modules/lua/services_discovery.c

   1 /*****************************************************************************
   2  * services_discovery.c : Services discovery using lua scripts
   3  *****************************************************************************
   4  * Copyright (C) 2010 VideoLAN and AUTHORS
   5  *
   6  * Authors: Fabio Ritrovato <sephiroth87 at videolan dot org>
   7  *          Rémi Duraffort <ivoire at videolan -dot- org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include "config.h"
  26 #endif
  27
  28 #include <assert.h>
  29 #include <vlc_common.h>
  30 #include <vlc_services_discovery.h>
  31
  32 #include "vlc.h"
  33 #include "libs.h"
  34
  35 /*****************************************************************************
  36  * Local prototypes
  37  *****************************************************************************/
  38 static void *Run( void * );
  39 static int DoSearch( services_discovery_t *p_sd, const char *psz_query );
  40 static int FillDescriptor( services_discovery_t *, services_discovery_descriptor_t * );
  41 static int Control( services_discovery_t *p_sd, int i_command, va_list args );
  42
  43 // When successful, the returned string is stored on top of the lua
  44 // stack and remains valid as long as it is kept in the stack.
  45 static const char *vlclua_sd_description( vlc_object_t *obj, lua_State *L,
  46                                           const char *filename )
  47 {
  48     lua_getglobal( L, "descriptor" );
  49     if( !lua_isfunction( L, -1 ) )
  50     {
  51         msg_Warn( obj, "No 'descriptor' function in '%s'", filename );
  52         lua_pop( L, 1 );
  53         return NULL;
  54     }
  55
  56     if( lua_pcall( L, 0, 1, 0 ) )
  57     {
  58         msg_Warn( obj, "Error while running script %s, "
  59                   "function descriptor(): %s", filename,
  60                   lua_tostring( L, -1 ) );
  61         lua_pop( L, 1 );
  62         return NULL;
  63     }
  64
  65     lua_getfield( L, -1, "title" );
  66     if ( !lua_isstring( L, -1 ) )
  67     {
  68         msg_Warn( obj, "'descriptor' function in '%s' returned no title",
  69                   filename );
  70         lua_pop( L, 2 );
  71         return NULL;
  72     }
  73
  74     return lua_tostring( L, -1 );
  75 }
  76
  77 int vlclua_probe_sd( vlc_object_t *obj, const char *name )
  78 {
  79     vlc_probe_t *probe = (vlc_probe_t *)obj;
  80
  81     char *filename = vlclua_find_file( "sd", name );
  82     if( filename == NULL )
  83     {
  84         // File suddenly disappeared - maybe a race condition, no problem
  85         msg_Err( probe, "Couldn't probe lua services discovery script \"%s\".",
  86                  name );
  87         return VLC_PROBE_CONTINUE;
  88     }
  89
  90     lua_State *L = luaL_newstate();
  91     if( !L )
  92     {
  93         msg_Err( probe, "Could not create new Lua State" );
  94         free( filename );
  95         return VLC_ENOMEM;
  96     }
  97     luaL_openlibs( L );
  98     if( vlclua_add_modules_path( L, filename ) )
  99     {
 100         msg_Err( probe, "Error while setting the module search path for %s",
 101                  filename );
 102         lua_close( L );
 103         free( filename );
 104         return VLC_ENOMEM;
 105     }
 106     if( vlclua_dofile( obj, L, filename ) )
 107     {
 108         msg_Err( probe, "Error loading script %s: %s", filename,
 109                  lua_tostring( L, -1 ) );
 110         lua_close( L );
 111         free( filename );
 112         return VLC_PROBE_CONTINUE;
 113     }
 114     const char *description = vlclua_sd_description( obj, L, filename );
 115     if( description == NULL )
 116         description = name;
 117
 118     int r = VLC_ENOMEM;
 119     char *name_esc = config_StringEscape( name );
 120     char *chain;
 121     if( asprintf( &chain, "lua{sd='%s'}", name_esc ) != -1 )
 122     {
 123         r = vlc_sd_probe_Add( probe, chain, description, SD_CAT_INTERNET );
 124         free( chain );
 125     }
 126     free( name_esc );
 127
 128     lua_close( L );
 129     free( filename );
 130     return r;
 131 }
 132
 133 static const char * const ppsz_sd_options[] = { "sd", NULL };
 134
 135 /*****************************************************************************
 136  * Local structures
 137  *****************************************************************************/
 138 struct services_discovery_sys_t
 139 {
 140     lua_State *L;
 141     char *psz_filename;
 142
 143     vlc_thread_t thread;
 144     vlc_mutex_t lock;
 145     vlc_cond_t cond;
 146
 147     char **ppsz_query;
 148     int i_query;
 149 };
 150 static const luaL_Reg p_reg[] = { { NULL, NULL } };
 151
 152 /*****************************************************************************
 153  * Open: initialize and create stuff
 154  *****************************************************************************/
 155 int Open_LuaSD( vlc_object_t *p_this )
 156 {
 157     if( lua_Disabled( p_this ) )
 158         return VLC_EGENERIC;
 159
 160     services_discovery_t *p_sd = ( services_discovery_t * )p_this;
 161     services_discovery_sys_t *p_sys;
 162     lua_State *L = NULL;
 163     char *psz_name;
 164
 165     if( !( p_sys = malloc( sizeof( services_discovery_sys_t ) ) ) )
 166         return VLC_ENOMEM;
 167
 168     if( !strcmp( p_sd->psz_name, "lua" ) ||
 169         !strcmp( p_sd->psz_name, "luasd" ) )
 170     {
 171         // We want to load the module name "lua"
 172         // This module can be used to load lua script not registered
 173         // as builtin lua SD modules.
 174         config_ChainParse( p_sd, "lua-", ppsz_sd_options, p_sd->p_cfg );
 175         psz_name = var_GetString( p_sd, "lua-sd" );
 176     }
 177     else
 178     {
 179         // We are loading a builtin lua sd module.
 180         psz_name = strdup(p_sd->psz_name);
 181     }
 182
 183     p_sd->p_sys = p_sys;
 184     p_sd->pf_control = Control;
 185     p_sys->psz_filename = vlclua_find_file( "sd", psz_name );
 186     if( !p_sys->psz_filename )
 187     {
 188         msg_Err( p_sd, "Couldn't find lua services discovery script \"%s\".",
 189                  psz_name );
 190         free( psz_name );
 191         goto error;
 192     }
 193     free( psz_name );
 194     L = luaL_newstate();
 195     if( !L )
 196     {
 197         msg_Err( p_sd, "Could not create new Lua State" );
 198         goto error;
 199     }
 200     vlclua_set_this( L, p_sd );
 201     luaL_openlibs( L );
 202     luaL_register_namespace( L, "vlc", p_reg );
 203     luaopen_input( L );
 204     luaopen_msg( L );
 205     luaopen_object( L );
 206     luaopen_sd_sd( L );
 207     luaopen_strings( L );
 208     luaopen_variables( L );
 209     luaopen_stream( L );
 210     luaopen_gettext( L );
 211     luaopen_xml( L );
 212     lua_pop( L, 1 );
 213
 214     if( vlclua_add_modules_path( L, p_sys->psz_filename ) )
 215     {
 216         msg_Warn( p_sd, "Error while setting the module search path for %s",
 217                   p_sys->psz_filename );
 218         goto error;
 219     }
 220     if( vlclua_dofile( VLC_OBJECT(p_sd), L, p_sys->psz_filename ) )
 221     {
 222         msg_Err( p_sd, "Error loading script %s: %s", p_sys->psz_filename,
 223                   lua_tostring( L, lua_gettop( L ) ) );
 224         lua_pop( L, 1 );
 225         goto error;
 226     }
 227
 228     // No strdup(), just don't remove the string from the lua stack
 229     p_sd->description = vlclua_sd_description( VLC_OBJECT(p_sd), L,
 230                                                p_sys->psz_filename );
 231     if( p_sd->description == NULL )
 232         p_sd->description = p_sd->psz_name;
 233
 234     p_sys->L = L;
 235     vlc_mutex_init( &p_sys->lock );
 236     vlc_cond_init( &p_sys->cond );
 237     TAB_INIT( p_sys->i_query, p_sys->ppsz_query );
 238
 239     if( vlc_clone( &p_sys->thread, Run, p_sd, VLC_THREAD_PRIORITY_LOW ) )
 240     {
 241         TAB_CLEAN( p_sys->i_query, p_sys->ppsz_query );
 242         vlc_cond_destroy( &p_sys->cond );
 243         vlc_mutex_destroy( &p_sys->lock );
 244         goto error;
 245     }
 246     return VLC_SUCCESS;
 247
 248 error:
 249     if( L )
 250         lua_close( L );
 251     free( p_sys->psz_filename );
 252     free( p_sys );
 253     return VLC_EGENERIC;
 254 }
 255
 256 /*****************************************************************************
 257  * Close: cleanup
 258  *****************************************************************************/
 259 void Close_LuaSD( vlc_object_t *p_this )
 260 {
 261     services_discovery_t *p_sd = ( services_discovery_t * )p_this;
 262     services_discovery_sys_t *p_sys = p_sd->p_sys;
 263
 264     vlc_cancel( p_sys->thread );
 265     vlc_join( p_sys->thread, NULL );
 266
 267     for( int i = 0; i < p_sys->i_query; i++ )
 268         free( p_sys->ppsz_query[i] );
 269     TAB_CLEAN( p_sys->i_query, p_sys->ppsz_query );
 270
 271     vlc_cond_destroy( &p_sys->cond );
 272     vlc_mutex_destroy( &p_sys->lock );
 273     free( p_sys->psz_filename );
 274     lua_close( p_sys->L );
 275     free( p_sys );
 276 }
 277
 278 /*****************************************************************************
 279  * Run: Thread entry-point
 280  ****************************************************************************/
 281 static void* Run( void *data )
 282 {
 283     services_discovery_t *p_sd = ( services_discovery_t * )data;
 284     services_discovery_sys_t *p_sys = p_sd->p_sys;
 285     lua_State *L = p_sys->L;
 286
 287     int cancel = vlc_savecancel();
 288
 289     lua_getglobal( L, "main" );
 290     if( !lua_isfunction( L, lua_gettop( L ) ) || lua_pcall( L, 0, 1, 0 ) )
 291     {
 292         msg_Err( p_sd, "Error while running script %s, "
 293                   "function main(): %s", p_sys->psz_filename,
 294                   lua_tostring( L, lua_gettop( L ) ) );
 295         lua_pop( L, 1 );
 296         vlc_restorecancel( cancel );
 297         return NULL;
 298     }
 299     msg_Dbg( p_sd, "LuaSD script loaded: %s", p_sys->psz_filename );
 300
 301     /* Force garbage collection, because the core will keep the SD
 302      * open, but lua will never gc until lua_close(). */
 303     lua_gc( L, LUA_GCCOLLECT, 0 );
 304
 305     vlc_restorecancel( cancel );
 306
 307     /* Main loop to handle search requests */
 308     vlc_mutex_lock( &p_sys->lock );
 309     mutex_cleanup_push( &p_sys->lock );
 310     for( ;; )
 311     {
 312         /* Wait for a request */
 313         if( !p_sys->i_query )
 314         {
 315             vlc_cond_wait( &p_sys->cond, &p_sys->lock );
 316             continue;
 317         }
 318
 319         /* Execute one query (protected against cancellation) */
 320         char *psz_query = p_sys->ppsz_query[p_sys->i_query - 1];
 321         TAB_ERASE(p_sys->i_query, p_sys->ppsz_query, p_sys->i_query - 1);
 322         vlc_mutex_unlock( &p_sys->lock );
 323
 324         cancel = vlc_savecancel();
 325         DoSearch( p_sd, psz_query );
 326         free( psz_query );
 327         /* Force garbage collection, because the core will keep the SD
 328          * open, but lua will never gc until lua_close(). */
 329         lua_gc( L, LUA_GCCOLLECT, 0 );
 330         vlc_restorecancel( cancel );
 331
 332         vlc_mutex_lock( &p_sys->lock );
 333     }
 334     vlc_cleanup_pop();
 335     vlc_assert_unreachable();
 336 }
 337
 338 /*****************************************************************************
 339  * Control: services discrovery control
 340  ****************************************************************************/
 341 static int Control( services_discovery_t *p_sd, int i_command, va_list args )
 342 {
 343     services_discovery_sys_t *p_sys = p_sd->p_sys;
 344
 345     switch( i_command )
 346     {
 347     case SD_CMD_SEARCH:
 348     {
 349         const char *psz_query = va_arg( args, const char * );
 350         vlc_mutex_lock( &p_sys->lock );
 351         TAB_APPEND( p_sys->i_query, p_sys->ppsz_query, strdup( psz_query ) );
 352         vlc_cond_signal( &p_sys->cond );
 353         vlc_mutex_unlock( &p_sys->lock );
 354         break;
 355     }
 356
 357     case SD_CMD_DESCRIPTOR:
 358     {
 359         services_discovery_descriptor_t *p_desc = va_arg( args,
 360                                 services_discovery_descriptor_t * );
 361         return FillDescriptor( p_sd, p_desc );
 362     }
 363     }
 364
 365     return VLC_SUCCESS;
 366 }
 367
 368 /*****************************************************************************
 369  * DoSearch: search for a given query
 370  ****************************************************************************/
 371 static int DoSearch( services_discovery_t *p_sd, const char *psz_query )
 372 {
 373     services_discovery_sys_t *p_sys = p_sd->p_sys;
 374     lua_State *L = p_sys->L;
 375
 376     /* Lookup for the 'search' function */
 377     lua_getglobal( L, "search" );
 378     if( !lua_isfunction( L, lua_gettop( L ) ) )
 379     {
 380         msg_Err( p_sd, "The script '%s' does not define any 'search' function",
 381                  p_sys->psz_filename );
 382         lua_pop( L, 1 );
 383         return VLC_EGENERIC;
 384     }
 385
 386     /* Push the query */
 387     lua_pushstring( L, psz_query );
 388
 389     /* Call the 'search' function */
 390     if( lua_pcall( L, 1, 0, 0 ) )
 391     {
 392         msg_Err( p_sd, "Error while running the script '%s': %s",
 393                  p_sys->psz_filename, lua_tostring( L, lua_gettop( L ) ) );
 394         lua_pop( L, 1 );
 395         return VLC_EGENERIC;
 396     }
 397
 398     return VLC_SUCCESS;
 399 }
 400
 401 /** List of capabilities */
 402 static const char *const ppsz_capabilities[] = {
 403     "search",
 404     NULL
 405 };
 406
 407 /*****************************************************************************
 408  * FillDescriptor: call the descriptor function and fill the structure
 409  ****************************************************************************/
 410 static int FillDescriptor( services_discovery_t *p_sd,
 411                            services_discovery_descriptor_t *p_desc )
 412 {
 413     services_discovery_sys_t *p_sys = p_sd->p_sys;
 414     int i_ret = VLC_EGENERIC;
 415
 416     /* Create a new lua thread */
 417     lua_State *L = luaL_newstate();
 418
 419     if( vlclua_dofile( VLC_OBJECT(p_sd), L, p_sys->psz_filename ) )
 420     {
 421         msg_Err( p_sd, "Error loading script %s: %s", p_sys->psz_filename,
 422                  lua_tostring( L, -1 ) );
 423         goto end;
 424     }
 425
 426     /* Call the "descriptor" function */
 427     lua_getglobal( L, "descriptor" );
 428     if( !lua_isfunction( L, -1 ) || lua_pcall( L, 0, 1, 0 ) )
 429     {
 430         msg_Warn( p_sd, "Error getting the descriptor in '%s': %s",
 431                   p_sys->psz_filename, lua_tostring( L, -1 ) );
 432         goto end;
 433     }
 434
 435     /* Get the different fields of the returned table */
 436     lua_getfield( L, -1, "short_description" );
 437     p_desc->psz_short_desc = luaL_strdupornull( L, -1 );
 438     lua_pop( L, 1 );
 439
 440     lua_getfield( L, -1, "icon" );
 441     p_desc->psz_icon_url = luaL_strdupornull( L, -1 );
 442     lua_pop( L, 1 );
 443
 444     lua_getfield( L, -1, "url" );
 445     p_desc->psz_url = luaL_strdupornull( L, -1 );
 446     lua_pop( L, 1 );
 447
 448     lua_getfield( L, -1, "capabilities" );
 449     p_desc->i_capabilities = 0;
 450     if( lua_istable( L, -1 ) )
 451     {
 452         /* List all table entries */
 453         lua_pushnil( L );
 454         while( lua_next( L, -2 ) != 0 )
 455         {
 456             /* Key is at index -2 and value at index -1 */
 457             const char *psz_cap = luaL_checkstring( L, -1 );
 458             int i_cap = 0;
 459             const char *psz_iter;
 460             for( psz_iter = *ppsz_capabilities; psz_iter;
 461                  psz_iter = ppsz_capabilities[ ++i_cap ] )
 462             {
 463                 if( !strcmp( psz_iter, psz_cap ) )
 464                 {
 465                     p_desc->i_capabilities |= 1 << i_cap;
 466                     break;
 467                 }
 468             }
 469
 470             lua_pop( L, 1 );
 471
 472             if( !psz_iter )
 473                 msg_Warn( p_sd, "Services discovery capability '%s' unknown in "
 474                                 "script '%s'", psz_cap, p_sys->psz_filename );
 475         }
 476     }
 477
 478     lua_pop( L, 1 );
 479     i_ret = VLC_SUCCESS;
 480
 481 end:
 482     lua_close( L );
 483     return i_ret;
 484
 485 }