Commit 2523c3fc authored by Joonwoo Park's avatar Joonwoo Park Committed by David S. Miller
Browse files

textsearch: ts_kmp: support case insensitive searching in Knuth-Morris-Pratt algorithm 



Add support for case insensitive search to Knuth-Morris-Pratt 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 3b76d081

lib/ts_kmp.c

+21 −8
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/module.h>

#include <linux/types.h>

#include <linux/string.h>

#include <linux/ctype.h>

#include <linux/textsearch.h>



struct ts_kmp
@@ -47,6 +48,7 @@ static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state) 
	struct ts_kmp *kmp = ts_config_priv(conf);

	unsigned int i, q = 0, text_len, consumed = state->offset;

	const u8 *text;

	const int icase = conf->flags & TS_IGNORECASE;



	for (;;) {

		text_len = conf->get_next_block(consumed, &text, conf, state);
@@ -55,9 +57,11 @@ static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state) 
			break;



		for (i = 0; i < text_len; i++) {

			while (q > 0 && kmp->pattern[q] != text[i])

			while (q > 0 && kmp->pattern[q]

			    != (icase ? toupper(text[i]) : text[i]))

				q = kmp->prefix_tbl[q - 1];

			if (kmp->pattern[q] == text[i])

			if (kmp->pattern[q]

			    == (icase ? toupper(text[i]) : text[i]))

				q++;

			if (unlikely(q == kmp->pattern_len)) {

				state->offset = consumed + i + 1;
@@ -72,24 +76,28 @@ static unsigned int kmp_find(struct ts_config *conf, struct ts_state *state) 
}



static inline void compute_prefix_tbl(const u8 *pattern, unsigned int len,

				      unsigned int *prefix_tbl)

				      unsigned int *prefix_tbl, int flags)

{

	unsigned int k, q;

	const u8 icase = flags & TS_IGNORECASE;



	for (k = 0, q = 1; q < len; q++) {

		while (k > 0 && pattern[k] != pattern[q])

		while (k > 0 && (icase ? toupper(pattern[k]) : pattern[k])

		    != (icase ? toupper(pattern[q]) : pattern[q]))

			k = prefix_tbl[k-1];

		if (pattern[k] == pattern[q])

		if ((icase ? toupper(pattern[k]) : pattern[k])

		    == (icase ? toupper(pattern[q]) : pattern[q]))

			k++;

		prefix_tbl[q] = k;

	}

}



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

				  gfp_t gfp_mask)

				  gfp_t gfp_mask, int flags)

{

	struct ts_config *conf;

	struct ts_kmp *kmp;

	int i;

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

	size_t priv_size = sizeof(*kmp) + len + prefix_tbl_len;
@@ -97,10 +105,15 @@ static struct ts_config *kmp_init(const void *pattern, unsigned int len, 
	if (IS_ERR(conf))

		return conf;



	conf->flags = flags;

	kmp = ts_config_priv(conf);

	kmp->pattern_len = len;

	compute_prefix_tbl(pattern, len, kmp->prefix_tbl);

	compute_prefix_tbl(pattern, len, kmp->prefix_tbl, flags);

	kmp->pattern = (u8 *) kmp->prefix_tbl + prefix_tbl_len;

	if (flags & TS_IGNORECASE)

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

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

	else

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



	return conf;