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- #include <linux/module.h>
- #include <linux/types.h>
- #include <linux/string.h>
- #include <linux/ctype.h>
- #include <linux/textsearch.h>
- struct ts_kmp
- {
- u8 * pattern;
- unsigned int pattern_len;
- unsigned int prefix_tbl[0];
- };
- 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);
- if (unlikely(text_len == 0))
- break;
- for (i = 0; i < text_len; i++) {
- while (q > 0 && kmp->pattern[q]
- != (icase ? toupper(text[i]) : text[i]))
- q = kmp->prefix_tbl[q - 1];
- if (kmp->pattern[q]
- == (icase ? toupper(text[i]) : text[i]))
- q++;
- if (unlikely(q == kmp->pattern_len)) {
- state->offset = consumed + i + 1;
- return state->offset - kmp->pattern_len;
- }
- }
- consumed += text_len;
- }
- return UINT_MAX;
- }
- static inline void compute_prefix_tbl(const u8 *pattern, unsigned int len,
- 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 && (icase ? toupper(pattern[k]) : pattern[k])
- != (icase ? toupper(pattern[q]) : pattern[q]))
- k = prefix_tbl[k-1];
- 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, 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;
- conf = alloc_ts_config(priv_size, gfp_mask);
- 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, 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;
- }
- static void *kmp_get_pattern(struct ts_config *conf)
- {
- struct ts_kmp *kmp = ts_config_priv(conf);
- return kmp->pattern;
- }
- static unsigned int kmp_get_pattern_len(struct ts_config *conf)
- {
- struct ts_kmp *kmp = ts_config_priv(conf);
- return kmp->pattern_len;
- }
- static struct ts_ops kmp_ops = {
- .name = "kmp",
- .find = kmp_find,
- .init = kmp_init,
- .get_pattern = kmp_get_pattern,
- .get_pattern_len = kmp_get_pattern_len,
- .owner = THIS_MODULE,
- .list = LIST_HEAD_INIT(kmp_ops.list)
- };
- static int __init init_kmp(void)
- {
- return textsearch_register(&kmp_ops);
- }
- static void __exit exit_kmp(void)
- {
- textsearch_unregister(&kmp_ops);
- }
- MODULE_LICENSE("GPL");
- module_init(init_kmp);
- module_exit(exit_kmp);
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