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Commit 3b76d081 authored by Joonwoo Park's avatar Joonwoo Park Committed by David S. Miller
Browse files

textsearch: ts_bm: support case insensitive searching in Boyer-Moore algorithm 



Add support for case insensitive search to Boyer-Moore algorithm.

Signed-off-by: default avatarJoonwoo Park <joonwpark81@gmail.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b9c79678

lib/ts_bm.c

+20 −6
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 
#include <linux/module.h>

#include <linux/types.h>

#include <linux/string.h>

#include <linux/ctype.h>

#include <linux/textsearch.h>



/* Alphabet size, use ASCII */
@@ -64,6 +65,7 @@ static unsigned int bm_find(struct ts_config *conf, struct ts_state *state) 
	unsigned int i, text_len, consumed = state->offset;

	const u8 *text;

	int shift = bm->patlen - 1, bs;

	const u8 icase = conf->flags & TS_IGNORECASE;



	for (;;) {

		text_len = conf->get_next_block(consumed, &text, conf, state);
@@ -75,7 +77,9 @@ static unsigned int bm_find(struct ts_config *conf, struct ts_state *state) 
			DEBUGP("Searching in position %d (%c)\n", 

				shift, text[shift]);

			for (i = 0; i < bm->patlen; i++) 

			     if (text[shift-i] != bm->pattern[bm->patlen-1-i])

				if ((icase ? toupper(text[shift-i])

				    : text[shift-i])

					!= bm->pattern[bm->patlen-1-i])

				     goto next;



			/* London calling... */
@@ -111,14 +115,18 @@ static int subpattern(u8 *pattern, int i, int j, int g) 
	return ret;

}



static void compute_prefix_tbl(struct ts_bm *bm)

static void compute_prefix_tbl(struct ts_bm *bm, int flags)

{

	int i, j, g;



	for (i = 0; i < ASIZE; i++)

		bm->bad_shift[i] = bm->patlen;

	for (i = 0; i < bm->patlen - 1; i++)

	for (i = 0; i < bm->patlen - 1; i++) {

		bm->bad_shift[bm->pattern[i]] = bm->patlen - 1 - i;

		if (flags & TS_IGNORECASE)

			bm->bad_shift[tolower(bm->pattern[i])]

			    = bm->patlen - 1 - i;

	}



	/* Compute the good shift array, used to match reocurrences 

	 * of a subpattern */
@@ -135,10 +143,11 @@ static void compute_prefix_tbl(struct ts_bm *bm) 
}



static struct ts_config *bm_init(const void *pattern, unsigned int len,

				 gfp_t gfp_mask)

				 gfp_t gfp_mask, int flags)

{

	struct ts_config *conf;

	struct ts_bm *bm;

	int i;

	unsigned int prefix_tbl_len = len * sizeof(unsigned int);

	size_t priv_size = sizeof(*bm) + len + prefix_tbl_len;
@@ -146,11 +155,16 @@ static struct ts_config *bm_init(const void *pattern, unsigned int len, 
	if (IS_ERR(conf))

		return conf;



	conf->flags = flags;

	bm = ts_config_priv(conf);

	bm->patlen = len;

	bm->pattern = (u8 *) bm->good_shift + prefix_tbl_len;

	if (flags & TS_IGNORECASE)

		for (i = 0; i < len; i++)

			bm->pattern[i] = toupper(((u8 *)pattern)[i]);

	else

		memcpy(bm->pattern, pattern, len);

	compute_prefix_tbl(bm);

	compute_prefix_tbl(bm, flags);



	return conf;

}