include/vlc_modules.h

   1 /*****************************************************************************
   2  * vlc_modules.h : Module descriptor and load functions
   3  *****************************************************************************
   4  * Copyright (C) 2001-2011 VLC authors and VideoLAN
   5  *
   6  * Authors: Samuel Hocevar <sam@zoy.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifndef VLC_MODULES_H
  24 #define VLC_MODULES_H 1
  25
  26 /**
  27  * \file
  28  * This file defines functions for modules in vlc
  29  */
  30
  31 typedef int (*vlc_activate_t)(void *func, bool forced, va_list args);
  32 struct vlc_logger;
  33
  34 /*****************************************************************************
  35  * Exported functions.
  36  *****************************************************************************/
  37
  38 /**
  39  * Finds and instantiates the best module of a certain type.
  40  * All candidates modules having the specified capability and name will be
  41  * sorted in decreasing order of priority. Then the probe callback will be
  42  * invoked for each module, until it succeeds (returns 0), or all candidate
  43  * module failed to initialize.
  44  *
  45  * The probe callback first parameter is the address of the module entry point.
  46  * Further parameters are passed as an argument list; it corresponds to the
  47  * variable arguments passed to this function. This scheme is meant to
  48  * support arbitrary prototypes for the module entry point.
  49  *
  50  * \param log logger for debugging (or NULL to ignore)
  51  * \param capability capability, i.e. class of module
  52  * \param name name of the module asked, if any
  53  * \param strict if true, do not fallback to plugin with a different name
  54  *                 but the same capability
  55  * \param probe module probe callback
  56  * \return the module or NULL in case of a failure
  57  */
  58 VLC_API module_t *vlc_module_load(struct vlc_logger *log, const char *cap,
  59                                   const char *name, bool strict,
  60                                   vlc_activate_t probe, ... ) VLC_USED;
  61 #ifndef __cplusplus
  62 #define vlc_module_load(ctx, cap, name, strict, ...) \
  63     _Generic ((ctx), \
  64         struct vlc_logger *: \
  65             vlc_module_load((void *)(ctx), cap, name, strict, __VA_ARGS__), \
  66         void *: \
  67             vlc_module_load((void *)(ctx), cap, name, strict, __VA_ARGS__), \
  68         default: \
  69             vlc_module_load(vlc_object_logger((vlc_object_t *)(ctx)), cap, \
  70                             name, strict, __VA_ARGS__))
  71 #endif
  72
  73 VLC_API module_t * module_need( vlc_object_t *, const char *, const char *, bool ) VLC_USED;
  74 #define module_need(a,b,c,d) module_need(VLC_OBJECT(a),b,c,d)
  75
  76 VLC_USED
  77 static inline module_t *module_need_var(vlc_object_t *obj, const char *cap,
  78                                         const char *varname)
  79 {
  80     char *list = var_InheritString(obj, varname);
  81     module_t *m = module_need(obj, cap, list, false);
  82
  83     free(list);
  84     return m;
  85 }
  86 #define module_need_var(a,b,c) module_need_var(VLC_OBJECT(a),b,c)
  87
  88 VLC_API void module_unneed( vlc_object_t *, module_t * );
  89 #define module_unneed(a,b) module_unneed(VLC_OBJECT(a),b)
  90
  91 /**
  92  * Checks if a module exists.
  93  *
  94  * \param name name of the module
  95  * \retval true if the module exists
  96  * \retval false if the module does not exist (in the running installation)
  97  */
  98 VLC_API bool module_exists(const char *) VLC_USED;
  99
 100 /**
 101  * Get a pointer to a module_t given it's name.
 102  *
 103  * \param name the name of the module
 104  * \return a pointer to the module or NULL in case of a failure
 105  */
 106 VLC_API module_t *module_find(const char *name) VLC_USED;
 107
 108 /**
 109  * Gets the table of module configuration items.
 110  *
 111  * \note Use module_config_free() to release the allocated memory.
 112  *
 113  * \param module the module
 114  * \param psize the size of the configuration returned
 115  * \return the configuration as an array
 116  */
 117 VLC_API module_config_t *module_config_get(const module_t *module,
 118                                            unsigned *restrict psize) VLC_USED;
 119
 120 /**
 121  * Releases the configuration items table.
 122  *
 123  * \param tab base address of a table returned by module_config_get()
 124  */
 125 VLC_API void module_config_free( module_config_t *tab);
 126
 127 VLC_API void module_list_free(module_t **);
 128 VLC_API module_t ** module_list_get(size_t *n) VLC_USED;
 129
 130 /**
 131  * Checks whether a module implements a capability.
 132  *
 133  * \param m the module
 134  * \param cap the capability to check
 135  * \retval true if the module has the capability
 136  * \retval false if the module has another capability
 137  */
 138 VLC_API bool module_provides(const module_t *m, const char *cap);
 139
 140 /**
 141  * Gets the internal name of a module.
 142  *
 143  * \param m the module
 144  * \return the module name
 145  */
 146 VLC_API const char * module_get_object(const module_t *m) VLC_USED;
 147
 148 /**
 149  * Gets the human-friendly name of a module.
 150  *
 151  * \param m the module
 152  * \param longname TRUE to have the long name of the module
 153  * \return the short or long name of the module
 154  */
 155 VLC_API const char *module_get_name(const module_t *m, bool longname) VLC_USED;
 156 #define module_GetLongName( m ) module_get_name( m, true )
 157
 158 /**
 159  * Gets the help text for a module.
 160  *
 161  * \param m the module
 162  * \return the help
 163  */
 164 VLC_API const char *module_get_help(const module_t *m) VLC_USED;
 165
 166 /**
 167  * Gets the capability string of a module.
 168  *
 169  * \param m the module
 170  * \return the capability, or "none" if unspecified
 171  */
 172 VLC_API const char *module_get_capability(const module_t *m) VLC_USED;
 173
 174 /**
 175  * Gets the precedence of a module.
 176  *
 177  * \param m the module
 178  * return the score for the capability
 179  */
 180 VLC_API int module_get_score(const module_t *m) VLC_USED;
 181
 182 /**
 183  * Translates a string using the module's text domain
 184  *
 185  * \param m the module
 186  * \param s the American English ASCII string to localize
 187  * \return the gettext-translated string
 188  */
 189 VLC_API const char *module_gettext(const module_t *m, const char *s) VLC_USED;
 190
 191 VLC_USED static inline module_t *module_get_main (void)
 192 {
 193     return module_find ("core");
 194 }
 195 #define module_get_main(a) module_get_main()
 196
 197 VLC_USED static inline bool module_is_main( const module_t * p_module )
 198 {
 199     return !strcmp( module_get_object( p_module ), "core" );
 200 }
 201
 202 #endif /* VLC_MODULES_H */