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 the candidate modules for given criteria.
  40  *
  41  * All candidates modules having the specified capability and name will be
  42  * sorted in decreasing order of priority and returned in a heap-allocated
  43  * table.
  44  *
  45  * \param capability capability, i.e. class of module
  46  * \param names string of comma-separated requested module shortcut names,
  47  *              or NULL for defaults
  48  * \param strict whether to exclude modules with no unmatching shortcut names
  49  * \param modules storage location for the base address of a sorted table
  50  *                of candidate modules (NULL on error) [OUT]
  51  * \param strict_matches storage location for the count of strictly matched
  52  *                       modules [OUT]
  53  * \return number of modules found or a strictly negative value on error
  54  */
  55 VLC_API
  56 ssize_t vlc_module_match(const char *capability, const char *names,
  57                          bool strict, module_t ***restrict modules,
  58                          size_t *restrict strict_matches);
  59
  60 /**
  61  * Maps a module in memory.
  62  *
  63  * This function attempts to map a given module in memory, if it is not
  64  * already mapped. If it is already mapped, this function does nothing.
  65  *
  66  * \param log message logger
  67  * \param mod module to map
  68  *
  69  * \return the module activation function on success, NULL on failure
  70  */
  71 VLC_API
  72 void *vlc_module_map(struct vlc_logger *log, module_t *mod);
  73
  74 /**
  75  * Finds and instantiates the best module of a certain type.
  76  * All candidates modules having the specified capability and name will be
  77  * sorted in decreasing order of priority. Then the probe callback will be
  78  * invoked for each module, until it succeeds (returns 0), or all candidate
  79  * module failed to initialize.
  80  *
  81  * The probe callback first parameter is the address of the module entry point.
  82  * Further parameters are passed as an argument list; it corresponds to the
  83  * variable arguments passed to this function. This scheme is meant to
  84  * support arbitrary prototypes for the module entry point.
  85  *
  86  * \param log logger for debugging (or NULL to ignore)
  87  * \param capability capability, i.e. class of module
  88  * \param name name of the module asked, if any
  89  * \param strict if true, do not fallback to plugin with a different name
  90  *                 but the same capability
  91  * \param probe module probe callback
  92  * \return the module or NULL in case of a failure
  93  */
  94 VLC_API module_t *vlc_module_load(struct vlc_logger *log, const char *cap,
  95                                   const char *name, bool strict,
  96                                   vlc_activate_t probe, ... ) VLC_USED;
  97 #ifndef __cplusplus
  98 #define vlc_module_load(ctx, cap, name, strict, ...) \
  99     _Generic ((ctx), \
 100         struct vlc_logger *: \
 101             vlc_module_load((void *)(ctx), cap, name, strict, __VA_ARGS__), \
 102         void *: \
 103             vlc_module_load((void *)(ctx), cap, name, strict, __VA_ARGS__), \
 104         default: \
 105             vlc_module_load(vlc_object_logger((vlc_object_t *)(ctx)), cap, \
 106                             name, strict, __VA_ARGS__))
 107 #endif
 108
 109 VLC_API module_t * module_need( vlc_object_t *, const char *, const char *, bool ) VLC_USED;
 110 #define module_need(a,b,c,d) module_need(VLC_OBJECT(a),b,c,d)
 111
 112 VLC_USED
 113 static inline module_t *module_need_var(vlc_object_t *obj, const char *cap,
 114                                         const char *varname)
 115 {
 116     char *list = var_InheritString(obj, varname);
 117     module_t *m = module_need(obj, cap, list, false);
 118
 119     free(list);
 120     return m;
 121 }
 122 #define module_need_var(a,b,c) module_need_var(VLC_OBJECT(a),b,c)
 123
 124 VLC_API void module_unneed( vlc_object_t *, module_t * );
 125 #define module_unneed(a,b) module_unneed(VLC_OBJECT(a),b)
 126
 127 /**
 128  * Checks if a module exists.
 129  *
 130  * \param name name of the module
 131  * \retval true if the module exists
 132  * \retval false if the module does not exist (in the running installation)
 133  */
 134 VLC_API bool module_exists(const char *) VLC_USED;
 135
 136 /**
 137  * Get a pointer to a module_t given it's name.
 138  *
 139  * \param name the name of the module
 140  * \return a pointer to the module or NULL in case of a failure
 141  */
 142 VLC_API module_t *module_find(const char *name) VLC_USED;
 143
 144 /**
 145  * Gets the table of module configuration items.
 146  *
 147  * \note Use module_config_free() to release the allocated memory.
 148  *
 149  * \param module the module
 150  * \param psize the size of the configuration returned
 151  * \return the configuration as an array
 152  */
 153 VLC_API module_config_t *module_config_get(const module_t *module,
 154                                            unsigned *restrict psize) VLC_USED;
 155
 156 /**
 157  * Releases the configuration items table.
 158  *
 159  * \param tab base address of a table returned by module_config_get()
 160  */
 161 VLC_API void module_config_free( module_config_t *tab);
 162
 163 VLC_API void module_list_free(module_t **);
 164 VLC_API module_t ** module_list_get(size_t *n) VLC_USED;
 165
 166 /**
 167  * Checks whether a module implements a capability.
 168  *
 169  * \param m the module
 170  * \param cap the capability to check
 171  * \retval true if the module has the capability
 172  * \retval false if the module has another capability
 173  */
 174 VLC_API bool module_provides(const module_t *m, const char *cap);
 175
 176 /**
 177  * Gets the internal name of a module.
 178  *
 179  * \param m the module
 180  * \return the module name
 181  */
 182 VLC_API const char * module_get_object(const module_t *m) VLC_USED;
 183
 184 /**
 185  * Gets the human-friendly name of a module.
 186  *
 187  * \param m the module
 188  * \param longname TRUE to have the long name of the module
 189  * \return the short or long name of the module
 190  */
 191 VLC_API const char *module_get_name(const module_t *m, bool longname) VLC_USED;
 192 #define module_GetLongName( m ) module_get_name( m, true )
 193
 194 /**
 195  * Gets the help text for a module.
 196  *
 197  * \param m the module
 198  * \return the help
 199  */
 200 VLC_API const char *module_get_help(const module_t *m) VLC_USED;
 201
 202 /**
 203  * Gets the capability string of a module.
 204  *
 205  * \param m the module
 206  * \return the capability, or "none" if unspecified
 207  */
 208 VLC_API const char *module_get_capability(const module_t *m) VLC_USED;
 209
 210 /**
 211  * Gets the precedence of a module.
 212  *
 213  * \param m the module
 214  * return the score for the capability
 215  */
 216 VLC_API int module_get_score(const module_t *m) VLC_USED;
 217
 218 /**
 219  * Translates a string using the module's text domain
 220  *
 221  * \param m the module
 222  * \param s the American English ASCII string to localize
 223  * \return the gettext-translated string
 224  */
 225 VLC_API const char *module_gettext(const module_t *m, const char *s) VLC_USED;
 226
 227 VLC_USED static inline module_t *module_get_main (void)
 228 {
 229     return module_find ("core");
 230 }
 231 #define module_get_main(a) module_get_main()
 232
 233 VLC_USED static inline bool module_is_main( const module_t * p_module )
 234 {
 235     return !strcmp( module_get_object( p_module ), "core" );
 236 }
 237
 238 #endif /* VLC_MODULES_H */