cregit-Linux how code gets into the kernel

Release 4.7 lib/textsearch.c

Directory: lib
/*
 * lib/textsearch.c     Generic text search interface
 *
 *              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>
 *              Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * ==========================================================================
 *
 * INTRODUCTION
 *
 *   The textsearch infrastructure provides text searching facilities for
 *   both linear and non-linear data. Individual search algorithms are
 *   implemented in modules and chosen by the user.
 *
 * ARCHITECTURE
 *
 *      User
 *     +----------------+
 *     |        finish()|<--------------(6)-----------------+
 *     |get_next_block()|<--------------(5)---------------+ |
 *     |                |                     Algorithm   | |
 *     |                |                    +------------------------------+
 *     |                |                    |  init()   find()   destroy() |
 *     |                |                    +------------------------------+
 *     |                |       Core API           ^       ^          ^
 *     |                |      +---------------+  (2)     (4)        (8)
 *     |             (1)|----->| prepare()     |---+       |          |
 *     |             (3)|----->| find()/next() |-----------+          |
 *     |             (7)|----->| destroy()     |----------------------+
 *     +----------------+      +---------------+
 *  
 *   (1) User configures a search by calling _prepare() specifying the
 *       search parameters such as the pattern and algorithm name.
 *   (2) Core requests the algorithm to allocate and initialize a search
 *       configuration according to the specified parameters.
 *   (3) User starts the search(es) by calling _find() or _next() to
 *       fetch subsequent occurrences. A state variable is provided
 *       to the algorithm to store persistent variables.
 *   (4) Core eventually resets the search offset and forwards the find()
 *       request to the algorithm.
 *   (5) Algorithm calls get_next_block() provided by the user continuously
 *       to fetch the data to be searched in block by block.
 *   (6) Algorithm invokes finish() after the last call to get_next_block
 *       to clean up any leftovers from get_next_block. (Optional)
 *   (7) User destroys the configuration by calling _destroy().
 *   (8) Core notifies the algorithm to destroy algorithm specific
 *       allocations. (Optional)
 *
 * USAGE
 *
 *   Before a search can be performed, a configuration must be created
 *   by calling textsearch_prepare() specifying the searching algorithm,
 *   the pattern to look for and flags. As a flag, you can set TS_IGNORECASE
 *   to perform case insensitive matching. But it might slow down
 *   performance of algorithm, so you should use it at own your risk.
 *   The returned configuration may then be used for an arbitrary
 *   amount of times and even in parallel as long as a separate struct
 *   ts_state variable is provided to every instance.
 *
 *   The actual search is performed by either calling textsearch_find_-
 *   continuous() for linear data or by providing an own get_next_block()
 *   implementation and calling textsearch_find(). Both functions return
 *   the position of the first occurrence of the pattern or UINT_MAX if
 *   no match was found. Subsequent occurrences can be found by calling
 *   textsearch_next() regardless of the linearity of the data.
 *
 *   Once you're done using a configuration it must be given back via
 *   textsearch_destroy.
 *
 * EXAMPLE
 *
 *   int pos;
 *   struct ts_config *conf;
 *   struct ts_state state;
 *   const char *pattern = "chicken";
 *   const char *example = "We dance the funky chicken";
 *
 *   conf = textsearch_prepare("kmp", pattern, strlen(pattern),
 *                             GFP_KERNEL, TS_AUTOLOAD);
 *   if (IS_ERR(conf)) {
 *       err = PTR_ERR(conf);
 *       goto errout;
 *   }
 *
 *   pos = textsearch_find_continuous(conf, &state, example, strlen(example));
 *   if (pos != UINT_MAX)
 *       panic("Oh my god, dancing chickens at %d\n", pos);
 *
 *   textsearch_destroy(conf);
 * ==========================================================================
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/err.h>
#include <linux/textsearch.h>
#include <linux/slab.h>

static LIST_HEAD(ts_ops);
static DEFINE_SPINLOCK(ts_mod_lock);


static inline struct ts_ops *lookup_ts_algo(const char *name) { struct ts_ops *o; rcu_read_lock(); list_for_each_entry_rcu(o, &ts_ops, list) { if (!strcmp(name, o->name)) { if (!try_module_get(o->owner)) o = NULL; rcu_read_unlock(); return o; } } rcu_read_unlock(); return NULL; }

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thomas grafthomas graf72100.00%1100.00%
Total72100.00%1100.00%

/** * textsearch_register - register a textsearch module * @ops: operations lookup table * * This function must be called by textsearch modules to announce * their presence. The specified &@ops must have %name set to a * unique identifier and the callbacks find(), init(), get_pattern(), * and get_pattern_len() must be implemented. * * Returns 0 or -EEXISTS if another module has already registered * with same name. */
int textsearch_register(struct ts_ops *ops) { int err = -EEXIST; struct ts_ops *o; if (ops->name == NULL || ops->find == NULL || ops->init == NULL || ops->get_pattern == NULL || ops->get_pattern_len == NULL) return -EINVAL; spin_lock(&ts_mod_lock); list_for_each_entry(o, &ts_ops, list) { if (!strcmp(ops->name, o->name)) goto errout; } list_add_tail_rcu(&ops->list, &ts_ops); err = 0; errout: spin_unlock(&ts_mod_lock); return err; }

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thomas grafthomas graf116100.00%1100.00%
Total116100.00%1100.00%

EXPORT_SYMBOL(textsearch_register); /** * textsearch_unregister - unregister a textsearch module * @ops: operations lookup table * * This function must be called by textsearch modules to announce * their disappearance for examples when the module gets unloaded. * The &ops parameter must be the same as the one during the * registration. * * Returns 0 on success or -ENOENT if no matching textsearch * registration was found. */
int textsearch_unregister(struct ts_ops *ops) { int err = 0; struct ts_ops *o; spin_lock(&ts_mod_lock); list_for_each_entry(o, &ts_ops, list) { if (o == ops) { list_del_rcu(&o->list); goto out; } } err = -ENOENT; out: spin_unlock(&ts_mod_lock); return err; }

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thomas grafthomas graf71100.00%1100.00%
Total71100.00%1100.00%

EXPORT_SYMBOL(textsearch_unregister); struct ts_linear_state { unsigned int len; const void *data; };
static unsigned int get_linear_data(unsigned int consumed, const u8 **dst, struct ts_config *conf, struct ts_state *state) { struct ts_linear_state *st = (struct ts_linear_state *) state->cb; if (likely(consumed < st->len)) { *dst = st->data + consumed; return st->len - consumed; } return 0; }

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thomas grafthomas graf73100.00%1100.00%
Total73100.00%1100.00%

/** * textsearch_find_continuous - search a pattern in continuous/linear data * @conf: search configuration * @state: search state * @data: data to search in * @len: length of data * * A simplified version of textsearch_find() for continuous/linear data. * Call textsearch_next() to retrieve subsequent matches. * * Returns the position of first occurrence of the pattern or * %UINT_MAX if no occurrence was found. */
unsigned int textsearch_find_continuous(struct ts_config *conf, struct ts_state *state, const void *data, unsigned int len) { struct ts_linear_state *st = (struct ts_linear_state *) state->cb; conf->get_next_block = get_linear_data; st->data = data; st->len = len; return textsearch_find(conf, state); }

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thomas grafthomas graf65100.00%1100.00%
Total65100.00%1100.00%

EXPORT_SYMBOL(textsearch_find_continuous); /** * textsearch_prepare - Prepare a search * @algo: name of search algorithm * @pattern: pattern data * @len: length of pattern * @gfp_mask: allocation mask * @flags: search flags * * Looks up the search algorithm module and creates a new textsearch * configuration for the specified pattern. * * Note: The format of the pattern may not be compatible between * the various search algorithms. * * Returns a new textsearch configuration according to the specified * parameters or a ERR_PTR(). If a zero length pattern is passed, this * function returns EINVAL. */
struct ts_config *textsearch_prepare(const char *algo, const void *pattern, unsigned int len, gfp_t gfp_mask, int flags) { int err = -ENOENT; struct ts_config *conf; struct ts_ops *ops; if (len == 0) return ERR_PTR(-EINVAL); ops = lookup_ts_algo(algo); #ifdef CONFIG_MODULES /* * Why not always autoload you may ask. Some users are * in a situation where requesting a module may deadlock, * especially when the module is located on a NFS mount. */ if (ops == NULL && flags & TS_AUTOLOAD) { request_module("ts_%s", algo); ops = lookup_ts_algo(algo); } #endif if (ops == NULL) goto errout; conf = ops->init(pattern, len, gfp_mask, flags); if (IS_ERR(conf)) { err = PTR_ERR(conf); goto errout; } conf->ops = ops; return conf; errout: if (ops) module_put(ops->owner); return ERR_PTR(err); }

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PersonTokensPropCommitsCommitProp
thomas grafthomas graf14989.76%120.00%
pablo neira ayusopablo neira ayuso137.83%120.00%
joonwoo parkjoonwoo park21.20%120.00%
al viroal viro10.60%120.00%
johannes bergjohannes berg10.60%120.00%
Total166100.00%5100.00%

EXPORT_SYMBOL(textsearch_prepare); /** * textsearch_destroy - destroy a search configuration * @conf: search configuration * * Releases all references of the configuration and frees * up the memory. */
void textsearch_destroy(struct ts_config *conf) { if (conf->ops) { if (conf->ops->destroy) conf->ops->destroy(conf); module_put(conf->ops->owner); } kfree(conf); }

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thomas grafthomas graf49100.00%1100.00%
Total49100.00%1100.00%

EXPORT_SYMBOL(textsearch_destroy);

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thomas grafthomas graf65093.39%19.09%
fabian frederickfabian frederick202.87%19.09%
pablo neira ayusopablo neira ayuso131.87%19.09%
tejun heotejun heo30.43%19.09%
franck bui-huufranck bui-huu30.43%19.09%
joonwoo parkjoonwoo park20.29%19.09%
raphael silvaraphael silva10.14%19.09%
jesper dangaard brouerjesper dangaard brouer10.14%19.09%
robert p. j. dayrobert p. j. day10.14%19.09%
al viroal viro10.14%19.09%
johannes bergjohannes berg10.14%19.09%
Total696100.00%11100.00%
Directory: lib
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