list.c

   1 /*
   2  * libuci - Library for the Unified Configuration Interface
   3  * Copyright (C) 2008 Felix Fietkau <nbd@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 /* initialize a list head/item */
  16 static inline void uci_list_init(struct uci_list *ptr)
  17 {
  18         ptr->prev = ptr;
  19         ptr->next = ptr;
  20 }
  21
  22 /* inserts a new list entry after a given entry */
  23 static inline void uci_list_insert(struct uci_list *list, struct uci_list *ptr)
  24 {
  25         list->next->prev = ptr;
  26         ptr->prev = list;
  27         ptr->next = list->next;
  28         list->next = ptr;
  29 }
  30
  31 /* inserts a new list entry at the tail of the list */
  32 static inline void uci_list_add(struct uci_list *head, struct uci_list *ptr)
  33 {
  34         /* NB: head->prev points at the tail */
  35         uci_list_insert(head->prev, ptr);
  36 }
  37
  38 static inline void uci_list_del(struct uci_list *ptr)
  39 {
  40         struct uci_list *next, *prev;
  41
  42         next = ptr->next;
  43         prev = ptr->prev;
  44
  45         prev->next = next;
  46         next->prev = prev;
  47
  48         uci_list_init(ptr);
  49 }
  50
  51 /*
  52  * uci_alloc_generic allocates a new uci_element with payload
  53  * payload is appended to the struct to save memory and reduce fragmentation
  54  */
  55 static struct uci_element *
  56 uci_alloc_generic(struct uci_context *ctx, int type, const char *name, int size)
  57 {
  58         struct uci_element *e;
  59         int datalen = size;
  60         void *ptr;
  61
  62         ptr = uci_malloc(ctx, datalen);
  63         e = (struct uci_element *) ptr;
  64         e->type = type;
  65         if (name) {
  66                 UCI_TRAP_SAVE(ctx, error);
  67                 e->name = uci_strdup(ctx, name);
  68                 UCI_TRAP_RESTORE(ctx);
  69         }
  70         uci_list_init(&e->list);
  71         goto done;
  72
  73 error:
  74         free(ptr);
  75         UCI_THROW(ctx, ctx->err);
  76
  77 done:
  78         return e;
  79 }
  80
  81 static void
  82 uci_free_element(struct uci_element *e)
  83 {
  84         if (e->name)
  85                 free(e->name);
  86         if (!uci_list_empty(&e->list))
  87                 uci_list_del(&e->list);
  88         free(e);
  89 }
  90
  91 static struct uci_option *
  92 uci_alloc_option(struct uci_section *s, const char *name, const char *value)
  93 {
  94         struct uci_package *p = s->package;
  95         struct uci_context *ctx = p->ctx;
  96         struct uci_option *o;
  97
  98         o = uci_alloc_element(ctx, option, name, strlen(value) + 1);
  99         o->type = UCI_TYPE_STRING;
 100         o->v.string = uci_dataptr(o);
 101         o->section = s;
 102         strcpy(o->v.string, value);
 103         uci_list_add(&s->options, &o->e.list);
 104
 105         return o;
 106 }
 107
 108 static inline void
 109 uci_free_option(struct uci_option *o)
 110 {
 111         struct uci_element *e, *tmp;
 112
 113         switch(o->type) {
 114         case UCI_TYPE_STRING:
 115                 if ((o->v.string != uci_dataptr(o)) &&
 116                         (o->v.string != NULL))
 117                         free(o->v.string);
 118                 break;
 119         case UCI_TYPE_LIST:
 120                 uci_foreach_element_safe(&o->v.list, tmp, e) {
 121                         uci_free_element(e);
 122                 }
 123                 break;
 124         default:
 125                 break;
 126         }
 127         uci_free_element(&o->e);
 128 }
 129
 130 static struct uci_option *
 131 uci_alloc_list(struct uci_section *s, const char *name)
 132 {
 133         struct uci_package *p = s->package;
 134         struct uci_context *ctx = p->ctx;
 135         struct uci_option *o;
 136
 137         o = uci_alloc_element(ctx, option, name, 0);
 138         o->type = UCI_TYPE_LIST;
 139         o->section = s;
 140         uci_list_init(&o->v.list);
 141         uci_list_add(&s->options, &o->e.list);
 142
 143         return o;
 144 }
 145
 146 /* fix up an unnamed section, e.g. after adding options to it */
 147 static void uci_fixup_section(struct uci_context *ctx, struct uci_section *s)
 148 {
 149         unsigned int hash = ~0;
 150         struct uci_element *e;
 151         char buf[16];
 152
 153         if (!s || s->e.name)
 154                 return;
 155
 156         /*
 157          * Generate a name for unnamed sections. This is used as reference
 158          * when locating or updating the section from apps/scripts.
 159          * To make multiple concurrent versions somewhat safe for updating,
 160          * the name is generated from a hash of its type and name/value
 161          * pairs of its option, and it is prefixed by a counter value.
 162          * If the order of the unnamed sections changes for some reason,
 163          * updates to them will be rejected.
 164          */
 165         hash = djbhash(hash, s->type);
 166         uci_foreach_element(&s->options, e) {
 167                 struct uci_option *o;
 168                 hash = djbhash(hash, e->name);
 169                 o = uci_to_option(e);
 170                 switch(o->type) {
 171                 case UCI_TYPE_STRING:
 172                         hash = djbhash(hash, o->v.string);
 173                         break;
 174                 default:
 175                         break;
 176                 }
 177         }
 178         sprintf(buf, "cfg%02x%04x", ++s->package->n_section, hash % (1 << 16));
 179         s->e.name = uci_strdup(ctx, buf);
 180 }
 181
 182 static struct uci_section *
 183 uci_alloc_section(struct uci_package *p, const char *type, const char *name)
 184 {
 185         struct uci_context *ctx = p->ctx;
 186         struct uci_section *s;
 187
 188         if (name && !name[0])
 189                 name = NULL;
 190
 191         s = uci_alloc_element(ctx, section, name, strlen(type) + 1);
 192         uci_list_init(&s->options);
 193         s->type = uci_dataptr(s);
 194         s->package = p;
 195         strcpy(s->type, type);
 196         if (name == NULL)
 197                 s->anonymous = true;
 198         p->n_section++;
 199
 200         uci_list_add(&p->sections, &s->e.list);
 201
 202         return s;
 203 }
 204
 205 static void
 206 uci_free_section(struct uci_section *s)
 207 {
 208         struct uci_element *o, *tmp;
 209
 210         uci_foreach_element_safe(&s->options, tmp, o) {
 211                 uci_free_option(uci_to_option(o));
 212         }
 213         if ((s->type != uci_dataptr(s)) &&
 214                 (s->type != NULL))
 215                 free(s->type);
 216         uci_free_element(&s->e);
 217 }
 218
 219 __plugin struct uci_package *
 220 uci_alloc_package(struct uci_context *ctx, const char *name)
 221 {
 222         struct uci_package *p;
 223
 224         p = uci_alloc_element(ctx, package, name, 0);
 225         p->ctx = ctx;
 226         uci_list_init(&p->sections);
 227         uci_list_init(&p->history);
 228         uci_list_init(&p->saved_history);
 229         return p;
 230 }
 231
 232 static void
 233 uci_free_package(struct uci_package **package)
 234 {
 235         struct uci_element *e, *tmp;
 236         struct uci_package *p = *package;
 237
 238         if(!p)
 239                 return;
 240
 241         if (p->path)
 242                 free(p->path);
 243         uci_foreach_element_safe(&p->sections, tmp, e) {
 244                 uci_free_section(uci_to_section(e));
 245         }
 246         uci_foreach_element_safe(&p->history, tmp, e) {
 247                 uci_free_history(uci_to_history(e));
 248         }
 249         uci_foreach_element_safe(&p->saved_history, tmp, e) {
 250                 uci_free_history(uci_to_history(e));
 251         }
 252         uci_free_element(&p->e);
 253         *package = NULL;
 254 }
 255
 256 static void
 257 uci_free_any(struct uci_element **e)
 258 {
 259         switch((*e)->type) {
 260         case UCI_TYPE_SECTION:
 261                 uci_free_section(uci_to_section(*e));
 262                 break;
 263         case UCI_TYPE_OPTION:
 264                 uci_free_option(uci_to_option(*e));
 265                 break;
 266         default:
 267                 break;
 268         }
 269         *e = NULL;
 270 }
 271
 272 static struct uci_element *uci_lookup_list(struct uci_list *list, const char *name)
 273 {
 274         struct uci_element *e;
 275
 276         uci_foreach_element(list, e) {
 277                 if (!strcmp(e->name, name))
 278                         return e;
 279         }
 280         return NULL;
 281 }
 282
 283 static struct uci_element *uci_lookup_ext_section(struct uci_context *ctx, struct uci_ptr *ptr)
 284 {
 285         char *idxstr, *t, *section, *name;
 286         struct uci_element *e = NULL;
 287         struct uci_section *s;
 288         int idx, c;
 289
 290         section = uci_strdup(ctx, ptr->section);
 291         name = idxstr = section + 1;
 292
 293         if (section[0] != '@')
 294                 goto error;
 295
 296         /* parse the section index part */
 297         idxstr = strchr(idxstr, '[');
 298         if (!idxstr)
 299                 goto error;
 300         *idxstr = 0;
 301         idxstr++;
 302
 303         t = strchr(idxstr, ']');
 304         if (!t)
 305                 goto error;
 306         if (t[1] != 0)
 307                 goto error;
 308         *t = 0;
 309
 310         t = NULL;
 311         idx = strtol(idxstr, &t, 10);
 312         if (t && *t)
 313                 goto error;
 314
 315         if (!*name)
 316                 name = NULL;
 317         else if (!uci_validate_str(name, false))
 318                 goto error;
 319
 320         /* if the given index is negative, it specifies the section number from
 321          * the end of the list */
 322         if (idx < 0) {
 323                 c = 0;
 324                 uci_foreach_element(&ptr->p->sections, e) {
 325                         s = uci_to_section(e);
 326                         if (name && (strcmp(s->type, name) != 0))
 327                                 continue;
 328
 329                         c++;
 330                 }
 331                 idx += c;
 332         }
 333
 334         c = 0;
 335         uci_foreach_element(&ptr->p->sections, e) {
 336                 s = uci_to_section(e);
 337                 if (name && (strcmp(s->type, name) != 0))
 338                         continue;
 339
 340                 if (idx == c)
 341                         goto done;
 342                 c++;
 343         }
 344         e = NULL;
 345         goto done;
 346
 347 error:
 348         e = NULL;
 349         memset(ptr, 0, sizeof(struct uci_ptr));
 350         UCI_THROW(ctx, UCI_ERR_INVAL);
 351 done:
 352         free(section);
 353         return e;
 354 }
 355
 356 int uci_lookup_ptr(struct uci_context *ctx, struct uci_ptr *ptr, char *str, bool extended)
 357 {
 358         struct uci_element *e;
 359
 360         UCI_HANDLE_ERR(ctx);
 361         UCI_ASSERT(ctx, ptr != NULL);
 362
 363         if (str)
 364                 UCI_INTERNAL(uci_parse_ptr, ctx, ptr, str);
 365
 366         ptr->flags |= UCI_LOOKUP_DONE;
 367
 368         /* look up the package first */
 369         e = uci_lookup_list(&ctx->root, ptr->package);
 370         if (!e) {
 371                 UCI_INTERNAL(uci_load, ctx, ptr->package, &ptr->p);
 372                 if (!ptr->p)
 373                         goto notfound;
 374         } else {
 375                 ptr->p = uci_to_package(e);
 376         }
 377
 378         if (!ptr->section)
 379                 goto complete;
 380
 381         /* if the section name validates as a regular name, pass through
 382          * to the regular uci_lookup function call */
 383         if (ptr->flags & UCI_LOOKUP_EXTENDED)
 384                 e = uci_lookup_ext_section(ctx, ptr);
 385         else
 386                 e = uci_lookup_list(&ptr->p->sections, ptr->section);
 387
 388         if (!e)
 389                 goto abort;
 390
 391         ptr->s = uci_to_section(e);
 392
 393         if (ptr->option) {
 394                 e = uci_lookup_list(&ptr->s->options, ptr->option);
 395                 if (!e)
 396                         goto abort;
 397
 398                 ptr->o = uci_to_option(e);
 399         }
 400
 401 complete:
 402         ptr->flags |= UCI_LOOKUP_COMPLETE;
 403 abort:
 404         return 0;
 405
 406 notfound:
 407         UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 408         return 0;
 409 }
 410
 411 int
 412 uci_fill_ptr(struct uci_context *ctx, struct uci_ptr *ptr, struct uci_element *e, bool complete)
 413 {
 414         UCI_HANDLE_ERR(ctx);
 415         UCI_ASSERT(ctx, ptr != NULL);
 416         UCI_ASSERT(ctx, e != NULL);
 417
 418         memset(ptr, 0, sizeof(struct uci_ptr));
 419         switch(e->type) {
 420         case UCI_TYPE_OPTION:
 421                 ptr->o = uci_to_option(e);
 422                 goto fill_option;
 423         case UCI_TYPE_SECTION:
 424                 ptr->s = uci_to_section(e);
 425                 goto fill_section;
 426         case UCI_TYPE_PACKAGE:
 427                 ptr->p = uci_to_package(e);
 428                 goto fill_package;
 429         default:
 430                 UCI_THROW(ctx, UCI_ERR_INVAL);
 431         }
 432
 433 fill_option:
 434         ptr->option = ptr->o->e.name;
 435         ptr->s = ptr->o->section;
 436 fill_section:
 437         ptr->section = ptr->s->e.name;
 438         ptr->p = ptr->s->package;
 439 fill_package:
 440         ptr->package = ptr->p->e.name;
 441
 442         ptr->flags |= UCI_LOOKUP_DONE;
 443         if (complete)
 444                 ptr->flags |= UCI_LOOKUP_COMPLETE;
 445
 446         return 0;
 447 }
 448
 449 static struct uci_element *
 450 expand_ptr(struct uci_context *ctx, struct uci_ptr *ptr, bool complete)
 451 {
 452         UCI_ASSERT(ctx, ptr != NULL);
 453
 454         if (!(ptr->flags & UCI_LOOKUP_DONE))
 455                 uci_lookup_ptr(ctx, ptr, NULL, 1);
 456         if (complete && !(ptr->flags & UCI_LOOKUP_COMPLETE))
 457                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 458         UCI_ASSERT(ctx, ptr->p != NULL);
 459
 460         /* fill in missing string info */
 461         if (ptr->p && !ptr->package)
 462                 ptr->package = ptr->p->e.name;
 463         if (ptr->s && !ptr->section)
 464                 ptr->section = ptr->s->e.name;
 465         if (ptr->o && !ptr->option)
 466                 ptr->option = ptr->o->e.name;
 467
 468         if (ptr->o)
 469                 return &ptr->o->e;
 470         if (ptr->s)
 471                 return &ptr->s->e;
 472         if (ptr->p)
 473                 return &ptr->p->e;
 474         else
 475                 return NULL;
 476 }
 477
 478 static void uci_add_element_list(struct uci_context *ctx, struct uci_ptr *ptr, bool internal)
 479 {
 480         struct uci_element *e;
 481         struct uci_package *p;
 482
 483         p = ptr->p;
 484         if (!internal && p->has_history)
 485                 uci_add_history(ctx, &p->history, UCI_CMD_LIST_ADD, ptr->section, ptr->option, ptr->value);
 486
 487         e = uci_alloc_generic(ctx, UCI_TYPE_ITEM, ptr->value, sizeof(struct uci_option));
 488         uci_list_add(&ptr->o->v.list, &e->list);
 489 }
 490
 491 int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, const char *value)
 492 {
 493         /* NB: UCI_INTERNAL use means without history tracking */
 494         bool internal = ctx->internal;
 495         struct uci_list *list;
 496         struct uci_element *e;
 497         struct uci_package *p;
 498         struct uci_section *s;
 499         struct uci_option *o;
 500         char *section;
 501         char *option;
 502         char *str;
 503         int size = 0;
 504
 505         UCI_HANDLE_ERR(ctx);
 506         UCI_ASSERT(ctx, (element != NULL) && (*element != NULL));
 507
 508         /* what the 'value' of an element means depends on the type
 509          * for a section, the 'value' means its type
 510          * for an option, the 'value' means its value string
 511          * when changing the value, shrink the element to its actual size
 512          * (it may have been allocated with a bigger size, to include
 513          *  its buffer)
 514          * then duplicate the string passed on the command line and
 515          * insert it into the structure.
 516          */
 517         e = *element;
 518         list = e->list.prev;
 519
 520         switch(e->type) {
 521         case UCI_TYPE_SECTION:
 522                 UCI_ASSERT(ctx, uci_validate_str(value, false));
 523                 size = sizeof(struct uci_section);
 524                 s = uci_to_section(e);
 525                 section = e->name;
 526                 option = NULL;
 527                 /* matches the currently set value */
 528                 if (!strcmp(value, s->type))
 529                         return 0;
 530                 break;
 531
 532         case UCI_TYPE_OPTION:
 533                 UCI_ASSERT(ctx, value != NULL);
 534                 o = uci_to_option(e);
 535                 s = o->section;
 536                 section = s->e.name;
 537                 option = o->e.name;
 538                 switch(o->type) {
 539                 case UCI_TYPE_STRING:
 540                         size = sizeof(struct uci_option);
 541                         /* matches the currently set value */
 542                         if (!strcmp(value, o->v.string))
 543                                 return 0;
 544                         break;
 545                 default:
 546                         /* default action for non-string datatypes is to delete
 547                          * the existing entry, then re-create it as a string */
 548                         break;
 549                 }
 550                 break;
 551
 552         default:
 553                 UCI_THROW(ctx, UCI_ERR_INVAL);
 554                 return 0;
 555         }
 556         p = s->package;
 557         if (!internal && p->has_history)
 558                 uci_add_history(ctx, &p->history, UCI_CMD_CHANGE, section, option, value);
 559
 560         if ((e->type == UCI_TYPE_OPTION) && (size == 0)) {
 561                 o = uci_alloc_option(s, option, value);
 562                 uci_free_any(&e);
 563                 *element = &o->e;
 564                 goto done;
 565         }
 566
 567         uci_list_del(&e->list);
 568         e = uci_realloc(ctx, e, size);
 569         str = uci_strdup(ctx, value);
 570         uci_list_insert(list, &e->list);
 571         *element = e;
 572
 573         switch(e->type) {
 574         case UCI_TYPE_SECTION:
 575                 uci_to_section(e)->type = str;
 576                 break;
 577         case UCI_TYPE_OPTION:
 578                 uci_to_option(e)->v.string = str;
 579                 break;
 580         default:
 581                 break;
 582         }
 583
 584 done:
 585         return 0;
 586 }
 587
 588 int uci_rename(struct uci_context *ctx, struct uci_ptr *ptr)
 589 {
 590         /* NB: UCI_INTERNAL use means without history tracking */
 591         bool internal = ctx->internal;
 592         struct uci_element *e;
 593         struct uci_package *p;
 594         char *n;
 595
 596         UCI_HANDLE_ERR(ctx);
 597
 598         e = expand_ptr(ctx, ptr, true);
 599         p = ptr->p;
 600
 601         UCI_ASSERT(ctx, ptr->s);
 602         UCI_ASSERT(ctx, ptr->value);
 603
 604         if (!internal && p->has_history)
 605                 uci_add_history(ctx, &p->history, UCI_CMD_RENAME, ptr->section, ptr->option, ptr->value);
 606
 607         n = uci_strdup(ctx, ptr->value);
 608         if (e->name)
 609                 free(e->name);
 610         e->name = n;
 611
 612         return 0;
 613 }
 614
 615 int uci_add_section(struct uci_context *ctx, struct uci_package *p, const char *type, struct uci_section **res)
 616 {
 617         bool internal = ctx->internal;
 618         struct uci_section *s;
 619
 620         UCI_HANDLE_ERR(ctx);
 621         UCI_ASSERT(ctx, p != NULL);
 622         s = uci_alloc_section(p, type, NULL);
 623         uci_fixup_section(ctx, s);
 624         *res = s;
 625         if (!internal && p->has_history)
 626                 uci_add_history(ctx, &p->history, UCI_CMD_ADD, s->e.name, NULL, type);
 627
 628         return 0;
 629 }
 630
 631 int uci_delete(struct uci_context *ctx, struct uci_ptr *ptr)
 632 {
 633         /* NB: pass on internal flag to uci_del_element */
 634         bool internal = ctx->internal;
 635         struct uci_package *p;
 636         struct uci_element *e;
 637
 638         UCI_HANDLE_ERR(ctx);
 639
 640         e = expand_ptr(ctx, ptr, true);
 641         p = ptr->p;
 642
 643         UCI_ASSERT(ctx, ptr->s);
 644
 645         if (!internal && p->has_history)
 646                 uci_add_history(ctx, &p->history, UCI_CMD_REMOVE, ptr->section, ptr->option, NULL);
 647
 648         uci_free_any(&e);
 649         return 0;
 650 }
 651
 652 int uci_add_list(struct uci_context *ctx, struct uci_ptr *ptr)
 653 {
 654         /* NB: UCI_INTERNAL use means without history tracking */
 655         bool internal = ctx->internal;
 656         struct uci_option *prev = NULL;
 657         const char *value2 = NULL;
 658
 659         UCI_HANDLE_ERR(ctx);
 660
 661         expand_ptr(ctx, ptr, false);
 662         UCI_ASSERT(ctx, ptr->s);
 663         UCI_ASSERT(ctx, ptr->value);
 664
 665         if (ptr->o) {
 666                 switch (ptr->o->type) {
 667                 case UCI_TYPE_STRING:
 668                         /* we already have a string value, convert that to a list */
 669                         prev = ptr->o;
 670                         value2 = ptr->value;
 671                         ptr->value = ptr->o->v.string;
 672                         break;
 673                 case UCI_TYPE_LIST:
 674                         uci_add_element_list(ctx, ptr, internal);
 675                         return 0;
 676                 default:
 677                         UCI_THROW(ctx, UCI_ERR_INVAL);
 678                         break;
 679                 }
 680         }
 681
 682         ptr->o = uci_alloc_list(ptr->s, ptr->option);
 683         if (prev) {
 684                 uci_add_element_list(ctx, ptr, true);
 685                 uci_free_option(prev);
 686                 ptr->value = value2;
 687         }
 688         uci_add_element_list(ctx, ptr, internal);
 689
 690         return 0;
 691 }
 692
 693 int uci_set(struct uci_context *ctx, struct uci_package *p, const char *section, const char *option, const char *value, struct uci_element **result)
 694 {
 695         /* NB: UCI_INTERNAL use means without history tracking */
 696         bool internal = ctx->internal;
 697         struct uci_element *e = NULL;
 698         struct uci_section *s = NULL;
 699         struct uci_option *o = NULL;
 700
 701         UCI_HANDLE_ERR(ctx);
 702         UCI_ASSERT(ctx, p != NULL);
 703         UCI_ASSERT(ctx, uci_validate_name(section));
 704         if (option) {
 705                 UCI_ASSERT(ctx, uci_validate_name(option));
 706                 UCI_ASSERT(ctx, value != NULL);
 707         } else {
 708                 UCI_ASSERT(ctx, uci_validate_str(value, false));
 709         }
 710
 711         /*
 712          * look up the package, section and option (if set)
 713          * if the section/option is to be modified and it is not found
 714          * create a new element in the appropriate list
 715          */
 716         e = uci_lookup_list(&p->sections, section);
 717         if (!e)
 718                 goto notfound;
 719
 720         s = uci_to_section(e);
 721         if (ctx->pctx && ctx->pctx->merge)
 722                 ctx->pctx->section = s;
 723
 724         if (option) {
 725                 e = uci_lookup_list(&s->options, option);
 726                 if (!e)
 727                         goto notfound;
 728                 o = uci_to_option(e);
 729         }
 730
 731         /*
 732          * no unknown element was supplied, assume that we can just update
 733          * an existing entry
 734          */
 735         if (o)
 736                 e = &o->e;
 737         else
 738                 e = &s->e;
 739         if (result)
 740                 *result = e;
 741         else
 742                 result = &e;
 743
 744         ctx->internal = internal;
 745         return uci_set_element_value(ctx, result, value);
 746
 747 notfound:
 748         /*
 749          * the entry that we need to update was not found,
 750          * check if the search failed prematurely.
 751          * this can happen if the package was not found, or if
 752          * an option was supplied, but the section wasn't found
 753          */
 754         if (!p || (!s && option))
 755                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 756
 757         /* now add the missing entry */
 758         if (!internal && p->has_history)
 759                 uci_add_history(ctx, &p->history, UCI_CMD_CHANGE, section, option, value);
 760         if (s) {
 761                 o = uci_alloc_option(s, option, value);
 762                 if (result)
 763                         *result = &o->e;
 764         } else {
 765                 s = uci_alloc_section(p, value, section);
 766                 if (result)
 767                         *result = &s->e;
 768                 if (ctx->pctx && ctx->pctx->merge)
 769                         ctx->pctx->section = s;
 770         }
 771
 772         return 0;
 773 }
 774
 775 int uci_unload(struct uci_context *ctx, struct uci_package *p)
 776 {
 777         UCI_HANDLE_ERR(ctx);
 778         UCI_ASSERT(ctx, p != NULL);
 779
 780         uci_free_package(&p);
 781         return 0;
 782 }
 783