lua/ubus.c

   1 /*
   2  * Copyright (C) 2012 Jo-Philipp Wich <jow@openwrt.org>
   3  * Copyright (C) 2012 John Crispin <blogic@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <unistd.h>
  16 #include <libubus.h>
  17 #include <libubox/blobmsg.h>
  18 #include <libubox/blobmsg_json.h>
  19 #include <lauxlib.h>
  20 #include <lua.h>
  21
  22 #define MODNAME         "ubus"
  23 #define METANAME        MODNAME ".meta"
  24
  25 static lua_State *state;
  26
  27 struct ubus_lua_connection {
  28         int timeout;
  29         struct blob_buf buf;
  30         struct ubus_context *ctx;
  31 };
  32
  33 struct ubus_lua_object {
  34         struct ubus_object o;
  35         int r;
  36 };
  37
  38 struct ubus_lua_event {
  39         struct ubus_event_handler e;
  40         int r;
  41 };
  42
  43 static int
  44 ubus_lua_parse_blob(lua_State *L, struct blob_attr *attr, bool table);
  45
  46 static int
  47 ubus_lua_parse_blob_array(lua_State *L, struct blob_attr *attr, int len, bool table)
  48 {
  49         int rv;
  50         int idx = 1;
  51         int rem = len;
  52         struct blob_attr *pos;
  53
  54         lua_newtable(L);
  55
  56         __blob_for_each_attr(pos, attr, rem)
  57         {
  58                 rv = ubus_lua_parse_blob(L, pos, table);
  59
  60                 if (rv > 1)
  61                         lua_rawset(L, -3);
  62                 else if (rv > 0)
  63                         lua_rawseti(L, -2, idx++);
  64         }
  65
  66         return 1;
  67 }
  68
  69 static int
  70 ubus_lua_parse_blob(lua_State *L, struct blob_attr *attr, bool table)
  71 {
  72         int len;
  73         int off = 0;
  74         void *data;
  75
  76         if (!blobmsg_check_attr(attr, false))
  77                 return 0;
  78
  79         if (table && blobmsg_name(attr)[0])
  80         {
  81                 lua_pushstring(L, blobmsg_name(attr));
  82                 off++;
  83         }
  84
  85         data = blobmsg_data(attr);
  86         len = blobmsg_data_len(attr);
  87
  88         switch (blob_id(attr))
  89         {
  90         case BLOBMSG_TYPE_BOOL:
  91                 lua_pushboolean(L, *(uint8_t *)data);
  92                 break;
  93
  94         case BLOBMSG_TYPE_INT16:
  95                 lua_pushinteger(L, be16_to_cpu(*(uint16_t *)data));
  96                 break;
  97
  98         case BLOBMSG_TYPE_INT32:
  99                 lua_pushinteger(L, be32_to_cpu(*(uint32_t *)data));
 100                 break;
 101
 102         case BLOBMSG_TYPE_INT64:
 103                 lua_pushnumber(L, (double) be64_to_cpu(*(uint64_t *)data));
 104                 break;
 105
 106         case BLOBMSG_TYPE_STRING:
 107                 lua_pushstring(L, data);
 108                 break;
 109
 110         case BLOBMSG_TYPE_ARRAY:
 111                 ubus_lua_parse_blob_array(L, data, len, false);
 112                 break;
 113
 114         case BLOBMSG_TYPE_TABLE:
 115                 ubus_lua_parse_blob_array(L, data, len, true);
 116                 break;
 117
 118         default:
 119                 lua_pushnil(L);
 120                 break;
 121         }
 122
 123         return off + 1;
 124 }
 125
 126
 127 static bool
 128 ubus_lua_format_blob_is_array(lua_State *L)
 129 {
 130         lua_Integer prv = 0;
 131         lua_Integer cur = 0;
 132
 133         /* Find out whether table is array-like */
 134         for (lua_pushnil(L); lua_next(L, -2); lua_pop(L, 1))
 135         {
 136 #ifdef LUA_TINT
 137                 if (lua_type(L, -2) != LUA_TNUMBER && lua_type(L, -2) != LUA_TINT)
 138 #else
 139                 if (lua_type(L, -2) != LUA_TNUMBER)
 140 #endif
 141                 {
 142                         lua_pop(L, 2);
 143                         return false;
 144                 }
 145
 146                 cur = lua_tointeger(L, -2);
 147
 148                 if ((cur - 1) != prv)
 149                 {
 150                         lua_pop(L, 2);
 151                         return false;
 152                 }
 153
 154                 prv = cur;
 155         }
 156
 157         return true;
 158 }
 159
 160 static int
 161 ubus_lua_format_blob_array(lua_State *L, struct blob_buf *b, bool table);
 162
 163 static int
 164 ubus_lua_format_blob(lua_State *L, struct blob_buf *b, bool table)
 165 {
 166         void *c;
 167         bool rv = true;
 168         const char *key = table ? lua_tostring(L, -2) : NULL;
 169
 170         switch (lua_type(L, -1))
 171         {
 172         case LUA_TBOOLEAN:
 173                 blobmsg_add_u8(b, key, (uint8_t)lua_toboolean(L, -1));
 174                 break;
 175
 176 #ifdef LUA_TINT
 177         case LUA_TINT:
 178 #endif
 179         case LUA_TNUMBER:
 180                 blobmsg_add_u32(b, key, (uint32_t)lua_tointeger(L, -1));
 181                 break;
 182
 183         case LUA_TSTRING:
 184         case LUA_TUSERDATA:
 185         case LUA_TLIGHTUSERDATA:
 186                 blobmsg_add_string(b, key, lua_tostring(L, -1));
 187                 break;
 188
 189         case LUA_TTABLE:
 190                 if (ubus_lua_format_blob_is_array(L))
 191                 {
 192                         c = blobmsg_open_array(b, key);
 193                         rv = ubus_lua_format_blob_array(L, b, false);
 194                         blobmsg_close_array(b, c);
 195                 }
 196                 else
 197                 {
 198                         c = blobmsg_open_table(b, key);
 199                         rv = ubus_lua_format_blob_array(L, b, true);
 200                         blobmsg_close_table(b, c);
 201                 }
 202                 break;
 203
 204         default:
 205                 rv = false;
 206                 break;
 207         }
 208
 209         return rv;
 210 }
 211
 212 static int
 213 ubus_lua_format_blob_array(lua_State *L, struct blob_buf *b, bool table)
 214 {
 215         for (lua_pushnil(L); lua_next(L, -2); lua_pop(L, 1))
 216         {
 217                 if (!ubus_lua_format_blob(L, b, table))
 218                 {
 219                         lua_pop(L, 1);
 220                         return false;
 221                 }
 222         }
 223
 224         return true;
 225 }
 226
 227
 228 static int
 229 ubus_lua_connect(lua_State *L)
 230 {
 231         struct ubus_lua_connection *c;
 232         const char *sockpath = luaL_optstring(L, 1, NULL);
 233         int timeout = luaL_optint(L, 2, 30);
 234
 235         if ((c = lua_newuserdata(L, sizeof(*c))) != NULL &&
 236                 (c->ctx = ubus_connect(sockpath)) != NULL)
 237         {
 238                 ubus_add_uloop(c->ctx);
 239                 c->timeout = timeout;
 240                 memset(&c->buf, 0, sizeof(c->buf));
 241                 luaL_getmetatable(L, METANAME);
 242                 lua_setmetatable(L, -2);
 243                 return 1;
 244         }
 245
 246         /* NB: no errors from ubus_connect() yet */
 247         lua_pushnil(L);
 248         lua_pushinteger(L, UBUS_STATUS_UNKNOWN_ERROR);
 249         return 2;
 250 }
 251
 252
 253 static void
 254 ubus_lua_objects_cb(struct ubus_context *c, struct ubus_object_data *o, void *p)
 255 {
 256         lua_State *L = (lua_State *)p;
 257
 258         lua_pushstring(L, o->path);
 259         lua_rawseti(L, -2, lua_objlen(L, -2) + 1);
 260 }
 261
 262 static int
 263 ubus_lua_objects(lua_State *L)
 264 {
 265         int rv;
 266         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 267
 268         lua_newtable(L);
 269         rv = ubus_lookup(c->ctx, NULL, ubus_lua_objects_cb, L);
 270
 271         if (rv != UBUS_STATUS_OK)
 272         {
 273                 lua_pop(L, 1);
 274                 lua_pushnil(L);
 275                 lua_pushinteger(L, rv);
 276                 return 2;
 277         }
 278
 279         return 1;
 280 }
 281
 282 static int
 283 ubus_method_handler(struct ubus_context *ctx, struct ubus_object *obj,
 284                 struct ubus_request_data *req, const char *method,
 285                 struct blob_attr *msg)
 286 {
 287         struct ubus_lua_object *o = container_of(obj, struct ubus_lua_object, o);
 288
 289         lua_getglobal(state, "__ubus_cb");
 290         lua_rawgeti(state, -1, o->r);
 291         lua_getfield(state, -1, method);
 292         lua_remove(state, -2);
 293         lua_remove(state, -2);
 294
 295         if (lua_isfunction(state, -1)) {
 296                 lua_pushlightuserdata(state, req);
 297                 if (!msg)
 298                         lua_pushnil(state);
 299                 else
 300                         ubus_lua_parse_blob_array(state, blob_data(msg), blob_len(msg), true);
 301                 lua_call(state, 2, 0);
 302         } else
 303                 lua_pop(state, 1);
 304
 305         return 0;
 306 }
 307
 308 static int lua_gettablelen(lua_State *L, int index)
 309 {
 310         int cnt = 0;
 311
 312         lua_pushnil(L);
 313         index -= 1;
 314         while (lua_next(L, index) != 0) {
 315                 cnt++;
 316                 lua_pop(L, 1);
 317         }
 318
 319         return cnt;
 320 }
 321
 322 static int ubus_lua_reply(lua_State *L)
 323 {
 324         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 325         struct ubus_request_data *req;
 326
 327         luaL_checktype(L, 3, LUA_TTABLE);
 328         blob_buf_init(&c->buf, 0);
 329
 330         if (!ubus_lua_format_blob_array(L, &c->buf, true))
 331         {
 332                 lua_pushnil(L);
 333                 lua_pushinteger(L, UBUS_STATUS_INVALID_ARGUMENT);
 334                 return 2;
 335         }
 336
 337         req = lua_touserdata(L, 2);
 338         ubus_send_reply(c->ctx, req, c->buf.head);
 339
 340         return 0;
 341 }
 342
 343 static int ubus_lua_load_methods(lua_State *L, struct ubus_method *m)
 344 {
 345         struct blobmsg_policy *p;
 346         int plen;
 347         int pidx = 0;
 348
 349         /* get the function pointer */
 350         lua_pushinteger(L, 1);
 351         lua_gettable(L, -2);
 352
 353         /* get the policy table */
 354         lua_pushinteger(L, 2);
 355         lua_gettable(L, -3);
 356
 357         /* check if the method table is valid */
 358         if ((lua_type(L, -2) != LUA_TFUNCTION) ||
 359                         (lua_type(L, -1) != LUA_TTABLE) ||
 360                         lua_objlen(L, -1)) {
 361                 lua_pop(L, 2);
 362                 return 1;
 363         }
 364
 365         /* store function pointer */
 366         lua_pushvalue(L, -2);
 367         lua_setfield(L, -6, lua_tostring(L, -5));
 368
 369         m->name = lua_tostring(L, -4);
 370         m->handler = ubus_method_handler;
 371
 372         plen = lua_gettablelen(L, -1);
 373
 374         /* exit if policy table is empty */
 375         if (!plen) {
 376                 lua_pop(L, 2);
 377                 return 0;
 378         }
 379
 380         /* setup the policy pointers */
 381         p = malloc(sizeof(struct blobmsg_policy) * plen);
 382         memset(p, 0, sizeof(struct blobmsg_policy) * plen);
 383         m->policy = p;
 384         lua_pushnil(L);
 385         while (lua_next(L, -2) != 0) {
 386                 int val = lua_tointeger(L, -1);
 387
 388                 /* check if the policy is valid */
 389                 if ((lua_type(L, -2) != LUA_TSTRING) ||
 390                                 (lua_type(L, -1) != LUA_TNUMBER) ||
 391                                 (val < 0) ||
 392                                 (val > BLOBMSG_TYPE_LAST)) {
 393                         lua_pop(L, 1);
 394                         continue;
 395                 }
 396                 p[pidx].name = lua_tostring(L, -2);
 397                 p[pidx].type = val;
 398                 lua_pop(L, 1);
 399                 pidx++;
 400         }
 401
 402         m->n_policy = pidx;
 403         lua_pop(L, 2);
 404
 405         return 0;
 406 }
 407
 408 static struct ubus_object* ubus_lua_load_object(lua_State *L)
 409 {
 410         struct ubus_lua_object *obj = NULL;
 411         int mlen = lua_gettablelen(L, -1);
 412         struct ubus_method *m;
 413         int midx = 0;
 414
 415         /* setup object pointers */
 416         obj = malloc(sizeof(struct ubus_lua_object));
 417         memset(obj, 0, sizeof(struct ubus_lua_object));
 418         obj->o.name = lua_tostring(L, -2);
 419
 420         /* setup method pointers */
 421         m = malloc(sizeof(struct ubus_method) * mlen);
 422         memset(m, 0, sizeof(struct ubus_method) * mlen);
 423         obj->o.methods = m;
 424
 425         /* setup type pointers */
 426         obj->o.type = malloc(sizeof(struct ubus_object_type));
 427         memset(obj->o.type, 0, sizeof(struct ubus_object_type));
 428         obj->o.type->name = lua_tostring(L, -2);
 429         obj->o.type->id = 0;
 430         obj->o.type->methods = obj->o.methods;
 431
 432         /* create the callback lookup table */
 433         lua_createtable(L, 1, 0);
 434         lua_getglobal(L, "__ubus_cb");
 435         lua_pushvalue(L, -2);
 436         obj->r = luaL_ref(L, -2);
 437         lua_pop(L, 1);
 438
 439         /* scan each method */
 440         lua_pushnil(L);
 441         while (lua_next(L, -3) != 0) {
 442                 /* check if it looks like a method */
 443                 if ((lua_type(L, -2) != LUA_TSTRING) ||
 444                                 (lua_type(L, -1) != LUA_TTABLE) ||
 445                                 !lua_objlen(L, -1)) {
 446                         lua_pop(L, 1);
 447                         continue;
 448                 }
 449
 450                 if (!ubus_lua_load_methods(L, &m[midx]))
 451                         midx++;
 452                 lua_pop(L, 1);
 453         }
 454
 455         obj->o.type->n_methods = obj->o.n_methods = midx;
 456
 457         /* pop the callback table */
 458         lua_pop(L, 1);
 459
 460         return &obj->o;
 461 }
 462
 463 static int ubus_lua_add(lua_State *L)
 464 {
 465         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 466
 467         /* verify top level object */
 468         if (lua_istable(L, 1)) {
 469                 lua_pushstring(L, "you need to pass a table");
 470                 lua_error(L);
 471                 return 0;
 472         }
 473
 474         /* scan each object */
 475         lua_pushnil(L);
 476         while (lua_next(L, -2) != 0) {
 477                 struct ubus_object *obj = NULL;
 478
 479                 /* check if the object has a table of methods */
 480                 if ((lua_type(L, -2) == LUA_TSTRING) && (lua_type(L, -1) == LUA_TTABLE)) {
 481                         obj = ubus_lua_load_object(L);
 482
 483                         if (obj)
 484                                 ubus_add_object(c->ctx, obj);
 485                 }
 486                 lua_pop(L, 1);
 487         }
 488
 489         return 0;
 490 }
 491
 492 static void
 493 ubus_lua_signatures_cb(struct ubus_context *c, struct ubus_object_data *o, void *p)
 494 {
 495         lua_State *L = (lua_State *)p;
 496
 497         if (!o->signature)
 498                 return;
 499
 500         ubus_lua_parse_blob_array(L, blob_data(o->signature), blob_len(o->signature), true);
 501 }
 502
 503 static int
 504 ubus_lua_signatures(lua_State *L)
 505 {
 506         int rv;
 507         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 508         const char *path = luaL_checkstring(L, 2);
 509
 510         rv = ubus_lookup(c->ctx, path, ubus_lua_signatures_cb, L);
 511
 512         if (rv != UBUS_STATUS_OK)
 513         {
 514                 lua_pop(L, 1);
 515                 lua_pushnil(L);
 516                 lua_pushinteger(L, rv);
 517                 return 2;
 518         }
 519
 520         return 1;
 521 }
 522
 523
 524 static void
 525 ubus_lua_call_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 526 {
 527         lua_State *L = (lua_State *)req->priv;
 528
 529         if (!msg)
 530                 lua_pushnil(L);
 531
 532         ubus_lua_parse_blob_array(L, blob_data(msg), blob_len(msg), true);
 533 }
 534
 535 static int
 536 ubus_lua_call(lua_State *L)
 537 {
 538         int rv, top;
 539         uint32_t id;
 540         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 541         const char *path = luaL_checkstring(L, 2);
 542         const char *func = luaL_checkstring(L, 3);
 543
 544         luaL_checktype(L, 4, LUA_TTABLE);
 545         blob_buf_init(&c->buf, 0);
 546
 547         if (!ubus_lua_format_blob_array(L, &c->buf, true))
 548         {
 549                 lua_pushnil(L);
 550                 lua_pushinteger(L, UBUS_STATUS_INVALID_ARGUMENT);
 551                 return 2;
 552         }
 553
 554         rv = ubus_lookup_id(c->ctx, path, &id);
 555
 556         if (rv)
 557         {
 558                 lua_pushnil(L);
 559                 lua_pushinteger(L, rv);
 560                 return 2;
 561         }
 562
 563         top = lua_gettop(L);
 564         rv = ubus_invoke(c->ctx, id, func, c->buf.head, ubus_lua_call_cb, L, c->timeout * 1000);
 565
 566         if (rv != UBUS_STATUS_OK)
 567         {
 568                 lua_pop(L, 1);
 569                 lua_pushnil(L);
 570                 lua_pushinteger(L, rv);
 571                 return 2;
 572         }
 573
 574         return lua_gettop(L) - top;
 575 }
 576
 577 static void
 578 ubus_event_handler(struct ubus_context *ctx, struct ubus_event_handler *ev,
 579                         const char *type, struct blob_attr *msg)
 580 {
 581         struct ubus_lua_event *listener = container_of(ev, struct ubus_lua_event, e);
 582
 583         lua_getglobal(state, "__ubus_cb_event");
 584         lua_rawgeti(state, -1, listener->r);
 585
 586         if (lua_isfunction(state, -1)) {
 587                 ubus_lua_parse_blob_array(state, blob_data(msg), blob_len(msg), true);
 588                 lua_call(state, 1, 0);
 589         }
 590 }
 591
 592 static struct ubus_event_handler*
 593 ubus_lua_load_event(lua_State *L)
 594 {
 595         struct ubus_lua_event* event = NULL;
 596
 597         event = malloc(sizeof(struct ubus_lua_event));
 598         memset(event, 0, sizeof(struct ubus_lua_event));
 599         event->e.cb = ubus_event_handler;
 600
 601         /* update the he callback lookup table */
 602         lua_getglobal(L, "__ubus_cb_event");
 603         lua_pushvalue(L, -2);
 604         event->r = luaL_ref(L, -2);
 605         lua_setfield(L, -1, lua_tostring(L, -3));
 606
 607         return &event->e;
 608 }
 609
 610 static int
 611 ubus_lua_listen(lua_State *L) {
 612         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 613
 614         /* verify top level object */
 615         luaL_checktype(L, 2, LUA_TTABLE);
 616
 617         /* scan each object */
 618         lua_pushnil(L);
 619         while (lua_next(L, -2) != 0) {
 620                 struct ubus_event_handler *listener;
 621
 622                 /* check if the key is a string and the value is a method */
 623                 if ((lua_type(L, -2) == LUA_TSTRING) && (lua_type(L, -1) == LUA_TFUNCTION)) {
 624                         listener = ubus_lua_load_event(L);
 625                         if(listener != NULL) {
 626                                 ubus_register_event_handler(c->ctx, listener, lua_tostring(L, -2));
 627                         }
 628                 }
 629                 lua_pop(L, 1);
 630         }
 631         return 0;
 632 }
 633
 634 static int
 635 ubus_lua_send(lua_State *L)
 636 {
 637         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 638         const char *event = luaL_checkstring(L, 2);
 639
 640         if (*event == 0)
 641                 return luaL_argerror(L, 2, "no event name");
 642
 643         // Event content convert to ubus form
 644         luaL_checktype(L, 3, LUA_TTABLE);
 645         blob_buf_init(&c->buf, 0);
 646
 647         if (!ubus_lua_format_blob_array(L, &c->buf, true)) {
 648                 lua_pushnil(L);
 649                 lua_pushinteger(L, UBUS_STATUS_INVALID_ARGUMENT);
 650                 return 2;
 651         }
 652
 653         // Send the event
 654         ubus_send_event(c->ctx, event, c->buf.head);
 655
 656         return 0;
 657 }
 658
 659
 660
 661 static int
 662 ubus_lua__gc(lua_State *L)
 663 {
 664         struct ubus_lua_connection *c = luaL_checkudata(L, 1, METANAME);
 665
 666         if (c->ctx != NULL)
 667         {
 668                 ubus_free(c->ctx);
 669                 memset(c, 0, sizeof(*c));
 670         }
 671
 672         return 0;
 673 }
 674
 675 static const luaL_Reg ubus[] = {
 676         { "connect", ubus_lua_connect },
 677         { "objects", ubus_lua_objects },
 678         { "add", ubus_lua_add },
 679         { "reply", ubus_lua_reply },
 680         { "signatures", ubus_lua_signatures },
 681         { "call", ubus_lua_call },
 682         { "close", ubus_lua__gc },
 683         { "listen", ubus_lua_listen },
 684         { "send", ubus_lua_send },
 685         { "__gc", ubus_lua__gc },
 686         { NULL, NULL },
 687 };
 688
 689 /* avoid missing prototype warning */
 690 int luaopen_ubus(lua_State *L);
 691
 692 int
 693 luaopen_ubus(lua_State *L)
 694 {
 695         /* create metatable */
 696         luaL_newmetatable(L, METANAME);
 697
 698         /* metatable.__index = metatable */
 699         lua_pushvalue(L, -1);
 700         lua_setfield(L, -2, "__index");
 701
 702         /* fill metatable */
 703         luaL_register(L, NULL, ubus);
 704         lua_pop(L, 1);
 705
 706         /* create module */
 707         luaL_register(L, MODNAME, ubus);
 708
 709         /* set some enum defines */
 710         lua_pushinteger(L, BLOBMSG_TYPE_ARRAY);
 711         lua_setfield(L, -2, "ARRAY");
 712         lua_pushinteger(L, BLOBMSG_TYPE_TABLE);
 713         lua_setfield(L, -2, "TABLE");
 714         lua_pushinteger(L, BLOBMSG_TYPE_STRING);
 715         lua_setfield(L, -2, "STRING");
 716         lua_pushinteger(L, BLOBMSG_TYPE_INT64);
 717         lua_setfield(L, -2, "INT64");
 718         lua_pushinteger(L, BLOBMSG_TYPE_INT32);
 719         lua_setfield(L, -2, "INT32");
 720         lua_pushinteger(L, BLOBMSG_TYPE_INT16);
 721         lua_setfield(L, -2, "INT16");
 722         lua_pushinteger(L, BLOBMSG_TYPE_INT8);
 723         lua_setfield(L, -2, "INT8");
 724         lua_pushinteger(L, BLOBMSG_TYPE_BOOL);
 725         lua_setfield(L, -2, "BOOLEAN");
 726
 727         /* used in our callbacks */
 728         state = L;
 729
 730         /* create the callback table */
 731         lua_createtable(L, 1, 0);
 732         lua_setglobal(L, "__ubus_cb");
 733
 734         /* create the event table */
 735         lua_createtable(L, 1, 0);
 736         lua_setglobal(L, "__ubus_cb_event");
 737
 738         return 0;
 739 }