text: /*
       This file is part of GNUnet.
       Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 GNUnet e.V.
  
       GNUnet 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 3, or (at your
       option) any later version.
  
       GNUnet is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       General Public License for more details.
  
       You should have received a copy of the GNU General Public License
       along with GNUnet; see the file COPYING.  If not, write to the
       Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
       Boston, MA 02110-1301, USA.
  */
  
  /**
   * @author Christian Grothoff
   *
   * @file
   * Plugin loading and unloading
   *
   * @defgroup plugin  Plugin library
   * Plugin loading and unloading
   * @{
   */
  
  #ifndef GNUNET_PLUGIN_LIB_H
  #define GNUNET_PLUGIN_LIB_H
  
  #ifdef __cplusplus
  extern "C"
  {
  #if 0                           /* keep Emacsens' auto-indent happy */
  }
  #endif
  #endif
  
  #include "gnunet_common.h"
  #include "gnunet_configuration_lib.h"
  
  
  /**
   * Signature of any function exported by a plugin.
   *
   * @param arg argument to the function (context)
   * @return some pointer, NULL if the plugin was
   *         shutdown or if there was an error, otherwise
   *         the plugin's API on success
   */
  typedef void *
  (*GNUNET_PLUGIN_Callback) (void *arg);
  
  
  /**
   * Test if a plugin exists.
   *
   * Note that the library must export a symbol called
   * "library_name_init" for the test to succeed.
   *
   * @param library_name name of the plugin to test if it is installed
   * @return #GNUNET_YES if the plugin exists, #GNUNET_NO if not
   */
  int
  GNUNET_PLUGIN_test (const char *library_name);
  
  
  /**
   * Setup plugin (runs the "init" callback and returns whatever "init"
   * returned).  If "init" returns NULL, the plugin is unloaded.
   *
   * Note that the library must export symbols called
   * "library_name_init" and "library_name_done".  These will be called
   * when the library is loaded and unloaded respectively.
   *
   * @param library_name name of the plugin to load
   * @param arg argument to the plugin initialization function
   * @return whatever the initialization function returned, NULL on error
   */
  void *
  GNUNET_PLUGIN_load (const char *library_name,
                      void *arg);
  
  
  /**
   * Signature of a function called by 'GNUNET_PLUGIN_load_all'.
   *
   * @param cls closure
   * @param library_name full name of the library (to be used with
   *        #GNUNET_PLUGIN_unload)
   * @param lib_ret return value from the initialization function
   *        of the library (same as what #GNUNET_PLUGIN_load would
   *        have returned for the given library name)
   */
  typedef void
  (*GNUNET_PLUGIN_LoaderCallback) (void *cls,
                                   const char *library_name,
                                   void *lib_ret);
  
  
  /**
   * Load all compatible plugins with the given base name.
   *
   * Note that the library must export symbols called
   * "basename_ANYTHING_init" and "basename_ANYTHING__done".  These will
   * be called when the library is loaded and unloaded respectively.
   *
   * @param basename basename of the plugins to load
   * @param arg argument to the plugin initialization function
   * @param cb function to call for each plugin found
   * @param cb_cls closure for @a cb
   */
  void
  GNUNET_PLUGIN_load_all (const char *basename,
                          void *arg,
                          GNUNET_PLUGIN_LoaderCallback cb,
                          void *cb_cls);
  
  
  /**
   * Unload plugin (runs the "done" callback and returns whatever "done"
   * returned).  The plugin is then unloaded.
   *
   * @param library_name name of the plugin to unload
   * @param arg argument to the plugin shutdown function
   * @return whatever the shutdown function returned, typically NULL
   *         or a "char *" representing the error message
   */
  void *
  GNUNET_PLUGIN_unload (const char *library_name,
                        void *arg);
  
  
  #if 0                           /* keep Emacsens' auto-indent happy */
  {
  #endif
  #ifdef __cplusplus
  }
  #endif
  
  /* ifndef GNUNET_PLUGIN_LIB_H */
  #endif
  
  /** @} */  /* end of group */
  
  /* end of gnunet_plugin_lib.h */
  