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 #include <vlc_queue.h>
  32
  33 #include "vlc.h"
  34 #include "libs.h"
  35
  36 /*****************************************************************************
  37  * Local prototypes
  38  *****************************************************************************/
  39 static void *Run( void * );
  40 static int DoSearch( services_discovery_t *p_sd, const char *psz_query );
  41 static int FillDescriptor( services_discovery_t *, services_discovery_descriptor_t * );
  42 static int Control( services_discovery_t *p_sd, int i_command, va_list args );
  43
  44 // When successful, the returned string is stored on top of the lua
  45 // stack and remains valid as long as it is kept in the stack.
  46 static const char *vlclua_sd_description( vlc_object_t *obj, lua_State *L,
  47                                           const char *filename )
  48 {
  49     lua_getglobal( L, "descriptor" );
  50     if( !lua_isfunction( L, -1 ) )
  51     {
  52         msg_Warn( obj, "No 'descriptor' function in '%s'", filename );
  53         lua_pop( L, 1 );
  54         return NULL;
  55     }
  56
  57     if( lua_pcall( L, 0, 1, 0 ) )
  58     {
  59         msg_Warn( obj, "Error while running script %s, "
  60                   "function descriptor(): %s", filename,
  61                   lua_tostring( L, -1 ) );
  62         lua_pop( L, 1 );
  63         return NULL;
  64     }
  65
  66     lua_getfield( L, -1, "title" );
  67     if ( !lua_isstring( L, -1 ) )
  68     {
  69         msg_Warn( obj, "'descriptor' function in '%s' returned no title",
  70                   filename );
  71         lua_pop( L, 2 );
  72         return NULL;
  73     }
  74
  75     return lua_tostring( L, -1 );
  76 }
  77
  78 int vlclua_probe_sd( vlc_object_t *obj, const char *name )
  79 {
  80     vlc_probe_t *probe = (vlc_probe_t *)obj;
  81
  82     char *filename = vlclua_find_file( "sd", name );
  83     if( filename == NULL )
  84     {
  85         // File suddenly disappeared - maybe a race condition, no problem
  86         msg_Err( probe, "Couldn't probe lua services discovery script \"%s\".",
  87                  name );
  88         return VLC_PROBE_CONTINUE;
  89     }
  90
  91     lua_State *L = luaL_newstate();
  92     if( !L )
  93     {
  94         msg_Err( probe, "Could not create new Lua State" );
  95         free( filename );
  96         return VLC_ENOMEM;
  97     }
  98     luaL_openlibs( L );
  99     if( vlclua_add_modules_path( L, filename ) )
 100     {
 101         msg_Err( probe, "Error while setting the module search path for %s",
 102                  filename );
 103         lua_close( L );
 104         free( filename );
 105         return VLC_ENOMEM;
 106     }
 107     if( vlclua_dofile( obj, L, filename ) )
 108     {
 109         msg_Err( probe, "Error loading script %s: %s", filename,
 110                  lua_tostring( L, -1 ) );
 111         lua_close( L );
 112         free( filename );
 113         return VLC_PROBE_CONTINUE;
 114     }
 115     const char *description = vlclua_sd_description( obj, L, filename );
 116     if( description == NULL )
 117         description = name;
 118
 119     int r = VLC_ENOMEM;
 120     char *name_esc = config_StringEscape( name );
 121     char *chain;
 122     if( asprintf( &chain, "lua{sd='%s'}", name_esc ) != -1 )
 123     {
 124         r = vlc_sd_probe_Add( probe, chain, description, SD_CAT_INTERNET );
 125         free( chain );
 126     }
 127     free( name_esc );
 128
 129     lua_close( L );
 130     free( filename );
 131     return r;
 132 }
 133
 134 static const char * const ppsz_sd_options[] = { "sd", NULL };
 135
 136 /*****************************************************************************
 137  * Local structures
 138  *****************************************************************************/
 139 typedef struct
 140 {
 141     lua_State *L;
 142     char *psz_filename;
 143
 144     vlc_thread_t thread;
 145     vlc_queue_t queue;
 146     bool dead;
 147 } services_discovery_sys_t;
 148 static const luaL_Reg p_reg[] = { { NULL, NULL } };
 149
 150 struct sd_query
 151 {
 152     struct sd_query *next;
 153     char query[];
 154 };
 155
 156 /*****************************************************************************
 157  * Open: initialize and create stuff
 158  *****************************************************************************/
 159 int Open_LuaSD( vlc_object_t *p_this )
 160 {
 161     if( lua_Disabled( p_this ) )
 162         return VLC_EGENERIC;
 163
 164     services_discovery_t *p_sd = ( services_discovery_t * )p_this;
 165     services_discovery_sys_t *p_sys;
 166     lua_State *L = NULL;
 167     char *psz_name;
 168
 169     if( !( p_sys = malloc( sizeof( services_discovery_sys_t ) ) ) )
 170         return VLC_ENOMEM;
 171
 172     if( !strcmp( p_sd->psz_name, "lua" ) ||
 173         !strcmp( p_sd->psz_name, "luasd" ) )
 174     {
 175         // We want to load the module name "lua"
 176         // This module can be used to load lua script not registered
 177         // as builtin lua SD modules.
 178         config_ChainParse( p_sd, "lua-", ppsz_sd_options, p_sd->p_cfg );
 179         psz_name = var_GetString( p_sd, "lua-sd" );
 180     }
 181     else
 182     {
 183         // We are loading a builtin lua sd module.
 184         psz_name = strdup(p_sd->psz_name);
 185     }
 186
 187     p_sd->p_sys = p_sys;
 188     p_sd->pf_control = Control;
 189     p_sys->psz_filename = vlclua_find_file( "sd", psz_name );
 190     if( !p_sys->psz_filename )
 191     {
 192         msg_Err( p_sd, "Couldn't find lua services discovery script \"%s\".",
 193                  psz_name );
 194         free( psz_name );
 195         goto error;
 196     }
 197     free( psz_name );
 198     L = luaL_newstate();
 199     if( !L )
 200     {
 201         msg_Err( p_sd, "Could not create new Lua State" );
 202         goto error;
 203     }
 204     vlclua_set_this( L, p_sd );
 205     luaL_openlibs( L );
 206     luaL_register_namespace( L, "vlc", p_reg );
 207     luaopen_input( L );
 208     luaopen_msg( L );
 209     luaopen_object( L );
 210     luaopen_sd_sd( L );
 211     luaopen_strings( L );
 212     luaopen_variables( L );
 213     luaopen_stream( L );
 214     luaopen_gettext( L );
 215     luaopen_xml( L );
 216     lua_pop( L, 1 );
 217
 218     if( vlclua_add_modules_path( L, p_sys->psz_filename ) )
 219     {
 220         msg_Warn( p_sd, "Error while setting the module search path for %s",
 221                   p_sys->psz_filename );
 222         goto error;
 223     }
 224     if( vlclua_dofile( VLC_OBJECT(p_sd), L, p_sys->psz_filename ) )
 225     {
 226         msg_Err( p_sd, "Error loading script %s: %s", p_sys->psz_filename,
 227                   lua_tostring( L, lua_gettop( L ) ) );
 228         lua_pop( L, 1 );
 229         goto error;
 230     }
 231
 232     // No strdup(), just don't remove the string from the lua stack
 233     p_sd->description = vlclua_sd_description( VLC_OBJECT(p_sd), L,
 234                                                p_sys->psz_filename );
 235     if( p_sd->description == NULL )
 236         p_sd->description = p_sd->psz_name;
 237
 238     p_sys->L = L;
 239     p_sys->dead = false;
 240     vlc_queue_Init( &p_sys->queue, offsetof (struct sd_query, next) );
 241
 242     if( vlc_clone( &p_sys->thread, Run, p_sd, VLC_THREAD_PRIORITY_LOW ) )
 243     {
 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_queue_Kill( &p_sys->queue, &p_sys->dead );
 265     vlc_join( p_sys->thread, NULL );
 266     free( p_sys->psz_filename );
 267     lua_close( p_sys->L );
 268     free( p_sys );
 269 }
 270
 271 /*****************************************************************************
 272  * Run: Thread entry-point
 273  ****************************************************************************/
 274 static void* Run( void *data )
 275 {
 276     services_discovery_t *p_sd = ( services_discovery_t * )data;
 277     services_discovery_sys_t *p_sys = p_sd->p_sys;
 278     lua_State *L = p_sys->L;
 279
 280     lua_getglobal( L, "main" );
 281     if( !lua_isfunction( L, lua_gettop( L ) ) || lua_pcall( L, 0, 1, 0 ) )
 282     {
 283         msg_Err( p_sd, "Error while running script %s, "
 284                   "function main(): %s", p_sys->psz_filename,
 285                   lua_tostring( L, lua_gettop( L ) ) );
 286         lua_pop( L, 1 );
 287         return NULL;
 288     }
 289     msg_Dbg( p_sd, "LuaSD script loaded: %s", p_sys->psz_filename );
 290
 291     /* Force garbage collection, because the core will keep the SD
 292      * open, but lua will never gc until lua_close(). */
 293     lua_gc( L, LUA_GCCOLLECT, 0 );
 294
 295     /* Main loop to handle search requests */
 296     struct sd_query *query;
 297
 298     while( (query = vlc_queue_DequeueKillable( &p_sys->queue,
 299                                                &p_sys->dead )) != NULL )
 300     {
 301         /* Execute one query */
 302         DoSearch( p_sd, query->query );
 303         free( query );
 304         /* Force garbage collection, because the core will keep the SD
 305          * open, but lua will never gc until lua_close(). */
 306         lua_gc( L, LUA_GCCOLLECT, 0 );
 307     }
 308     return NULL;
 309 }
 310
 311 /*****************************************************************************
 312  * Control: services discrovery control
 313  ****************************************************************************/
 314 static int Control( services_discovery_t *p_sd, int i_command, va_list args )
 315 {
 316     services_discovery_sys_t *p_sys = p_sd->p_sys;
 317
 318     switch( i_command )
 319     {
 320     case SD_CMD_SEARCH:
 321     {
 322         const char *psz_query = va_arg( args, const char * );
 323         size_t len = strlen(psz_query) + 1;
 324         struct sd_query *query = malloc(sizeof (*query) + len);
 325
 326         if (unlikely(query == NULL))
 327             return VLC_ENOMEM;
 328
 329         query->next = NULL;
 330         memcpy(query->query, psz_query, len);
 331         vlc_queue_Enqueue(&p_sys->queue, query);
 332         break;
 333     }
 334
 335     case SD_CMD_DESCRIPTOR:
 336     {
 337         services_discovery_descriptor_t *p_desc = va_arg( args,
 338                                 services_discovery_descriptor_t * );
 339         return FillDescriptor( p_sd, p_desc );
 340     }
 341     }
 342
 343     return VLC_SUCCESS;
 344 }
 345
 346 /*****************************************************************************
 347  * DoSearch: search for a given query
 348  ****************************************************************************/
 349 static int DoSearch( services_discovery_t *p_sd, const char *psz_query )
 350 {
 351     services_discovery_sys_t *p_sys = p_sd->p_sys;
 352     lua_State *L = p_sys->L;
 353
 354     /* Lookup for the 'search' function */
 355     lua_getglobal( L, "search" );
 356     if( !lua_isfunction( L, lua_gettop( L ) ) )
 357     {
 358         msg_Err( p_sd, "The script '%s' does not define any 'search' function",
 359                  p_sys->psz_filename );
 360         lua_pop( L, 1 );
 361         return VLC_EGENERIC;
 362     }
 363
 364     /* Push the query */
 365     lua_pushstring( L, psz_query );
 366
 367     /* Call the 'search' function */
 368     if( lua_pcall( L, 1, 0, 0 ) )
 369     {
 370         msg_Err( p_sd, "Error while running the script '%s': %s",
 371                  p_sys->psz_filename, lua_tostring( L, lua_gettop( L ) ) );
 372         lua_pop( L, 1 );
 373         return VLC_EGENERIC;
 374     }
 375
 376     return VLC_SUCCESS;
 377 }
 378
 379 /** List of capabilities */
 380 static const char *const ppsz_capabilities[] = {
 381     "search",
 382     NULL
 383 };
 384
 385 /*****************************************************************************
 386  * FillDescriptor: call the descriptor function and fill the structure
 387  ****************************************************************************/
 388 static int FillDescriptor( services_discovery_t *p_sd,
 389                            services_discovery_descriptor_t *p_desc )
 390 {
 391     services_discovery_sys_t *p_sys = p_sd->p_sys;
 392     int i_ret = VLC_EGENERIC;
 393
 394     /* Create a new lua thread */
 395     lua_State *L = luaL_newstate();
 396
 397     if( vlclua_dofile( VLC_OBJECT(p_sd), L, p_sys->psz_filename ) )
 398     {
 399         msg_Err( p_sd, "Error loading script %s: %s", p_sys->psz_filename,
 400                  lua_tostring( L, -1 ) );
 401         goto end;
 402     }
 403
 404     /* Call the "descriptor" function */
 405     lua_getglobal( L, "descriptor" );
 406     if( !lua_isfunction( L, -1 ) || lua_pcall( L, 0, 1, 0 ) )
 407     {
 408         msg_Warn( p_sd, "Error getting the descriptor in '%s': %s",
 409                   p_sys->psz_filename, lua_tostring( L, -1 ) );
 410         goto end;
 411     }
 412
 413     /* Get the different fields of the returned table */
 414     lua_getfield( L, -1, "short_description" );
 415     p_desc->psz_short_desc = luaL_strdupornull( L, -1 );
 416     lua_pop( L, 1 );
 417
 418     lua_getfield( L, -1, "icon" );
 419     p_desc->psz_icon_url = luaL_strdupornull( L, -1 );
 420     lua_pop( L, 1 );
 421
 422     lua_getfield( L, -1, "url" );
 423     p_desc->psz_url = luaL_strdupornull( L, -1 );
 424     lua_pop( L, 1 );
 425
 426     lua_getfield( L, -1, "capabilities" );
 427     p_desc->i_capabilities = 0;
 428     if( lua_istable( L, -1 ) )
 429     {
 430         /* List all table entries */
 431         lua_pushnil( L );
 432         while( lua_next( L, -2 ) != 0 )
 433         {
 434             /* Key is at index -2 and value at index -1 */
 435             const char *psz_cap = luaL_checkstring( L, -1 );
 436             int i_cap = 0;
 437             const char *psz_iter;
 438             for( psz_iter = *ppsz_capabilities; psz_iter;
 439                  psz_iter = ppsz_capabilities[ ++i_cap ] )
 440             {
 441                 if( !strcmp( psz_iter, psz_cap ) )
 442                 {
 443                     p_desc->i_capabilities |= 1 << i_cap;
 444                     break;
 445                 }
 446             }
 447
 448             lua_pop( L, 1 );
 449
 450             if( !psz_iter )
 451                 msg_Warn( p_sd, "Services discovery capability '%s' unknown in "
 452                                 "script '%s'", psz_cap, p_sys->psz_filename );
 453         }
 454     }
 455
 456     lua_pop( L, 1 );
 457     i_ret = VLC_SUCCESS;
 458
 459 end:
 460     lua_close( L );
 461     return i_ret;
 462
 463 }