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

1 files changed, 21 insertions, 8 deletions

diff --git a/lib/ts_kmp.c b/lib/ts_kmp.c
index 3ced628cab4b..632f783e65f1 100644
--- a/lib/ts_kmp.c
+++ b/lib/ts_kmp.c
@@ -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;
 
@@ -97,11 +105,16 @@ 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;
-        memcpy(kmp->pattern, pattern, 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;
 }