v4.19.13 snapshot.
diff --git a/lib/ts_kmp.c b/lib/ts_kmp.c
new file mode 100644
index 0000000..ffbe66c
--- /dev/null
+++ b/lib/ts_kmp.c
@@ -0,0 +1,157 @@
+/*
+ * lib/ts_kmp.c Knuth-Morris-Pratt text search implementation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors: Thomas Graf <tgraf@suug.ch>
+ *
+ * ==========================================================================
+ *
+ * Implements a linear-time string-matching algorithm due to Knuth,
+ * Morris, and Pratt [1]. Their algorithm avoids the explicit
+ * computation of the transition function DELTA altogether. Its
+ * matching time is O(n), for n being length(text), using just an
+ * auxiliary function PI[1..m], for m being length(pattern),
+ * precomputed from the pattern in time O(m). The array PI allows
+ * the transition function DELTA to be computed efficiently
+ * "on the fly" as needed. Roughly speaking, for any state
+ * "q" = 0,1,...,m and any character "a" in SIGMA, the value
+ * PI["q"] contains the information that is independent of "a" and
+ * is needed to compute DELTA("q", "a") [2]. Since the array PI
+ * has only m entries, whereas DELTA has O(m|SIGMA|) entries, we
+ * save a factor of |SIGMA| in the preprocessing time by computing
+ * PI rather than DELTA.
+ *
+ * [1] Cormen, Leiserson, Rivest, Stein
+ * Introdcution to Algorithms, 2nd Edition, MIT Press
+ * [2] See finite automaton theory
+ */
+
+#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);