diff options
Diffstat (limited to 'lib/ts_bm.c')
| -rw-r--r-- | lib/ts_bm.c | 56 |
1 files changed, 36 insertions, 20 deletions
diff --git a/lib/ts_bm.c b/lib/ts_bm.c index 9e66ee4020e9..eed5967238c5 100644 --- a/lib/ts_bm.c +++ b/lib/ts_bm.c @@ -1,11 +1,7 @@ +// SPDX-License-Identifier: GPL-2.0-or-later /* * lib/ts_bm.c Boyer-Moore text search implementation * - * 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: Pablo Neira Ayuso <pablo@eurodev.net> * * ========================================================================== @@ -15,7 +11,7 @@ * [1] A Fast String Searching Algorithm, R.S. Boyer and Moore. * Communications of the Association for Computing Machinery, * 20(10), 1977, pp. 762-772. - * http://www.cs.utexas.edu/users/moore/publications/fstrpos.pdf + * https://www.cs.utexas.edu/users/moore/publications/fstrpos.pdf * * [2] Handbook of Exact String Matching Algorithms, Thierry Lecroq, 2004 * http://www-igm.univ-mlv.fr/~lecroq/string/string.pdf @@ -56,37 +52,56 @@ struct ts_bm u8 * pattern; unsigned int patlen; unsigned int bad_shift[ASIZE]; - unsigned int good_shift[0]; + unsigned int good_shift[]; }; +static unsigned int matchpat(const u8 *pattern, unsigned int patlen, + const u8 *text, bool icase) +{ + unsigned int i; + + for (i = 0; i < patlen; i++) { + u8 t = *(text-i); + + if (icase) + t = toupper(t); + + if (t != *(pattern-i)) + break; + } + + return i; +} + static unsigned int bm_find(struct ts_config *conf, struct ts_state *state) { struct ts_bm *bm = ts_config_priv(conf); unsigned int i, text_len, consumed = state->offset; const u8 *text; - int shift = bm->patlen - 1, bs; + int bs; const u8 icase = conf->flags & TS_IGNORECASE; for (;;) { + int shift = bm->patlen - 1; + text_len = conf->get_next_block(consumed, &text, conf, state); if (unlikely(text_len == 0)) break; while (shift < text_len) { - DEBUGP("Searching in position %d (%c)\n", - shift, text[shift]); - for (i = 0; i < bm->patlen; i++) - if ((icase ? toupper(text[shift-i]) - : text[shift-i]) - != bm->pattern[bm->patlen-1-i]) - goto next; - - /* London calling... */ - DEBUGP("found!\n"); - return consumed += (shift-(bm->patlen-1)); + DEBUGP("Searching in position %d (%c)\n", + shift, text[shift]); + + i = matchpat(&bm->pattern[bm->patlen-1], bm->patlen, + &text[shift], icase); + if (i == bm->patlen) { + /* London calling... */ + DEBUGP("found!\n"); + return consumed + (shift-(bm->patlen-1)); + } -next: bs = bm->bad_shift[text[shift-i]]; + bs = bm->bad_shift[text[shift-i]]; /* Now jumping to... */ shift = max_t(int, shift-i+bs, shift+bm->good_shift[i]); @@ -201,6 +216,7 @@ static void __exit exit_bm(void) textsearch_unregister(&bm_ops); } +MODULE_DESCRIPTION("Boyer-Moore text search implementation"); MODULE_LICENSE("GPL"); module_init(init_bm); |