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

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

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/ts_bm.c b/lib/ts_bm.c
index 4a7fce72898ed40f13d58bca7cc1d97293d8bba0..9e66ee4020e9085a5cde0c84bf18516335c691da 100644 (file)
--- a/lib/ts_bm.c
+++ b/lib/ts_bm.c
@@ -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;
-       memcpy(bm->pattern, pattern, len);
-       compute_prefix_tbl(bm);
+       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, flags);
 
        return conf;
 }