwoo park186.64%133.33%
al viroal viro10.37%133.33%
Total271100.00%3100.00%


static void *fsm_get_pattern(struct ts_config *conf) { struct ts_fsm *fsm = ts_config_priv(conf); return fsm->tokens; }

Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf27100.00%1100.00%
Total27100.00%1100.00%


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); }

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PersonTokensPropCommitsCommitProp
thomas grafthomas graf33100.00%1100.00%
Total33100.00%1100.00%

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); }

Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf16100.00%1100.00%
Total16100.00%1100.00%


static void __exit exit_fsm(void) { textsearch_unregister(&fsm_ops); }

Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf15100.00%1100.00%
Total15100.00%1100.00%

MODULE_LICENSE("GPL"); module_init(init_fsm); module_exit(exit_fsm);

Overall Contributors

PersonTokensPropCommitsCommitProp
thomas grafthomas graf234499.07%125.00%
joonwoo parkjoonwoo park180.76%125.00%
andreas mohrandreas mohr30.13%125.00%
al viroal viro10.04%125.00%
Total2366100.00%4100.00%
Directory: lib