module.h

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2008, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 * Kevin P. Fleming <[email protected]>
 * Luigi Rizzo <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 * \brief Asterisk module definitions.
 *
 * This file contains the definitons for functions Asterisk modules should
 * provide and some other module related functions.
 */

/*! \li \ref module.h uses the configuration file \ref modules.conf
 * \addtogroup configuration_file
 */

/*! \page modules.conf modules.conf
 * \verbinclude modules.conf.sample
 */

#ifndef _ASTERISK_MODULE_H
#define _ASTERISK_MODULE_H

#include "asterisk/utils.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

/*! \brief The text the key() function should return. */
#define ASTERISK_GPL_KEY \
"This paragraph is copyright (c) 2006 by Digium, Inc. \
In order for your module to load, it must return this \
key via a function called \"key\". Any code which \
includes this paragraph must be licensed under the GNU \
General Public License version 2 or later (at your \
option). In addition to Digium's general reservations \
of rights, Digium expressly reserves the right to \
allow other parties to license this paragraph under \
different terms. Any use of Digium, Inc. trademarks or \
logos (including \"Asterisk\" or \"Digium\") without \
express written permission of Digium, Inc. is prohibited.\n"

#define AST_MODULE_CONFIG "modules.conf" /*!< \brief Module configuration file */

enum ast_module_unload_mode {
 AST_FORCE_SOFT = 0, /*!< Softly unload a module, only if not in use */
 AST_FORCE_FIRM = 1, /*!< Firmly unload a module, even if in use */
 AST_FORCE_HARD = 2, /*!< as FIRM, plus dlclose() on the module. Not recommended
 as it may cause crashes */
};

enum ast_module_load_result {
 /*! Module is loaded and configured. */
 AST_MODULE_LOAD_SUCCESS = 0,
 /*!
 * \brief Module has failed to load, may be in an inconsistent state.
 *
 * This value is used when a module fails to start but does not risk
 * system-wide stability. Declined modules will prevent any other
 * dependent module from starting.
 */
 AST_MODULE_LOAD_DECLINE = 1,
 /*! \internal
 * \brief Module was skipped for some reason.
 *
 * \note For loader.c use only. Should never be returned by modules.
 */
 AST_MODULE_LOAD_SKIP = 2,
 /*! \internal
 * \brief Module is not loaded yet, but is added to priority list.
 *
 * \note For loader.c use only. Should never be returned by modules.
 */
 AST_MODULE_LOAD_PRIORITY = 3,
 /*!
 * \brief Module could not be loaded properly.
 *
 * This return should only be returned by modules for unrecoverable
 * failures that cause the whole system to become unstable. In almost
 * all cases \ref AST_MODULE_LOAD_DECLINE should be used instead.
 *
 * \warning Returning this code from any module will cause startup to abort.
 * If startup is already completed this code has the same effect as
 * \ref AST_MODULE_LOAD_DECLINE.
 */
 AST_MODULE_LOAD_FAILURE = -1,
};

/*!
 * \since 12
 * \brief Possible return types for \ref ast_module_reload
 */
enum ast_module_reload_result {
 AST_MODULE_RELOAD_SUCCESS = 0, /*!< The module was reloaded succesfully */
 AST_MODULE_RELOAD_QUEUED, /*!< The module reload request was queued */
 AST_MODULE_RELOAD_NOT_FOUND, /*!< The requested module was not found */
 AST_MODULE_RELOAD_ERROR, /*!< An error occurred while reloading the module */
 AST_MODULE_RELOAD_IN_PROGRESS, /*!< A module reload request is already in progress */
 AST_MODULE_RELOAD_UNINITIALIZED, /*!< The module has not been initialized */
 AST_MODULE_RELOAD_NOT_IMPLEMENTED, /*!< This module doesn't support reloading */
};

enum ast_module_support_level {
 AST_MODULE_SUPPORT_UNKNOWN,
 AST_MODULE_SUPPORT_CORE,
 AST_MODULE_SUPPORT_EXTENDED,
 AST_MODULE_SUPPORT_DEPRECATED,
};

/*! Used to specify which modules should be returned by ast_module_helper. */
enum ast_module_helper_type {
 /*! Modules that are loaded by dlopen. */
 AST_MODULE_HELPER_LOADED = 0,
 /*! Running modules that include a reload callback. */
 AST_MODULE_HELPER_RELOAD = 1,
 /*! Modules that can be loaded or started. */
 AST_MODULE_HELPER_LOAD,
 /*! Modules that can be unloaded. */
 AST_MODULE_HELPER_UNLOAD,
 /*! Running modules */
 AST_MODULE_HELPER_RUNNING,
};

/*!
 * \brief Load a module.
 * \param resource_name The name of the module to load.
 *
 * This function is run by the PBX to load the modules. It performs
 * all loading and initialization tasks. Basically, to load a module, just
 * give it the name of the module and it will do the rest.
 *
 * \return See possible enum values for ast_module_load_result.
 */
enum ast_module_load_result ast_load_resource(const char *resource_name);

/*!
 * \brief Unload a module.
 * \param resource_name The name of the module to unload.
 * \param ast_module_unload_mode The force flag. This should be set using one of the AST_FORCE flags.
 *
 * This function unloads a module. It will only unload modules that are not in
 * use (usecount not zero), unless #AST_FORCE_FIRM or #AST_FORCE_HARD is
 * specified. Setting #AST_FORCE_FIRM or #AST_FORCE_HARD will unload the
 * module regardless of consequences (NOT RECOMMENDED).
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
int ast_unload_resource(const char *resource_name, enum ast_module_unload_mode);

/*!
 * \brief Reload asterisk modules.
 * \param name the name of the module to reload
 *
 * This function reloads the specified module, or if no modules are specified,
 * it will reload all loaded modules.
 *
 * \note Modules are reloaded using their reload() functions, not unloading
 * them and loading them again.
 *
 * \retval The \ref ast_module_reload_result status of the module load request
 */
enum ast_module_reload_result ast_module_reload(const char *name);

/*!
 * \brief Notify when usecount has been changed.
 *
 * This function calulates use counts and notifies anyone trying to keep track
 * of them. It should be called whenever your module's usecount changes.
 *
 * \note The ast_module_user_* functions take care of calling this function for you.
 */
void ast_update_use_count(void);

/*!
 * \brief Ask for a list of modules, descriptions, use counts and status.
 * \param modentry A callback to an updater function.
 * \param like
 *
 * For each of the modules loaded, modentry will be executed with the resource,
 * description, and usecount values of each particular module.
 *
 * \return the number of modules loaded
 */
int ast_update_module_list(int (*modentry)(const char *module, const char *description,
 int usecnt, const char *status, const char *like,
 enum ast_module_support_level support_level),
 const char *like);

/*!
 * \brief Ask for a list of modules, descriptions, use counts and status.
 * \param modentry A callback to an updater function
 * \param like
 * \param data Data passed into the callback for manipulation
 *
 * For each of the modules loaded, modentry will be executed with the resource,
 * description, and usecount values of each particular module.
 *
 * \return the number of modules loaded
 * \since 13.5.0
 */
int ast_update_module_list_data(int (*modentry)(const char *module, const char *description,
 int usecnt, const char *status, const char *like,
 enum ast_module_support_level support_level,
 void *data),
 const char *like, void *data);

/*!
 * \brief Ask for a list of modules, descriptions, use counts and status.
 * \param modentry A callback to an updater function
 * \param like
 * \param data Data passed into the callback for manipulation
 * \param condition The condition to meet
 *
 * For each of the modules loaded, modentry will be executed with the resource,
 * description, and usecount values of each particular module.
 *
 * \return the number of conditions met
 * \since 13.5.0
 */
int ast_update_module_list_condition(int (*modentry)(const char *module, const char *description,
 int usecnt, const char *status, const char *like,
 enum ast_module_support_level support_level,
 void *data, const char *condition),
 const char *like, void *data, const char *condition);

/*!
 * \brief Check if module with the name given is loaded
 * \param name Module name, like "chan_sip.so"
 * \retval 1 if true
 * \retval 0 if false
 */
int ast_module_check(const char *name);

/*!
 * \brief Add a procedure to be run when modules have been updated.
 * \param updater The function to run when modules have been updated.
 *
 * This function adds the given function to a linked list of functions to be
 * run when the modules are updated.
 *
 * \retval 0 on success
 * \retval -1 on failure.
 */
int ast_loader_register(int (*updater)(void));

/*!
 * \brief Remove a procedure to be run when modules are updated.
 * \param updater The updater function to unregister.
 *
 * This removes the given function from the updater list.
 *
 * \retval 0 on success
 * \retval -1 on failure.
 */
int ast_loader_unregister(int (*updater)(void));

/*!
 * \brief Match modules names for the Asterisk cli.
 * \param line Unused by this function, but this should be the line we are
 * matching.
 * \param word The partial name to match.
 * \param pos The position the word we are completing is in.
 * \param state The possible match to return.
 * \param rpos The position we should be matching. This should be the same as
 * pos.
 * \param type The type of action that will be performed by CLI.
 *
 * \retval A possible completion of the partial match.
 * \retval NULL if no matches were found.
 */
char *ast_module_helper(const char *line, const char *word, int pos, int state, int rpos, enum ast_module_helper_type type);

/* Opaque type for module handles generated by the loader */

struct ast_module;

/*!
 * \brief Get the name of a module.
 * \param mod A pointer to the module.
 * \return the name of the module
 * \retval NULL if mod or mod->info is NULL
 */
const char *ast_module_name(const struct ast_module *mod);

/* User count routines keep track of which channels are using a given module
 resource. They can help make removing modules safer, particularly if
 they're in use at the time they have been requested to be removed */

struct ast_module_user;
struct ast_module_user_list;

/*! \page ModMngmnt The Asterisk Module management interface
 *
 * All modules must implement the module API (load, unload...)
 */

enum ast_module_flags {
 AST_MODFLAG_DEFAULT = 0,
 AST_MODFLAG_GLOBAL_SYMBOLS = (1 << 0),
 AST_MODFLAG_LOAD_ORDER = (1 << 1),
};

enum ast_module_load_priority {
 AST_MODPRI_REALTIME_DEPEND = 10, /*!< Dependency for a realtime driver */
 AST_MODPRI_REALTIME_DEPEND2 = 20, /*!< Second level dependency for a realtime driver (func_curl needs res_curl, but is needed by res_config_curl) */
 AST_MODPRI_REALTIME_DRIVER = 30, /*!< A realtime driver, which provides configuration services for other modules */
 AST_MODPRI_CORE = 40, /*!< A core module originally meant to start between preload and load. */
 AST_MODPRI_TIMING = 50, /*!< Dependency for a channel (MOH needs timing interfaces to be fully loaded) */
 AST_MODPRI_CHANNEL_DEPEND = 60, /*!< Channel driver dependency (may depend upon realtime, e.g. MOH) */
 AST_MODPRI_CHANNEL_DRIVER = 70, /*!< Channel drivers (provide devicestate) */
 AST_MODPRI_APP_DEPEND = 80, /*!< Dependency for an application */
 AST_MODPRI_DEVSTATE_PROVIDER = 90, /*!< Applications and other modules that _provide_ devicestate (e.g. meetme) */
 AST_MODPRI_DEVSTATE_PLUGIN = 100, /*!< Plugin for a module that provides devstate (e.g. res_calendar_*) */
 AST_MODPRI_CDR_DRIVER = 110, /*!< CDR or CEL backend */
 AST_MODPRI_DEFAULT = 128, /*!< Modules not otherwise defined (such as most apps) will load here */
 AST_MODPRI_DEVSTATE_CONSUMER = 150, /*!< Certain modules, which consume devstate, need to load after all others (e.g. app_queue) */
};

struct ast_module_info {
 /*!
 * The 'self' pointer for a module; it will be set by the loader before
 * it calls the module's load_module() entrypoint, and used by various
 * other macros that need to identify the module.
 */
 struct ast_module *self;
 /*! Register stuff etc. Optional. */
 enum ast_module_load_result (*load)(void);
 /*! Config etc. Optional. */
 int (*reload)(void);
 /*! Unload. called with the module locked */
 int (*unload)(void);
 /*! Name of the module for loader reference and CLI commands */
 const char *name;
 /*! User friendly description of the module. */
 const char *description;

 /*!
 * This holds the ASTERISK_GPL_KEY, signifiying that you agree to the terms of
 * the Asterisk license as stated in the ASTERISK_GPL_KEY. Your module will not
 * load if it does not return the EXACT key string.
 */
 const char *key;
 unsigned int flags;

 /*! The value of AST_BUILDOPT_SUM when this module was compiled */
 const char buildopt_sum[33];

 /*! This value represents the order in which a module's load() function is initialized.
 * The lower this value, the higher the priority. The value is only checked if the
 * AST_MODFLAG_LOAD_ORDER flag is set. If the AST_MODFLAG_LOAD_ORDER flag is not set,
 * this value will never be read and the module will be given the lowest possible priority
 * on load. */
 unsigned char load_pri;

 /*! Modules which must always be started first, in comma-separated string format. */
 const char *requires;

 /*!
 * \brief Comma-separated list of optionally required modules.
 *
 * The listed modules are optional, but load order is enforced. For example
 * app_voicemail optionally requires res_adsi. This means that app_voicemail
 * will happily load without res_adsi, but if both are being loaded the module
 * loader will force res_adsi to start first.
 */
 const char *optional_modules;

 /*!
 * \brief Modules that we provide enhanced functionality for.
 *
 * This is similar to a "requires" but specifies that we add functionality to
 * the other modules. Any module that requires something we "enhances" will
 * also require us, but only if we are dlopen'ed.
 *
 * Example:
 * - res_fax_spandsp has .enhances = "res_fax".
 * - res_my_module has .requires = "res_fax" but has no direct knowledge
 * of res_fax_spandsp.
 *
 * This forces the following startup order among the 3 modules:
 * 1) res_fax starts.
 * 2) res_fax_spandsp starts, holds a reference to res_fax.
 * 3) res_mymod starts, holds a reference to res_fax and res_fax_spandsp.
 *
 * If res_fax_spandsp were not being loaded res_mymod would load with
 * res_fax only. If res_fax_spandsp were later loaded res_mymod would
 * get a reference to it.
 */
 const char *enhances;

 /*! These reserved fields should be NULL, they exist to allow addition to this
 * structure in a non-breaking way. */
 void *reserved1;
 void *reserved2;
 void *reserved3;
 void *reserved4;

 /*! The support level for the given module */
 enum ast_module_support_level support_level;
};

void ast_module_register(const struct ast_module_info *);
void ast_module_unregister(const struct ast_module_info *);

struct ast_module_user *__ast_module_user_add(struct ast_module *, struct ast_channel *);
void __ast_module_user_remove(struct ast_module *, struct ast_module_user *);
void __ast_module_user_hangup_all(struct ast_module *);

#define ast_module_user_add(chan) __ast_module_user_add(AST_MODULE_SELF, chan)
#define ast_module_user_remove(user) __ast_module_user_remove(AST_MODULE_SELF, user)
#define ast_module_user_hangup_all() __ast_module_user_hangup_all(AST_MODULE_SELF)

struct ast_module *__ast_module_ref(struct ast_module *mod, const char *file, int line, const char *func);
struct ast_module *__ast_module_running_ref(struct ast_module *mod, const char *file, int line, const char *func);
void __ast_module_shutdown_ref(struct ast_module *mod, const char *file, int line, const char *func);
void __ast_module_unref(struct ast_module *mod, const char *file, int line, const char *func);

/*!
 * \brief Hold a reference to the module
 * \param mod Module to reference
 * \return mod
 *
 * \note A module reference will prevent the module
 * from being unloaded.
 */
#define ast_module_ref(mod) __ast_module_ref(mod, __FILE__, __LINE__, __PRETTY_FUNCTION__)

/*!
 * \brief Hold a reference to the module if it is running.
 * \param mod Module to reference
 * \retval mod if running
 * \retval NULL if not running
 *
 * The returned pointer should be released with ast_module_unref.
 *
 * \note A module reference will prevent the module from being unloaded.
 */
#define ast_module_running_ref(mod) \
 __ast_module_running_ref(mod, __FILE__, __LINE__, __PRETTY_FUNCTION__)

/*!
 * \brief Prevent unload of the module before shutdown
 * \param mod Module to hold
 *
 * \note This should not be balanced by a call to ast_module_unref.
 */
#define ast_module_shutdown_ref(mod) __ast_module_shutdown_ref(mod, __FILE__, __LINE__, __PRETTY_FUNCTION__)
/*!
 * \brief Release a reference to the module
 * \param mod Module to release
 */
#define ast_module_unref(mod) __ast_module_unref(mod, __FILE__, __LINE__, __PRETTY_FUNCTION__)

#if defined(__cplusplus) || defined(c_plusplus)
#define AST_MODULE_INFO(keystr, flags_to_set, desc, load_func, unload_func, reload_func, load_pri, support_level) \
 static struct ast_module_info __mod_info = { \
 NULL, \
 load_func, \
 reload_func, \
 unload_func, \
 AST_MODULE, \
 desc, \
 keystr, \
 flags_to_set, \
 AST_BUILDOPT_SUM, \
 load_pri, \
 NULL, \
 NULL, \
 NULL, \
 NULL, \
 NULL, \
 NULL, \
 NULL, \
 support_level, \
 }; \
 static void __attribute__((constructor)) __reg_module(void) \
 { \
 ast_module_register(&__mod_info); \
 } \
 static void __attribute__((destructor)) __unreg_module(void) \
 { \
 ast_module_unregister(&__mod_info); \
 } \
 struct ast_module *AST_MODULE_SELF_SYM(void) \
 { \
 return __mod_info.self; \
 } \
 static const __attribute__((unused)) struct ast_module_info *ast_module_info = &__mod_info


#define AST_MODULE_INFO_STANDARD(keystr, desc) \
 AST_MODULE_INFO(keystr, AST_MODFLAG_LOAD_ORDER, desc, \
 load_module, \
 unload_module, \
 NULL, \
 AST_MODPRI_DEFAULT, \
 AST_MODULE_SUPPORT_CORE \
 )

#define AST_MODULE_INFO_STANDARD_EXTENDED(keystr, desc) \
 AST_MODULE_INFO(keystr, AST_MODFLAG_LOAD_ORDER, desc, \
 load_module, \
 unload_module, \
 NULL, \
 AST_MODPRI_DEFAULT, \
 AST_MODULE_SUPPORT_EXTENDED \
 )
#define AST_MODULE_INFO_STANDARD_DEPRECATED(keystr, desc) \
 AST_MODULE_INFO(keystr, AST_MODFLAG_LOAD_ORDER, desc, \
 load_module, \
 unload_module, \
 NULL, \
 AST_MODPRI_DEFAULT, \
 AST_MODULE_SUPPORT_DEPRECATED \
 )

#else /* plain C */

/* forward declare this pointer in modules, so that macro/function
 calls that need it can get it, since it will actually be declared
 and populated at the end of the module's source file... */
#if !defined(AST_IN_CORE)
static const __attribute__((unused)) struct ast_module_info *ast_module_info;
#endif

#define AST_MODULE_INFO(keystr, flags_to_set, desc, fields...) \
 static struct ast_module_info \
 __mod_info = { \
 .name = AST_MODULE, \
 .flags = flags_to_set, \
 .description = desc, \
 .key = keystr, \
 .buildopt_sum = AST_BUILDOPT_SUM, \
 fields \
 }; \
 static void __attribute__((constructor)) __reg_module(void) \
 { \
 ast_module_register(&__mod_info); \
 } \
 static void __attribute__((destructor)) __unreg_module(void) \
 { \
 ast_module_unregister(&__mod_info); \
 } \
 struct ast_module *AST_MODULE_SELF_SYM(void) \
 { \
 return __mod_info.self; \
 } \
 static const struct ast_module_info *ast_module_info = &__mod_info

#define AST_MODULE_INFO_STANDARD(keystr, desc) \
 AST_MODULE_INFO(keystr, AST_MODFLAG_LOAD_ORDER, desc, \
 .load = load_module, \
 .unload = unload_module, \
 .load_pri = AST_MODPRI_DEFAULT, \
 .support_level = AST_MODULE_SUPPORT_CORE, \
 )

#define AST_MODULE_INFO_STANDARD_EXTENDED(keystr, desc) \
 AST_MODULE_INFO(keystr, AST_MODFLAG_LOAD_ORDER, desc, \
 .load = load_module, \
 .unload = unload_module, \
 .load_pri = AST_MODPRI_DEFAULT, \
 .support_level = AST_MODULE_SUPPORT_EXTENDED, \
 )

#define AST_MODULE_INFO_STANDARD_DEPRECATED(keystr, desc) \
 AST_MODULE_INFO(keystr, AST_MODFLAG_LOAD_ORDER, desc, \
 .load = load_module, \
 .unload = unload_module, \
 .load_pri = AST_MODPRI_DEFAULT, \
 .support_level = AST_MODULE_SUPPORT_DEPRECATED, \
 )

#endif /* plain C */

/*!
 * \brief Register an application.
 *
 * \param app Short name of the application
 * \param execute a function callback to execute the application. It should return
 * non-zero if the channel needs to be hung up.
 * \param synopsis a short description (one line synopsis) of the application
 * \param description long description with all of the details about the use of
 * the application
 *
 * This registers an application with Asterisk's internal application list.
 * \note The individual applications themselves are responsible for registering and unregistering
 * and unregistering their own CLI commands.
 *
 * \retval 0 success
 * \retval -1 failure.
 */
#define ast_register_application(app, execute, synopsis, description) ast_register_application2(app, execute, synopsis, description, AST_MODULE_SELF)

/*!
 * \brief Register an application using XML documentation.
 *
 * \param app Short name of the application
 * \param execute a function callback to execute the application. It should return
 * non-zero if the channel needs to be hung up.
 *
 * This registers an application with Asterisk's internal application list.
 * \note The individual applications themselves are responsible for registering and unregistering
 * and unregistering their own CLI commands.
 *
 * \retval 0 success
 * \retval -1 failure.
 */
#define ast_register_application_xml(app, execute) ast_register_application(app, execute, NULL, NULL)


/*!
 * \brief Register an application.
 *
 * \param app Short name of the application
 * \param execute a function callback to execute the application. It should return
 * non-zero if the channel needs to be hung up.
 * \param synopsis a short description (one line synopsis) of the application
 * \param description long description with all of the details about the use of
 * the application
 * \param mod module this application belongs to
 *
 * This registers an application with Asterisk's internal application list.
 * \note The individual applications themselves are responsible for registering and unregistering
 * and unregistering their own CLI commands.
 *
 * \retval 0 success
 * \retval -1 failure.
 */
int ast_register_application2(const char *app, int (*execute)(struct ast_channel *, const char *),
 const char *synopsis, const char *description, void *mod);

/*!
 * \brief Unregister an application
 *
 * \param app name of the application (does not have to be the same string as the one that was registered)
 *
 * This unregisters an application from Asterisk's internal application list.
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_unregister_application(const char *app);

const char *ast_module_support_level_to_string(enum ast_module_support_level support_level);

/*! Macro to safely ref and unref the self module for the current scope */
#define SCOPED_MODULE_USE(module) \
 RAII_VAR(struct ast_module *, __self__ ## __LINE__, ast_module_ref(module), ast_module_unref)

#if defined(__cplusplus) || defined(c_plusplus)
}
#endif

#endif /* _ASTERISK_MODULE_H */