[LIB]: Textsearch infrastructure.

The textsearch infrastructure provides text searching
facitilies for both linear and non-linear data.
Individual search algorithms are implemented in modules
and chosen by the user.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 180 insertions, 0 deletions

diff --git a/include/linux/textsearch.h b/include/linux/textsearch.h
new file mode 100644
index 000000000000..941f45ac117a
--- /dev/null
+++ b/include/linux/textsearch.h
@@ -0,0 +1,180 @@
+#ifndef __LINUX_TEXTSEARCH_H
+#define __LINUX_TEXTSEARCH_H
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/err.h>
+
+struct ts_config;
+
+/**
+ * TS_AUTOLOAD - Automatically load textsearch modules when needed
+ */
+#define TS_AUTOLOAD     1
+
+/**
+ * struct ts_state - search state
+ * @offset: offset for next match
+ * @cb: control buffer, for persistant variables of get_next_block()
+ */
+struct ts_state
+{
+        unsigned int            offset;
+        char                    cb[40];
+};
+
+/**
+ * struct ts_ops - search module operations
+ * @name: name of search algorithm
+ * @init: initialization function to prepare a search
+ * @find: find the next occurrence of the pattern
+ * @destroy: destroy algorithm specific parts of a search configuration
+ * @get_pattern: return head of pattern
+ * @get_pattern_len: return length of pattern
+ * @owner: module reference to algorithm
+ */
+struct ts_ops
+{
+        const char              *name;
+        struct ts_config *      (*init)(const void *, unsigned int, int);
+        unsigned int            (*find)(struct ts_config *,
+                                        struct ts_state *);
+        void                    (*destroy)(struct ts_config *);
+        void *                  (*get_pattern)(struct ts_config *);
+        unsigned int            (*get_pattern_len)(struct ts_config *);
+        struct module           *owner;
+        struct list_head        list;
+};
+
+/**
+ * struct ts_config - search configuration
+ * @ops: operations of chosen algorithm
+ * @get_next_block: callback to fetch the next block to search in
+ * @finish: callback to finalize a search
+ */
+struct ts_config
+{
+        struct ts_ops           *ops;
+
+        /**
+         * get_next_block - fetch next block of data
+         * @consumed: number of bytes consumed by the caller
+         * @dst: destination buffer
+         * @conf: search configuration
+         * @state: search state
+         *
+         * Called repeatedly until 0 is returned. Must assign the
+         * head of the next block of data to &*dst and return the length
+         * of the block or 0 if at the end. consumed == 0 indicates
+         * a new search. May store/read persistant values in state->cb.
+         */
+        unsigned int            (*get_next_block)(unsigned int consumed,
+                                                  const u8 **dst,
+                                                  struct ts_config *conf,
+                                                  struct ts_state *state);
+
+        /**
+         * finish - finalize/clean a series of get_next_block() calls
+         * @conf: search configuration
+         * @state: search state
+         *
+         * Called after the last use of get_next_block(), may be used
+         * to cleanup any leftovers.
+         */
+        void                    (*finish)(struct ts_config *conf,
+                                          struct ts_state *state);
+};
+
+/**
+ * textsearch_next - continue searching for a pattern
+ * @conf: search configuration
+ * @state: search state
+ *
+ * Continues a search looking for more occurrences of the pattern.
+ * textsearch_find() must be called to find the first occurrence
+ * in order to reset the state.
+ *
+ * Returns the position of the next occurrence of the pattern or
+ * UINT_MAX if not match was found.
+ */ 
+static inline unsigned int textsearch_next(struct ts_config *conf,
+                                           struct ts_state *state)
+{
+        unsigned int ret = conf->ops->find(conf, state);
+
+        if (conf->finish)
+                conf->finish(conf, state);
+
+        return ret;
+}
+
+/**
+ * textsearch_find - start searching for a pattern
+ * @conf: search configuration
+ * @state: search state
+ *
+ * Returns the position of first occurrence of the pattern or
+ * UINT_MAX if no match was found.
+ */ 
+static inline unsigned int textsearch_find(struct ts_config *conf,
+                                           struct ts_state *state)
+{
+        state->offset = 0;
+        return textsearch_next(conf, state);
+}
+
+/**
+ * textsearch_get_pattern - return head of the pattern
+ * @conf: search configuration
+ */
+static inline void *textsearch_get_pattern(struct ts_config *conf)
+{
+        return conf->ops->get_pattern(conf);
+}
+
+/**
+ * textsearch_get_pattern_len - return length of the pattern
+ * @conf: search configuration
+ */
+static inline unsigned int textsearch_get_pattern_len(struct ts_config *conf)
+{
+        return conf->ops->get_pattern_len(conf);
+}
+
+extern int textsearch_register(struct ts_ops *);
+extern int textsearch_unregister(struct ts_ops *);
+extern struct ts_config *textsearch_prepare(const char *, const void *,
+                                            unsigned int, int, int);
+extern void textsearch_destroy(struct ts_config *conf);
+extern unsigned int textsearch_find_continuous(struct ts_config *,
+                                               struct ts_state *,
+                                               const void *, unsigned int);
+
+
+#define TS_PRIV_ALIGNTO 8
+#define TS_PRIV_ALIGN(len) (((len) + TS_PRIV_ALIGNTO-1) & ~(TS_PRIV_ALIGNTO-1))
+
+static inline struct ts_config *alloc_ts_config(size_t payload, int gfp_mask)
+{
+        struct ts_config *conf;
+
+        conf = kmalloc(TS_PRIV_ALIGN(sizeof(*conf)) + payload, gfp_mask);
+        if (conf == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        memset(conf, 0, TS_PRIV_ALIGN(sizeof(*conf)) + payload);
+        return conf;
+}
+
+static inline void *ts_config_priv(struct ts_config *conf)
+{
+        return ((u8 *) conf + TS_PRIV_ALIGN(sizeof(struct ts_config)));
+}
+
+#endif /* __KERNEL__ */
+
+#endif