/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2008, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 * Kevin P. Fleming <kpfleming@digium.com>
 * Luigi Rizzo <rizzo@icir.org>
 *
 * 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 {
	AST_MODULE_LOAD_SUCCESS = 0,    /*!< Module loaded and configured */
	AST_MODULE_LOAD_DECLINE = 1,    /*!< Module is not configured */
	AST_MODULE_LOAD_SKIP = 2,       /*!< Module was skipped for some reason */
	AST_MODULE_LOAD_PRIORITY = 3,   /*!< Module is not loaded yet, but is added to prioity heap */
	AST_MODULE_LOAD_FAILURE = -1,   /*!< Module could not be loaded properly */
};

/*!
 * \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,
};

/*! 
 * \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 Run the unload() callback for all loaded modules
 *
 * This function should be called when Asterisk is shutting down gracefully.
 */
void ast_module_shutdown(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 needsreload This should be 1 if we need to reload this module and 0
 *        otherwise.  This function will only return modules that are reloadble
 *        if this is 1.
 *
 * \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, int needsreload);

/* 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_TIMING =             40,  /*!< Dependency for a channel (MOH needs timing interfaces to be fully loaded) */
	AST_MODPRI_CHANNEL_DEPEND =     50,  /*!< Channel driver dependency (may depend upon realtime, e.g. MOH) */
	AST_MODPRI_CHANNEL_DRIVER =     60,  /*!< Channel drivers (provide devicestate) */
	AST_MODPRI_APP_DEPEND =         70,  /*!< Dependency for an application */
	AST_MODPRI_DEVSTATE_PROVIDER =  80,  /*!< Applications and other modules that _provide_ devicestate (e.g. meetme) */
	AST_MODPRI_DEVSTATE_PLUGIN =    90,  /*!< Plugin for a module that provides devstate (e.g. res_calendar_*) */
	AST_MODPRI_CDR_DRIVER =        100,  /*!< 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;
	enum ast_module_load_result (*load)(void);	/*!< register stuff etc. Optional. */
	int (*reload)(void);			/*!< config etc. Optional. */
	int (*unload)(void);			/*!< unload. called with the module locked */
	int (*backup_globals)(void);		/*!< for embedded modules, backup global data */
	void (*restore_globals)(void);		/*!< for embedded modules, restore global data */
	const char *name;			/*!< name of the module for loader reference and CLI commands */
	const char *description;		/*!< user friendly description of the module. */

	/*! 
	 * 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 should be loaded first, in comma-separated string format.
	 * These are only required for loading, when the optional_api header file
	 * detects that the compiler does not support the optional API featureset. */
	const char *nonoptreq;
	/*! 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_info->self, chan)
#define ast_module_user_remove(user) __ast_module_user_remove(ast_module_info->self, user)
#define ast_module_user_hangup_all() __ast_module_user_hangup_all(ast_module_info->self)

struct ast_module *__ast_module_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 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,                                                   \
		NULL,                                                          \
		NULL,                                                          \
		AST_MODULE,                                                    \
		desc,                                                          \
		keystr,                                                        \
		flags_to_set,                                                  \
		AST_BUILDOPT_SUM,                                              \
		load_pri,                                                      \
		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);                            \
	}                                                                  \
	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... */
static const __attribute__((unused)) struct ast_module_info *ast_module_info;

#if !defined(EMBEDDED_MODULE)
#define __MODULE_INFO_SECTION
#define __MODULE_INFO_GLOBALS
#else
/*
 * For embedded modules we need additional information to backup and
 * restore the global variables in the module itself, so we can unload
 * reload the module.
 * EMBEDDED_MODULE is defined as the module name, so the calls to make_var()
 * below will actually define different symbols for each module.
 */
#define __MODULE_INFO_SECTION	__attribute__((section(".embed_module")))
#define __MODULE_INFO_GLOBALS	.backup_globals = __backup_globals, .restore_globals = __restore_globals,

#define make_var_sub(mod, type) __ ## mod ## _ ## type
#define make_var(mod, type) make_var_sub(mod, type)

extern void make_var(EMBEDDED_MODULE, bss_start);
extern void make_var(EMBEDDED_MODULE, bss_end);
extern void make_var(EMBEDDED_MODULE, data_start);
extern void make_var(EMBEDDED_MODULE, data_end);

static void * __attribute__((section(".embed_module"))) __global_backup;

static int __backup_globals(void)
{
	size_t data_size = & make_var(EMBEDDED_MODULE, data_end) - & make_var(EMBEDDED_MODULE, data_start);

	if (__global_backup)
		return 0;

	if (!data_size)
		return 0;

	if (!(__global_backup = ast_malloc(data_size)))
		return -1;

	memcpy(__global_backup, & make_var(EMBEDDED_MODULE, data_start), data_size);

	return 0;
}

static void __restore_globals(void)
{
	size_t data_size = & make_var(EMBEDDED_MODULE, data_end) - & make_var(EMBEDDED_MODULE, data_start);
	size_t bss_size = & make_var(EMBEDDED_MODULE, bss_end) - & make_var(EMBEDDED_MODULE, bss_start);

	if (bss_size)
		memset(& make_var(EMBEDDED_MODULE, bss_start), 0, bss_size);

	if (!data_size || !__global_backup)
		return;

	memcpy(& make_var(EMBEDDED_MODULE, data_start), __global_backup, data_size);
}
#undef make_var
#undef make_var_sub
#endif /* EMBEDDED_MODULE */

#define AST_MODULE_INFO(keystr, flags_to_set, desc, fields...)	\
	static struct ast_module_info 				\
		__MODULE_INFO_SECTION				\
		__mod_info = {					\
		__MODULE_INFO_GLOBALS				\
		.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); \
	} \
	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_info->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 */
