[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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

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

lib/Kconfig

@@ -63,5 +63,11 @@ config REED_SOLOMON_ENC16
 config REED_SOLOMON_DEC16
 	boolean
 
-endmenu
+config TEXTSEARCH
+	boolean "Textsearch infrastructure"
+	default y
+	help
+	  Say Y here if you want to provide a textsearch infrastructure
+	  to other subsystems.
 
+endmenu

lib/Makefile

@@ -36,6 +36,8 @@ obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/
 obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate/
 obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
 
+lib-$(CONFIG_TEXTSEARCH) += textsearch.o
+
 hostprogs-y	:= gen_crc32table
 clean-files	:= crc32table.h