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