[LIB]: Naive finite state machine based textsearch
A finite state machine consists of n states (struct ts_fsm_token)
representing the pattern as a finite automation. The data is read
sequentially on a octet basis. Every state token specifies the number
of recurrences and the type of value accepted which can be either a
specific character or ctype based set of characters. The available
type of recurrences include 1, (0|1), [0 n], and [1 n].
The algorithm differs between strict/non-strict mode specyfing
whether the pattern has to start at the first octect. Strict mode
is enabled by default and can be disabled by inserting
TS_FSM_HEAD_IGNORE as the first token in the chain.
The runtime performance of the algorithm should be around O(n),
however while in strict mode the average runtime can be better.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/textsearch_fsm.h b/include/linux/textsearch_fsm.h
new file mode 100644
index 0000000..fdfa078
--- /dev/null
+++ b/include/linux/textsearch_fsm.h
@@ -0,0 +1,48 @@
+#ifndef __LINUX_TEXTSEARCH_FSM_H
+#define __LINUX_TEXTSEARCH_FSM_H
+
+#include <linux/types.h>
+
+enum {
+ TS_FSM_SPECIFIC, /* specific character */
+ TS_FSM_WILDCARD, /* any character */
+ TS_FSM_DIGIT, /* isdigit() */
+ TS_FSM_XDIGIT, /* isxdigit() */
+ TS_FSM_PRINT, /* isprint() */
+ TS_FSM_ALPHA, /* isalpha() */
+ TS_FSM_ALNUM, /* isalnum() */
+ TS_FSM_ASCII, /* isascii() */
+ TS_FSM_CNTRL, /* iscntrl() */
+ TS_FSM_GRAPH, /* isgraph() */
+ TS_FSM_LOWER, /* islower() */
+ TS_FSM_UPPER, /* isupper() */
+ TS_FSM_PUNCT, /* ispunct() */
+ TS_FSM_SPACE, /* isspace() */
+ __TS_FSM_TYPE_MAX,
+};
+#define TS_FSM_TYPE_MAX (__TS_FSM_TYPE_MAX - 1)
+
+enum {
+ TS_FSM_SINGLE, /* 1 occurrence */
+ TS_FSM_PERHAPS, /* 1 or 0 occurrence */
+ TS_FSM_ANY, /* 0..n occurrences */
+ TS_FSM_MULTI, /* 1..n occurrences */
+ TS_FSM_HEAD_IGNORE, /* 0..n ignored occurrences at head */
+ __TS_FSM_RECUR_MAX,
+};
+#define TS_FSM_RECUR_MAX (__TS_FSM_RECUR_MAX - 1)
+
+/**
+ * struct ts_fsm_token - state machine token (state)
+ * @type: type of token
+ * @recur: number of recurrences
+ * @value: character value for TS_FSM_SPECIFIC
+ */
+struct ts_fsm_token
+{
+ __u16 type;
+ __u8 recur;
+ __u8 value;
+};
+
+#endif