src/modules/modules.c

   1 /*****************************************************************************
   2  * modules.c : Builtin and plugin modules management functions
   3  *****************************************************************************
   4  * Copyright (C) 2001-2011 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Sam Hocevar <sam@zoy.org>
   8  *          Ethan C. Baldridge <BaldridgeE@cadmus.com>
   9  *          Hans-Peter Jansen <hpj@urpla.net>
  10  *          Gildas Bazin <gbazin@videolan.org>
  11  *          Rémi Denis-Courmont
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms of the GNU Lesser General Public License as published by
  15  * the Free Software Foundation; either version 2.1 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  21  * GNU Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public License
  24  * along with this program; if not, write to the Free Software Foundation,
  25  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  26  *****************************************************************************/
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #ifdef ENABLE_NLS
  35 # include <libintl.h>
  36 #endif
  37 #include <assert.h>
  38
  39 #include <vlc_common.h>
  40 #include <vlc_modules.h>
  41 #include "libvlc.h"
  42 #include "config/configuration.h"
  43 #include "vlc_arrays.h"
  44 #include "modules/modules.h"
  45
  46 /**
  47  * Checks whether a module implements a capability.
  48  *
  49  * \param m the module
  50  * \param cap the capability to check
  51  * \return TRUE if the module have the capability
  52  */
  53 bool module_provides( const module_t *m, const char *cap )
  54 {
  55     if (unlikely(m->psz_capability == NULL))
  56         return false;
  57     return !strcmp( m->psz_capability, cap );
  58 }
  59
  60 /**
  61  * Get the internal name of a module
  62  *
  63  * \param m the module
  64  * \return the module name
  65  */
  66 const char *module_get_object( const module_t *m )
  67 {
  68     if (unlikely(m->i_shortcuts == 0))
  69         return "unnamed";
  70     return m->pp_shortcuts[0];
  71 }
  72
  73 /**
  74  * Get the human-friendly name of a module.
  75  *
  76  * \param m the module
  77  * \param long_name TRUE to have the long name of the module
  78  * \return the short or long name of the module
  79  */
  80 const char *module_get_name( const module_t *m, bool long_name )
  81 {
  82     if( long_name && ( m->psz_longname != NULL) )
  83         return m->psz_longname;
  84
  85     if (m->psz_shortname != NULL)
  86         return m->psz_shortname;
  87     return module_get_object (m);
  88 }
  89
  90 /**
  91  * Get the help for a module
  92  *
  93  * \param m the module
  94  * \return the help
  95  */
  96 const char *module_get_help( const module_t *m )
  97 {
  98     return m->psz_help;
  99 }
 100
 101 /**
 102  * Get the capability for a module
 103  *
 104  * \param m the module
 105  * return the capability
 106  */
 107 const char *module_get_capability( const module_t *m )
 108 {
 109     return m->psz_capability;
 110 }
 111
 112 /**
 113  * Get the score for a module
 114  *
 115  * \param m the module
 116  * return the score for the capability
 117  */
 118 int module_get_score( const module_t *m )
 119 {
 120     return m->i_score;
 121 }
 122
 123 /**
 124  * Translate a string using the module's text domain
 125  *
 126  * \param m the module
 127  * \param str the American English ASCII string to localize
 128  * \return the gettext-translated string
 129  */
 130 const char *module_gettext (const module_t *m, const char *str)
 131 {
 132     if (m->parent != NULL)
 133         m = m->parent;
 134     if (unlikely(str == NULL || *str == '\0'))
 135         return "";
 136 #ifdef ENABLE_NLS
 137     const char *domain = m->domain;
 138     return dgettext ((domain != NULL) ? domain : PACKAGE_NAME, str);
 139 #else
 140     (void)m;
 141     return str;
 142 #endif
 143 }
 144
 145 #undef module_start
 146 int module_start (vlc_object_t *obj, const module_t *m)
 147 {
 148    int (*activate) (vlc_object_t *) = m->pf_activate;
 149
 150    return (activate != NULL) ? activate (obj) : VLC_SUCCESS;
 151 }
 152
 153 #undef module_stop
 154 void module_stop (vlc_object_t *obj, const module_t *m)
 155 {
 156    void (*deactivate) (vlc_object_t *) = m->pf_deactivate;
 157
 158     if (deactivate != NULL)
 159         deactivate (obj);
 160 }
 161
 162 typedef struct module_list_t
 163 {
 164     module_t *p_module;
 165     int16_t  i_score;
 166     bool     b_force;
 167 } module_list_t;
 168
 169 static int modulecmp (const void *a, const void *b)
 170 {
 171     const module_list_t *la = a, *lb = b;
 172     /* Note that qsort() uses _ascending_ order,
 173      * so the smallest module is the one with the biggest score. */
 174     return lb->i_score - la->i_score;
 175 }
 176
 177 #undef vlc_module_load
 178 /**
 179  * Finds and instantiates the best module of a certain type.
 180  * All candidates modules having the specified capability and name will be
 181  * sorted in decreasing order of priority. Then the probe callback will be
 182  * invoked for each module, until it succeeds (returns 0), or all candidate
 183  * module failed to initialize.
 184  *
 185  * The probe callback first parameter is the address of the module entry point.
 186  * Further parameters are passed as an argument list; it corresponds to the
 187  * variable arguments passed to this function. This scheme is meant to
 188  * support arbitrary prototypes for the module entry point.
 189  *
 190  * \param p_this VLC object
 191  * \param psz_capability capability, i.e. class of module
 192  * \param psz_name name name of the module asked, if any
 193  * \param b_strict if true, do not fallback to plugin with a different name
 194  *                 but the same capability
 195  * \param probe module probe callback
 196  * \return the module or NULL in case of a failure
 197  */
 198 module_t *vlc_module_load(vlc_object_t *p_this, const char *psz_capability,
 199                           const char *psz_name, bool b_strict,
 200                           vlc_activate_t probe, ...)
 201 {
 202     module_list_t *p_list;
 203     module_t *p_module;
 204     int i_shortcuts = 0;
 205     char *psz_shortcuts = NULL, *psz_var = NULL, *psz_alias = NULL;
 206     bool b_force_backup = p_this->b_force;
 207
 208     /* Deal with variables */
 209     if( psz_name && psz_name[0] == '$' )
 210     {
 211         psz_name = psz_var = var_CreateGetString( p_this, psz_name + 1 );
 212     }
 213
 214     /* Count how many different shortcuts were asked for */
 215     if( psz_name && *psz_name )
 216     {
 217         char *psz_parser, *psz_last_shortcut;
 218
 219         /* If the user wants none, give him none. */
 220         if( !strcmp( psz_name, "none" ) )
 221         {
 222             free( psz_var );
 223             return NULL;
 224         }
 225
 226         i_shortcuts++;
 227         psz_parser = psz_shortcuts = psz_last_shortcut = strdup( psz_name );
 228
 229         while( ( psz_parser = strchr( psz_parser, ',' ) ) )
 230         {
 231              *psz_parser = '\0';
 232              i_shortcuts++;
 233              psz_last_shortcut = ++psz_parser;
 234         }
 235
 236         /* Check if the user wants to override the "strict" mode */
 237         if( psz_last_shortcut )
 238         {
 239             if( !strcmp(psz_last_shortcut, "none") )
 240             {
 241                 b_strict = true;
 242                 i_shortcuts--;
 243             }
 244             else if( !strcmp(psz_last_shortcut, "any") )
 245             {
 246                 b_strict = false;
 247                 i_shortcuts--;
 248             }
 249         }
 250     }
 251
 252     /* Sort the modules and test them */
 253     size_t count;
 254     module_t **p_all = module_list_get (&count);
 255     p_list = malloc( count * sizeof( module_list_t ) );
 256
 257     /* Parse the module list for capabilities and probe each of them */
 258     count = 0;
 259     for (size_t i = 0; (p_module = p_all[i]) != NULL; i++)
 260     {
 261         int i_shortcut_bonus = 0;
 262
 263         /* Test that this module can do what we need */
 264         if( !module_provides( p_module, psz_capability ) )
 265             continue;
 266
 267         /* If we required a shortcut, check this plugin provides it. */
 268         if( i_shortcuts > 0 )
 269         {
 270             const char *name = psz_shortcuts;
 271
 272             for( unsigned i_short = i_shortcuts; i_short > 0; i_short-- )
 273             {
 274                 for( unsigned i = 0; i < p_module->i_shortcuts; i++ )
 275                 {
 276                     char *c;
 277                     if( ( c = strchr( name, '@' ) )
 278                         ? !strncasecmp( name, p_module->pp_shortcuts[i],
 279                                         c-name )
 280                         : !strcasecmp( name, p_module->pp_shortcuts[i] ) )
 281                     {
 282                         /* Found it */
 283                         if( c && c[1] )
 284                             psz_alias = c+1;
 285                         i_shortcut_bonus = i_short * 10000;
 286                         goto found_shortcut;
 287                     }
 288                 }
 289
 290                 /* Go to the next shortcut... This is so lame! */
 291                 name += strlen( name ) + 1;
 292             }
 293
 294             /* If we are in "strict" mode and we couldn't
 295              * find the module in the list of provided shortcuts,
 296              * then kick the bastard out of here!!! */
 297             if( b_strict )
 298                 continue;
 299         }
 300
 301         /* Trash <= 0 scored plugins (they can only be selected by shortcut) */
 302         if( p_module->i_score <= 0 )
 303             continue;
 304
 305 found_shortcut:
 306         /* Store this new module */
 307         p_list[count].p_module = p_module;
 308         p_list[count].i_score = p_module->i_score + i_shortcut_bonus;
 309         p_list[count].b_force = i_shortcut_bonus && b_strict;
 310         count++;
 311     }
 312
 313     /* We can release the list, interesting modules are held */
 314     module_list_free (p_all);
 315
 316     /* Sort candidates by descending score */
 317     qsort (p_list, count, sizeof (p_list[0]), modulecmp);
 318     msg_Dbg( p_this, "looking for %s module: %zu candidate%s", psz_capability,
 319              count, count == 1 ? "" : "s" );
 320
 321     /* Parse the linked list and use the first successful module */
 322     va_list args;
 323
 324     va_start(args, probe);
 325     p_module = NULL;
 326
 327     for (size_t i = 0; (i < count) && (p_module == NULL); i++)
 328     {
 329         module_t *p_cand = p_list[i].p_module;
 330
 331         if (module_Map (p_this, p_cand))
 332             continue;
 333         p_this->b_force = p_list[i].b_force;
 334
 335         int ret;
 336
 337         if (likely(p_cand->pf_activate != NULL))
 338         {
 339             va_list ap;
 340
 341             va_copy(ap, args);
 342             ret = probe(p_cand->pf_activate, ap);
 343             va_end(ap);
 344         }
 345         else
 346             ret = VLC_SUCCESS;
 347
 348         switch (ret)
 349         {
 350         case VLC_SUCCESS:
 351             /* good module! */
 352             p_module = p_cand;
 353             break;
 354
 355         case VLC_ETIMEOUT:
 356             /* good module, but aborted */
 357             break;
 358
 359         default: /* bad module */
 360             continue;
 361         }
 362     }
 363
 364     va_end (args);
 365     free( p_list );
 366     p_this->b_force = b_force_backup;
 367
 368     if( p_module != NULL )
 369     {
 370         msg_Dbg( p_this, "using %s module \"%s\"",
 371                  psz_capability, module_get_object(p_module) );
 372         vlc_object_set_name( p_this, psz_alias ? psz_alias
 373                                                : module_get_object(p_module) );
 374     }
 375     else if( count == 0 )
 376         msg_Dbg( p_this, "no %s module matched \"%s\"",
 377                  psz_capability, (psz_name && *psz_name) ? psz_name : "any" );
 378     else
 379         msg_Dbg( p_this, "no %s module matching \"%s\" could be loaded",
 380                   psz_capability, (psz_name && *psz_name) ? psz_name : "any" );
 381
 382     free( psz_shortcuts );
 383     free( psz_var );
 384
 385     /* Don't forget that the module is still locked */
 386     return p_module;
 387 }
 388
 389
 390 /**
 391  * Deinstantiates a module.
 392  * \param module the module pointer as returned by vlc_module_load()
 393  * \param deinit deactivation callback
 394  */
 395 void vlc_module_unload(module_t *module, vlc_deactivate_t deinit, ...)
 396 {
 397     if (module->pf_deactivate != NULL)
 398     {
 399         va_list ap;
 400
 401         va_start(ap, deinit);
 402         deinit(module->pf_deactivate, ap);
 403         va_end(ap);
 404     }
 405 }
 406
 407
 408 static int generic_start(void *func, va_list ap)
 409 {
 410     vlc_object_t *obj = va_arg(ap, vlc_object_t *);
 411     int (*activate)(vlc_object_t *) = func;
 412
 413     return activate(obj);
 414 }
 415
 416 static void generic_stop(void *func, va_list ap)
 417 {
 418     vlc_object_t *obj = va_arg(ap, vlc_object_t *);
 419     void (*deactivate)(vlc_object_t *) = func;
 420
 421     deactivate(obj);
 422 }
 423
 424 #undef module_need
 425 module_t *module_need(vlc_object_t *obj, const char *cap, const char *name,
 426                       bool strict)
 427 {
 428     return vlc_module_load(obj, cap, name, strict, generic_start, obj);
 429 }
 430
 431 #undef module_unneed
 432 void module_unneed(vlc_object_t *obj, module_t *module)
 433 {
 434     msg_Dbg(obj, "removing module \"%s\"", module_get_object(module));
 435     vlc_module_unload(module, generic_stop, obj);
 436 }
 437
 438 /**
 439  * Get a pointer to a module_t given it's name.
 440  *
 441  * \param name the name of the module
 442  * \return a pointer to the module or NULL in case of a failure
 443  */
 444 module_t *module_find (const char *name)
 445 {
 446     module_t **list, *module;
 447
 448     assert (name != NULL);
 449     list = module_list_get (NULL);
 450     if (!list)
 451         return NULL;
 452
 453     for (size_t i = 0; (module = list[i]) != NULL; i++)
 454     {
 455         if (unlikely(module->i_shortcuts == 0))
 456             continue;
 457         if (!strcmp (module->pp_shortcuts[0], name))
 458             break;
 459     }
 460     module_list_free (list);
 461     return module;
 462 }
 463
 464 /**
 465  * Tell if a module exists and release it in thic case
 466  *
 467  * \param psz_name th name of the module
 468  * \return TRUE if the module exists
 469  */
 470 bool module_exists (const char * psz_name)
 471 {
 472     return module_find (psz_name) != NULL;
 473 }
 474
 475 /**
 476  * Get a pointer to a module_t that matches a shortcut.
 477  * This is a temporary hack for SD. Do not re-use (generally multiple modules
 478  * can have the same shortcut, so this is *broken* - use module_need()!).
 479  *
 480  * \param psz_shortcut shortcut of the module
 481  * \param psz_cap capability of the module
 482  * \return a pointer to the module or NULL in case of a failure
 483  */
 484 module_t *module_find_by_shortcut (const char *psz_shortcut)
 485 {
 486     module_t **list, *module;
 487
 488     list = module_list_get (NULL);
 489     if (!list)
 490         return NULL;
 491
 492     for (size_t i = 0; (module = list[i]) != NULL; i++)
 493         for (size_t j = 0; j < module->i_shortcuts; j++)
 494             if (!strcmp (module->pp_shortcuts[j], psz_shortcut))
 495                 goto out;
 496 out:
 497     module_list_free (list);
 498     return module;
 499 }
 500
 501 /**
 502  * Get the configuration of a module
 503  *
 504  * \param module the module
 505  * \param psize the size of the configuration returned
 506  * \return the configuration as an array
 507  */
 508 module_config_t *module_config_get( const module_t *module, unsigned *restrict psize )
 509 {
 510     unsigned i,j;
 511     unsigned size = module->confsize;
 512     module_config_t *config = malloc( size * sizeof( *config ) );
 513
 514     assert( psize != NULL );
 515     *psize = 0;
 516
 517     if( !config )
 518         return NULL;
 519
 520     for( i = 0, j = 0; i < size; i++ )
 521     {
 522         const module_config_t *item = module->p_config + i;
 523         if( item->b_internal /* internal option */
 524          || item->b_removed /* removed option */ )
 525             continue;
 526
 527         memcpy( config + j, item, sizeof( *config ) );
 528         j++;
 529     }
 530     *psize = j;
 531
 532     return config;
 533 }
 534
 535 /**
 536  * Release the configuration
 537  *
 538  * \param the configuration
 539  * \return nothing
 540  */
 541 void module_config_free( module_config_t *config )
 542 {
 543     free( config );
 544 }