208 lines
6.8 KiB
C
208 lines
6.8 KiB
C
/*
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plugin.h - Plugin loader
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Copyright (C) Lumiera.org
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2008, Christian Thaeter <ct@pipapo.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef LUMIERA_PLUGIN_H
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#define LUMIERA_PLUGIN_H
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#include "lib/psplay.h"
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#include "lib/error.h"
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#include "lib/interface.h"
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#include <stdlib.h>
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#include <nobug.h>
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/**
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* @file
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* Lumiera plugins defines 'interfaces' as shown in interface.h, the plugin system handles the loading
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* of all kinds of plugins under the hood, invoked from the interface system. Most things defined here
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* are called internally and should not be used by other parts of the application.
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*
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* Plugin discovery
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* The plugin_discover() function offers a automatic way to load and register new plugins. It traverses
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* all configured plugin directories. It takes to function for loading and registering plugins as
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* parameter, by now this only uses the here defined plugin_load() and plugin_register() functions
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* which lets it load any newly found plugin unconditionally. Later these callbacks will be replaced by
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* a smarter system (plugindb) which makes it possible to load plugins on-demand and select proper
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* plugins based on their version and capabilities.
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*
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* Plugin loading
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* Plugins are loaded and initialized in a sequence of steps:
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* plugin_load() dispatches to a specific loader function depending on the type (extension) of a plugin.
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* This loader allocates a new plugin structure with plugin_new() and then does it work and eventually
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* finalizing the plugin structure initialization with plugin_init() by providing a handle to a
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* lumieraorg__plugin interface. plugin_init() also stores the current error state (which might be clean)
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* into the plugin. After that the plugin can be registered which records it in the pluginregistry and if
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* its error state is clean, registering all interfaces it offers in the interface registry. With that
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* the plugin is ready to be used. Plugins with the error state set should still be registered to prevent
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* further discovery runs to try loading them again.
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*
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*/
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LUMIERA_ERROR_DECLARE(PLUGIN_INIT);
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LUMIERA_ERROR_DECLARE(PLUGIN_OPEN);
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LUMIERA_ERROR_DECLARE(PLUGIN_WTF);
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LUMIERA_ERROR_DECLARE(PLUGIN_REGISTER);
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LUMIERA_ERROR_DECLARE(PLUGIN_VERSION);
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NOBUG_DECLARE_FLAG (plugin);
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/* tool macros*/
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struct lumiera_plugin_struct;
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typedef struct lumiera_plugin_struct lumiera_plugin;
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typedef lumiera_plugin* LumieraPlugin;
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/**
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* Allocates an preinitializes a plugin structure
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* @internal
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* @param name path/filename of the plugin
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* @return new allocated/preinitialized plugin structure with its error state set to LUMIERA_ERROR_PLUGIN_INIT
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*/
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LumieraPlugin
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lumiera_plugin_new (const char* name);
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/**
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* Complete plugin initialization
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* @internal
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* Stores any pending error (from loading) in self which clears out the LUMIERA_ERROR_PLUGIN_INIT error state
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* which was initialized by lumiera_plugin_new(), stores the handle and plugin pointers in the plugin struct.
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* @param self pointer to the plugin struct
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* @param handle opaque handle referring to some plugin type specific data
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* @param plugin a lumieraorg__plugin interface which will be used to initialize this plugin
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*/
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LumieraPlugin
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lumiera_plugin_init (LumieraPlugin self, void* handle, LumieraInterface plugin);
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/**
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* Tries to load a plugin
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* Creates a new plugin structure and tries to load and initialize the plugin.
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* The plugins error state may be set on any problem which should be queried later.
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* @param plugin path/filename of the plugin to load
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* @return pointer to the new plugin structure (always, never NULL, check error state)
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*/
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LumieraPlugin
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lumiera_plugin_load (const char* plugin);
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/**
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* Register a plugin and its interfaces.
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* Registers the plugin (unconditionally) at the pluginregistry.
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* When the error state of the plugin is NULL then use its lumieraorg__plugin interface
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* to register all interfaces offered by the plugin at the interface registry.
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* Registered plugins will be automatic unloaded at application end.
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* @param self the plugin to be registered (calling with NULL is a no-op)
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* @return 1 on success (including calling with NULL) and 0 when a error occured
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*/
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int
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lumiera_plugin_register (LumieraPlugin self);
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/**
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* Query the error state of a plugin
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* @param self plugin to query
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* @return error identifier, NULL if no error was set
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*/
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lumiera_err
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lumiera_plugin_error (LumieraPlugin self);
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/**
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* Query the plugin handle
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* @param self plugin to query
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* @return opaque handle set by the loader functions
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*/
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void*
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lumiera_plugin_handle (LumieraPlugin self);
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/**
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* Query the plugin name
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* The name is the path and filname under which it was loaded
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* @param self plugin to query
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* @return pointer to the name string
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*/
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const char*
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lumiera_plugin_name (LumieraPlugin self);
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/**
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* Increment refcount
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* @internal
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* @param self plugin which refcount to increment
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*/
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void
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lumiera_plugin_refinc (LumieraPlugin self);
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/**
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* Decrement refcount
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* @internal
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* @param self plugin which refcount to decrement
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*/
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void
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lumiera_plugin_refdec (LumieraPlugin self);
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/**
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* Tries to unload a plugin.
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* When the Plugin is unused, then all resources associated with it are freed and it will be removed from memory
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* @param plugin the plugin to be unloaded.
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* @return 0 on success, else the refcount of users which keeping the plugin loaded
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*/
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unsigned
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lumiera_plugin_unload (LumieraPlugin self);
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/**
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* Lookup a plugin handle in the pluginregistry
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* @param name name of the plugin to be looked up
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* @return plugin handle on success, NULL if the plugin is not found in the registry
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*/
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LumieraPlugin
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lumiera_plugin_lookup (const char* name);
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/**
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* discover new plugins
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* traverses the configured plugin paths and calls the callback_load function for any plugin
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* not actually loaded. If callback_load returns a plugin (and not NULL) then this is feed to
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* the callback_register function.
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*/
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int
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lumiera_plugin_discover (LumieraPlugin (*callback_load)(const char* plugin),
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int (*callback_register) (LumieraPlugin));
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/* psplay support functions */
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int
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lumiera_plugin_cmp_fn (const void* keya, const void* keyb);
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const void*
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lumiera_plugin_key_fn (const PSplaynode node);
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void
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lumiera_plugin_delete_fn (PSplaynode node);
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#endif /* LUMIERA_PLUGIN_H */
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