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 inline struct uci_element *
 273 uci_lookup_list(struct uci_list *list, const char *name)
 274 {
 275         struct uci_element *e;
 276
 277         uci_foreach_element(list, e) {
 278                 if (!strcmp(e->name, name))
 279                         return e;
 280         }
 281         return NULL;
 282 }
 283
 284 static struct uci_element *
 285 uci_lookup_ext_section(struct uci_context *ctx, struct uci_ptr *ptr)
 286 {
 287         char *idxstr, *t, *section, *name;
 288         struct uci_element *e = NULL;
 289         struct uci_section *s;
 290         int idx, c;
 291
 292         section = uci_strdup(ctx, ptr->section);
 293         name = idxstr = section + 1;
 294
 295         if (section[0] != '@')
 296                 goto error;
 297
 298         /* parse the section index part */
 299         idxstr = strchr(idxstr, '[');
 300         if (!idxstr)
 301                 goto error;
 302         *idxstr = 0;
 303         idxstr++;
 304
 305         t = strchr(idxstr, ']');
 306         if (!t)
 307                 goto error;
 308         if (t[1] != 0)
 309                 goto error;
 310         *t = 0;
 311
 312         t = NULL;
 313         idx = strtol(idxstr, &t, 10);
 314         if (t && *t)
 315                 goto error;
 316
 317         if (!*name)
 318                 name = NULL;
 319         else if (!uci_validate_str(name, false))
 320                 goto error;
 321
 322         /* if the given index is negative, it specifies the section number from
 323          * the end of the list */
 324         if (idx < 0) {
 325                 c = 0;
 326                 uci_foreach_element(&ptr->p->sections, e) {
 327                         s = uci_to_section(e);
 328                         if (name && (strcmp(s->type, name) != 0))
 329                                 continue;
 330
 331                         c++;
 332                 }
 333                 idx += c;
 334         }
 335
 336         c = 0;
 337         uci_foreach_element(&ptr->p->sections, e) {
 338                 s = uci_to_section(e);
 339                 if (name && (strcmp(s->type, name) != 0))
 340                         continue;
 341
 342                 if (idx == c)
 343                         goto done;
 344                 c++;
 345         }
 346         e = NULL;
 347         goto done;
 348
 349 error:
 350         e = NULL;
 351         memset(ptr, 0, sizeof(struct uci_ptr));
 352         UCI_THROW(ctx, UCI_ERR_INVAL);
 353 done:
 354         free(section);
 355         ptr->section = e->name;
 356         return e;
 357 }
 358
 359 int
 360 uci_lookup_ptr(struct uci_context *ctx, struct uci_ptr *ptr, char *str, bool extended)
 361 {
 362         struct uci_element *e;
 363
 364         UCI_HANDLE_ERR(ctx);
 365         UCI_ASSERT(ctx, ptr != NULL);
 366
 367         if (str)
 368                 UCI_INTERNAL(uci_parse_ptr, ctx, ptr, str);
 369
 370         ptr->flags |= UCI_LOOKUP_DONE;
 371
 372         /* look up the package first */
 373         e = uci_lookup_list(&ctx->root, ptr->package);
 374         if (!e) {
 375                 UCI_INTERNAL(uci_load, ctx, ptr->package, &ptr->p);
 376                 if (!ptr->p)
 377                         goto notfound;
 378                 ptr->last = &ptr->p->e;
 379         } else {
 380                 ptr->p = uci_to_package(e);
 381                 ptr->last = e;
 382         }
 383
 384         if (!ptr->section)
 385                 goto complete;
 386
 387         /* if the section name validates as a regular name, pass through
 388          * to the regular uci_lookup function call */
 389         if (ptr->flags & UCI_LOOKUP_EXTENDED)
 390                 e = uci_lookup_ext_section(ctx, ptr);
 391         else
 392                 e = uci_lookup_list(&ptr->p->sections, ptr->section);
 393
 394         if (!e)
 395                 goto abort;
 396
 397         ptr->last = e;
 398         ptr->s = uci_to_section(e);
 399
 400         if (ptr->option) {
 401                 e = uci_lookup_list(&ptr->s->options, ptr->option);
 402                 if (!e)
 403                         goto abort;
 404
 405                 ptr->o = uci_to_option(e);
 406                 ptr->last = e;
 407         }
 408
 409 complete:
 410         ptr->flags |= UCI_LOOKUP_COMPLETE;
 411 abort:
 412         return 0;
 413
 414 notfound:
 415         UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 416         return 0;
 417 }
 418
 419 int
 420 uci_fill_ptr(struct uci_context *ctx, struct uci_ptr *ptr, struct uci_element *e, bool complete)
 421 {
 422         UCI_HANDLE_ERR(ctx);
 423         UCI_ASSERT(ctx, ptr != NULL);
 424         UCI_ASSERT(ctx, e != NULL);
 425
 426         memset(ptr, 0, sizeof(struct uci_ptr));
 427         switch(e->type) {
 428         case UCI_TYPE_OPTION:
 429                 ptr->o = uci_to_option(e);
 430                 goto fill_option;
 431         case UCI_TYPE_SECTION:
 432                 ptr->s = uci_to_section(e);
 433                 goto fill_section;
 434         case UCI_TYPE_PACKAGE:
 435                 ptr->p = uci_to_package(e);
 436                 goto fill_package;
 437         default:
 438                 UCI_THROW(ctx, UCI_ERR_INVAL);
 439         }
 440
 441 fill_option:
 442         ptr->option = ptr->o->e.name;
 443         ptr->s = ptr->o->section;
 444 fill_section:
 445         ptr->section = ptr->s->e.name;
 446         ptr->p = ptr->s->package;
 447 fill_package:
 448         ptr->package = ptr->p->e.name;
 449
 450         ptr->flags |= UCI_LOOKUP_DONE;
 451         if (complete)
 452                 ptr->flags |= UCI_LOOKUP_COMPLETE;
 453
 454         return 0;
 455 }
 456
 457 static struct uci_element *
 458 expand_ptr(struct uci_context *ctx, struct uci_ptr *ptr, bool complete)
 459 {
 460         UCI_ASSERT(ctx, ptr != NULL);
 461
 462         if (!(ptr->flags & UCI_LOOKUP_DONE))
 463                 uci_lookup_ptr(ctx, ptr, NULL, 1);
 464         if (complete && !(ptr->flags & UCI_LOOKUP_COMPLETE))
 465                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 466         UCI_ASSERT(ctx, ptr->p != NULL);
 467
 468         /* fill in missing string info */
 469         if (ptr->p && !ptr->package)
 470                 ptr->package = ptr->p->e.name;
 471         if (ptr->s && !ptr->section)
 472                 ptr->section = ptr->s->e.name;
 473         if (ptr->o && !ptr->option)
 474                 ptr->option = ptr->o->e.name;
 475
 476         if (ptr->o)
 477                 return &ptr->o->e;
 478         if (ptr->s)
 479                 return &ptr->s->e;
 480         if (ptr->p)
 481                 return &ptr->p->e;
 482         else
 483                 return NULL;
 484 }
 485
 486 static void uci_add_element_list(struct uci_context *ctx, struct uci_ptr *ptr, bool internal)
 487 {
 488         struct uci_element *e;
 489         struct uci_package *p;
 490
 491         p = ptr->p;
 492         if (!internal && p->has_history)
 493                 uci_add_history(ctx, &p->history, UCI_CMD_LIST_ADD, ptr->section, ptr->option, ptr->value);
 494
 495         e = uci_alloc_generic(ctx, UCI_TYPE_ITEM, ptr->value, sizeof(struct uci_option));
 496         uci_list_add(&ptr->o->v.list, &e->list);
 497 }
 498
 499 int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, const char *value)
 500 {
 501         /* NB: UCI_INTERNAL use means without history tracking */
 502         bool internal = ctx->internal;
 503         struct uci_list *list;
 504         struct uci_element *e;
 505         struct uci_package *p;
 506         struct uci_section *s;
 507         struct uci_option *o;
 508         char *section;
 509         char *option;
 510         char *str;
 511         int size = 0;
 512
 513         UCI_HANDLE_ERR(ctx);
 514         UCI_ASSERT(ctx, (element != NULL) && (*element != NULL));
 515
 516         /* what the 'value' of an element means depends on the type
 517          * for a section, the 'value' means its type
 518          * for an option, the 'value' means its value string
 519          * when changing the value, shrink the element to its actual size
 520          * (it may have been allocated with a bigger size, to include
 521          *  its buffer)
 522          * then duplicate the string passed on the command line and
 523          * insert it into the structure.
 524          */
 525         e = *element;
 526         list = e->list.prev;
 527
 528         switch(e->type) {
 529         case UCI_TYPE_SECTION:
 530                 UCI_ASSERT(ctx, uci_validate_str(value, false));
 531                 size = sizeof(struct uci_section);
 532                 s = uci_to_section(e);
 533                 section = e->name;
 534                 option = NULL;
 535                 /* matches the currently set value */
 536                 if (!strcmp(value, s->type))
 537                         return 0;
 538                 break;
 539
 540         case UCI_TYPE_OPTION:
 541                 UCI_ASSERT(ctx, value != NULL);
 542                 o = uci_to_option(e);
 543                 s = o->section;
 544                 section = s->e.name;
 545                 option = o->e.name;
 546                 switch(o->type) {
 547                 case UCI_TYPE_STRING:
 548                         size = sizeof(struct uci_option);
 549                         /* matches the currently set value */
 550                         if (!strcmp(value, o->v.string))
 551                                 return 0;
 552                         break;
 553                 default:
 554                         /* default action for non-string datatypes is to delete
 555                          * the existing entry, then re-create it as a string */
 556                         break;
 557                 }
 558                 break;
 559
 560         default:
 561                 UCI_THROW(ctx, UCI_ERR_INVAL);
 562                 return 0;
 563         }
 564         p = s->package;
 565         if (!internal && p->has_history)
 566                 uci_add_history(ctx, &p->history, UCI_CMD_CHANGE, section, option, value);
 567
 568         if ((e->type == UCI_TYPE_OPTION) && (size == 0)) {
 569                 o = uci_alloc_option(s, option, value);
 570                 uci_free_any(&e);
 571                 *element = &o->e;
 572                 goto done;
 573         }
 574
 575         uci_list_del(&e->list);
 576         e = uci_realloc(ctx, e, size);
 577         str = uci_strdup(ctx, value);
 578         uci_list_insert(list, &e->list);
 579         *element = e;
 580
 581         switch(e->type) {
 582         case UCI_TYPE_SECTION:
 583                 uci_to_section(e)->type = str;
 584                 break;
 585         case UCI_TYPE_OPTION:
 586                 uci_to_option(e)->v.string = str;
 587                 break;
 588         default:
 589                 break;
 590         }
 591
 592 done:
 593         return 0;
 594 }
 595
 596 int uci_rename(struct uci_context *ctx, struct uci_ptr *ptr)
 597 {
 598         /* NB: UCI_INTERNAL use means without history tracking */
 599         bool internal = ctx->internal;
 600         struct uci_element *e;
 601         struct uci_package *p;
 602         char *n;
 603
 604         UCI_HANDLE_ERR(ctx);
 605
 606         e = expand_ptr(ctx, ptr, true);
 607         p = ptr->p;
 608
 609         UCI_ASSERT(ctx, ptr->s);
 610         UCI_ASSERT(ctx, ptr->value);
 611
 612         if (!internal && p->has_history)
 613                 uci_add_history(ctx, &p->history, UCI_CMD_RENAME, ptr->section, ptr->option, ptr->value);
 614
 615         n = uci_strdup(ctx, ptr->value);
 616         if (e->name)
 617                 free(e->name);
 618         e->name = n;
 619
 620         return 0;
 621 }
 622
 623 int uci_add_section(struct uci_context *ctx, struct uci_package *p, const char *type, struct uci_section **res)
 624 {
 625         bool internal = ctx->internal;
 626         struct uci_section *s;
 627
 628         UCI_HANDLE_ERR(ctx);
 629         UCI_ASSERT(ctx, p != NULL);
 630         s = uci_alloc_section(p, type, NULL);
 631         uci_fixup_section(ctx, s);
 632         *res = s;
 633         if (!internal && p->has_history)
 634                 uci_add_history(ctx, &p->history, UCI_CMD_ADD, s->e.name, NULL, type);
 635
 636         return 0;
 637 }
 638
 639 int uci_delete(struct uci_context *ctx, struct uci_ptr *ptr)
 640 {
 641         /* NB: pass on internal flag to uci_del_element */
 642         bool internal = ctx->internal;
 643         struct uci_package *p;
 644         struct uci_element *e;
 645
 646         UCI_HANDLE_ERR(ctx);
 647
 648         e = expand_ptr(ctx, ptr, true);
 649         p = ptr->p;
 650
 651         UCI_ASSERT(ctx, ptr->s);
 652
 653         if (!internal && p->has_history)
 654                 uci_add_history(ctx, &p->history, UCI_CMD_REMOVE, ptr->section, ptr->option, NULL);
 655
 656         uci_free_any(&e);
 657         return 0;
 658 }
 659
 660 int uci_add_list(struct uci_context *ctx, struct uci_ptr *ptr)
 661 {
 662         /* NB: UCI_INTERNAL use means without history tracking */
 663         bool internal = ctx->internal;
 664         struct uci_option *prev = NULL;
 665         const char *value2 = NULL;
 666
 667         UCI_HANDLE_ERR(ctx);
 668
 669         expand_ptr(ctx, ptr, false);
 670         UCI_ASSERT(ctx, ptr->s);
 671         UCI_ASSERT(ctx, ptr->value);
 672
 673         if (ptr->o) {
 674                 switch (ptr->o->type) {
 675                 case UCI_TYPE_STRING:
 676                         /* we already have a string value, convert that to a list */
 677                         prev = ptr->o;
 678                         value2 = ptr->value;
 679                         ptr->value = ptr->o->v.string;
 680                         break;
 681                 case UCI_TYPE_LIST:
 682                         uci_add_element_list(ctx, ptr, internal);
 683                         return 0;
 684                 default:
 685                         UCI_THROW(ctx, UCI_ERR_INVAL);
 686                         break;
 687                 }
 688         }
 689
 690         ptr->o = uci_alloc_list(ptr->s, ptr->option);
 691         if (prev) {
 692                 uci_add_element_list(ctx, ptr, true);
 693                 uci_free_option(prev);
 694                 ptr->value = value2;
 695         }
 696         uci_add_element_list(ctx, ptr, internal);
 697
 698         return 0;
 699 }
 700
 701 int uci_set(struct uci_context *ctx, struct uci_package *p, const char *section, const char *option, const char *value, struct uci_element **result)
 702 {
 703         /* NB: UCI_INTERNAL use means without history tracking */
 704         bool internal = ctx->internal;
 705         struct uci_element *e = NULL;
 706         struct uci_section *s = NULL;
 707         struct uci_option *o = NULL;
 708
 709         UCI_HANDLE_ERR(ctx);
 710         UCI_ASSERT(ctx, p != NULL);
 711         UCI_ASSERT(ctx, uci_validate_name(section));
 712         if (option) {
 713                 UCI_ASSERT(ctx, uci_validate_name(option));
 714                 UCI_ASSERT(ctx, value != NULL);
 715         } else {
 716                 UCI_ASSERT(ctx, uci_validate_str(value, false));
 717         }
 718
 719         /*
 720          * look up the package, section and option (if set)
 721          * if the section/option is to be modified and it is not found
 722          * create a new element in the appropriate list
 723          */
 724         e = uci_lookup_list(&p->sections, section);
 725         if (!e)
 726                 goto notfound;
 727
 728         s = uci_to_section(e);
 729         if (ctx->pctx && ctx->pctx->merge)
 730                 ctx->pctx->section = s;
 731
 732         if (option) {
 733                 e = uci_lookup_list(&s->options, option);
 734                 if (!e)
 735                         goto notfound;
 736                 o = uci_to_option(e);
 737         }
 738
 739         /*
 740          * no unknown element was supplied, assume that we can just update
 741          * an existing entry
 742          */
 743         if (o)
 744                 e = &o->e;
 745         else
 746                 e = &s->e;
 747         if (result)
 748                 *result = e;
 749         else
 750                 result = &e;
 751
 752         ctx->internal = internal;
 753         return uci_set_element_value(ctx, result, value);
 754
 755 notfound:
 756         /*
 757          * the entry that we need to update was not found,
 758          * check if the search failed prematurely.
 759          * this can happen if the package was not found, or if
 760          * an option was supplied, but the section wasn't found
 761          */
 762         if (!p || (!s && option))
 763                 UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 764
 765         /* now add the missing entry */
 766         if (!internal && p->has_history)
 767                 uci_add_history(ctx, &p->history, UCI_CMD_CHANGE, section, option, value);
 768         if (s) {
 769                 o = uci_alloc_option(s, option, value);
 770                 if (result)
 771                         *result = &o->e;
 772         } else {
 773                 s = uci_alloc_section(p, value, section);
 774                 if (result)
 775                         *result = &s->e;
 776                 if (ctx->pctx && ctx->pctx->merge)
 777                         ctx->pctx->section = s;
 778         }
 779
 780         return 0;
 781 }
 782
 783 int uci_unload(struct uci_context *ctx, struct uci_package *p)
 784 {
 785         UCI_HANDLE_ERR(ctx);
 786         UCI_ASSERT(ctx, p != NULL);
 787
 788         uci_free_package(&p);
 789         return 0;
 790 }
 791